National Report on Biochemical Indicators of 

Diet and Nutrition in the U.S. Population 

1999–2002 

National Report on Biochemical Indicators of 

Diet and Nutrition in the U.S. Population 

1999–2002 

July 2008 

Department of Health and Human Services
 

Centers for Disease Control and Prevention
 
Centers for Disease Control and Prevention
 

National Center for Environmental Health
 

Division of Laboratory Sciences
 

Atlanta, Georgia 30341-3724
 

NCEH Pub. No. 08-2982c
 

The Centers for Disease Control and Prevention (CDC) protects people’s health and safety by 

preventing and controlling diseases and injuries; enhances health decisions by providing credible 

information on critical health issues; and promotes healthy living through strong partnerships 

with local, national, and international organizations. 
Table of Contents
 

Introduction ......................................................................................................... 1
 

Background 

Addressing Data Needs 

Public Health Uses 

Data Presented for Each Biochemical Indicator 

Interpreting the Data 

Useful Sources of Information about Using Nutrition Monitoring to Interpret Data 

The National Health and Nutrition Examination Survey (NHANES) 

Data Analysis 

References 

1 Water-Soluble Vitamins & Related Biochemical Compounds .......................11
 

Folate (serum and red blood cell), Vitamin B12, Homocysteine, Methylmalonic Acid 

2 Fat-Soluble Vitamins & Micronutrients .......................................................... 33
 

Vitamins A and E and Carotenoids
 

Vitamin D
 

3 Iron-Status Indicators ......................................................................................71
 

Ferritin, Iron, Total Iron-Binding Capacity, Transferrin Saturation, Protoporphyrin 

4 Trace Elements ................................................................................................. 89 


Iodine
 

Selenium
 

5 Isoflavones & Lignans (so-called Phystoestrogens) ......................................107
 

Genistein, Daidzein, Equol O-Desmethylangolensin, Enterodiol, Enterolactone 

Appendices ........................................................................................................... 141
 

Appendix A NHANES Reports Related to Nutritional Status 

Appendix B References for Analytical Methods for Biochemical Indicators 

Appendix C Confidence Interval Estimation for Percentiles 

Appendix D Limit of Detection Table 

Appendix E Selected References of Descriptive NHANES Papers on Biochemical 

Indicators of Diet and Nutrition 
6 6
Introduction 

•	 Background 

•	 Addressing Data Needs 

•	 Public Health Uses 

•	 Data Presented for Each Biochemical Indicator 

•	 Interpreting the Data 

•	 Useful Sources of Information about Using 

Nutrition Monitoring to Interpret Data 

•	 The National Health and Nutrition 

Examination Survey (NHANES) 

•	 Data Analysis 

•	 References 

1 
2 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Introduction
 

Background 

This report provides reference information for blood or urine concentrations of 27 

biochemical indicators of diet and nutrition measured by the Centers for Disease 

Control and Prevention (CDC), Division of Laboratory Sciences at the National 

Center for Environmental Health (NCEH/DLS). The indicators were measured in 

specimens from a representative sample of the noninstitutionalized civilian U.S. 

population during all or part of the four-year period from 1999 through 2002. These 

specimens were collected by CDC’s National Health and Nutrition Examination 

Survey (NHANES), which is conducted by CDC’s National Center for Health Statistics 

(NCHS). NHANES is a series of surveys designed to collect data on the health and 

nutritional status of the U.S. population. This report covers one important facet in the 

assessment of nutritional status of the U.S. population: biochemical measurements. 

Other aspects, such as anthropometric body measurements, hematologic 

measurements, clinical signs of nutritional deficiency or excess, and dietary intake, 

are not covered. 

For this report, a biochemical indicator means a vitamin, iron-status indicator, trace 

element, or other dietary indicator with potential health relevance. Although most 

biochemical indicators presented in this report enter the human body from foods 

or supplements, the body itself produces some indicators in response to dietary 

intake. Blood and urine concentrations reflect the amount of nutrients and dietary 

compounds actually in the body from all of these sources. 

The biochemical indicators covered in this report are: 

•	 Water-soluble vitamins and related biochemical compounds. 

•	 Fat-soluble vitamins and micronutrients. 

•	 Iron-status indicators. 

•	 Trace elements. 

•	 Isoflavones and lignans (so-called phytoestrogens). 

Some indicators covered in this report have no nutritional value (e.g., homocysteine, 


methylmalonic acid, iron-status indicators, phytoestrogens). Yet, they are important 


because 1) they reflect micronutrient or metabolic status or 2) because they are a 


naturally occurring ingredient in the human diet (i.e., they are consumed as food 


or as dietary supplements) and have been associated with potential positive or 


negative health outcomes.
 

On the other hand, some important micronutrients, such as vitamin C, vitamin 


B6, or certain minerals (e.g., sodium, potassium, calcium, phosphorus, chloride, 


magnesium) are omitted from this report. Data were either unavailable for the report 


years covered or were not representative of micronutrient status. Future reports may, 


however, include other biochemical indicators of diet and nutrition.
 

 Introduction 3
Addressing Data Needs
 

This report is CDC’s first product that presents data—in a single source—concerning 

NCEH/DLS measurements of a wide range of biochemical indicators of diet and 

nutrition from the most recent continuous NHANES survey, starting in 1999. 

NCHS has historically released or commissioned a variety of products presenting 

NHANES results. Among these are Data Briefs, Data Tables, Advance Data, Series 

Reports, and Reports through the Life Sciences Research Office (LSRO). See the 

following for further information: http://www.cdc.gov/nchs/about/major/nhanes/ 

survey_results_and_products.htm. 

NHANES Series Reports (mainly Series 11) and LSRO Reports have always been of 

particular value to the nutrition community (see Appendix A). The two latest reports on 

nutritional biochemistry reference data were prepared for NHANES III (1988–1994). 

One covered hematologic and iron-related analytes, and the other covered blood 

folate and vitamin B12. 

Public Health Uses 

The primary purpose of this report is to improve our understanding of the 

concentrations of biochemical indicators of diet and nutrition in the general U.S. 

population and in selected subpopulations. These data will help assess inadequate or 

excess intake and will inform analyses on the relation between biochemical indicators 

and health outcomes. Other potential public health uses of the information include 

the following: 

•	 Establishing and improving upon existing population reference levels 

that physicians, clinicians, scientists, and public health officials can use to 

determine whether a person or a group of people has an unusually high or 

low level of a biochemical indicator of diet and nutrition. 

•	 Determining whether the nutritional status of special population groups, such 

as minorities, children, women of childbearing age, or the elderly is different 

from that of other groups, or whether it needs improvement. 

•	 Tracking, over time, trends in biochemical indicator levels in the population. 

•	 Assessing the effectiveness of public health efforts to improve the diet and 

nutritional status of U.S. residents. 

•	 Stimulating research to perform more in-depth analyses of the NHANES data 

and to generate hypotheses for future nutrition and human health studies. 

4 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Data Presented for Each Biochemical Indicator 

This publication contains tables of descriptive statistics on the distribution 

of blood and urine concentrations for each biochemical indicator of diet and 

nutrition. Statistics include unadjusted geometric means and selected percentiles 

with confidence intervals. 

The data are grouped by age, sex, and race/ethnicity. A geometric mean provides 

a better estimate of central tendency for data distributions with a long tail at the 

upper end of the distribution. When measuring biochemical indicators, this type of 

distribution is common. The geometric mean is influenced less by high values than is 

the arithmetic mean. Scientists can use the presented percentile levels (5th or 10th, 

50th, and 90th or 95th) to determine which serum, blood, or urine concentrations of 

indicators are common to people in the U.S. population and which concentrations 

are unusual. We used the unweighted sample size as a criterion for indicating reliable 

results (U.S. Centers for Disease for Control and Prevention 1996, Appendix B, Table 1). We assumed 

an average design effect of 1.4 and used a sample size of at least 112 persons to 

define estimates for the 10th and 90th percentiles as reliable and a sample size of 

at least 224 persons to define estimates for the 5th and 95th percentiles as reliable. 

We present 10th and 90th percentile levels for a biochemical indicator when the 

sample size was too small for 5th and 95th percentile levels in several subgroups. This 

is the case after stratifying by age, sex, and race/ethnicity with data from only two 

years (carotenoids, 25-hydroxyvitamin D, some iron-status indicators) or with data 

from only a subset of the population (iodine, selenium, phytoestrogens). For urine 

measurements, data are shown for both the concentration and for the concentration 

corrected for the urinary creatinine level. 

General information is provided for each indicator that also aids in interpreting 

levels. 

To address sources of these nutrients, biochemical pathways in the body, and known 

health effects, the text contains a brief overview about each indicator. 

Selected observations and highlights—mainly derived from the data tables 

provided in this publication—are presented in each chapter. 

The observations describe categorical differences between demographic subgroups, 

whereas the highlights summarize the observations in a public health context. 

 Introduction 5
Interpreting the Data
 

Chemists prepare serum material for quality 

assurance. 

Adequate serum or blood concentrations of biochemical indicators do not 

necessarily indicate that NHANES participants consume healthful and balanced diets. 

Some foods are fortified with micronutrients (e.g., iron, thiamin, riboflavin, niacin, 

folate, vitamin A, vitamin D), and some people take dietary supplements that contain 

vitamins, minerals, or both. 

Although certain dietary deficiencies are well documented and have characteristic 

signs and symptoms, suboptimal concentrations have been associated with the risk 

for adverse health effects such as cardiovascular disease, stroke, impaired cognitive 

function, cancer, eye diseases, poor bone health, and other conditions. Adverse 

health effects, including toxicity, are also possible from consuming excess amounts 

of certain nutrients. Research studies, separate from this report, are required to 

determine those concentrations of a biochemical indicator that may indicate 

risk for disease and those concentrations that are of negligible health concern. 

In collaboration with other agencies and institutions, CDC encourages, and itself 

conducts, measurements for this type of research. 

This report contains unadjusted geometric means and selected percentiles of 

biochemical indicators of diet and nutrition for the civilian, noninstitutionalized U.S. 

population. A limited interpretation of relative differences 

between population groups is possible by identifying groups 

with non-overlapping confidence intervals. These observed 

differences, however, should not be interpreted as causal. 

The intent is to describe the characteristics of the population 

and of selected subgroups, and not to explain why the 

groups look the way they do or why they differ from each 

other. For example, for biochemical indicators correlated with 

age, age may account for some of the effects. Furthermore, 

differences in biochemical indicator concentrations of 

selected subgroups do not necessarily imply health 

problems. More in-depth statistical analyses, such as 

adjusting for demographic variables or covariates, and taking 

interactions or predictive variables into consideration, are 

beyond the scope of this publication. We hope nonetheless 

that scientists will be stimulated to examine the data further 

by analyzing the raw data available at this Web site: http:// 

www.cdc.gov/nchs/nhanes.htm. 

Laboratories may use different methods for measuring the 

indicators reported here. Different methods may result in 

different method-specific reference ranges. Consequently, 

to apply these results, health science professionals should 

check with their particular laboratory to be sure their 

methods compare closely with those used in this report (see 

Appendix B). 

6 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Useful Sources of Information about Using 

Nutrition Monitoring to Interpret Data 

Information about dietary intake is critical to research examining the reasons for 

nutritional inadequacies and for programs to improve diet and nutritional status. 

Selected NCHS Advance Data Reports provide useful overviews (see Appendix A). Also 

of value are the U.S. Department of Agriculture’s (USDA) databases on food surveys 

and food composition: 

What We Eat in America (WWEIA) is the dietary intake interview section of NHANES 

(http://www.ars.usda.gov/foodsurvey). 

The Food and Nutrient Database for Dietary Studies (FNDDS) (http://www.ars.usda.gov/ 

Services/docs.htm?docid=12089) is a database of foods, their nutrient values, and weights 

for typical food portions. This database helps to analyze data from the WWEIA survey 

by using the nutrient values from the National Nutrient Database for Standard 

Reference (http://www.ars.usda.gov/Services/docs.htm?docid=8964). 

The Directory of Federal and State Nutrition Monitoring and Related Research Activities 

(Interagency Board for Nutrition Monitoring and Related Research 2000) is the fourth update in a 

series that provides information on the complex system of nutrition monitoring in the 

United States. It is a guide to those federal and state survey, surveillance, and research 

activities that are part of the National Nutrition Monitoring and Related Research 

Program (http://www.cdc.gov/nchs/about/otheract/nutrishn/nutrishn.htm). 

The Third Report on Nutrition Monitoring in the United States (Interagency Board for 

Nutrition Monitoring and Related Research 1995) provides the latest update on the dietary, 

nutritional, and nutrition-related health status of United States residents, the relation 

between diet and health, and the factors that influence dietary and nutritional status. 

The National Health and Nutrition Examination 

Survey (NHANES) 

CDC laboratory scientists used biological specimens obtained from participants in 

NHANES to measure biochemical indicators of diet and nutrition for this publication. 

NHANES is a series of NCHS-conducted surveys designed to collect data on the 

health and nutritional status of the U.S. population. This is the only national survey 

that collects biological samples. The NHANES surveys began in 1960 with the fielding 

of the first Health Examination Survey (HES 1). The nutritional component was 

added in the early 1970s in NHANES I. In 1999 NHANES became a continuous survey, 

sampling the U.S. population annually and releasing the data in two-year cycles. 

 Introduction 7
NHANES collects information on a wide range of health-related behaviors, conducts 

physical examinations, and collects samples for laboratory tests. Because of physical 

examination and biological measures, NHANES is unique in its ability to examine 

public health issues, such as risk factors for cardiovascular disease, in the U.S. 

population. To select a representative sample of the civilian, noninstitutionalized 

population in the United States, the survey sampling plan follows a complex, 

stratified, multistage, probability-cluster design. The civilian, noninstitutionalized 

population consists of persons who are neither in the military nor institutionalized 

(e.g., residents of nursing homes, college dormitories, or prisons). 

The NHANES protocol includes a home interview followed by a standardized 

physical examination at a mobile examination center. As part of the examination, 

for participants aged 1 year and older, blood is obtained by venipuncture. Urine 

specimens are collected from participants aged 6 years and older. By design, 

approximately half of the participants are evaluated after an overnight fast. 

Furthermore, close to 90 percent of all participants have fasted for more than 3 hours 

before providing a biological sample. Because the mobile examination centers can be 

adversely affected by weather, data are collected in northern latitudes in summer and 

in southern latitudes in winter. This seasonal-latitude structure might indirectly affect 

biochemical indicators. 

Additional detailed information about the design and conduct of the NHANES survey 

is available at: http://www.cdc.gov/nchs/nhanes.htm. Information about how biological 

specimens are collected is available at the following Web site: http://www.cdc.gov/nchs/ 

data/nhanes/blood.pdf and in the Laboratory Procedures Manual, which can be found at: 

http://www.cdc.gov/nchs/data/nhanes/lab1-6.pdf or at http://www.cdc.gov/nchs/data/nhanes/ 

lab7-11.pdf. 

Data Analysis 

NCHS has developed a comprehensive Web-based tutorial (http://www.cdc.gov/nchs/ 

tutorials/Nhanes/index.htm) to help users better understand the complex survey design 

and to help them analyze continuous NHANES data. 

Because the NHANES sample design is complex, sample weights adjust for the 

unequal probability of selection into the survey. Sample weights also adjust for 

possible bias resulting from nonresponse and are post-stratified to U.S. Census 

Bureau estimates of the U.S. population. Data were analyzed using the statistical 

software package Statistical Analysis System (SAS) (SAS Institute Inc., 2002) and the 

statistical software package SUDAAN (SUDAAN Release 8.0, 2001). SUDAAN uses 

sample weights and calculates variance estimates that account for the complex 

survey design. Guidelines for the analysis of NHANES data are provided by NCHS at: 

http://www.cdc.gov/nchs/about/major/nhanes/nhanes2003-2004/analytical_guidelines.htm. Variance 

estimates were calculated using the Taylor series (linearization) method within 

SUDAAN. The Korn and Graubard method was used to compute Clopper-Pearson 95 

percent confidence intervals (see Appendix C). 

8 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
The tables show selected percentiles and unadjusted geometric means of analyte 

concentrations. Geometric means were calculated by taking the log of each 

concentration, calculating the mean of those log values, then taking the antilog 

of that mean (the calculation can be done using any log base, such as 10 or e). 

Percentile estimates were calculated using SAS Proc Univariate with weighted data. 

Results are shown for the total population and also by age group, sex, and race/ 

ethnicity as defined in NHANES. For these analyses, sex is coded as male or female, 

and race/ethnicity is categorized as Mexican American, non-Hispanic black, and nonHispanic white. Other racial or ethnic groups are sampled, but the proportion of the 

total population represented by these other groups is not large enough to produce 

valid estimates. Other racial/ethnic groups are included in estimates based on the 

entire population sample. Data for each racial/ethnic group are presented in three 

separate tables. 

For calculation of geometric means, concentrations less than the limit of detection 

(LOD) were assigned a value equal to the LOD divided by the square root of 2. The 

LOD is the level at which the measurement has a 95 percent probability of being 

greater than zero (Taylor 1987). By comparison, assigning a value of the LOD divided 

by 2 made little difference in geometric mean estimates. Percentile estimates less 

than the LOD for the nutritional indicators are reported as "< LOD." If the proportion 

of results below the LOD was greater than 40 percent, geometric means were not 

calculated. Appendix D contains a table of LOD values for each biochemical indicator. 

As a result of changes to analytical methods, even for the same indicator, LOD values 

may change over the time period of the report. This was the case only for urinary 

phytoestrogens. We used the higher of the two LOD values for the analysis of the 

combined four-year data. 

For biochemical indicators measured in urine, we present separate tables for the 

concentration of the indicator expressed as “per volume of urine” (uncorrected 

table) and the concentration of the indicator expressed as “per gram of creatinine” 

(creatinine-corrected table). Comparison of an individual participant’s result to 

population data in the tables requires correction for urinary dilution: thus, an 

individual creatinine-corrected result is best compared to the creatinine-corrected 

data tables. Study populations of sufficient size can be compared to the tables 

having either of the corresponding units. We used the uncorrected tables to 

compare urine concentrations across groups. Because instrument responses are 

measured in units of weight per volume, LOD calculations were performed using 

the concentration of the indicator expressed as per volume of urine. For this reason, 

LOD results for urine measurements in Appendix D are in weight per volume of 

urine. In the creatinine-corrected tables, a result for a geometric mean or percentile 

was reported as less than the LOD (< LOD) if the corresponding geometric mean 

or percentile was < LOD in the uncorrected table. Thus, for example, if the 5th 

percentile for males was < LOD in the uncorrected table, it would also be < LOD in 

the creatinine-corrected table. 

 Introduction 9
References 

Interagency Board for Nutrition Monitoring and Related Research. Third report on 

nutrition monitoring in the United States. Hyattsville (MD): National Center for Health 

Statistics; 1995. 

Interagency Board for Nutrition Monitoring and Related Research. Bialostosky K, 

editor. Nutrition monitoring in the United States: the directory of federal and state 

nutrition monitoring and related research activities. Hyattsville (MD): National Center 

for Health Statistics; 2000. 

Taylor JK. Quality assurance of chemical measurements. Chelsea (MI): Lewis 

Publishing; 1987. 

U.S. Centers for Disease Control and Prevention. NHANES Analytic guidelines, the 

Third National Health and Nutrition Examination Survey, NHANES III (1988-94). 

Hyattsville (MD): National Center for Health Statistics; October 1996 [cited 2008]. 

Available from: http://www.cdc.gov/nchs/data/nhanes/nhanes3/nh3gui.pdf. 

10 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
1 

Water-Soluble Vitamins & 

Related Biochemical Compounds 

•	 Folate (serum and red blood cell) 

•	 Vitamin B12 

•	 Homocysteine 

•	 Methylmalonic acid 

11 
12 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Water-Soluble Vitamins & 

Related Biochemical 

Compounds 

Folate and vitamin B12 belong to the group of water-soluble B vitamins 

that occur naturally in food. Leafy green vegetables (such as spinach and 

turnip greens), fruits (such as citrus fruits and juices), and dried beans 

and peas are all natural sources of folate. Folic acid is the synthetic form 

of folate found in supplements and added to fortified foods. Because of 

wide consumption of fortified foods in the United States, these products 

have become an important contributor of folic acid to the U.S. diet. Folate 

functions as a coenzyme in single-carbon transfers in the metabolism 

of nucleic and amino acids and is therefore especially important during 

periods of rapid cell division and growth, such as occurs during infancy 

and pregnancy. 

Vitamin B12 (cobalamin) is found naturally in animal foods including fish, 

meat, poultry, eggs, milk, and milk products. For vegetarians, fortified 

breakfast cereals are a particularly valuable source of vitamin B12. Vitamin 

B12 functions as a coenzyme for a critical methyl transfer reaction that 

converts homocysteine to methionine and for a separate reaction that 

converts L-methylmalonyl-coenzyme A to succinyl-coenzyme A. 

Homocysteine (Hcy) is an amino acid naturally found in the blood. Plasma 

Hcy concentrations are strongly influenced by diet as well as by genetic 

factors. Elevated concentrations are found in people whose folate, vitamin 

B12, or vitamin B6 status is suboptimal (Selhub 1993), and in people with 

impaired renal function (Wollensen 1999). 

Methylmalonic acid (MMA) is a dicarboxylic acid naturally found in the 

blood. Plasma MMA concentrations are elevated when serum vitamin 

B12 concentrations are low or intermediate and are therefore a useful 

diagnostic test for confirming vitamin B12 deficiency (Baik 1999). 

A chronic dietary deficiency of either folate or vitamin B12 causes 

macrocytic anemia, although strict dietary deficiencies are rare. Certain 

drugs (e.g., alcohol, methotrexate, anticonvulsants, sulfa drugs) may 

interfere with the absorption or utilization of folate, and disorders of the 

small bowel that limit absorption (e.g., Crohn’s disease, jejunal bypass 

1 Water-Soluble Vitamins & Related Biochemical Compounds 13 
surgery) can cause folate deficiency (Halsted 1990). Most people who develop a vitamin 

B12 deficiency have an underlying stomach or intestinal disorder that limits the 

absorption of vitamin B12. Subtly reduced cognitive function resulting from early 

vitamin B12 deficiency is sometimes the only symptom of these intestinal disorders. 

Severe vitamin B12 deficiency can cause permanent nerve damage and dementia. 

Hematologic signs, however, are not always present in vitamin B12 deficiency and 

hematologic signs and neurologic abnormalities can be inversely correlated (Baik 

1999). 

Clinical trials have shown that folic acid supplementation effectively reduces the 

number of neural tube birth defects (NTDs) (Czeizel 1992; MRC Vitamin Study Research Group 

1991). Thus, CDC and the U.S. Public Health Service have recommended that every 

woman who could become pregnant consume at least 400 micrograms (μg) of folic 

acid each day (U.S. Centers for Disease Control and Prevention 1992). Since 1998, the U.S. Food 

and Drug Administration (FDA) has required the addition of folic acid to enriched 

breads, cereals, flours, corn meals, pastas, rice, and other grain products (U.S. Food 

and Drug Administration 1996a). Recent observational studies have suggested potential 

benefits of the U.S. folic acid fortification, such as reduced NTD rates (Williams 2005), 

decreased prevalence of inadequate serum and RBC folate concentrations (Pfeiffer 

2005), and declines in the incidence of stroke (Yang 2006) and neuroblastoma (French 

2003). Potential roles are currently being studied for 1) folate in altering the risks 

for heart disease and cancer, 2) vitamin B12 in modulating the risks for cognitive 

impairment, and 3) Hcy as a risk factor for or a marker of cardiovascular disease. 

The recommended dietary allowance (RDA) for both men and women is 400 μg per 

day of dietary folate equivalents (DFEs). DFEs adjust for the nearly 50 percent lower 

bioavailability of dietary folate compared with the bioavailability of folic acid: 1 μg 

of dietary folate equivalent equals 0.6 μg of folic acid from fortified food or from a 

supplement taken on an empty stomach (Institute of Medicine 1998). The RDA for vitamin 

B12 for adults is 2.4 μg per day. Because as many as 10 to 30 percent of older people 

may be unable to absorb naturally occurring vitamin B12, it is advisable for people 

older than 50 years to meet their RDA mainly by consuming foods fortified with 

vitamin B12 or by taking a supplement containing vitamin B12. People with vitamin 

B12 deficiency caused by a lack of intrinsic factor or intestinal malabsorption require 

parenteral B12 treatment (Institute of Medicine 1998). 

Excess folic acid may mask and potentially delay diagnosis of anemia among people 

with vitamin B12 deficiency resulting in increased risk for neurological damage. 

Consequently, the Institute of Medicine (1998) recommends that folic acid intake for 

adults (aged 19 years and older) not exceed 1000 μg per day. Because no data were 

available for children, the Institute of Medicine used the level for adults adjusted by 

weight: 300–800 μg per day, depending on the age group. Folate intake from food is 

not associated with any health risk. 

Clinical laboratories typically use conventional units for measuring concentrations of 

folate (nanograms per milliliter [ng/mL]) and vitamin B12 (picograms [pg]/mL) but 

use international system (SI) units for Hcy and MMA (micromole per liter [μmol/L]). 

14 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Conversion factors to SI units are as follows: 1 ng/mL = 2.266 nanomol (nmol)/L for 

folate and 1 pg/mL = 0.738 picomol (pmol)/L for vitamin B12. 

Several methods measure concentrations in blood of these B vitamins and related 

biochemical compounds. Because of significant differences in measuring folate 

concentrations, caution should be used when comparing other data sets with the 

tables in this report. Method-specific cut-off values and reference ranges should be 

used in medical diagnostics (Life Sciences Research Office 1994). Folate data presented 

in this report were generated using 

the BioRad Quantaphase II radioassay. 

This assay measures approximately 35 

percent lower than the microbiologic 

gold-standard assay (Life Sciences Research 

Office 1994). As a result, for this report, 

the conventional cut-off values of less 

than 3 ng/mL for low serum folate 

concentrations and less than 140 ng/ 

mL for low red blood cell (RBC) folate 

concentrations (Life Sciences Research 

Office 1984) should be adjusted to less 

than 2 ng/mL and less than 95 ng/mL, 

respectively. Common methods for 

measuring serum vitamin B12, plasma 

Hcy, and MMA generally produce 

comparable results. A widely used cutoff value for low serum vitamin B12 

concentrations is 200 pg/mL (Gibson 1990). 

Generally used cut-off values for elevated concentrations of plasma Hcy and MMA 

are 13 μmol/L (Jacques 1999) and 0.37 μmol/L (Hølleland 1999), respectively. 

For more information on B vitamins and related biochemical indicators, see the 

Institute of Medicine’s Dietary Reference Intake reports (Institute of Medicine 1998), fact 

sheets from the National Institutes of Health (NIH), Office of Dietary Supplements 

(http://ods.od.nih.gov/Health_Information/Information_About_Individual_Dietary_Supplements.aspx), 

as well as information from the American Society for Nutrition (http://jn.nutrition.org/ 

nutinfo/). 

One national health objective for Healthy People 2010 is to increase the proportion 

of pregnancies for which RBC folate concentration is optimum by increasing the 

median RBC folate concentration to 220 ng/mL among women aged 15–44 years 

(objective 16.16b; U.S. Department of Health and Human Services 2000). 

Monitoring the folate status of the U.S. population over time has been a priority since 

serum and RBC folate results from NHANES II (1976–1980) (Senti 1985) and NHANES III 

(1988–1994) (Wright 1998) suggested that the folate status of some population groups 

might be of public health concern. Vitamin B12 status of the U.S. population has 

been monitored since the second phase of NHANES III (1991–1994) (Wright 1998). In 

Chemist reviews data for methylmalonic acid. 

1 Water-Soluble Vitamins & Related Biochemical Compounds 15 
a recent (2007) study, Pfeiffer et al. showed that, in women of childbearing age, the 

introduction of folic acid fortification has dramatically lowered the prevalence of low 

serum (< 3 ng/mL) and RBC folate concentrations (< 140 ng/mL) from 21 percent and 

38 percent, respectively, to less than 1 percent and 5 percent, respectively. Serum 

vitamin B12 concentrations, however, did not change appreciably. Circulating Hcy 

concentrations from prefortification to postfortification decreased by approximately 

10 percent in a national sample of the U.S. population (Pfeiffer 2008). 

Selected Observations and Highlights 

The following representative observations are taken from the tables of 1999–2002 

data contained in this report. Statements about categorical differences between 

demographic groups noted below are based on non-overlapping confidence limits 

from univariate analysis without adjusting for demographic variables (e.g., age, 

sex, race/ethnicity) or other blood concentration determinants (e.g., dietary intake, 

supplement usage, smoking, BMI). A multivariate analysis may alter the size and 

statistical significance of these categorical differences. Furthermore, additional 

significant differences of smaller magnitude may be present despite their lack of 

mention here (e.g., if confidence limits slightly overlap or if differences are not 

statistically significant before covariate adjustment has occurred). For a selection of 

citations of descriptive NHANES papers related to these biochemical indicators of diet 

and nutrition, see Appendix E. 

General Observations 

•	 Serum and RBC folate concentrations show a U-shaped age pattern with 

higher concentrations in children and older people (≥ 60 years) than in young 

or middle-aged adults. 

•	 Serum vitamin B12 concentrations first decline from childhood to middle-age, 

then stabilize. Plasma MMA concentrations are similar across all age groups, 

except that older people have higher concentrations. 

•	 Plasma Hcy concentrations increase with age. 

•	 Women have higher serum and RBC folate concentrations than do men, and 

men have higher plasma Hcy and MMA concentrations. 

•	 For serum and RBC folate, non-Hispanic whites have higher concentrations 

than do Mexican Americans, who themselves have higher concentrations than 

do non-Hispanic blacks. 

•	 Serum vitamin B12 concentrations are higher in non-Hispanic blacks than 

in the other two racial/ethnic groups, and plasma MMA concentrations are 

higher in non-Hispanic whites than in either Mexican Americans or in nonHispanic blacks. 

•	 Plasma Hcy concentrations are higher in non-Hispanic whites than in the 

other two racial/ethnic groups. 

16 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
•	 Less than 5 percent of adolescent and adult women have low serum (< 2 ng/ 

mL) and RBC folate concentrations (< 95 ng/mL)–cut-off values indicative of 

inadequate folate status (based on 5th percentile). 

•	 Approximately 5 percent of older people have moderately low concentrations 

of serum vitamin B12 (< 200 pg/mL) (based on 5th percentile), and over 5 

percent of older people have elevated concentrations of plasma Hcy (> 13 

μmol/L) and of MMA (> 0.37 μmol/L) (based on 95th percentile). 

Highlights 

Since 1998, when fortification of enriched grains and cereal products with folic acid 

became mandatory, serum folate concentrations have more than doubled, and 

RBC folate concentrations have increased by about 50 percent in all population 

subgroups (Fig. 1.a). This greater than expected increase in blood concentrations 

was shown previously (Pfeiffer 2007). Underreporting of foods consumed, increased 

consumer selection of folate-rich foods as a result of health claims, and increasing 

availability of the number and types of nonstandardized folate-fortified foods 

(e.g., breakfast cereals) could be some of the reasons for the greater than expected 

increase in blood concentrations (U.S. Food and Drug Administration 1996b). 

Figure 1.a. 

Geometric mean concentrations (95 percent confidence intervals) of serum folate in the U.S. 

population, aged 3 years and older, and in population subgroups, National Health and Nutrition 

Examination Survey, 1988–2002. Data shown for NHANES 1988–1994 are not part of the tables 

displayed in this report but were analyzed separately to generate this figure. 

1 Water-Soluble Vitamins & Related Biochemical Compounds 17 
18 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 

The Healthy People 2010 objective to increase the median RBC folate concentration 

in women to 220 ng/mL was achieved for Mexican-American and non-Hispanic white 

women aged 20–39 years: their median RBC folate concentrations were 250 ng/ 

mL and 278 ng/mL, respectively (Fig. 1.b). This objective was, however, not achieved 

for non-Hispanic black women (210 ng/mL) (Fig. 1.b). Interestingly, offspring of nonHispanic black women have the lowest incidence of NTDs, whereas offspring of 

Mexican-American women have the highest NTD incidence (Williams 2005). These 

findings show that RBC folate concentrations alone do not account for differences in 

NTD rates among race/ethnic groups in the U.S. population. 

Figure 1.b 

Median concentrations (95 percent confidence intervals) of red blood cell (RBC) folate among 

20–39 year-old women by race/ethnicity, National Health and Nutrition Examination Survey, 

1999–2002. 
1 Water-Soluble Vitamins & Related Biochemical Compounds 19

Although the majority (> 95 percent) of females have an adequate folate status, it 

is interesting to note that adolescents (aged 12–19 years) and adult women (aged 

20–59 years), age groups for which good folate status is most critical, have lower 

serum folate concentrations than do females in other age groups (Fig. 1.c). Adolescent 

females aged 12–19 years also have lower RBC folate concentrations than do females 

in other age groups (Fig. 1.c). 

Figure 1.c 

Cross-sectional age pattern showing geometric mean concentrations (95 percent confidence 

intervals) of serum and red blood cell (RBC) folate in females, National Health and Nutrition 

Examination Survey, 1999–2002. 
Table 1.1.a. Serum folate: Total population 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 13.5 (13.1-13.8) 5.70 (5.50-6.00) 13.6 (13.2-13.9) 30.8 (29.9-32.0) 15912

 3–5 years 18.5 (17.7-19.3) 9.90 (8.80-10.8) 18.3 (17.7-18.8) 34.8 (32.0-41.0) 799

 6–11 years 18.1 (17.6-18.7) 9.90 (9.40-10.6) 18.0 (17.6-18.5) 33.2 (31.6-35.0) 1908

 12–19 years 12.6 (12.2-13.1) 6.00 (5.60-6.30) 12.8 (12.4-13.4) 24.7 (23.0-26.6) 4332

 20–39 years 11.4 (11.0-11.9) 5.10 (4.80-5.40) 11.2 (10.8-11.8) 25.1 (23.4-26.9) 3184

 40–59 years 12.8 (12.3-13.2) 5.50 (5.20-5.90) 12.9 (12.4-13.3) 28.7 (27.1-30.1) 2674

 60 years and older 16.8 (16.3-17.3) 6.80 (6.40-7.20) 17.0 (16.4-17.6) 40.3 (37.4-43.0) 3015 

Males 

Total, 3 years and older 12.8 (12.4-13.2) 5.50 (5.20-5.90) 13.0 (12.5-13.4) 28.3 (27.4-29.4) 7747

 3–5 years 18.2 (17.1-19.4) 9.40 (8.60-10.7) 17.7 (16.4-18.6) 41.0 (31.2-44.8) 417

 6–11 years 17.8 (17.0-18.6) 9.70 (8.90-10.7) 17.7 (16.8-18.4) 32.3 (29.6-35.9) 973

 12–19 years 12.5 (12.0-13.0) 6.00 (5.50-6.30) 12.9 (12.3-13.3) 24.6 (22.8-26.6) 2169

 20–39 years 10.7 (10.3-11.2) 5.00 (4.40-5.60) 10.8 (10.2-11.3) 21.9 (19.8-23.2) 1355

 40–59 years 12.3 (11.9-12.7) 5.40 (4.70-5.90) 12.4 (12.1-12.9) 26.7 (25.1-28.1) 1337

 60 years and older 15.2 (14.7-15.8) 6.10 (5.70-6.70) 15.3 (14.7-16.1) 35.4 (34.1-37.6) 1496 

Females 

Total, 3 years and older 14.1 (13.7-14.5) 5.80 (5.60-6.20) 14.3 (13.8-14.7) 32.9 (31.2-34.5) 8165

 3–5 years 18.8 (18.0-19.7) 10.3 (8.30-11.6) 18.7 (17.5-19.1) 33.5 (31.0-36.6) 382

 6–11 years 18.5 (18.0-19.1) 10.0 (9.30-10.7) 18.6 (17.8-19.0) 33.4 (30.0-37.4) 935

 12–19 years 12.7 (12.2-13.3) 6.20 (5.70-6.60) 12.8 (12.3-13.5) 24.8 (22.2-28.1) 2163

 20–39 years 12.1 (11.6-12.6) 5.40 (5.10-5.60) 12.0 (11.4-12.8) 28.7 (26.2-30.8) 1829

 40–59 years 13.2 (12.7-13.8) 5.50 (5.10-6.20) 13.4 (12.7-14.0) 30.2 (27.5-34.1) 1337

 60 years and older 18.1 (17.3-18.8) 7.40 (6.80-7.80) 18.2 (17.3-18.9) 43.0 (39.8-45.6) 1519 

Table 1.1.b. Serum folate: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 12.4 (11.9-12.9) 5.70 (5.30-6.20) 12.5 (12.0-12.9) 26.3 (24.8-28.1) 4695

 3–5 years 18.1 (17.1-19.2) 10.9 (9.90-11.5) 17.7 (16.7-18.7) 33.6 (28.6-36.8) 266

 6–11 years 17.7 (17.1-18.4) 10.4 (9.60-11.0) 17.3 (16.7-17.9) 31.0 (28.8-34.8) 652

 12–19 years 12.4 (12.0-12.8) 6.60 (6.10-6.90) 12.6 (12.0-13.2) 22.4 (21.7-24.0) 1637

 20–39 years 10.5 (9.96-11.0) 5.00 (4.20-5.60) 10.3 (9.80-11.0) 20.1 (19.4-21.9) 866

 40–59 years 11.8 (11.1-12.5) 5.90 (5.10-6.50) 11.9 (11.2-12.4) 23.8 (20.6-28.0) 634

 60 years and older 14.4 (13.6-15.2) 6.00 (5.00-6.90) 14.8 (13.5-15.8) 34.1 (30.2-38.7) 640 

Males 

Total, 3 years and older 12.0 (11.4-12.5) 5.50 (4.80-6.20) 12.1 (11.4-12.6) 25.3 (23.5-27.4) 2293

 3–5 years 17.7 (16.6-18.9) 10.5† (9.70-11.6) 17.4 (16.1-18.5) 34.0† (27.1-44.8) 139

 6–11 years 17.6 (16.7-18.5) 10.1 (9.00-11.0) 17.5 (16.4-18.4) 32.1 (26.2-42.0) 338

 12–19 years 12.5 (12.0-13.1) 6.40 (5.80-7.00) 12.6 (12.0-13.3) 24.1 (22.1-26.3) 811

 20–39 years 9.85 (9.24-10.5) 4.50 (3.80-5.60) 9.80 (9.20-10.6) 19.3 (17.2-20.0) 383

 40–59 years 11.6 (10.8-12.5) 5.80 (5.10-6.60) 11.7 (10.7-12.6) 22.0 (18.4-28.7) 301

 60 years and older 13.5 (12.5-14.5) 6.20 (5.00-7.10) 13.2 (12.2-14.8) 29.8 (24.0-48.3) 321 

Females 

Total, 3 years and older 12.9 (12.4-13.4) 5.90 (5.70-6.40) 13.0 (12.6-13.7) 27.2 (25.6-28.8) 2402

 3–5 years 18.5 (17.1-20.0) 11.0† (9.60-12.0) 18.3 (16.9-19.0) 31.6† (27.4-36.6) 127

 6–11 years 17.9 (17.2-18.6) 10.5 (9.60-11.7) 17.3 (16.6-18.2) 30.8 (28.8-32.1) 314

 12–19 years 12.2 (11.8-12.7) 6.60 (6.10-7.00) 12.5 (11.8-13.3) 21.6 (19.8-22.4) 826

 20–39 years 11.2 (10.7-11.8) 5.20 (4.90-5.90) 11.0 (10.3-11.7) 22.3 (20.0-27.6) 483

 40–59 years 11.9 (11.1-12.8) 5.90 (4.60-6.50) 12.0 (11.1-12.5) 25.4 (21.4-26.6) 333

 60 years and older 15.2 (14.3-16.2) 6.10 (5.00-7.20) 15.8 (14.4-16.7) 36.0 (31.5-39.6) 319 

† Estimate is subject to greater uncertainty due to small cell size. 

20 20 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 1.1.c. Serum folate: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 11.3 (10.9-11.8) 5.10 (4.60-5.30) 11.1 (10.6-11.6) 25.5 (23.9-27.1) 3716

 3–5 years 16.9 (16.0-17.8) 9.80 (8.70-10.5) 16.2 (15.1-17.8) 34.8 (28.2-39.3) 235

 6–11 years 16.9 (16.2-17.6) 9.60 (8.80-10.6) 16.4 (15.8-17.4) 31.8 (28.0-39.5) 604

 12–19 years 10.9 (10.5-11.4) 5.30 (5.00-5.70) 11.0 (10.5-11.4) 19.8 (19.0-21.0) 1256

 20–39 years 9.73 (9.18-10.3) 5.10 (4.50-5.40) 9.60 (9.10-10.4) 19.8 (18.7-21.4) 593

 40–59 years 10.3 (9.86-10.8) 4.40 (4.10-5.10) 10.1 (9.60-10.8) 22.7 (19.4-26.0) 541

 60 years and older 12.7 (11.6-13.8) 4.80 (4.20-5.40) 12.2 (11.0-14.0) 38.1 (31.1-43.3) 487 

Males 

Total, 3 years and older 10.9 (10.5-11.3) 4.80 (4.40-5.10) 10.8 (10.5-11.3) 22.7 (21.2-25.0) 1822

 3–5 years 16.6 (15.3-17.9) 9.00† (7.50-10.6) 15.6 (14.4-17.2) 36.5† (26.1-55.9) 122

 6–11 years 17.0 (16.3-17.8) 9.60 (8.80-10.8) 16.6 (15.9-17.6) 31.6 (26.8-39.5) 305

 12–19 years 11.0 (10.5-11.5) 5.10 (4.60-5.80) 11.2 (10.5-11.7) 20.1 (19.2-22.2) 640

 20–39 years 9.17 (8.63-9.74) 4.50 (3.50-5.10) 9.50 (8.40-10.2) 17.4 (16.3-19.5) 249

 40–59 years 9.69 (9.20-10.2) 4.20 (3.00-4.70) 9.80 (9.20-10.2) 19.2 (17.8-20.6) 274

 60 years and older 11.3 (10.3-12.4) 4.60 (3.90-5.20) 11.3 (9.90-12.6) 33.8 (20.0-40.4) 232 

Females 

Total, 3 years and older 11.7 (11.1-12.3) 5.40 (4.80-5.70) 11.2 (10.7-11.9) 27.4 (25.1-30.4) 1894

 3–5 years 17.2 (15.8-18.8) 10.2† (7.80-10.9) 17.2 (15.2-18.8) 30.9† (27.1-36.3) 113

 6–11 years 16.7 (16.0-17.5) 9.60 (7.90-10.5) 16.3 (15.5-17.3) 32.5 (27.1-38.4) 299

 12–19 years 10.8 (10.3-11.4) 5.40 (5.00-5.80) 10.8 (10.3-11.3) 19.4 (18.3-21.0) 616

 20–39 years 10.2 (9.49-10.9) 5.40 (4.50-5.70) 9.70 (9.20-10.7) 21.4 (19.2-24.0) 344

 40–59 years 10.9 (10.2-11.7) 4.70 (3.50-5.90) 10.6 (9.50-12.1) 24.8 (19.6-29.2) 267

 60 years and older 13.6 (12.2-15.2) 5.10 (3.80-6.60) 12.7 (11.6-14.9) 39.5 (30.5-48.0) 255 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 1.1.d. Serum folate: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 14.1 (13.6-14.6) 6.00 (5.70-6.30) 14.2 (13.7-14.8) 32.0 (30.9-33.3) 6147

 3–5 years 19.6 (18.3-21.1) 10.1† (8.30-12.3) 18.9 (17.8-20.2) 38.0† (31.5-48.9) 219

 6–11 years 18.7 (17.9-19.5) 9.70 (8.90-10.8) 18.8 (17.9-19.5) 34.2 (31.6-37.8) 494

 12–19 years 13.3 (12.8-13.9) 6.20 (5.70-6.70) 13.6 (13.1-14.3) 26.5 (24.0-27.6) 1073

 20–39 years 11.9 (11.4-12.6) 5.50 (4.80-5.90) 12.2 (11.2-12.9) 26.3 (24.0-29.1) 1381

 40–59 years 13.3 (12.7-13.8) 5.60 (5.20-6.10) 13.3 (12.9-14.0) 29.8 (27.4-31.0) 1276

 60 years and older 17.4 (16.8-18.0) 7.20 (6.60-7.60) 17.8 (16.9-18.4) 41.0 (37.4-43.5) 1704 

Males 

Total, 3 years and older 13.3 (12.9-13.9) 6.00 (5.60-6.30) 13.6 (13.0-14.1) 29.4 (28.1-30.6) 3013

 3–5 years 19.2 (17.2-21.4) 9.00† (7.80-11.1) 18.7 (16.3-19.9) 42.0† (29.9-57.6) 116

 6–11 years 18.2 (17.0-19.5) 8.90 (7.60-11.0) 18.0 (16.8-19.2) 34.7 (29.7-38.0) 260

 12–19 years 13.0 (12.4-13.7) 6.20 (5.60-6.80) 13.4 (12.8-13.9) 26.0 (22.8-27.3) 536

 20–39 years 11.3 (10.6-12.0) 5.40 (4.40-6.10) 11.3 (10.4-12.4) 23.0 (20.2-24.5) 577

 40–59 years 12.7 (12.2-13.3) 5.70 (5.20-6.40) 13.0 (12.3-13.5) 27.3 (25.4-28.8) 666

 60 years and older 15.8 (15.1-16.5) 6.30 (6.10-7.30) 16.0 (15.2-17.0) 35.9 (33.6-37.6) 858 

Females 

Total, 3 years and older 14.9 (14.3-15.4) 6.10 (5.80-6.50) 15.1 (14.5-15.7) 34.2 (32.4-35.8) 3134

 3–5 years 20.1 (18.8-21.5) 11.6† (8.30-14.1) 19.1 (18.4-21.6) 33.5† (28.9-39.0) 103

 6–11 years 19.2 (18.3-20.1) 10.2 (8.90-11.1) 19.4 (18.8-20.2) 33.6 (29.4-40.3) 234

 12–19 years 13.7 (12.9-14.5) 6.40 (5.20-7.10) 13.9 (13.2-14.7) 26.6 (23.0-31.6) 537

 20–39 years 12.6 (12.0-13.4) 5.60 (5.10-5.90) 13.0 (11.8-13.7) 30.4 (26.3-32.4) 804

 40–59 years 13.8 (13.1-14.6) 5.70 (5.10-6.30) 13.9 (12.9-15.1) 31.0 (28.7-35.0) 610

 60 years and older 18.8 (18.0-19.7) 7.70 (7.20-8.60) 18.9 (18.0-19.8) 43.6 (40.0-46.1) 846 

† Estimate is subject to greater uncertainty due to small cell size. 

1 Water-Soluble Vitamins & Related Biochemical Compounds 21
Table 1.2.a. Red blood cell (RBC) folate: Total population 

Geometric mean and selected percentiles of RBC concentrations (in ng/mL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 280 (273-287) 154 (149-159) 276 (270-282) 526 (510-541) 16102

 3–5 years 288 (281-296) 192 (184-203) 286 (278-293) 464 (403-512) 840

 6–11 years 280 (273-287) 186 (178-192) 277 (269-284) 431 (413-482) 1938

 12–19 years 244 (237-251) 150 (145-155) 240 (234-246) 411 (393-436) 4362

 20–39 years 255 (248-262) 142 (135-149) 252 (241-261) 452 (437-474) 3195

 40–59 years 291 (283-299) 159 (151-167) 289 (282-297) 538 (500-576) 2709

 60 years and older 338 (330-345) 169 (160-178) 341 (331-351) 667 (634-688) 3058 

Males 

Total, 3 years and older 272 (265-279) 153 (148-159) 268 (260-275) 494 (480-515) 7827

 3–5 years 291 (278-304) 192 (180-206) 287 (277-300) 477 (394-559) 438

 6–11 years 287 (279-295) 201 (189-209) 280 (272-288) 448 (423-504) 989

 12–19 years 240 (232-249) 150 (142-159) 238 (232-245) 398 (372-436) 2179

 20–39 years 246 (238-254) 146 (139-151) 245 (235-256) 418 (395-440) 1358

 40–59 years 282 (274-291) 157 (148-168) 280 (271-291) 516 (481-545) 1349

 60 years and older 325 (314-337) 159 (147-170) 324 (310-339) 644 (593-702) 1514 

Females 

Total, 3 years and older 288 (281-295) 155 (149-161) 285 (278-292) 552 (531-573) 8275

 3–5 years 286 (277-295) 190 (177-201) 287 (276-293) 441 (386-519) 402

 6–11 years 272 (264-280) 178 (171-185) 271 (261-281) 402 (385-469) 949

 12–19 years 247 (239-255) 148 (145-155) 244 (235-251) 422 (386-476) 2183

 20–39 years 264 (256-274) 140 (132-152) 261 (251-273) 492 (455-540) 1837

 40–59 years 300 (288-312) 164 (151-174) 297 (285-309) 565 (505-595) 1360

 60 years and older 347 (340-355) 176 (163-185) 353 (339-364) 673 (634-698) 1544 

Table 1.2.b. Red blood cell (RBC) folate: Mexican Americans 

Geometric mean and selected percentiles of RBC concentrations (in ng/mL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 258 (251-265) 155 (146-161) 254 (248-261) 456 (435-473) 4726

 3–5 years 289 (280-298) 201 (194-210) 278 (270-289) 458 (403-524) 273

 6–11 years 282 (276-288) 197 (180-211) 276 (270-282) 444 (402-492) 658

 12–19 years 245 (239-252) 156 (145-164) 241 (237-248) 408 (381-428) 1642

 20–39 years 239 (231-248) 140 (126-149) 235 (229-243) 423 (392-443) 870

 40–59 years 273 (263-283) 167 (160-172) 267 (255-275) 496 (454-552) 634

 60 years and older 301 (285-317) 161 (141-180) 291 (275-314) 590 (534-711) 649 

Males 

Total, 3 years and older 250 (242-258) 145 (133-155) 251 (241-257) 430 (401-457) 2306

 3–5 years 297 (284-311) 210† (196-220) 283 (270-299) 514† (401-599) 144

 6–11 years 287 (280-295) 201 (185-214) 283 (274-292) 443 (383-511) 339

 12–19 years 241 (234-248) 155 (141-166) 238 (233-246) 376 (356-406) 813

 20–39 years 227 (215-239) 129 (114-147) 225 (211-237) 392 (351-435) 385

 40–59 years 263 (252-275) 165 (152-171) 265 (251-278) 432 (392-498) 302

 60 years and older 293 (269-318) 152 (133-190) 285 (266-299) 567 (525-702) 323 

Females 

Total, 3 years and older 268 (260-275) 159 (155-168) 260 (251-266) 488 (457-517) 2420

 3–5 years 279 (267-292) 188† (182-203) 272 (259-289) 418† (371-458) 129

 6–11 years 276 (268-285) 194 (173-212) 268 (263-275) 434 (384-492) 319

 12–19 years 250 (242-258) 157 (145-167) 243 (237-250) 434 (393-486) 829

 20–39 years 255 (246-265) 152 (141-159) 250 (233-260) 436 (421-512) 485

 40–59 years 284 (269-299) 171 (163-181) 269 (248-291) 538 (464-624) 332

 60 years and older 308 (295-321) 168 (154-184) 305 (280-318) 600 (532-785) 326 

† Estimate is subject to greater uncertainty due to small cell size. 

22 22 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 1.2.c. Red blood cell (RBC) folate: Non-Hispanic blacks 

Geometric mean and selected percentiles of RBC concentrations (in ng/mL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 221 (216-226) 123 (120-129) 220 (214-224) 383 (370-399) 3783

 3–5 years 247 (240-254) 166 (159-180) 244 (235-251) 364 (326-411) 248

 6–11 years 238 (232-243) 161 (151-172) 240 (233-247) 336 (322-350) 623

 12–19 years 200 (196-205) 123 (117-129) 203 (197-209) 310 (295-320) 1265

 20–39 years 209 (202-216) 117 (113-124) 209 (201-215) 361 (340-385) 598

 40–59 years 222 (215-230) 120 (111-130) 222 (213-231) 396 (367-427) 553

 60 years and older 254 (243-267) 125 (110-136) 255 (240-267) 535 (476-590) 496 

Males 

Total, 3 years and older 216 (210-222) 122 (116-132) 219 (212-226) 360 (341-372) 1856

 3–5 years 246 (235-257) 168† (145-188) 244 (234-254) 364† (314-508) 130

 6–11 years 243 (237-250) 161 (153-178) 248 (238-255) 334 (313-361) 316

 12–19 years 203 (198-209) 124 (116-131) 208 (202-214) 310 (292-327) 645

 20–39 years 203 (194-211) 118 (101-135) 207 (197-214) 322 (302-350) 249

 40–59 years 211 (202-221) 121 (104-132) 211 (194-226) 364 (348-396) 277

 60 years and older 244 (229-260) 117 (103-134) 248 (227-266) 460 (403-592) 239 

Females 

Total, 3 years and older 225 (219-231) 124 (117-130) 221 (216-226) 411 (378-453) 1927

 3–5 years 248 (238-258) 165† (159-181) 244 (233-258) 379† (319-453) 118

 6–11 years 232 (224-240) 158 (132-177) 230 (221-242) 336 (319-369) 307

 12–19 years 197 (192-202) 124 (111-131) 197 (189-201) 303 (291-320) 620

 20–39 years 214 (205-223) 119 (113-127) 210 (200-220) 379 (352-445) 349

 40–59 years 233 (222-244) 122 (109-141) 233 (220-247) 409 (370-512) 276

 60 years and older 262 (246-279) 127 (104-151) 262 (241-277) 553 (496-599) 257 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 1.2.d. Red blood cell (RBC) folate: Non-Hispanic whites 

Geometric mean and selected percentiles of RBC concentrations (in ng/mL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 297 (289-304) 166 (160-172) 292 (284-299) 551 (536-570) 6210

 3–5 years 303 (289-318) 204 (180-231) 300 (290-309) 474 (390-546) 231

 6–11 years 292 (283-301) 189 (183-207) 290 (282-296) 464 (422-519) 498

 12–19 years 257 (249-265) 160 (152-164) 253 (246-261) 436 (400-458) 1083

 20–39 years 268 (257-279) 150 (135-165) 265 (252-278) 475 (449-524) 1383

 40–59 years 305 (296-313) 173 (166-180) 302 (293-309) 545 (506-597) 1291

 60 years and older 352 (342-361) 182 (170-193) 355 (344-365) 674 (639-702) 1724 

Males 

Total, 3 years and older 287 (279-296) 165 (158-173) 281 (272-291) 523 (501-544) 3037

 3–5 years 308 (286-332) 204† (165-231) 310 (290-324) 512† (403-634) 120

 6–11 years 300 (289-311) 211 (189-225) 290 (276-299) 473 (422-533) 263

 12–19 years 251 (241-261) 158 (145-164) 246 (238-256) 410 (372-454) 538

 20–39 years 258 (247-269) 157 (147-165) 256 (241-270) 432 (402-463) 578

 40–59 years 295 (286-304) 171 (157-180) 292 (280-303) 527 (491-601) 672

 60 years and older 339 (325-355) 170 (158-190) 342 (322-359) 660 (601-717) 866 

Females 

Total, 3 years and older 306 (297-315) 167 (159-174) 302 (293-310) 580 (551-604) 3173

 3–5 years 298 (285-311) 201† (189-236) 294 (279-307) 436† (382-546) 111

 6–11 years 283 (273-294) 182 (173-192) 290 (277-298) 453 (381-508) 235

 12–19 years 264 (253-275) 160 (149-167) 262 (250-270) 451 (395-539) 545

 20–39 years 278 (265-293) 143 (130-167) 278 (261-293) 548 (490-591) 805

 40–59 years 315 (300-330) 176 (165-190) 308 (295-327) 570 (503-611) 619

 60 years and older 361 (354-369) 191 (182-201) 364 (351-372) 680 (639-711) 858 

† Estimate is subject to greater uncertainty due to small cell size. 

1 Water-Soluble Vitamins & Related Biochemical Compounds 23
Table 1.3.a. Serum vitamin B12: Total population 

Geometric mean and selected percentiles of serum concentrations (in pg/mL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 488 (483-494) 237 (234-242) 485 (477-492) 1000 (977-1030) 15914

 3–5 years 783 (745-822) 446 (425-475) 788 (741-823) 1380 (1300-1520) 800

 6–11 years 692 (672-712) 369 (344-410) 700 (682-718) 1260 (1190-1310) 1907

 12–19 years 505 (496-515) 267 (254-279) 510 (499-523) 941 (912-979) 4331

 20–39 years 446 (439-453) 233 (222-238) 446 (438-455) 812 (787-843) 3185

 40–59 years 461 (453-469) 233 (224-241) 452 (442-460) 919 (883-973) 2676

 60 years and older 478 (466-489) 225 (212-233) 474 (467-485) 1010 (976-1060) 3015 

Males 

Total, 3 years and older 488 (480-497) 248 (240-258) 485 (477-494) 961 (922-993) 7741

 3–5 years 763 (715-814) 432 (373-468) 756 (699-824) 1450 (1250-1650) 417

 6–11 years 690 (667-715) 368 (344-393) 697 (673-718) 1270 (1200-1330) 972

 12–19 years 507 (493-522) 278 (254-297) 512 (494-528) 920 (892-952) 2165

 20–39 years 458 (446-470) 243 (231-263) 460 (445-475) 795 (766-826) 1355

 40–59 years 458 (447-469) 241 (226-256) 452 (438-460) 847 (792-898) 1337

 60 years and older 451 (439-464) 224 (204-236) 456 (439-469) 907 (859-1000) 1495 

Females 

Total, 3 years and older 488 (482-494) 232 (226-237) 483 (475-492) 1040 (1010-1080) 8173

 3–5 years 806 (762-852) 475 (446-514) 804 (755-859) 1340 (1270-1440) 383

 6–11 years 694 (668-720) 382 (338-425) 700 (676-731) 1250 (1110-1310) 935

 12–19 years 504 (494-514) 256 (241-267) 509 (495-525) 966 (936-1000) 2166

 20–39 years 435 (427-443) 222 (210-232) 433 (418-447) 839 (784-913) 1830

 40–59 years 463 (448-479) 223 (201-238) 453 (435-473) 1000 (920-1120) 1339

 60 years and older 499 (482-515) 227 (209-237) 494 (479-510) 1060 (994-1140) 1520 

Table 1.3.b. Serum vitamin B12: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in pg/mL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 532 (513-553) 260 (249-273) 514 (493-531) 1120 (1060-1200) 4695

 3–5 years 821 (784-860) 447 (402-526) 809 (764-870) 1470 (1330-1530) 266

 6–11 years 701 (672-731) 415 (390-447) 705 (676-731) 1190 (1090-1270) 652

 12–19 years 507 (491-523) 268 (249-288) 504 (494-519) 883 (847-920) 1637

 20–39 years 477 (452-504) 242 (213-260) 453 (437-469) 1010 (875-1180) 866

 40–59 years 518 (491-546) 264 (258-295) 475 (452-514) 1100 (947-1500) 634

 60 years and older 497 (464-532) 215 (203-237) 482 (454-514) 1090 (969-1460) 640 

Males 

Total, 3 years and older 507 (486-529) 263 (245-278) 494 (473-516) 999 (936-1100) 2293

 3–5 years 798 (744-855) 428† (351-553) 779 (704-833) 1490† (1250-2310) 139

 6–11 years 690 (646-738) 411 (379-455) 694 (659-729) 1190 (1040-1370) 338

 12–19 years 489 (472-507) 264 (242-292) 488 (479-501) 849 (808-896) 811

 20–39 years 454 (423-489) 249 (200-279) 452 (423-468) 771 (731-858) 383

 40–59 years 486 (465-507) 292 (264-308) 469 (429-514) 891 (792-1390) 301

 60 years and older 451 (414-491) 206 (162-238) 444 (410-473) 1070 (911-1250) 321 

Females 

Total, 3 years and older 562 (536-589) 257 (241-269) 533 (514-552) 1200 (1120-1360) 2402

 3–5 years 848 (799-901) 451† (408-548) 853 (775-933) 1390† (1200-1520) 127

 6–11 years 713 (681-747) 424 (382-475) 711 (689-746) 1160 (1080-1280) 314

 12–19 years 527 (505-549) 277 (254-296) 525 (504-534) 915 (870-939) 826

 20–39 years 506 (463-553) 232 (202-257) 461 (444-482) 1190 (1040-1720) 483

 40–59 years 553 (507-603) 258 (214-277) 491 (461-528) 1310 (1000-4570) 333

 60 years and older 540 (494-592) 235 (196-271) 525 (484-581) 1180 (965-2170) 319 

† Estimate is subject to greater uncertainty due to small cell size. 

24 24 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 1.3.c. Serum vitamin B12: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in pg/mL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 568 (558-579) 273 (263-289) 569 (556-583) 1180 (1150-1220) 3712

 3–5 years 867 (829-906) 486 (403-567) 859 (815-929) 1540 (1330-1700) 234

 6–11 years 803 (775-832) 413 (375-452) 812 (786-845) 1460 (1320-1630) 603

 12–19 years 585 (569-602) 298 (274-313) 588 (566-609) 1150 (1070-1230) 1254

 20–39 years 508 (491-525) 261 (233-289) 511 (492-530) 939 (864-977) 593

 40–59 years 525 (506-545) 263 (251-277) 522 (502-553) 1110 (1020-1190) 541

 60 years and older 542 (511-576) 246 (224-280) 560 (506-605) 1190 (1030-1410) 487 

Males 

Total, 3 years and older 558 (543-574) 270 (254-291) 563 (545-575) 1150 (1090-1230) 1818

 3–5 years 861 (799-928) 479† (361-558) 859 (791-931) 1650† (1320-1880) 121

 6–11 years 780 (744-818) 413 (368-478) 775 (752-822) 1390 (1250-1520) 304

 12–19 years 561 (540-583) 295 (256-324) 567 (535-602) 1000 (952-1080) 638

 20–39 years 511 (483-541) 253 (228-296) 518 (492-549) 939 (838-1170) 249

 40–59 years 507 (485-531) 261 (245-294) 507 (477-551) 1020 (888-1140) 274

 60 years and older 493 (458-531) 239 (215-269) 481 (458-542) 1030 (910-1320) 232 

Females 

Total, 3 years and older 577 (566-589) 277 (264-291) 576 (560-590) 1200 (1160-1260) 1894

 3–5 years 873 (815-934) 564† (419-611) 857 (804-953) 1430† (1250-1560) 113

 6–11 years 827 (791-865) 409 (373-452) 854 (803-891) 1490 (1320-1930) 299

 12–19 years 611 (592-630) 302 (270-315) 607 (584-634) 1280 (1160-1460) 616

 20–39 years 505 (485-526) 271 (238-301) 505 (476-530) 911 (814-975) 344

 40–59 years 542 (516-568) 263 (228-287) 538 (507-575) 1160 (1100-1250) 267

 60 years and older 577 (539-617) 249 (219-300) 607 (554-647) 1260 (1080-1630) 255 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 1.3.d. Serum vitamin B12: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in pg/mL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 472 (465-479) 235 (230-238) 471 (461-479) 938 (904-976) 6150

 3–5 years 728 (679-781) 440† (389-471) 730 (659-795) 1300† (1110-1510) 219

 6–11 years 662 (639-686) 350 (336-385) 680 (660-699) 1170 (1060-1280) 494

 12–19 years 493 (478-508) 265 (244-276) 503 (483-523) 918 (883-963) 1072

 20–39 years 431 (422-441) 228 (216-236) 434 (422-450) 763 (741-800) 1382

 40–59 years 449 (440-457) 228 (218-238) 440 (428-456) 882 (831-934) 1279

 60 years and older 473 (460-486) 226 (209-236) 471 (462-480) 1000 (954-1060) 1704 

Males 

Total, 3 years and older 477 (466-487) 244 (236-256) 474 (463-486) 897 (868-944) 3011

 3–5 years 701 (635-773) 424† (303-471) 682 (612-778) 1200† (1070-1590) 116

 6–11 years 666 (634-699) 344 (310-369) 679 (647-713) 1250 (1080-1430) 260

 12–19 years 500 (479-522) 279 (253-299) 509 (482-532) 903 (846-935) 534

 20–39 years 451 (436-468) 245 (233-271) 454 (436-475) 762 (721-811) 577

 40–59 years 452 (439-465) 236 (220-251) 445 (429-461) 817 (772-883) 667

 60 years and older 452 (438-467) 226 (204-244) 457 (439-471) 893 (836-986) 857 

Females 

Total, 3 years and older 467 (459-475) 226 (215-234) 467 (453-478) 976 (930-1010) 3139

 3–5 years 760 (703-820) 471† (424-517) 754 (690-820) 1310† (1100-1510) 103

 6–11 years 657 (627-689) 378 (336-425) 679 (632-701) 1090 (976-1250) 234

 12–19 years 486 (470-502) 248 (236-267) 497 (470-523) 940 (870-1000) 538

 20–39 years 413 (403-423) 216 (206-227) 412 (398-424) 758 (736-859) 805

 40–59 years 445 (428-463) 218 (192-236) 434 (413-459) 920 (853-1060) 612

 60 years and older 490 (472-508) 227 (199-238) 482 (470-502) 1060 (983-1170) 847 

† Estimate is subject to greater uncertainty due to small cell size. 

1 Water-Soluble Vitamins & Related Biochemical Compounds 25
Table 1.4.a. Plasma homocysteine: Total population 

Geometric mean and selected percentiles of plasma concentrations (in μmol/L) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 7.36 (7.26-7.46) 3.92 (3.83-4.02) 7.36 (7.25-7.47) 13.6 (13.3-14.1) 16071

 3–5 years 4.26 (4.15-4.37) 2.84 (2.70-3.04) 4.24 (4.17-4.38) 6.16 (5.81-6.40) 830

 6–11 years 4.53 (4.44-4.63) 3.06 (2.93-3.23) 4.51 (4.42-4.60) 6.74 (6.53-6.97) 1933

 12–19 years 5.98 (5.87-6.10) 3.82 (3.65-3.95) 5.90 (5.79-6.03) 9.57 (9.34-9.91) 4357

 20–39 years 7.25 (7.15-7.36) 4.37 (4.21-4.53) 7.21 (7.12-7.31) 12.0 (11.6-12.4) 3194

 40–59 years 8.28 (8.17-8.38) 5.25 (5.17-5.35) 8.13 (8.02-8.23) 13.4 (12.8-14.1) 2703

 60 years and older 10.0 (9.80-10.3) 6.20 (6.12-6.32) 9.67 (9.40-9.93) 18.4 (17.6-19.0) 3054 

Males 

Total, 3 years and older 7.92 (7.81-8.03) 4.14 (4.02-4.23) 8.06 (7.92-8.17) 14.3 (13.8-14.7) 7811

 3–5 years 4.35 (4.23-4.48) 3.05 (2.69-3.31) 4.31 (4.20-4.48) 6.16 (5.82-6.32) 432

 6–11 years 4.60 (4.48-4.71) 3.08 (2.91-3.26) 4.57 (4.48-4.70) 6.90 (6.47-7.23) 988

 12–19 years 6.35 (6.21-6.49) 3.96 (3.74-4.23) 6.24 (6.14-6.40) 9.96 (9.54-10.9) 2177

 20–39 years 8.21 (8.06-8.36) 5.58 (5.37-5.74) 8.07 (7.87-8.20) 12.8 (12.1-13.8) 1358

 40–59 years 9.10 (8.94-9.26) 6.20 (5.99-6.50) 8.90 (8.70-9.13) 14.0 (13.0-14.7) 1345

 60 years and older 10.7 (10.5-10.9) 6.85 (6.53-7.09) 10.4 (10.1-10.7) 18.5 (17.6-19.0) 1511 

Females 

Total, 3 years and older 6.87 (6.76-6.98) 3.76 (3.65-3.87) 6.79 (6.67-6.88) 12.9 (12.5-13.3) 8260

 3–5 years 4.16 (4.01-4.32) 2.74 (2.60-3.01) 4.22 (4.03-4.37) 6.16 (5.76-6.53) 398

 6–11 years 4.47 (4.36-4.58) 3.04 (2.91-3.23) 4.45 (4.27-4.59) 6.58 (6.18-7.02) 945

 12–19 years 5.62 (5.48-5.77) 3.65 (3.46-3.90) 5.58 (5.42-5.73) 8.84 (8.28-9.57) 2180

 20–39 years 6.43 (6.30-6.57) 3.85 (3.64-4.08) 6.42 (6.25-6.55) 10.4 (9.81-11.4) 1836

 40–59 years 7.56 (7.43-7.69) 4.94 (4.75-5.05) 7.36 (7.20-7.52) 12.9 (12.3-13.4) 1358

 60 years and older 9.58 (9.29-9.87) 6.07 (5.93-6.18) 9.12 (8.90-9.37) 18.2 (16.9-19.4) 1543 

Table 1.4.b. Plasma homocysteine: Mexican Americans 

Geometric mean and selected percentiles of plasma concentrations (in μmol/L) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 6.35 (6.18-6.52) 3.54 (3.45-3.62) 6.35 (6.14-6.51) 11.6 (11.2-12.0) 4725

 3–5 years 4.10 (3.92-4.29) 2.84 (2.66-3.11) 4.09 (3.84-4.33) 5.80 (5.37-6.41) 271

 6–11 years 4.45 (4.34-4.56) 3.04 (2.82-3.25) 4.43 (4.30-4.61) 6.47 (6.18-6.60) 656

 12–19 years 5.73 (5.58-5.90) 3.74 (3.59-3.92) 5.65 (5.47-5.85) 9.06 (8.59-9.54) 1643

 20–39 years 6.77 (6.62-6.93) 4.08 (3.88-4.24) 6.80 (6.60-6.93) 11.8 (10.9-12.5) 870

 40–59 years 7.66 (7.38-7.94) 4.79 (4.47-5.08) 7.48 (7.18-7.89) 11.7 (11.3-12.4) 634

 60 years and older 9.57 (9.03-10.1) 5.63 (5.35-6.21) 9.34 (8.61-10.1) 17.7 (16.1-19.4) 651 

Males 

Total, 3 years and older 6.98 (6.81-7.17) 3.76 (3.60-3.87) 7.02 (6.87-7.20) 12.4 (11.9-12.8) 2305

 3–5 years 4.13 (3.97-4.29) 2.69† (2.60-3.20) 4.11 (3.84-4.48) 5.68† (5.26-6.40) 142

 6–11 years 4.59 (4.47-4.71) 3.04 (2.80-3.37) 4.62 (4.42-4.77) 6.56 (6.42-7.11) 339

 12–19 years 6.23 (6.07-6.40) 4.10 (3.92-4.22) 6.23 (6.01-6.42) 9.84 (9.07-10.7) 814

 20–39 years 7.77 (7.54-8.02) 5.01 (4.66-5.32) 7.43 (7.18-7.76) 12.8 (11.9-14.8) 386

 40–59 years 8.52 (8.17-8.89) 5.63 (5.27-6.22) 8.41 (8.04-8.91) 12.0 (11.4-14.5) 301

 60 years and older 10.1 (9.53-10.7) 6.34 (5.58-6.73) 10.1 (9.19-10.6) 18.7 (16.5-20.3) 323 

Females 

Total, 3 years and older 5.72 (5.53-5.92) 3.43 (3.30-3.56) 5.65 (5.47-5.80) 10.0 (9.26-11.2) 2420

 3–5 years 4.07 (3.78-4.39) 3.06† (2.72-3.23) 4.01 (3.69-4.31) 5.83† (4.89-8.23) 129

 6–11 years 4.31 (4.18-4.44) 3.04 (2.82-3.23) 4.28 (4.12-4.46) 5.91 (5.77-6.38) 317

 12–19 years 5.24 (5.07-5.40) 3.48 (3.31-3.69) 5.19 (5.01-5.41) 8.05 (7.65-8.31) 829

 20–39 years 5.75 (5.60-5.90) 3.66 (3.51-3.90) 5.79 (5.52-5.93) 8.56 (8.15-9.20) 484

 40–59 years 6.86 (6.54-7.19) 4.40 (3.92-4.82) 6.68 (6.35-7.08) 11.2 (9.70-13.7) 333

 60 years and older 9.16 (8.46-9.92) 5.44 (5.14-5.88) 8.84 (8.01-9.97) 17.2 (15.0-21.6) 328 

† Estimate is subject to greater uncertainty due to small cell size. 

26 26 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 1.4.c. Plasma homocysteine: Non-Hispanic blacks 

Geometric mean and selected percentiles of plasma concentrations (in μmol/L) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 7.14 (6.95-7.33) 3.72 (3.58-3.84) 7.07 (6.84-7.29) 14.3 (13.3-14.9) 3777

 3–5 years 4.16 (4.01-4.32) 2.82 (2.67-3.08) 4.08 (3.91-4.34) 6.18 (5.81-6.43) 246

 6–11 years 4.43 (4.29-4.57) 2.99 (2.84-3.21) 4.42 (4.29-4.57) 6.43 (6.23-6.75) 621

 12–19 years 5.96 (5.83-6.10) 3.73 (3.57-3.92) 5.92 (5.78-6.05) 9.66 (9.34-10.1) 1265

 20–39 years 7.22 (7.03-7.42) 4.33 (4.12-4.43) 7.22 (7.00-7.46) 11.9 (11.3-12.8) 597

 40–59 years 8.71 (8.33-9.09) 5.27 (4.87-5.66) 8.43 (8.08-8.83) 15.3 (13.7-18.8) 552

 60 years and older 10.9 (10.5-11.3) 6.39 (6.12-6.67) 10.2 (9.86-10.8) 21.3 (18.9-25.9) 496 

Males 

Total, 3 years and older 7.68 (7.43-7.92) 3.83 (3.72-4.00) 7.77 (7.52-8.04) 15.2 (14.6-15.9) 1853

 3–5 years 4.38 (4.17-4.60) 3.05† (2.68-3.34) 4.27 (4.06-4.61) 6.38† (5.79-6.57) 127

 6–11 years 4.53 (4.38-4.69) 2.99 (2.81-3.39) 4.53 (4.38-4.64) 6.51 (6.23-6.80) 314

 12–19 years 6.37 (6.22-6.52) 3.87 (3.69-4.08) 6.32 (6.16-6.44) 10.4 (9.70-11.0) 646

 20–39 years 8.46 (8.18-8.74) 5.54 (5.34-5.91) 8.22 (7.96-8.59) 14.3 (11.9-15.5) 249

 40–59 years 9.49 (9.03-9.97) 6.04 (5.32-6.45) 9.20 (8.62-9.54) 18.1 (14.7-20.2) 278

 60 years and older 11.5 (11.0-12.0) 6.83 (6.13-7.33) 11.0 (10.2-11.9) 21.3 (18.4-25.9) 239 

Females 

Total, 3 years and older 6.71 (6.50-6.94) 3.60 (3.50-3.76) 6.59 (6.38-6.78) 12.8 (12.2-13.7) 1924

 3–5 years 3.93 (3.72-4.16) 2.72† (2.54-2.97) 3.85 (3.58-4.29) 5.85† (5.13-6.39) 119

 6–11 years 4.33 (4.18-4.47) 2.94 (2.71-3.21) 4.33 (4.18-4.47) 6.39 (5.90-6.81) 307

 12–19 years 5.58 (5.41-5.75) 3.65 (3.46-3.82) 5.62 (5.45-5.77) 8.51 (7.92-9.32) 619

 20–39 years 6.41 (6.18-6.64) 4.07 (3.70-4.33) 6.42 (6.18-6.75) 9.75 (9.08-10.0) 348

 40–59 years 8.07 (7.67-8.50) 4.91 (4.63-5.33) 7.72 (7.38-8.48) 13.3 (11.7-19.2) 274

 60 years and older 10.6 (10.1-11.1) 6.20 (5.89-6.62) 9.92 (9.55-10.5) 22.5 (17.5-27.7) 257 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 1.4.d. Plasma homocysteine: Non-Hispanic whites 

Geometric mean and selected percentiles of plasma concentrations (in μmol/L) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 7.59 (7.47-7.71) 4.07 (3.97-4.19) 7.60 (7.48-7.74) 14.0 (13.4-14.4) 6192

 3–5 years 4.30 (4.14-4.45) 2.74 (2.64-3.19) 4.28 (4.19-4.49) 6.19 (5.74-6.90) 229

 6–11 years 4.56 (4.44-4.69) 3.14 (2.94-3.26) 4.51 (4.40-4.68) 6.94 (6.60-7.13) 497

 12–19 years 5.99 (5.86-6.12) 3.83 (3.59-4.03) 5.89 (5.76-6.07) 9.54 (9.23-10.2) 1078

 20–39 years 7.36 (7.24-7.49) 4.66 (4.37-4.83) 7.33 (7.16-7.49) 12.0 (11.5-12.4) 1383

 40–59 years 8.31 (8.19-8.42) 5.30 (5.18-5.44) 8.17 (8.03-8.28) 13.4 (12.5-14.1) 1286

 60 years and older 10.0 (9.74-10.3) 6.22 (6.12-6.44) 9.63 (9.33-9.92) 18.2 (17.4-19.0) 1719 

Males 

Total, 3 years and older 8.12 (7.99-8.25) 4.25 (4.15-4.38) 8.23 (8.11-8.38) 14.3 (13.9-14.8) 3026

 3–5 years 4.39 (4.18-4.61) 3.10† (2.44-3.48) 4.28 (4.20-4.56) 6.14† (5.65-7.22) 120

 6–11 years 4.62 (4.49-4.75) 3.15 (2.94-3.31) 4.55 (4.41-4.76) 6.91 (6.47-7.23) 264

 12–19 years 6.28 (6.11-6.46) 3.95 (3.64-4.25) 6.19 (6.00-6.36) 9.72 (9.38-11.4) 534

 20–39 years 8.21 (8.03-8.41) 5.62 (5.37-5.81) 8.10 (7.84-8.28) 12.4 (11.7-12.9) 577

 40–59 years 9.10 (8.92-9.28) 6.31 (5.99-6.56) 8.91 (8.68-9.18) 13.8 (12.7-14.4) 668

 60 years and older 10.7 (10.4-11.0) 6.88 (6.53-7.25) 10.3 (10.0-10.7) 18.2 (17.3-19.0) 863 

Females 

Total, 3 years and older 7.11 (6.97-7.25) 3.89 (3.69-4.07) 7.01 (6.89-7.14) 13.4 (12.8-14.2) 3166

 3–5 years 4.20 (3.97-4.44) 2.71† (2.06-3.19) 4.25 (4.04-4.59) 6.17† (5.58-6.90) 109

 6–11 years 4.50 (4.33-4.68) 3.11 (2.91-3.30) 4.47 (4.19-4.73) 6.94 (6.16-7.35) 233

 12–19 years 5.70 (5.52-5.88) 3.68 (3.43-3.97) 5.63 (5.40-5.84) 9.09 (8.36-10.2) 544

 20–39 years 6.61 (6.45-6.78) 3.90 (3.63-4.32) 6.52 (6.37-6.72) 11.2 (9.87-12.0) 806

 40–59 years 7.57 (7.40-7.75) 4.97 (4.67-5.13) 7.36 (7.18-7.57) 12.9 (11.7-14.0) 618

 60 years and older 9.53 (9.19-9.89) 6.04 (5.82-6.19) 9.09 (8.78-9.31) 18.2 (16.6-19.8) 856 

† Estimate is subject to greater uncertainty due to small cell size. 

1 Water-Soluble Vitamins & Related Biochemical Compounds 27
Table 1.5.a. Plasma methylmalonic acid: Total population 

Geometric mean and selected percentiles of plasma concentrations (in μmol/L) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older .131 (.129-.134) .070 (.060-.070) .120 (.120-.130) .290 (.280-.300) 16048

 3–5 years .120 (.116-.124) .060 (.060-.070) .120 (.110-.120) .230 (.200-.250) 829

 6–11 years .121 (.117-.125) .070 (.060-.070) .120 (.110-.120) .210 (.190-.220) 1929

 12–19 years .116 (.113-.120) .050 (.050-.060) .110 (.100-.110) .230 (.210-.240) 4352

 20–39 years .122 (.119-.125) .060 (.060-.070) .110 (.110-.120) .260 (.240-.270) 3189

 40–59 years .132 (.129-.134) .060 (.060-.070) .120 (.120-.130) .250 (.240-.270) 2701

 60 years and older .171 (.166-.176) .080 (.070-.080) .160 (.150-.160) .450 (.410-.530) 3048 

Males 

Total, 3 years and older .135 (.132-.138) .070 (.060-.070) .130 (.120-.130) .280 (.270-.300) 7799

 3–5 years .123 (.118-.129) .060 (.060-.070) .110 (.110-.120) .230 (.200-.280) 432

 6–11 years .125 (.120-.130) .060 (.060-.070) .110 (.110-.120) .200 (.180-.220) 986

 12–19 years .122 (.118-.126) .070 (.060-.070) .120 (.110-.120) .230 (.220-.270) 2175

 20–39 years .128 (.123-.132) .060 (.060-.070) .130 (.120-.130) .250 (.230-.290) 1355

 40–59 years .136 (.132-.140) .080 (.070-.080) .130 (.120-.130) .270 (.240-.300) 1343

 60 years and older .173 (.168-.178) .070 (.070-.080) .160 (.150-.160) .450 (.420-.500) 1508 

Females 

Total, 3 years and older .128 (.126-.131) .070 (.060-.070) .110 (.110-.120) .280 (.260-.280) 8249

 3–5 years .116 (.111-.122) .060 (.060-.070) .110 (.110-.120) .200 (.180-.250) 397

 6–11 years .117 (.112-.123) .070 (.060-.070) .110 (.110-.120) .190 (.180-.200) 943

 12–19 years .111 (.107-.116) .050 (.050-.060) .100 (.100-.110) .220 (.200-.260) 2177

 20–39 years .117 (.114-.120) .050 (.050-.060) .100 (.100-.110) .260 (.230-.270) 1834

 40–59 years .127 (.124-.131) .060 (.060-.070) .110 (.110-.120) .250 (.230-.300) 1358

 60 years and older .170 (.164-.177) .070 (.070-.080) .150 (.140-.150) .460 (.380-.570) 1540 

Table 1.5.b. Plasma methylmalonic acid: Mexican Americans 

Geometric mean and selected percentiles of plasma concentrations (in μmol/L) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older .111 (.108-.113) .050 (.050-.060) .110 (.100-.110) .220 (.220-.240) 4726

 3–5 years .108 (.103-.112) .070 (.060-.070) .110 (.100-.110) .180 (.170-.210) 271

 6–11 years .104 (.100-.109) .060 (<LOD-.060) .100 (.090-.100) .180 (.160-.190) 656

 12–19 years .104 (.102-.107) .060 (.050-.060) .100 (.090-.100) .190 (.180-.220) 1644

 20–39 years .108 (.103-.113) .050 (<LOD-.060) .100 (.090-.100) .230 (.210-.270) 870

 40–59 years .116 (.112-.120) .060 (.050-.060) .110 (.100-.110) .230 (.220-.270) 634

 60 years and older .150 (.145-.155) .060 (.060-.080) .130 (.120-.130) .440 (.400-.530) 651 

Males 

Total, 3 years and older .117 (.114-.121) .060 (<LOD-.060) .100 (.100-.110) .250 (.230-.280) 2305

 3–5 years .108 (.102-.115) .060† (.050-.080) .100 (.100-.110) .180† (.160-.210) 142

 6–11 years .104 (.099-.109) .050 (<LOD-.070) .110 (.100-.110) .170 (.150-.200) 339

 12–19 years .111 (.107-.115) .050 (<LOD-.060) .110 (.100-.110) .210 (.190-.230) 814

 20–39 years .118 (.112-.125) .060 (<LOD-.060) .110 (.100-.110) .280 (.230-.390) 385

 40–59 years .125 (.119-.132) .070 (.060-.070) .110 (.110-.120) .260 (.220-.350) 301

 60 years and older .151 (.141-.162) .070 (.060-.080) .140 (.130-.150) .500 (.330-.630) 324 

Females 

Total, 3 years and older .104 (.102-.106) .050 (.050-.060) .095 (.090-.100) .210 (.190-.220) 2421

 3–5 years .107 (.100-.114) .060† (<LOD-.070) .110 (.100-.120) .170† (.160-.210) 129

 6–11 years .105 (.100-.111) .070 (.060-.070) .100 (.090-.100) .170 (.150-.200) 317

 12–19 years .097 (.095-.100) .060 (.050-.060) .100 (.090-.100) .170 (.170-.200) 830

 20–39 years .097 (.093-.103) < LOD .100 (.090-.100) .170 (.160-.210) 485

 40–59 years .107 (.102-.112) .060 (.050-.060) .090 (.090-.100) .190 (.180-.220) 333

 60 years and older .148 (.140-.157) .070 (<LOD-.080) .120 (.120-.130) .430 (.380-.560) 327 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

28 28 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 1.5.c. Plasma methylmalonic acid: Non-Hispanic blacks 

Geometric mean and selected percentiles of plasma concentrations (in μmol/L) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older .110 (.107-.114) .050 (.050-.060) .100 (.100-.110) .220 (.210-.240) 3768

 3–5 years .102 (.097-.107) .060 (<LOD-.060) .090 (.090-.100) .170 (.160-.200) 245

 6–11 years .103 (.099-.107) .070 (.060-.070) .100 (.090-.100) .170 (.150-.190) 619

 12–19 years .101 (.097-.105) .050 (.050-.060) .100 (.090-.100) .180 (.180-.200) 1264

 20–39 years .101 (.097-.106) .060 (.050-.060) .100 (.090-.100) .180 (.160-.220) 596

 40–59 years .115 (.109-.122) .060 (<LOD-.060) .110 (.100-.110) .230 (.190-.270) 551

 60 years and older .156 (.148-.165) .070 (.070-.080) .140 (.130-.140) .400 (.310-.500) 493 

Males 

Total, 3 years and older .115 (.111-.119) .050 (.050-.060) .100 (.100-.110) .230 (.220-.260) 1846

 3–5 years .103 (.096-.110) .060† (<LOD-.060) .090 (.090-.110) .180† (.150-.230) 127

 6–11 years .104 (.100-.109) .060 (<LOD-.060) .100 (.090-.100) .160 (.150-.190) 312

 12–19 years .107 (.102-.112) .060 (<LOD-.060) .100 (.090-.100) .190 (.180-.240) 645

 20–39 years .110 (.103-.119) .060 (<LOD-.070) .100 (.100-.110) .220 (.170-.260) 248

 40–59 years .119 (.111-.128) < LOD .120 (.110-.120) .250 (.200-.290) 277

 60 years and older .155 (.143-.167) .070 (.050-.070) .140 (.120-.150) .450 (.310-.560) 237 

Females 

Total, 3 years and older .107 (.104-.110) .050 (.050-.060) .090 (.090-.100) .220 (.200-.230) 1922

 3–5 years .101 (.094-.109) .050† (<LOD-.070) .100 (.090-.100) .150† (.130-.190) 118

 6–11 years .102 (.097-.107) .060 (.060-.070) .100 (.090-.100) .170 (.150-.200) 307

 12–19 years .095 (.090-.100) < LOD .080 (.080-.090) .170 (.160-.180) 619

 20–39 years .095 (.092-.099) .060 (.050-.060) .080 (.080-.090) .160 (.140-.180) 348

 40–59 years .112 (.104-.121) .050 (<LOD-.070) .110 (.100-.110) .210 (.170-.230) 274

 60 years and older .157 (.147-.168) .080 (.070-.080) .140 (.120-.140) .390 (.270-.620) 256 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 1.5.d. Plasma methylmalonic acid: Non-Hispanic whites 

Geometric mean and selected percentiles of plasma concentrations (in μmol/L) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older .139 (.136-.142) .080 (.070-.080) .130 (.120-.130) .290 (.280-.300) 6178

 3–5 years .129 (.123-.136) .080 (.070-.080) .120 (.110-.120) .240 (.210-.270) 229

 6–11 years .130 (.124-.137) .070 (.070-.080) .130 (.110-.130) .230 (.200-.270) 495

 12–19 years .124 (.120-.128) .070 (.060-.070) .110 (.110-.120) .230 (.220-.280) 1073

 20–39 years .130 (.126-.133) .070 (.060-.070) .120 (.120-.130) .250 (.230-.270) 1380

 40–59 years .136 (.132-.139) .070 (.070-.080) .130 (.120-.130) .250 (.240-.280) 1285

 60 years and older .174 (.168-.179) .090 (.080-.090) .160 (.150-.160) .450 (.380-.530) 1716 

Males 

Total, 3 years and older .141 (.138-.145) .080 (.070-.080) .140 (.130-.140) .280 (.270-.300) 3021

 3–5 years .136 (.127-.146) .080† (.050-.080) .130 (.120-.140) .250† (.210-.340) 120

 6–11 years .134 (.126-.143) .080 (.060-.080) .120 (.110-.130) .240 (.200-.310) 264

 12–19 years .129 (.124-.134) .060 (.060-.070) .110 (.110-.120) .240 (.220-.280) 533

 20–39 years .132 (.127-.138) .060 (.060-.070) .130 (.120-.130) .250 (.230-.290) 576

 40–59 years .139 (.134-.144) .070 (.070-.080) .120 (.120-.130) .270 (.240-.300) 667

 60 years and older .174 (.168-.180) .090 (.080-.100) .170 (.160-.170) .440 (.380-.490) 861 

Females 

Total, 3 years and older .137 (.134-.140) .080 (.070-.080) .120 (.120-.130) .290 (.280-.310) 3157

 3–5 years .122 (.113-.132) .070† (.070-.090) .120 (.110-.120) .200† (.160-.250) 109

 6–11 years .125 (.117-.134) .070 (.060-.080) .110 (.110-.130) .210 (.180-.270) 231

 12–19 years .119 (.114-.125) .070 (.060-.070) .100 (.100-.110) .230 (.200-.300) 540

 20–39 years .127 (.123-.131) .060 (.060-.070) .110 (.110-.120) .260 (.250-.280) 804

 40–59 years .132 (.128-.137) .080 (.070-.080) .130 (.120-.130) .250 (.220-.300) 618

 60 years and older .173 (.166-.181) .090 (.080-.090) .160 (.150-.160) .450 (.370-.570) 855 

† Estimate is subject to greater uncertainty due to small cell size. 

1 Water-Soluble Vitamins & Related Biochemical Compounds 29
References 

Baik HW, Russel RM. Vitamin B12 deficiency in the elderly. Annu Rev Nutr. 1999;19:357-77. 

Czeizel AE, Dudas I. Prevention of the first occurrence of neural-tube defects by periconceptional vitamin 

supplementation. N Engl J Med. 1992;327:1832-5. 

French AE, Grant R, Weitzman S, Ray JG, Vermeulen MJ, Sung L, et al. Folic acid food fortification is 

associated with a decline in neuroblastoma. Clin Pharmacol Ther. 2003;74:288-94. 

Gibson RS. Principles of nutritional assessment. New York: Oxford University Press; 1990. 

Halsted CH. Intestinal absorption of dietary folates. In: Picciano MF, Stokstad ELR, Gregory JF, editors. 

Folic acid metabolism in health and disease. New York: Wiley-Liss, Inc.; 1990. p. 23-45. 

Hølleland G, Schneede J, Ueland PM, Lund PK, Refsum H, Sandberg S. Cobalamin deficiency in 

general practice. Assessment of the diagnostic utility and cost-benefit analysis of methylmalonic acid 

determination in relation to current diagnostic strategies. Clin Chem. 1999;45:189-98. 

Institute of Medicine, Food and Nutrition Board. Dietary reference intakes: thiamin, riboflavin, niacin, 

vitamin B6, folate, vitamin B12, pantothenic acid, biotin, and choline. Washington, D.C.: National 

Academy Press; 1998. 

Jacques PF, Selhub J, Bostom AG, Wilson PF, Rosenberg IH. The effect of folic acid fortification on plasma 

folate and total homocysteine concentrations. N Engl J Med. 1999;340:1449-54. 

Life Sciences Research Office, Center for Food Safety and Applied Nutrition. Assessment of the folate 

nutritional status of the U.S. population based on data collected in the Second National Health and 

Nutrition Survey, 1976–1980. Washington, D.C.: U.S. Food and Drug Administration, Department of 

Health and Human Services; 1984. 

Life Sciences Research Office, Center for Food Safety and Applied Nutrition. Assessment of folate 

methodology used in the Third National Health and Nutrition Survey (NHANES 1988–1994). Washington, 

D.C.: U.S. Food and Drug Administration, Department of Health and Human Services; 1994. 

MRC Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research 

Council Vitamin Study. Lancet. 1991;338:131-7. 

Pfeiffer CM, Caudill SP, Gunter EW, Osterloh J, Sampson EJ. Biochemical indicators of B vitamin status 

in the U.S. population after folic acid fortification: results from the National Health and Nutrition 

Examination Survey, 1999–2000. Am J Clin Nutr. 2005;82:442-50. 

Pfeiffer CM, Johnson CL, Jain RB, Yetley EA, Picciano MF, Rader JI, Fisher KD, Mulinare J, Osterloh J. 

Trends in blood folate and vitamin B12 concentrations in the United States, 1988–2004. Am J Clin Nutr. 

2007;86:718-27. 

Pfeiffer CM, Osterloh JD, Kennedy-Stephenson J, Picciano MF, Yetley EA, Rader JI, Johnson CL. Trends 

in circulating concentrations of total homocysteine among US adolescents and adults: findings 

from the 1991–1994 and 1999–2004 National Health and Nutrition Examination Surveys. Clin Chem. 

2008;54:801-13. 

Selhub J, Jacques PF, Wilson PWF, Rush D, Rosenberg IH. Vitamin status and intake as primary 

determinants of homocysteinemia in an elderly population. JAMA. 1993;270:2693-8. 

30 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Senti FR, Pilch SM. Analysis of folate data from the Second National Health and Nutrition Examination 

Survey (NHANES II). J Nutr. 1985;115:1398–402. 

U.S. Centers for Disease Control and Prevention. Recommendations for the use of folic acid to reduce 

the number of cases of spina bifida and other neural tube defects. Morb Mort Wkly Rep. 1992;41(No. 

RR-14):001. 

U.S. Department of Health and Human Services. Healthy people 2010: understanding and improving 

health. 2nd ed. Washington, D.C.: U.S. Government Printing Office; November 2000. 

U.S. Food and Drug Administration. Food standards: amendment of standards of identity for enriched 

grain products to require addition of folic acid. Final rule. Fed Regist. 1996a;61(44):8781–97. 

U.S. Food and Drug Administration. Food labeling: health claims and label statements; folate and neural 

tube defects. Final rule. Fed Regist. 1996b;61(44):8752–81. 

Williams LJ, Rasmussen SA, Flores A, Kirby RS, Edmonds LD. Decline in the prevalence of spina bifida and 

anencephaly by race/ethnicity: 1995-2002. Pediatrics. 2005;116:580–6. 

Wollensen F, Brattstrom L, Refsum H, Ueland PM, Berglund L, Berne C. Plasma total homocysteine and 

cysteine in relation to glomerular filtration rate in diabetes mellitus. Kidney Int. 1999;55:1028–35. 

Wright JD, Bialostosky K, Gunter EW, Carroll MD, Najjar MF, Bowman BA, et al. Blood folate and vitamin 

B12: United States, 1988-1994. National Center for Health Statistics. Vital Health Stat Series No. 11(243), 

1998. 

Yang Q, Botto LD, Erickson JD, Berry RJ, Sambell C, Johansen H, et al. Improvement in stroke mortality in 

Canada and the United States, 1990–2002. Circulation. 2006;113:1335–43. 

1 Water-Soluble Vitamins & Related Biochemical Compounds 31 
32 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
2 

Fat-Soluble Vitamins 

& Micronutrients 

Vitamins A and E and Carotenoids 

•	 Vitamin A 

•	 Vitamin E 

•	 gamma-Tocopherol 

•	 alpha-Carotene 

•	 trans-beta -Carotene 

•	 beta -Cryptoxanthin 

•	 Lutein/zeaxanthin 

•	 trans-Lycopene 

Vitamin D 

•	 25-Hydroxyvitamin D 

33 
34 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Fat-Soluble Vitamins & Micronutrients: 

Vitamins A and E and 

Carotenoids 

Vitamins A (retinol) and E (tocopherol) and the carotenoids are fat-soluble 

micronutrients that are found in many foods, including some vegetables, 

fruits, meats, and animal products. Fish-liver oils, liver, egg yolks, butter, 

and cream are known for their higher content of vitamin A. Nuts and 

seeds are particularly rich sources of vitamin E (Thomas 2006). At least 700 

carotenoids—fat-soluble red and yellow pigments—are found in nature 

(Britton 2004). Americans consume 40–50 of these carotenoids, primarily 

in fruits and vegetables (Khachik 1992), and smaller amounts in poultry 

products, including egg yolks, and in seafoods (Boylston 2007). Six major 

carotenoids are found in human serum: alpha-carotene, beta-carotene, 

beta-cryptoxanthin, lutein, trans-lycopene, and zeaxanthin. Major 

carotene sources are orange-colored fruits and vegetables such as carrots, 

pumpkins, and mangos. Lutein and zeaxanthin are also found in dark 

green leafy vegetables, where any orange coloring is overshadowed by 

chlorophyll. Trans-Lycopene is obtained primarily from tomato and tomato 

products. For information on the carotenoid content of U.S. foods, see the 

1998 carotenoid database created by the U.S. Department of Agriculture 

and the Nutrition Coordinating Center at the University of Minnesota 

(http://www.nal.usda.gov/fnic/foodcomp/Data/car98/car98.html). 

Vitamin A, found in foods that come from animal sources, is called 

preformed vitamin A. Some carotenoids found in colorful fruits and 

vegetables are called provitamin A; they are metabolized in the body to 

vitamin A. Among the carotenoids, beta-carotene, a retinol dimer, has 

the most significant provitamin A activity. Because of limitations in the 

body’s ability to absorb and metabolize vitamin A, approximately 12 

micrograms (μg) of dietary beta-carotene are needed to equal 1 μg of 

retinol. Other provitamin A carotenoids, such as alpha-carotene and betacryptoxanthin, are half as active as beta-carotene (Institute of Medicine 2000). 

The bioconversion of carotenoids to vitamin A is highly variable from 

person to person (Krinsky 2005). Vitamin E activity is derived from at least 

eight naturally occurring tocopherols, the most potent of which is alphatocopherol. Other less active forms of vitamin E are plentiful in the U.S. 

diet, with gamma-tocopherol being the predominant form. 

2 Fat-Soluble Vitamins & Micronutrients 35 
The absorption of fat-soluble micronutrients from the gastrointestinal tract 

depends on processes responsible for fat absorption or metabolism. Thus, people 

with conditions resulting in fat malabsorption (e.g., celiac disease, Crohn’s disease, 

pancreatic disorders) can develop vitamin A deficiency over time. Vitamin A also 

has interactions with other nutrients. Iron and zinc deficiency can affect vitamin A 

metabolism and transport of vitamin A stores from the liver to body tissues (Institute 

of Medicine 2001). The absorption of carotenoids from foods is highly dependent on 

cooking techniques that break down plant cell walls and release carotenoids and 

also on the availability of dietary fat to enhance carotenoid uptake (Krinsky 2005). 

The liver regulates the concentration of vitamin A in the circulation by releasing 

stored retinyl esters as needed; only when liver reserves are nearly exhausted does 

serum vitamin A fall into the deficient range (Napoli 2006). The variation in serum 

carotenoid concentrations among people in the United States is relatively large, 

primarily reflecting wide-ranging differences in dietary intake (Lacher 2005). Plasma 

concentrations of tocopherols vary widely among healthy individuals and are highly 

correlated with plasma lipid concentrations (Ford 1999; Ford 2006). 

Inadequate or excessive intake of vitamins A or E can lead to various disorders. For 

example, vitamin A deficiency is considered to be the main cause of childhood 

blindness (Roodhooft 2002), a rare condition in the United States. Prominent signs of 

vitamin A deficiency include night blindness, corneal thinning, and conjunctival 

metaplasia. Vitamin A is also essential for proper immune function, epithelial 

growth and repair, bone growth, reproduction, and normal embryonic and fetal 

development (West 2006). Acute toxicity, resulting from single or short-term large 

doses of preformed vitamin A, is characterized by nausea, vomiting, headache, 

vertigo, blurred vision, increased cerebrospinal fluid pressure, and lack of muscular 

coordination. Central nervous system effects, liver abnormalities, bone and skin 

changes, and other nonspecific adverse effects can be indicative of chronic 

hypervitaminosis A. Consuming excess amounts of vitamin A during early pregnancy 

may lead to serious birth defects (Institute of Medicine 2001). The U.S. Food and Drug 

Administration (FDA) currently recommends that pregnant women obtain vitamin A 

from foods containing beta-carotene (U.S. Food and Drug Administration 1995). 

Carotenoids are considered among the best biological markers for fruit 

and vegetable intake. The strongest dietary predictors of serum carotenoid 

concentrations are fruits (for sources of beta-cryptoxanthin), carrots and root 

vegetables (for sources of carotenes), and tomato products (for sources of translycopene) (Al-Delaimy 2005). Research studies have shown inconsistencies in the relation 

between carotenoid intake and protection from cancer. Carotenoids in foods, even 

when consumed over long periods and in large amounts, are not known to produce 

adverse health effects. However, results of intervention studies of smokers who used 

20-30 milligrams (mg) of beta-carotene per day showed that this group had more 

lung cancers than placebo-treated groups (Redlich 1998; Albanes 1996). 

Vitamin E deficiency occurs only rarely in people, and overt deficiency symptoms in 

people consuming low-vitamin E diets have never been described (Institute of Medicine 

2000). The main manifestation of vitamin E deficiency is peripheral neuropathy 

characterized by the degeneration of the large-caliber axons of sensory neurons 

36 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
(Institute of Medicine 2000). The upper limit (UL) for vitamin E intake (1000 mg/day) was 

based on hemorrhagic effects; however, a causal association between excess alphatocopherol intake in apparently healthy individuals and adverse health outcomes 

has not consistently been shown (Institute of Medicine 2000). Studies evaluating 

tocopherols to reduce the risk for cardiovascular disease demonstrated inconsistent 

findings (Agency for Healthcare Research and Quality 2003). The American Heart Association 

currently advises that antioxidant supplements (such as vitamins E and C and betacarotene) should not be used for primary or secondary prevention of cardiovascular 

disease (Lichtenstein 2006). Nevertheless, the American Heart Association recommends 

consuming food sources of antioxidant nutrients, principally from a variety of plantderived foods such as fruits, vegetables, whole grains, and vegetable oils. 

The National Academy of Sciences has established dietary-requirement intake values 

for vitamins A and E by determining the adequate intake (AI) for infants and the 

recommended dietary allowance (RDA) for older age groups (Institute of Medicine 2000 

and 2001). The RDA for vitamin A for adults is 900 μg/day of retinol equivalents; for 

children, the RDA ranges from 300–700 μg/day. For infants (aged 0–12 months), the 

AI is set at 400–500 μg/day of retinol equivalents. For adults, the RDA for vitamin E 

is 15 mg/day of alpha-tocopherol; for children (1–18 years), the RDA ranges from 

6 mg to 15 mg/day. There is no RDA for other forms of vitamin E such as gammatocopherol. Although no quantitative recommendations are available for the intake 

of carotenoids, existing recommendations support increased consumption of 

carotenoid-rich fruits and vegetables. Current public health guidelines advise that 

people consume 5 to 13 servings of fruits and vegetables a day, depending on caloric 

need, to ensure adequate nutrient intake (U.S. Department of Health and Human Services and 

U.S. Department of Agriculture 2005). 

Clinical laboratories typically use 

conventional units for serum 

concentrations of these fat-soluble 

micronutrients (μg per deciliter 

[dL]). Conversion factors to 

international system (SI) units are 1 

μg/dL = 0.0349 micromole per liter 

(μmol/L) for vitamin A and 1 μg/ 

dL = 0.02322 μmol/L for vitamin 

E. Depending on its molecular 

weight, each carotenoid has a 

specific conversion factor. 

The diagnosis of vitamin A or 

E deficiency is supported by 

measuring these concentrations in 

the body. Vitamin A deficiency can 

be diagnosed in a number of ways. 

People with serum concentrations of retinol of less than 20 μg/dL are considered 

vitamin A deficient, and those with serum concentrations of less than 10 μg/dL are 

considered severely deficient (West 2006). Carotenoid deficiency has no defined serum 

Chemists perform extraction of fat-soluble vitamins from serum. 

2 Fat-Soluble Vitamins & Micronutrients 37 
concentrations. The laboratory diagnosis of vitamin E deficiency is based on serum 

concentrations of alpha-tocopherol (less than 500 μg/dL or less than 0.8 mg of alphatocopherol per gram of total lipids) (Beers 2006). Such concentrations are associated 

with in vitro hydrogen peroxide-induced red blood cell lysis, not with clinical 

deficiency symptoms (Institute of Medicine 2000). Among most laboratories participating 

in an external quality assurance program, standardized high performance liquid 

chromatography (HPLC) methods for measuring fat-soluble micronutrients show 

consistent agreement of values (Duewer 2000). 

For more information on these fat-soluble micronutrients, see the Institute of 

Medicine’s Dietary Reference Intake reports (Institute of Medicine 2000 and 2001), 

the vitamin fact sheets from the National Institutes of Health, Office of Dietary 

Supplements (http://ods.od.nih.gov/Health_Information/Vitamin_and_Mineral 

_Supplement_Fact_Sheets.aspx), as well as information from the American Society for 

Nutrition (http://jn.nutrition.org/nutinfo/). 

Since 1971, various fat-soluble micronutrients have been measured in the serum 

of NHANES participants. In NHANES III (1988–1994), clinically low concentrations of 

serum retinol were uncommon in U.S. residents aged 4 years and older, although 

racial/ethnic and socioeconomic differences existed (Ballew 2001). Variations in serum 

carotenoid concentrations by ethnicity and sex were found for adults, children, and 

adolescents (Ford 2000; Ford 2002). Ford et al. also found sociodemographic variations 

in serum concentrations of alpha-tocopherol among U.S. adults in NHANES III (1999) 

and alpha- and gamma-tocopherol in NHANES 1999–2000 (2006). Application of the 

most common cut-off value for serum alpha-tocopherol concentrations in NHANES 

1999–2000 (500 μg/dL), resulted in a low prevalence of vitamin E deficiency, despite 

the fact that the U.S. Department of Agriculture (USDA) estimated dietary intakes of 

vitamin E were low and that most of the U.S. population (> 90 percent) did not meet 

dietary recommendations either in 1999–2000 (Ahuja 2004) or in 2001–2002 (Moshfegh 

2005). However, the USDA report is based on intakes from food only and does not 

include dietary supplements. Furthermore, in NHANES only alpha-tocopherol is 

estimated for assessing dietary vitamin E intake. In NHANES 2001–2002, 44 percent 

of survey participants had an estimated dietary intake (from food only) of vitamin 

A (including carotenoids) that was less than the vitamin A estimated average 

requirement (EAR) (Moshfegh 2005). Low dietary intakes of certain micronutrients 

without widespread manifestation of deficiency suggest the need for further 

evaluations to determine whether improved estimates are necessary, either in the 

nutrient tables or in dietary intake. 

38 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Selected Observations and Highlights 

The following sample observations are taken from the tables of 1999–2002 (for 

vitamins A and E) or 2001–2002 data (for all carotenoids) contained in this report.	

Statements about categorical differences between demographic groups noted 

below are based on non-overlapping confidence limits from univariate analysis 

without adjusting for demographic variables (e.g., age, sex, race/ethnicity) or other 

determinants of these blood concentrations (e.g., dietary intake, supplement usage, 

smoking, BMI). A multivariate analysis may alter the size and statistical significance 

of these categorical differences. Furthermore, additional significant differences 

of smaller magnitude may be present despite their lack of mention here (e.g., if 

confidence limits slightly overlap or if differences are unobservable before covariate 

adjustment has occurred). For a selection of citations of descriptive NHANES papers 

related to these biochemical indicators of diet and nutrition, see Appendix E. 

General Observations 

•	 Serum vitamin A and E concentrations are lower in children and adolescents 

than in adults. 

•	 Serum beta-carotene concentrations are higher in older people (≥ 60 years), 

whereas serum alpha-carotene and lutein/zeaxanthin concentrations are 

higher in middle-aged and older people compared with people in younger 

age groups. 

•	 Serum beta-cryptoxanthin concentrations are higher in children than in 

adolescents or adults. 

•	 Serum trans-lycopene and gamma-tocopherol concentrations are lower in 

young children and older people than in people in other age groups. 

•	 Serum alpha-carotene and lutein/zeaxanthin concentrations are lower in 

adolescents, whereas serum beta-carotene concentrations are lower in 

adolescents and in adults 20–39 years old than in people in other age groups. 

•	 Females have lower concentrations of serum vitamin A and trans-lycopene 

than do males. Females have higher concentrations of serum vitamin E and 

beta-carotene than do males. 

•	 Non-Hispanic blacks and Mexican Americans have lower serum 


concentrations of vitamin A than do non-Hispanic whites.
 

•	 Non-Hispanic blacks have lower serum concentrations of vitamin E than do 

Mexican Americans, who have lower serum concentrations of vitamin E than 

do non-Hispanic whites. 

•	 Non-Hispanic blacks have higher serum concentrations of gamma-tocopherol 

than do Mexican Americans and non-Hispanic whites. 

2 Fat-Soluble Vitamins & Micronutrients 39 
•	 Non-Hispanic blacks have lower serum concentrations of alpha-carotene than 

do non-Hispanic whites or Mexican Americans. 

•	 Non-Hispanic whites have lower serum concentrations of beta-cryptoxanthin 

than do non-Hispanic blacks, who have lower serum concentrations of betacryptoxanthin than do Mexican Americans. 

•	 Non-Hispanic blacks have higher serum concentrations of trans-lycopene than 

do Mexican Americans. 

Highlights 

The majority of the U.S. population (> 95 percent) has adequate serum concentrations of 

vitamin A (≥ 20 μg/dL) and vitamin E (≥ 500 μg/dL). 

40 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
2 Fat-Soluble Vitamins & Micronutrients 41 
Table 2.1.a. Serum vitamin A: Total population 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 53.5 (52.7-54.3) 30.9 (30.3-31.7) 54.5 (53.6-55.4) 87.0 (85.8-88.4) 15819

 3–5 years 33.1 (32.6-33.7) 22.7 (21.4-24.4) 33.7 (33.0-34.4) 46.5 (44.1-47.8) 782

 6–11 years 36.3 (35.7-37.0) 26.0 (24.8-26.3) 36.4 (35.7-37.1) 51.2 (49.4-52.6) 1880

 12–19 years 47.0 (46.3-47.6) 30.8 (30.1-31.4) 47.4 (46.6-48.0) 70.6 (68.9-72.1) 4317

 20–39 years 53.6 (52.6-54.6) 33.6 (32.5-34.6) 54.6 (53.5-55.6) 82.3 (80.3-83.8) 3177

 40–59 years 59.7 (58.8-60.6) 37.1 (35.0-38.7) 60.6 (59.4-61.4) 92.6 (88.9-95.2) 2665

 60 years and older 63.8 (62.9-64.7) 40.2 (38.1-41.4) 64.5 (63.2-65.3) 98.8 (95.6-102) 2998 

Males 

Total, 3 years and older 56.3 (55.3-57.3) 31.7 (30.8-32.9) 58.1 (56.9-59.3) 88.7 (86.5-91.2) 7701

 3–5 years 32.9 (32.1-33.7) 21.9 (17.1-25.0) 33.9 (33.0-35.0) 45.4 (43.2-47.5) 410

 6–11 years 36.1 (35.2-37.1) 26.0 (24.5-26.5) 36.1 (35.3-37.1) 51.3 (49.4-52.6) 956

 12–19 years 49.1 (48.2-50.1) 32.1 (30.9-33.8) 49.8 (48.8-50.9) 71.3 (69.3-72.9) 2164

 20–39 years 58.4 (57.5-59.4) 40.3 (39.0-41.6) 59.0 (58.0-60.1) 83.5 (80.9-85.5) 1349

 40–59 years 64.6 (63.3-65.9) 42.4 (40.4-44.3) 66.0 (65.0-67.7) 95.3 (92.8-98.4) 1332

 60 years and older 65.4 (63.9-66.9) 41.2 (38.7-42.7) 66.1 (64.6-68.2) 101 (96.4-106) 1490 

Females 

Total, 3 years and older 50.9 (50.1-51.7) 30.3 (29.4-31.1) 50.9 (50.1-51.8) 85.2 (83.3-87.2) 8118

 3–5 years 33.4 (32.7-34.1) 24.1 (22.2-25.3) 33.1 (32.5-34.5) 47.1 (44.7-49.7) 372

 6–11 years 36.5 (35.8-37.2) 26.2 (24.7-26.9) 36.7 (36.1-37.5) 50.4 (49.0-52.2) 924

 12–19 years 44.8 (43.9-45.6) 29.7 (29.0-30.9) 44.7 (43.5-45.9) 68.8 (66.0-71.9) 2153

 20–39 years 49.2 (48.1-50.4) 30.7 (29.7-31.8) 49.1 (47.3-50.7) 80.8 (78.0-82.4) 1828

 40–59 years 55.3 (54.3-56.3) 34.4 (32.4-35.4) 55.5 (54.2-56.4) 87.3 (84.8-91.3) 1333

 60 years and older 62.6 (61.6-63.6) 39.4 (36.2-41.4) 63.0 (62.0-64.4) 96.8 (92.0-101) 1508 

Table 2.1.b. Serum vitamin A: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 46.8 (46.0-47.7) 28.1 (27.2-28.9) 47.1 (46.0-48.1) 75.6 (73.7-77.8) 4662

 3–5 years 31.6 (30.7-32.6) 22.6 (21.7-23.8) 31.9 (30.2-33.7) 43.2 (40.4-45.6) 261

 6–11 years 35.4 (34.8-36.0) 24.6 (23.8-26.2) 35.6 (34.9-36.2) 48.9 (47.2-50.8) 644

 12–19 years 44.8 (44.2-45.5) 30.7 (28.7-31.9) 45.0 (44.1-45.8) 64.6 (63.6-65.9) 1626

 20–39 years 50.6 (49.6-51.6) 31.9 (29.8-33.5) 50.9 (49.0-52.8) 75.2 (73.8-77.8) 866

 40–59 years 52.8 (51.4-54.3) 32.5 (30.4-35.0) 53.9 (52.4-55.3) 83.7 (78.8-87.4) 628

 60 years and older 55.9 (52.9-59.2) 34.0 (31.2-36.5) 55.3 (52.2-59.9) 91.0 (82.4-107) 637 

Males 

Total, 3 years and older 50.6 (49.7-51.6) 29.8 (28.8-30.5) 51.7 (50.5-53.2) 79.1 (77.0-82.4) 2277

 3–5 years 32.5 (30.6-34.5) 22.4† (20.1-25.0) 32.9 (30.7-34.5) 45.2† (41.1-51.2) 136

 6–11 years 35.4 (34.6-36.2) 24.6 (23.2-27.1) 35.4 (34.5-36.2) 49.2 (45.9-51.3) 333

 12–19 years 48.1 (47.1-49.1) 33.7 (32.1-34.9) 48.3 (47.0-49.7) 67.8 (65.6-69.7) 807

 20–39 years 56.6 (55.3-57.9) 39.3 (37.4-41.9) 57.5 (55.8-59.1) 78.3 (75.2-86.5) 382

 40–59 years 57.9 (55.9-59.9) 36.3 (32.4-40.4) 57.9 (56.1-60.2) 87.4 (83.0-95.3) 298

 60 years and older 57.0 (54.3-60.0) 35.3 (33.1-37.1) 55.5 (52.9-61.3) 93.4 (79.8-118) 321 

Females 

Total, 3 years and older 43.0 (42.1-43.9) 27.0 (26.1-27.8) 42.6 (41.5-43.6) 69.8 (65.7-73.1) 2385

 3–5 years 30.8 (29.4-32.2) 22.6† (20.3-24.7) 30.4 (27.9-33.3) 40.0† (38.9-43.7) 125

 6–11 years 35.3 (34.4-36.3) 23.8 (23.1-26.5) 35.9 (34.7-36.7) 48.6 (47.2-51.2) 311

 12–19 years 41.5 (40.8-42.3) 28.4 (26.9-30.8) 41.1 (40.5-41.5) 60.3 (57.6-62.2) 819

 20–39 years 44.3 (43.1-45.5) 28.7 (26.4-30.7) 44.6 (42.8-46.3) 69.1 (63.4-72.8) 484

 40–59 years 48.1 (46.4-49.9) 30.6 (25.7-34.1) 48.1 (46.4-50.1) 74.7 (68.3-77.1) 330

 60 years and older 55.0 (51.2-59.0) 31.8 (27.8-39.3) 54.8 (51.3-59.9) 90.0 (82.9-99.0) 316 

† Estimate is subject to greater uncertainty due to small cell size. 

42 42 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 2.1.c. Serum vitamin A: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 46.0 (45.1-47.0) 27.3 (26.3-27.9) 45.7 (44.4-47.1) 79.3 (75.9-81.6) 3680

 3–5 years 31.8 (30.6-33.1) 21.6 (19.3-23.9) 32.1 (30.8-33.3) 44.6 (41.6-47.9) 226

 6–11 years 35.0 (34.1-35.9) 23.7 (21.9-25.6) 35.1 (34.0-36.5) 50.5 (48.2-52.2) 591

 12–19 years 41.4 (40.6-42.2) 27.9 (26.7-28.6) 41.7 (40.6-42.6) 61.9 (60.2-64.1) 1252

 20–39 years 46.1 (44.8-47.5) 28.4 (27.6-30.7) 46.8 (45.2-48.5) 72.0 (67.7-74.6) 590

 40–59 years 52.2 (50.4-54.1) 30.6 (27.3-34.0) 52.1 (50.6-54.0) 87.3 (80.6-95.6) 540

 60 years and older 58.6 (56.6-60.6) 33.5 (31.2-36.7) 59.0 (56.8-60.4) 102 (93.4-117) 481 

Males 

Total, 3 years and older 48.5 (47.6-49.5) 27.9 (26.9-28.7) 49.6 (48.5-50.7) 80.7 (77.6-84.3) 1806

 3–5 years 32.7 (31.2-34.2) 22.6† (19.3-24.9) 32.7 (31.0-34.6) 45.4† (41.9-53.6) 119

 6–11 years 34.5 (33.5-35.5) 24.2 (20.8-25.5) 34.4 (33.2-35.6) 50.7 (47.2-54.3) 297

 12–19 years 43.7 (42.7-44.6) 28.7 (28.0-30.0) 43.5 (42.4-44.6) 64.8 (62.6-67.5) 640

 20–39 years 51.7 (50.1-53.4) 34.3 (28.8-37.8) 53.2 (51.2-55.2) 74.8 (70.3-79.6) 246

 40–59 years 56.3 (53.8-58.9) 34.4 (30.2-38.1) 56.3 (53.1-59.3) 92.9 (80.8-107) 274

 60 years and older 59.3 (56.1-62.7) 34.9 (30.0-39.9) 58.5 (53.5-62.8) 106 (87.7-144) 230 

Females 

Total, 3 years and older 44.0 (42.7-45.3) 26.7 (25.5-27.9) 42.9 (41.9-43.9) 75.6 (72.6-80.4) 1874

 3–5 years 30.9 (29.3-32.6) 19.5† (16.1-23.6) 31.7 (29.9-33.1) 42.7† (38.6-45.7) 107

 6–11 years 35.5 (34.3-36.7) 23.6 (21.5-26.7) 36.0 (34.3-37.6) 50.4 (48.0-52.2) 294

 12–19 years 39.2 (38.3-40.1) 26.0 (24.5-27.5) 39.5 (38.5-40.7) 56.8 (54.5-59.0) 612

 20–39 years 42.3 (40.4-44.2) 27.6 (24.7-29.1) 41.7 (39.8-43.8) 66.3 (62.0-72.4) 344

 40–59 years 48.9 (46.5-51.4) 29.3 (25.2-31.5) 47.7 (44.5-51.1) 82.0 (74.4-92.0) 266

 60 years and older 58.1 (55.3-61.1) 32.9 (30.2-36.8) 59.4 (56.8-61.2) 97.8 (86.7-115) 251 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 2.1.d. Serum vitamin A: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 56.3 (55.3-57.4) 33.1 (32.1-34.2) 57.3 (56.2-58.8) 88.9 (87.4-90.9) 6128

 3–5 years 34.0 (33.1-34.8) 24.0† (21.4-25.8) 34.2 (33.0-35.7) 47.2† (44.1-49.7) 217

 6–11 years 36.8 (35.9-37.7) 26.5 (25.4-28.3) 36.7 (35.8-37.9) 51.3 (49.0-52.7) 489

 12–19 years 49.0 (47.9-50.0) 32.6 (31.3-34.2) 49.0 (48.0-50.0) 72.9 (70.9-75.0) 1073

 20–39 years 56.1 (54.8-57.4) 36.1 (34.6-37.6) 57.0 (55.0-58.7) 83.9 (81.9-86.8) 1377

 40–59 years 62.0 (60.9-63.1) 40.1 (38.1-42.0) 63.1 (61.5-64.3) 93.5 (90.3-96.2) 1276

 60 years and older 65.2 (64.3-66.2) 41.6 (40.1-43.1) 65.5 (64.4-67.5) 99.1 (96.1-102) 1696 

Males 

Total, 3 years and older 58.9 (57.6-60.2) 33.6 (32.0-35.1) 60.8 (59.3-62.9) 91.4 (88.7-93.5) 3001

 3–5 years 33.4 (32.3-34.4) 21.4† (17.1-25.8) 34.4 (32.7-36.6) 45.6† (41.4-47.8) 115

 6–11 years 36.6 (35.2-38.0) 26.2 (24.3-28.6) 36.4 (35.1-38.4) 52.2 (48.6-53.0) 257

 12–19 years 50.6 (49.3-51.9) 32.4 (30.5-36.0) 51.0 (49.8-52.3) 72.9 (70.0-74.9) 535

 20–39 years 60.4 (59.1-61.7) 41.7 (40.5-43.1) 60.4 (59.2-63.0) 84.8 (81.6-87.5) 575

 40–59 years 66.6 (65.1-68.1) 44.5 (42.5-47.8) 68.2 (66.3-69.8) 96.2 (92.9-99.9) 665

 60 years and older 66.8 (65.2-68.4) 42.0 (40.4-44.6) 67.9 (65.3-70.1) 101 (96.6-105) 854 

Females 

Total, 3 years and older 54.0 (52.9-55.2) 32.6 (31.6-34.1) 54.5 (52.8-55.8) 87.5 (85.9-89.4) 3127

 3–5 years 34.7 (33.3-36.1) 26.2† (24.0-27.8) 34.0 (32.5-36.3) 49.1† (45.9-51.8) 102

 6–11 years 37.0 (36.0-38.0) 26.2 (24.7-28.4) 36.8 (36.0-38.0) 50.2 (48.1-54.0) 232

 12–19 years 47.3 (46.0-48.6) 33.2 (31.2-34.3) 46.9 (45.3-47.9) 72.1 (68.3-76.8) 538

 20–39 years 52.2 (50.5-54.0) 34.1 (30.9-35.9) 51.7 (49.9-54.8) 83.1 (80.5-87.3) 802

 40–59 years 57.7 (56.5-58.8) 36.0 (34.6-39.2) 57.2 (56.0-58.4) 88.8 (86.1-94.8) 611

 60 years and older 64.1 (62.9-65.2) 41.4 (39.0-43.5) 64.5 (62.5-65.6) 97.4 (92.0-102) 842 

† Estimate is subject to greater uncertainty due to small cell size. 

2 Fat-Soluble Vitamins & Micronutrients 43
Table 2.2.a. Serum vitamin E: Total population 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 1090 (1070-1110) 615 (604-626) 1030 (1010-1050) 2380 (2300-2480) 15766

 3–5 years 800 (777-824) 567 (547-593) 782 (758-813) 1160 (1110-1310) 777

 6–11 years 794 (779-810) 556 (546-570) 790 (772-812) 1130 (1090-1180) 1873

 12–19 years 762 (750-774) 532 (518-548) 753 (741-766) 1140 (1100-1200) 4314

 20–39 years 991 (977-1010) 629 (618-645) 963 (943-980) 1740 (1650-1800) 3168

 40–59 years 1300 (1280-1330) 774 (743-792) 1250 (1220-1280) 2620 (2470-2760) 2655

 60 years and older 1530 (1500-1560) 808 (771-850) 1480 (1440-1520) 3220 (3010-3330) 2979 

Males 

Total, 3 years and older 1070 (1040-1090) 605 (593-617) 1010 (984-1030) 2280 (2170-2380) 7673

 3–5 years 796 (768-825) 569 (556-594) 791 (759-823) 1110 (1030-1300) 406

 6–11 years 789 (770-809) 554 (543-576) 785 (760-815) 1130 (1040-1210) 951

 12–19 years 749 (731-767) 521 (503-544) 739 (724-757) 1120 (1060-1200) 2163

 20–39 years 993 (972-1020) 625 (611-646) 969 (940-985) 1750 (1660-1880) 1344

 40–59 years 1310 (1270-1350) 752 (724-776) 1250 (1220-1280) 2570 (2390-2830) 1328

 60 years and older 1420 (1380-1450) 769 (727-803) 1370 (1330-1400) 2850 (2740-3010) 1481 

Females 

Total, 3 years and older 1120 (1100-1140) 626 (612-640) 1050 (1030-1070) 2480 (2350-2620) 8093

 3–5 years 804 (772-838) 560 (513-602) 774 (750-812) 1270 (1120-1460) 371

 6–11 years 801 (779-822) 560 (542-587) 799 (775-820) 1140 (1090-1190) 922

 12–19 years 776 (763-788) 548 (539-556) 769 (756-784) 1160 (1110-1210) 2151

 20–39 years 990 (974-1010) 630 (615-654) 955 (933-978) 1700 (1620-1830) 1824

 40–59 years 1300 (1260-1340) 797 (744-820) 1240 (1200-1280) 2670 (2360-2970) 1327

 60 years and older 1620 (1580-1660) 860 (819-889) 1590 (1530-1650) 3370 (3170-3550) 1498 

Table 2.2.b. Serum vitamin E: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 967 (944-990) 587 (572-602) 919 (904-938) 1800 (1720-1950) 4662

 3–5 years 768 (748-788) 569 (514-593) 762 (737-787) 1050 (980-1110) 261

 6–11 years 770 (758-782) 555 (538-573) 765 (746-780) 1090 (1050-1110) 640

 12–19 years 754 (744-764) 516 (503-531) 744 (729-758) 1150 (1110-1200) 1628

 20–39 years 987 (954-1020) 642 (605-667) 959 (931-983) 1680 (1550-1780) 867

 40–59 years 1260 (1210-1310) 757 (720-804) 1230 (1160-1280) 2250 (2070-2620) 629

 60 years and older 1380 (1320-1440) 762 (696-810) 1310 (1260-1390) 2810 (2610-3350) 637 

Males 

Total, 3 years and older 968 (943-995) 580 (564-590) 922 (902-943) 1810 (1690-2010) 2277

 3–5 years 766 (736-797) 567† (530-608) 749 (719-784) 1070† (971-1230) 135

 6–11 years 768 (748-789) 544 (532-577) 758 (736-785) 1070 (1030-1160) 331

 12–19 years 741 (723-759) 503 (490-516) 733 (718-753) 1110 (1080-1150) 808

 20–39 years 999 (954-1050) 617 (587-662) 964 (923-1020) 1650 (1530-1920) 383

 40–59 years 1300 (1210-1400) 790 (707-860) 1250 (1160-1340) 2370 (2060-3340) 299

 60 years and older 1280 (1220-1350) 729 (651-799) 1230 (1200-1300) 2610 (2080-3530) 321 

Females 

Total, 3 years and older 965 (939-992) 593 (574-616) 915 (898-939) 1780 (1690-1980) 2385

 3–5 years 770 (740-800) 577† (495-594) 780 (735-819) 992† (953-1110) 126

 6–11 years 772 (756-789) 558 (526-586) 768 (744-790) 1090 (1040-1170) 309

 12–19 years 769 (761-777) 539 (529-551) 757 (732-778) 1220 (1130-1260) 820

 20–39 years 972 (945-1000) 651 (592-675) 947 (921-981) 1670 (1480-1750) 484

 40–59 years 1220 (1170-1260) 739 (715-795) 1190 (1130-1260) 2100 (1810-2400) 330

 60 years and older 1470 (1380-1570) 780 (587-929) 1400 (1330-1470) 2850 (2670-3490) 316 

† Estimate is subject to greater uncertainty due to small cell size. 

44 44 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 2.2.c. Serum vitamin E: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 917 (897-936) 579 (564-595) 884 (865-903) 1700 (1620-1820) 3670

 3–5 years 761 (736-787) 560† (511-586) 748 (728-768) 1120† (1080-1170) 222

 6–11 years 769 (752-786) 548 (521-583) 765 (745-789) 1070 (1010-1120) 592

 12–19 years 728 (714-741) 530 (512-542) 721 (707-740) 1030 (1010-1060) 1249

 20–39 years 879 (860-899) 607 (567-627) 867 (840-895) 1390 (1300-1470) 589

 40–59 years 1090 (1050-1120) 686 (636-712) 1040 (1010-1070) 2250 (1840-2390) 539

 60 years and older 1200 (1140-1250) 692 (655-736) 1150 (1090-1190) 2280 (2070-2780) 479 

Males 

Total, 3 years and older 888 (866-912) 573 (554-589) 864 (842-883) 1620 (1450-1770) 1802

 3–5 years 761 (725-798) 550† (497-614) 749 (702-782) 1100† (989-1130) 117

 6–11 years 780 (763-797) 565 (531-580) 772 (757-811) 1080 (1010-1160) 297

 12–19 years 722 (706-738) 528 (506-539) 716 (701-732) 1020 (975-1050) 639

 20–39 years 870 (834-908) 614 (567-643) 863 (809-900) 1340 (1200-1560) 246

 40–59 years 1040 (995-1080) 636 (579-707) 1010 (971-1070) 1850 (1620-2250) 274

 60 years and older 1110 (1060-1170) 655 (582-721) 1070 (1020-1140) 2180 (1910-2390) 229 

Females 

Total, 3 years and older 942 (916-968) 588 (560-609) 907 (884-923) 1800 (1640-2080) 1868

 3–5 years 761 (731-792) 545† (491-586) 748 (713-800) 1150† (1010-1240) 105

 6–11 years 757 (732-783) 536 (505-588) 757 (726-788) 1010 (982-1120) 295

 12–19 years 734 (719-748) 534 (503-560) 733 (706-758) 1050 (1000-1100) 610

 20–39 years 886 (863-909) 605 (519-626) 877 (839-907) 1450 (1300-1510) 343

 40–59 years 1130 (1090-1180) 712 (679-780) 1050 (1020-1090) 2410 (2020-2700) 265

 60 years and older 1250 (1180-1330) 727 (686-815) 1180 (1140-1270) 2690 (1930-3650) 250 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 2.2.d. Serum vitamin E: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 1150 (1130-1180) 638 (620-652) 1090 (1050-1120) 2530 (2440-2630) 6085

 3–5 years 822 (782-865) 567† (547-622) 803 (757-853) 1240† (1110-1460) 216

 6–11 years 804 (782-826) 556 (545-577) 800 (772-825) 1150 (1090-1230) 485

 12–19 years 774 (757-791) 543 (526-556) 763 (744-777) 1180 (1100-1250) 1071

 20–39 years 1010 (991-1030) 646 (619-665) 978 (957-994) 1780 (1660-1930) 1368

 40–59 years 1340 (1310-1370) 796 (770-820) 1280 (1250-1310) 2670 (2500-2980) 1266

 60 years and older 1580 (1540-1610) 831 (795-868) 1530 (1500-1580) 3300 (3070-3460) 1679 

Males 

Total, 3 years and older 1120 (1090-1150) 619 (598-643) 1060 (1020-1100) 2420 (2300-2540) 2977

 3–5 years 819 (773-867) 576† (556-622) 818 (751-860) 1100† (1010-1470) 114

 6–11 years 788 (759-818) 550 (502-575) 779 (746-825) 1130 (1030-1220) 254

 12–19 years 758 (731-785) 532 (509-556) 742 (724-771) 1150 (1040-1300) 534

 20–39 years 1010 (974-1040) 637 (607-669) 976 (939-1000) 1850 (1620-2060) 569

 40–59 years 1350 (1310-1400) 774 (728-810) 1280 (1250-1330) 2630 (2470-3150) 660

 60 years and older 1450 (1410-1500) 779 (734-815) 1400 (1370-1440) 2880 (2750-3240) 846 

Females 

Total, 3 years and older 1180 (1150-1210) 654 (639-670) 1120 (1090-1160) 2640 (2490-2770) 3108

 3–5 years 826 (770-886) 564† (430-662) 776 (742-874) 1440† (1150-1520) 102

 6–11 years 822 (793-852) 557 (530-603) 811 (781-851) 1150 (1100-1400) 231

 12–19 years 791 (773-810) 554 (537-568) 781 (761-811) 1180 (1110-1250) 537

 20–39 years 1020 (996-1030) 647 (623-682) 982 (951-1010) 1760 (1620-1930) 799

 40–59 years 1330 (1290-1380) 818 (783-852) 1280 (1230-1320) 2690 (2360-3090) 606

 60 years and older 1680 (1630-1730) 884 (853-924) 1660 (1600-1740) 3460 (3230-3760) 833 

† Estimate is subject to greater uncertainty due to small cell size. 

2 Fat-Soluble Vitamins & Micronutrients 45
Table 2.3.a. Serum gamma-tocopherol: Total population 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 198 (190-206) 65.7 (61.0-71.0) 212 (204-221) 462 (438-482) 14738

 3–5 years 176 (162-192) 63.0 (52.0-83.5) 186 (170-199) 364 (340-407) 730

 6–11 years 207 (198-217) 97.8 (92.0-105) 217 (206-225) 389 (363-428) 1730

 12–19 years 197 (190-204) 100 (93.0-108) 201 (192-208) 372 (359-386) 4009

 20–39 years 206 (198-215) 83.0 (71.7-89.2) 219 (208-227) 442 (427-468) 3005

 40–59 years 205 (194-218) 60.0 (55.0-68.0) 225 (213-238) 530 (478-568) 2491

 60 years and older 174 (165-184) 47.8 (46.0-51.0) 190 (177-203) 496 (462-531) 2773 

Males 

Total, 3 years and older 199 (191-208) 65.1 (59.0-72.0) 212 (204-221) 466 (442-481) 7169

 3–5 years 167 (151-184) 58.6 (42.8-89.0) 178 (165-193) 340 (298-400) 380

 6–11 years 201 (190-213) 92.0 (81.0-104) 213 (195-225) 366 (361-408) 870

 12–19 years 193 (186-200) 98.1 (91.0-108) 193 (187-201) 371 (341-390) 2005

 20–39 years 208 (200-217) 75.5 (66.0-88.5) 223 (210-233) 473 (436-481) 1279

 40–59 years 214 (200-228) 61.0 (57.0-72.0) 230 (216-248) 548 (499-608) 1253

 60 years and older 169 (160-180) 43.9 (40.0-47.8) 191 (176-200) 463 (427-510) 1382 

Females 

Total, 3 years and older 197 (189-205) 65.8 (62.0-71.0) 213 (202-221) 457 (433-484) 7569

 3–5 years 188 (172-205) 72.0 (56.0-95.9) 195 (176-215) 385 (328-446) 350

 6–11 years 214 (203-226) 106 (95.0-117) 221 (206-238) 408 (361-473) 860

 12–19 years 202 (194-211) 102 (89.0-111) 208 (198-219) 373 (357-391) 2004

 20–39 years 203 (193-214) 85.0 (75.0-91.4) 216 (202-226) 424 (410-440) 1726

 40–59 years 198 (186-210) 57.2 (51.0-67.0) 221 (206-233) 505 (453-559) 1238

 60 years and older 178 (167-189) 51.3 (47.1-55.2) 189 (175-207) 508 (482-542) 1391 

Table 2.3.b. Serum gamma-tocopherol: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 206 (199-214) 92.0 (87.9-99.0) 211 (203-218) 437 (404-466) 3983

 3–5 years 180 (168-192) 93.0 (82.2-109) 185 (175-200) 318 (287-370) 224

 6–11 years 219 (210-229) 112 (99.9-122) 226 (217-239) 419 (372-456) 546

 12–19 years 203 (197-209) 108 (103-117) 206 (197-214) 370 (349-394) 1399

 20–39 years 196 (185-208) 91.0 (84.0-99.6) 199 (187-213) 397 (363-456) 771

 40–59 years 232 (220-244) 88.9 (74.0-104) 235 (220-251) 544 (469-631) 535

 60 years and older 209 (194-225) 67.0 (56.0-80.7) 231 (205-254) 496 (449-527) 508 

Males 

Total, 3 years and older 206 (198-215) 93.0 (84.0-101) 211 (203-217) 448 (402-473) 1937

 3–5 years 180 (167-194) 93.5† (82.2-112) 183 (173-195) 312† (283-340) 115

 6–11 years 222 (210-234) 116 (105-124) 221 (212-242) 440 (364-483) 272

 12–19 years 198 (190-207) 106 (98.0-116) 201 (192-212) 367 (332-398) 691

 20–39 years 197 (183-211) 91.5 (72.0-102) 199 (183-214) 408 (371-469) 346

 40–59 years 234 (214-256) 78.0 (58.0-103) 246 (219-267) 544 (456-659) 258

 60 years and older 212 (189-237) 66.0 (47.0-85.0) 237 (211-274) 443 (371-527) 255 

Females 

Total, 3 years and older 206 (198-215) 92.0 (86.0-101) 212 (201-224) 428 (399-460) 2046

 3–5 years 180 (161-201) 88.3† (45.0-116) 196 (160-209) 355† (252-392) 109

 6–11 years 217 (204-231) 105 (83.5-123) 228 (216-243) 401 (361-452) 274

 12–19 years 209 (200-218) 113 (105-123) 210 (194-226) 372 (338-418) 708

 20–39 years 195 (183-209) 90.0 (76.0-102) 200 (186-216) 349 (336-418) 425

 40–59 years 229 (216-243) 89.3 (74.0-105) 230 (216-250) 494 (460-640) 277

 60 years and older 206 (189-225) 70.0 (52.9-80.0) 226 (183-252) 515 (462-683) 253 

† Estimate is subject to greater uncertainty due to small cell size. 

46 46 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 2.3.c. Serum gamma-tocopherol: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 223 (215-232) 97.9 (86.0-106) 235 (223-245) 444 (427-458) 3578

 3–5 years 188 (174-203) 90.0† (75.0-109) 196 (182-209) 336† (309-367) 220

 6–11 years 218 (207-230) 116 (104-124) 221 (206-237) 393 (365-441) 569

 12–19 years 208 (202-215) 109 (101-121) 212 (204-218) 356 (334-384) 1217

 20–39 years 222 (209-236) 98.5 (86.0-115) 234 (213-253) 426 (394-452) 571

 40–59 years 234 (223-247) 84.4 (65.0-111) 257 (241-271) 470 (440-508) 529

 60 years and older 238 (223-254) 69.0 (54.0-90.0) 270 (256-282) 515 (492-575) 472 

Males 

Total, 3 years and older 214 (205-224) 97.1 (80.4-109) 222 (212-233) 417 (402-442) 1756

 3–5 years 189 (171-207) 83.5† (63.0-119) 194 (180-211) 331† (287-364) 116

 6–11 years 213 (201-224) 107 (93.0-120) 213 (201-229) 386 (365-427) 288

 12–19 years 202 (194-209) 104 (95.0-118) 206 (195-215) 351 (321-386) 620

 20–39 years 215 (199-231) 98.5 (80.3-115) 226 (202-248) 404 (370-450) 237

 40–59 years 224 (206-243) 84.0 (44.7-130) 249 (219-268) 418 (393-553) 267

 60 years and older 223 (206-242) 69.0 (54.0-103) 248 (214-265) 511 (449-583) 228 

Females 

Total, 3 years and older 231 (221-242) 97.9 (84.4-109) 244 (230-257) 460 (437-480) 1822

 3–5 years 188 (167-210) 78.0† (74.0-111) 195 (167-220) 356† (314-380) 104

 6–11 years 224 (209-240) 124 (114-138) 224 (210-247) 393 (351-455) 281

 12–19 years 216 (207-225) 122 (104-132) 215 (206-226) 369 (338-428) 597

 20–39 years 229 (212-247) 98.0 (79.0-124) 245 (212-270) 435 (390-469) 334

 40–59 years 244 (226-264) 84.4 (70.6-109) 271 (244-293) 478 (440-559) 262

 60 years and older 249 (229-270) 61.8 (45.2-91.0) 282 (265-304) 524 (492-583) 244 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 2.3.d. Serum gamma-tocopherol: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 3 years and older 194 (184-205) 60.0 (55.0-65.0) 211 (200-221) 473 (444-499) 5877

 3–5 years 176 (155-199) 56.0† (42.8-83.0) 188 (162-215) 366† (329-441) 211

 6–11 years 204 (192-218) 90.9 (82.2-102) 215 (199-231) 408 (359-484) 469

 12–19 years 195 (185-204) 94.9 (88.0-103) 199 (188-210) 375 (357-393) 1036

 20–39 years 207 (196-219) 77.4 (65.6-88.9) 221 (208-232) 453 (430-477) 1326

 40–59 years 199 (185-215) 57.0 (51.0-64.8) 221 (203-235) 532 (481-573) 1217

 60 years and older 170 (160-180) 46.7 (44.9-50.7) 186 (170-198) 498 (460-537) 1618 

Males 

Total, 3 years and older 196 (186-208) 59.0 (51.0-67.0) 212 (202-224) 473 (446-502) 2885

 3–5 years 164 (142-189) 47.1† (22.5-89.0) 186 (153-199) 355† (298-489) 112

 6–11 years 195 (180-211) 82.2 (78.0-97.7) 212 (174-230) 365 (327-408) 246

 12–19 years 191 (181-201) 94.3 (86.0-108) 189 (183-200) 378 (340-399) 519

 20–39 years 211 (198-224) 71.0 (51.2-89.2) 230 (214-242) 473 (441-484) 554

 40–59 years 209 (192-227) 59.0 (53.0-69.6) 226 (211-249) 548 (471-617) 635

 60 years and older 165 (154-177) 42.8 (39.8-46.7) 186 (170-197) 463 (426-520) 819 

Females 

Total, 3 years and older 192 (182-203) 61.9 (56.9-65.6) 209 (196-221) 478 (439-506) 2992

 3–5 years 190 (164-220) 58.0† (52.0-96.0) 204 (164-241) 388† (313-482) 99

 6–11 years 216 (199-234) 99.0† (87.0-112) 221 (197-248) 418† (361-555) 223

 12–19 years 199 (186-212) 95.1 (82.0-108) 207 (188-224) 367 (345-402) 517

 20–39 years 204 (190-218) 84.0 (65.0-97.0) 217 (199-227) 428 (406-478) 772

 40–59 years 190 (174-207) 51.0 (43.8-60.2) 213 (187-230) 511 (452-572) 582

 60 years and older 173 (161-186) 51.3 (47.0-55.9) 185 (167-203) 525 (479-546) 799 

† Estimate is subject to greater uncertainty due to small cell size. 

2 Fat-Soluble Vitamins & Micronutrients 47
Table 2.4.a. Serum alpha-carotene: Total population 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 2.48 (2.23-2.76) .700 (<LOD-.800) 2.36 (2.10-2.70) 8.50 (7.40-9.30) 8359

 3–5 years 2.41 (2.13-2.74) .800 (<LOD-1.00) 2.20 (1.90-2.50) 8.50 (7.00-10.3) 430

 6–11 years 2.24 (2.00-2.51) .800 (.800-.900) 2.00 (1.80-2.30) 6.10 (5.20-7.70) 1014

 12–19 years 1.68 (1.52-1.86) < LOD 1.40 (1.30-1.60) 5.10 (4.40-6.20) 2206

 20–39 years 2.22 (1.93-2.56) < LOD 2.20 (1.90-2.50) 7.80 (6.70-8.80) 1716

 40–59 years 2.98 (2.60-3.42) .800 (.700-1.00) 2.80 (2.50-3.30) 10.7 (8.60-13.0) 1470

 60 years and older 3.08 (2.74-3.46) .800 (<LOD-1.00) 3.10 (2.70-3.60) 9.10 (8.60-9.80) 1523 

Males 

Total, 3 years and older 2.22 (1.98-2.49) < LOD 2.10 (1.90-2.30) 7.20 (6.30-8.60) 4052

 3–5 years 2.29 (1.91-2.74) .700 (<LOD-.800) 2.00 (1.70-2.40) 7.20 (5.00-11.1) 217

 6–11 years 2.28 (1.96-2.65) .800 (.800-1.00) 2.00 (1.80-2.40) 6.60 (5.00-8.50) 507

 12–19 years 1.55 (1.38-1.75) < LOD 1.40 (1.20-1.60) 4.40 (3.80-6.00) 1092

 20–39 years 1.99 (1.72-2.31) < LOD 1.80 (1.50-2.10) 6.90 (5.60-8.60) 724

 40–59 years 2.53 (2.17-2.95) .800 (<LOD-.900) 2.40 (2.00-2.90) 8.60 (6.30-11.3) 763

 60 years and older 2.81 (2.48-3.18) .800 (<LOD-.900) 2.90 (2.50-3.50) 8.40 (7.40-9.30) 749 

Females 

Total, 3 years and older 2.75 (2.47-3.07) .700 (<LOD-.900) 2.70 (2.30-3.00) 9.20 (8.20-10.5) 4307

 3–5 years 2.55 (1.99-3.26) .700 (<LOD-1.50) 2.30 (1.80-3.10) 9.70 (7.10-12.4) 213

 6–11 years 2.20 (1.97-2.45) .800 (.800-.900) 2.10 (1.80-2.30) 5.80 (4.90-6.50) 507

 12–19 years 1.83 (1.63-2.04) < LOD 1.70 (1.50-2.00) 5.40 (4.60-6.90) 1114

 20–39 years 2.45 (2.10-2.86) < LOD 2.30 (1.90-2.70) 8.10 (6.80-9.20) 992

 40–59 years 3.55 (3.10-4.06) 1.10 (.900-1.30) 3.40 (2.90-3.70) 12.4 (10.5-15.8) 707

 60 years and older 3.30 (2.87-3.79) 1.00 (.800-1.20) 3.20 (2.80-3.90) 9.70 (8.70-10.4) 774 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

Table 2.4.b. Serum alpha-carotene: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 2.72 (2.39-3.10) 1.00 (.900-1.10) 2.50 (2.30-2.80) 7.40 (6.30-8.90) 2116

 3–5 years 2.56 (2.12-3.08) 1.00 (.800-1.50) 2.20 (2.10-2.50) 6.40 (4.50-9.00) 126

 6–11 years 2.43 (2.12-2.79) .900 (.800-1.10) 2.20 (2.00-2.70) 5.40 (4.70-6.70) 290

 12–19 years 1.90 (1.71-2.11) .700 (<LOD-.800) 1.70 (1.50-2.10) 5.30 (3.90-6.40) 696

 20–39 years 2.92 (2.48-3.43) 1.00 (.800-1.30) 2.80 (2.50-3.40) 8.00 (6.60-9.10) 460

 40–59 years 3.39 (2.71-4.24) 1.10 (.900-1.40) 3.30 (2.60-4.10) 8.70 (7.20-14.3) 289

 60 years and older 3.04 (2.35-3.94) .900 (<LOD-1.30) 2.90 (2.30-4.00) 8.90 (6.20-13.7) 255 

Males 

Total, 3 years and older 2.46 (2.13-2.83) .800 (.700-1.00) 2.44 (2.20-2.70) 6.60 (5.30-8.00) 1019

 3–5 years 2.37 (1.70-3.32) .800† (<LOD-1.50) 2.20 (1.70-2.80) 5.90† (2.90-12.1) 62

 6–11 years 2.39 (1.89-3.03) .800 (.700-1.00) 2.20 (1.70-2.90) 5.50 (3.90-8.40) 140

 12–19 years 1.69 (1.48-1.92) .700 (<LOD-.800) 1.50 (1.30-1.90) 4.20 (3.30-6.20) 330

 20–39 years 2.51 (2.06-3.06) .800 (<LOD-1.10) 2.60 (2.10-3.10) 6.70 (5.20-7.90) 213

 40–59 years 3.33 (2.61-4.23) 1.20 (.800-1.70) 3.20 (2.50-4.10) 8.10 (5.90-13.2) 149

 60 years and older 2.49 (1.83-3.38) .700 (<LOD-1.10) 2.60 (1.90-3.00) 7.00 (5.50-9.10) 125 

Females 

Total, 3 years and older 3.04 (2.66-3.48) 1.00 (.900-1.20) 2.80 (2.50-3.30) 8.50 (7.10-10.8) 1097

 3–5 years 2.75 (2.28-3.32) 1.20† (<LOD-1.60) 2.40 (2.00-3.10) 6.00† (4.20-9.00) 64

 6–11 years 2.48 (2.16-2.85) 1.20 (.900-1.50) 2.30 (1.90-3.00) 5.00 (4.00-6.00) 150

 12–19 years 2.16 (1.92-2.43) .800 (.700-.900) 2.00 (1.60-2.50) 5.80 (4.40-7.30) 366

 20–39 years 3.45 (2.87-4.15) 1.20 (.900-1.40) 3.20 (2.60-4.30) 9.10 (8.00-12.7) 247

 40–59 years 3.46 (2.66-4.49) .900 (.700-1.40) 3.30 (2.40-4.80) 10.8 (8.00-14.8) 140

 60 years and older 3.58 (2.63-4.86) 1.30 (.900-1.80) 3.60 (2.40-4.80) 11.5 (6.00-15.2) 130 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

48 48 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 2.4.c. Serum alpha-carotene: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 1.77 (1.51-2.08) < LOD 1.60 (1.30-1.90) 6.10 (4.80-8.20) 1992

 3–5 years 1.75 (1.40-2.17) < LOD 1.40 (1.10-1.80) 5.00 (3.20-13.9) 128

 6–11 years 1.92 (1.69-2.19) .900 (.800-1.00) 1.70 (1.40-1.90) 4.30 (3.50-5.60) 340

 12–19 years 1.38 (1.20-1.59) < LOD 1.20 (1.10-1.50) 3.90 (2.80-5.30) 671

 20–39 years 1.71 (1.27-2.29) < LOD 1.50 (1.10-2.10) 5.80 (3.90-11.4) 319

 40–59 years 1.88 (1.65-2.13) < LOD 1.80 (1.50-2.00) 7.20 (6.10-9.70) 291

 60 years and older 2.22 (1.70-2.90) < LOD 2.00 (1.40-2.70) 9.30 (4.90-15.1) 243 

Males 

Total, 3 years and older 1.65 (1.38-1.96) < LOD 1.40 (1.20-1.80) 5.80 (4.20-7.40) 984

 3–5 years 1.54 (1.18-2.02) < LOD† 1.30 (1.00-1.90) 3.90† (2.20-13.9) 64

 6–11 years 2.08 (1.82-2.36) .900 (.800-1.20) 1.90 (1.70-2.20) 4.60 (3.50-6.60) 175

 12–19 years 1.32 (1.11-1.57) < LOD 1.10 (1.00-1.34) 3.30 (2.70-5.50) 340

 20–39 years 1.55 (1.07-2.24) < LOD 1.40 (.900-2.30) 6.10 (3.40-9.60) 132

 40–59 years 1.71 (1.44-2.03) < LOD 1.80 (1.20-2.10) 6.60 (4.50-8.40) 154

 60 years and older 1.94 (1.56-2.43) < LOD 1.50 (1.30-2.40) 6.70 (4.20-12.5) 119 

Females 

Total, 3 years and older 1.88 (1.58-2.23) < LOD 1.70 (1.40-1.90) 6.50 (4.90-9.40) 1008

 3–5 years 1.98 (1.52-2.60) < LOD† 1.70 (1.30-2.20) 6.00† (3.20-33.8) 64

 6–11 years 1.76 (1.40-2.22) .700 (<LOD-.900) 1.60 (1.30-1.90) 3.70 (2.60-8.30) 165

 12–19 years 1.45 (1.27-1.65) < LOD 1.30 (1.10-1.60) 4.00 (2.90-5.50) 331

 20–39 years 1.83 (1.33-2.50) < LOD 1.80 (1.10-2.20) 5.30 (3.90-11.5) 187

 40–59 years 2.04 (1.69-2.46) < LOD 1.70 (1.50-2.10) 7.90 (5.90-13.8) 137

 60 years and older 2.44 (1.71-3.47) < LOD 2.10 (1.40-3.20) 9.40 (5.90-17.6) 124 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 2.4.d. Serum alpha-carotene: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 2.57 (2.25-2.94) .800 (<LOD-.900) 2.40 (2.10-2.90) 8.80 (7.70-10.2) 3583

 3–5 years 2.46 (1.95-3.11) .800 (<LOD-1.40) 2.10 (1.70-3.00) 8.50 (5.60-11.1) 133

 6–11 years 2.29 (1.98-2.65) .700 (<LOD-.900) 2.20 (1.80-2.50) 6.50 (4.90-10.2) 301

 12–19 years 1.69 (1.48-1.93) < LOD 1.40 (1.20-1.70) 5.30 (4.40-6.50) 656

 20–39 years 2.17 (1.86-2.55) < LOD 2.00 (1.60-2.30) 8.10 (6.30-9.20) 772

 40–59 years 3.12 (2.66-3.67) .900 (.800-1.20) 2.90 (2.50-3.40) 11.3 (8.60-14.2) 777

 60 years and older 3.16 (2.78-3.58) .900 (<LOD-1.00) 3.30 (2.80-3.80) 9.20 (8.50-9.90) 944 

Males 

Total, 3 years and older 2.28 (1.99-2.62) < LOD 2.10 (1.90-2.60) 7.80 (6.30-9.20) 1739

 3–5 years 2.44 (1.99-2.98) 1.00† (<LOD-1.30) 2.20 (1.70-2.50) 8.50† (4.40-11.3) 72

 6–11 years 2.35 (1.87-2.96) .900 (<LOD-1.10) 2.00 (1.60-2.70) 8.10 (4.40-13.4) 157

 12–19 years 1.53 (1.31-1.79) < LOD 1.30 (1.10-1.70) 4.40 (3.80-6.20) 323

 20–39 years 1.95 (1.66-2.28) < LOD 1.90 (1.50-2.10) 7.30 (5.20-8.90) 312

 40–59 years 2.59 (2.16-3.11) .800 (<LOD-.900) 2.50 (2.00-3.00) 8.80 (5.70-12.0) 407

 60 years and older 2.86 (2.47-3.32) .800 (<LOD-.900) 3.00 (2.30-3.70) 8.40 (7.40-9.80) 468 

Females 

Total, 3 years and older 2.89 (2.49-3.35) .700 (<LOD-.900) 2.90 (2.40-3.20) 9.70 (8.30-11.5) 1844

 3–5 years 2.49 (1.49-4.17) < LOD† 2.20 (1.50-4.70) 8.50† (5.40-14.7) 61

 6–11 years 2.22 (1.97-2.50) .700 (<LOD-.900) 2.20 (1.80-2.60) 6.00 (4.40-8.40) 144

 12–19 years 1.86 (1.58-2.19) < LOD 1.70 (1.50-2.20) 5.90 (4.80-7.50) 333

 20–39 years 2.40 (2.00-2.89) < LOD 2.30 (1.80-2.80) 8.30 (7.20-10.5) 460

 40–59 years 3.83 (3.26-4.51) 1.20 (.900-1.40) 3.60 (3.10-4.50) 12.7 (10.4-17.0) 370

 60 years and older 3.40 (2.92-3.96) 1.10 (.800-1.30) 3.37 (2.90-4.10) 9.50 (8.60-10.5) 476 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

2 Fat-Soluble Vitamins & Micronutrients 49
Table 2.5.a. Serum trans-beta-carotene: Total population 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 12.2 (11.5-13.0) 4.30 (4.10-4.70) 11.9 (11.3-12.5) 34.3 (31.7-37.4) 8358

 3–5 years 13.6 (12.6-14.6) 5.80 (4.90-7.10) 13.5 (12.1-15.3) 31.1 (27.5-35.9) 429

 6–11 years 13.3 (12.7-13.9) 6.50 (6.10-6.90) 13.2 (12.6-13.9) 27.0 (23.3-29.8) 1012

 12–19 years 9.69 (9.20-10.2) 4.20 (3.90-4.70) 9.60 (9.00-10.4) 21.6 (20.1-23.7) 2206

 20–39 years 10.3 (9.38-11.2) 3.70 (3.30-4.20) 9.90 (9.10-10.9) 29.0 (25.7-32.8) 1716

 40–59 years 13.3 (12.1-14.7) 4.20 (3.70-4.90) 12.9 (12.0-14.2) 42.8 (35.3-49.8) 1471

 60 years and older 16.5 (14.9-18.3) 5.50 (4.40-6.10) 17.6 (15.3-19.6) 46.0 (41.5-50.9) 1524 

Males 

Total, 3 years and older 10.9 (10.2-11.7) 3.90 (3.60-4.30) 11.0 (10.3-11.7) 30.2 (26.8-33.0) 4053

 3–5 years 13.3 (11.7-15.2) 5.60 (5.00-6.80) 14.2 (11.9-16.1) 30.1 (23.8-44.8) 216

 6–11 years 13.5 (12.4-14.7) 6.50 (6.10-7.10) 13.4 (11.9-14.7) 26.4 (23.0-31.3) 507

 12–19 years 9.27 (8.57-10.0) 4.10 (3.80-4.40) 9.10 (8.30-10.2) 20.1 (18.8-22.0) 1092

 20–39 years 9.07 (8.24-10.0) 3.40 (2.90-4.10) 8.80 (7.90-9.80) 24.6 (21.3-29.6) 724

 40–59 years 11.3 (10.2-12.7) 3.70 (3.30-4.10) 11.6 (10.2-12.6) 33.0 (27.0-43.9) 764

 60 years and older 14.5 (13.0-16.2) 4.30 (3.60-5.20) 15.5 (13.6-17.3) 42.2 (35.0-47.0) 750 

Females 

Total, 3 years and older 13.6 (12.7-14.6) 5.10 (4.70-5.50) 13.0 (12.2-14.2) 38.2 (35.3-41.4) 4305

 3–5 years 13.8 (12.1-15.7) 5.80 (4.30-7.90) 12.6 (10.9-15.7) 32.6 (24.6-55.1) 213

 6–11 years 13.0 (12.3-13.7) 6.30 (5.70-7.10) 12.6 (12.0-13.5) 28.0 (22.3-31.3) 505

 12–19 years 10.1 (9.53-10.8) 4.50 (3.90-5.30) 10.3 (9.60-11.0) 23.3 (20.3-26.4) 1114

 20–39 years 11.4 (10.3-12.6) 4.20 (3.50-4.80) 10.8 (9.50-12.3) 32.1 (28.9-37.0) 992

 40–59 years 15.8 (14.1-17.8) 5.50 (4.70-5.90) 15.1 (13.4-17.1) 49.9 (39.1-63.2) 707

 60 years and older 18.1 (16.0-20.6) 6.00 (5.00-7.60) 19.0 (16.9-21.8) 48.1 (42.6-55.8) 774 

Table 2.5.b. Serum trans-beta-carotene: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 12.5 (11.7-13.4) 4.70 (4.20-5.50) 12.8 (11.7-13.9) 31.0 (28.4-33.6) 2116

 3–5 years 13.9 (11.7-16.5) 7.10 (4.80-9.70) 13.0 (10.9-16.1) 24.3 (22.0-29.0) 126

 6–11 years 13.4 (12.4-14.4) 6.60 (5.70-7.60) 13.6 (12.1-14.9) 28.2 (24.2-30.8) 289

 12–19 years 10.0 (9.53-10.5) 4.50 (4.10-4.80) 10.2 (9.60-10.6) 21.8 (19.3-25.4) 696

 20–39 years 12.4 (11.2-13.7) 4.30 (3.70-5.70) 13.0 (10.8-14.5) 30.6 (27.0-34.1) 460

 40–59 years 13.8 (11.7-16.4) 4.30 (3.70-5.70) 13.9 (11.1-17.4) 37.7 (33.1-45.6) 289

 60 years and older 14.6 (12.7-16.7) 4.10 (3.20-5.00) 15.8 (13.2-17.6) 39.1 (35.5-52.1) 256 

Males 

Total, 3 years and older 11.3 (10.4-12.3) 4.20 (3.80-5.10) 11.4 (9.90-13.2) 28.0 (25.2-29.4) 1020

 3–5 years 13.8 (10.4-18.4) 7.20† (4.80-10.6) 12.6 (9.70-17.3) 24.1† (17.4-41.5) 62

 6–11 years 13.0 (11.4-14.9) 5.80 (4.70-7.70) 13.4 (10.0-16.4) 24.6 (22.0-31.4) 140

 12–19 years 8.98 (8.36-9.65) 4.20 (3.80-4.70) 9.10 (7.90-10.0) 18.9 (17.0-20.9) 330

 20–39 years 10.6 (9.13-12.3) 3.90 (3.00-5.20) 11.1 (9.00-13.5) 25.8 (22.4-29.4) 213

 40–59 years 13.3 (11.4-15.6) 4.30 (3.60-6.50) 13.0 (10.2-17.1) 33.9 (28.6-45.6) 149

 60 years and older 11.8 (9.61-14.5) 3.60 (1.90-5.50) 12.6 (9.20-16.5) 37.3 (27.6-58.4) 126 

Females 

Total, 3 years and older 14.1 (13.0-15.2) 5.60 (5.00-6.10) 14.2 (13.3-15.0) 33.9 (29.2-40.8) 1096

 3–5 years 14.0 (12.0-16.4) 6.70† (4.60-9.70) 13.0 (10.2-20.1) 25.1† (21.9-32.6) 64

 6–11 years 13.7 (12.5-15.1) 7.00 (5.70-8.40) 13.7 (12.0-14.7) 26.5 (22.1-33.5) 149

 12–19 years 11.3 (10.3-12.3) 4.70 (4.10-5.90) 11.4 (10.1-12.7) 25.4 (21.6-29.7) 366

 20–39 years 14.8 (12.7-17.1) 5.70 (3.70-7.60) 14.8 (13.0-17.4) 36.7 (27.4-48.1) 247

 40–59 years 14.4 (11.3-18.4) 4.30 (3.10-5.70) 14.4 (10.9-20.4) 39.3 (29.3-64.9) 140

 60 years and older 17.3 (14.0-21.3) 4.20 (3.30-8.30) 18.4 (13.9-21.6) 40.1 (36.1-52.1) 130 

† Estimate is subject to greater uncertainty due to small cell size. 

50 50 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 2.5.c. Serum trans-beta-carotene: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 10.8 (9.96-11.8) 4.00 (3.40-4.50) 10.8 (10.0-11.5) 28.7 (25.8-33.0) 1992

 3–5 years 11.5 (10.3-12.9) 5.10 (4.00-6.00) 11.3 (10.0-13.4) 24.6 (18.9-31.4) 128

 6–11 years 12.9 (12.1-13.6) 6.50 (5.90-7.40) 12.4 (11.5-12.9) 27.7 (22.7-31.8) 340

 12–19 years 9.64 (8.86-10.5) 4.40 (4.00-5.00) 9.70 (8.70-10.7) 20.5 (18.4-23.4) 671

 20–39 years 9.62 (7.80-11.9) 3.50 (2.90-4.50) 9.50 (7.50-12.3) 25.6 (17.6-37.0) 319

 40–59 years 10.3 (9.20-11.6) 3.00 (2.50-4.20) 10.4 (9.10-11.4) 30.5 (24.5-39.4) 291

 60 years and older 16.6 (13.8-19.9) 5.00 (4.10-6.80) 17.0 (14.4-20.9) 46.6 (36.0-65.7) 243 

Males 

Total, 3 years and older 10.1 (9.24-11.0) 4.10 (3.20-4.50) 10.3 (9.60-11.2) 25.6 (22.4-28.7) 984

 3–5 years 11.3 (9.60-13.2) 5.10† (4.60-7.00) 12.0 (8.30-14.3) 22.7† (16.0-30.1) 64

 6–11 years 14.4 (13.0-16.0) 7.40 (6.30-8.40) 13.5 (12.7-15.5) 28.7 (22.7-35.1) 175

 12–19 years 9.20 (8.22-10.3) 4.20 (3.30-5.20) 9.40 (8.30-10.8) 20.1 (17.6-22.5) 340

 20–39 years 8.88 (6.97-11.3) 3.40 (2.90-4.40) 9.10 (6.60-11.7) 23.6 (14.8-34.0) 132

 40–59 years 9.09 (7.95-10.4) 2.90 (1.90-4.10) 9.60 (8.00-10.9) 25.8 (18.6-37.1) 154

 60 years and older 13.0 (10.6-15.9) 3.80 (3.20-5.00) 14.1 (10.8-17.0) 42.1 (26.8-51.3) 119 

Females 

Total, 3 years and older 11.5 (10.4-12.7) 4.00 (3.50-4.80) 11.2 (10.3-12.7) 32.5 (27.1-38.2) 1008

 3–5 years 11.8 (9.69-14.3) 4.60† (3.60-6.50) 11.4 (9.20-14.4) 31.1† (16.5-57.7) 64

 6–11 years 11.3 (9.51-13.5) 5.80 (5.10-6.60) 10.5 (9.30-12.5) 21.7 (17.0-35.5) 165

 12–19 years 10.1 (9.10-11.2) 4.70 (4.30-5.40) 10.0 (8.50-11.3) 20.9 (18.3-26.2) 331

 20–39 years 10.2 (7.98-12.9) 3.50 (2.80-4.90) 10.0 (7.50-13.6) 27.3 (17.6-42.6) 187

 40–59 years 11.6 (9.90-13.7) 3.00 (2.10-5.60) 12.2 (9.50-15.3) 37.1 (26.1-45.6) 137

 60 years and older 19.6 (15.1-25.3) 6.80 (3.00-11.9) 19.7 (15.2-25.2) 51.7 (36.9-93.4) 124 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 2.5.d. Serum trans-beta-carotene: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 12.6 (11.6-13.7) 4.50 (4.10-5.00) 12.1 (11.4-13.1) 36.4 (32.8-40.6) 3582

 3–5 years 14.0 (12.2-16.0) 6.10 (4.20-7.90) 14.7 (11.7-16.7) 30.9 (26.1-36.4) 132

 6–11 years 13.6 (12.5-14.8) 6.80 (5.70-8.20) 13.4 (12.0-14.9) 27.9 (22.7-31.1) 300

 12–19 years 9.69 (8.94-10.5) 4.20 (3.60-4.90) 9.30 (8.60-10.5) 22.0 (19.6-24.9) 656

 20–39 years 10.1 (8.99-11.3) 3.90 (3.20-4.60) 9.50 (8.60-10.7) 29.0 (23.7-36.2) 772

 40–59 years 13.9 (12.5-15.5) 4.70 (4.00-5.30) 13.5 (12.2-14.7) 44.4 (35.2-55.1) 778

 60 years and older 16.5 (14.7-18.5) 5.50 (4.30-6.40) 17.6 (15.1-19.9) 45.8 (40.8-51.5) 944 

Males 

Total, 3 years and older 11.2 (10.3-12.3) 3.90 (3.50-4.30) 11.3 (10.2-12.1) 32.1 (27.9-36.2) 1739

 3–5 years 14.1 (12.2-16.2) 5.60† (3.80-6.80) 15.0 (11.9-16.6) 31.4† (23.8-46.0) 71

 6–11 years 13.8 (12.2-15.7) 6.70 (5.60-8.40) 13.8 (11.9-15.9) 25.8 (22.1-33.0) 157

 12–19 years 9.28 (8.36-10.3) 4.00 (3.50-4.60) 9.00 (8.00-10.3) 20.3 (18.4-24.0) 323

 20–39 years 9.02 (8.00-10.2) 3.80 (3.10-4.60) 8.60 (7.70-9.50) 26.4 (19.3-33.6) 312

 40–59 years 11.7 (10.5-13.2) 3.80 (3.40-4.30) 11.9 (10.2-12.9) 35.0 (28.4-44.4) 408

 60 years and older 14.7 (13.0-16.7) 4.50 (3.40-5.70) 15.6 (13.7-17.9) 43.0 (35.2-50.9) 468 

Females 

Total, 3 years and older 14.0 (12.7-15.5) 5.10 (4.70-5.70) 13.5 (12.1-15.1) 40.1 (36.0-45.1) 1843

 3–5 years 13.8 (10.4-18.4) 7.60† (3.20-9.50) 12.8 (9.60-17.3) 30.6† (17.1-73.7) 61

 6–11 years 13.3 (12.1-14.7) 6.70 (5.30-8.00) 12.8 (11.8-15.1) 28.6 (21.5-31.3) 143

 12–19 years 10.1 (9.16-11.2) 4.50 (3.50-5.70) 10.0 (8.60-11.5) 24.2 (19.4-30.0) 333

 20–39 years 11.1 (9.78-12.6) 4.30 (3.40-5.00) 10.4 (9.10-12.1) 32.8 (27.4-39.8) 460

 40–59 years 16.8 (14.5-19.4) 5.70 (5.30-6.60) 15.7 (13.8-18.4) 54.7 (40.2-76.2) 370

 60 years and older 18.0 (15.7-20.7) 5.70 (4.80-7.60) 19.0 (16.8-23.0) 48.1 (41.1-56.3) 476 

† Estimate is subject to greater uncertainty due to small cell size. 

2 Fat-Soluble Vitamins & Micronutrients 51
Table 2.6.a. Serum beta-cryptoxanthin: Total population 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 7.51 (7.12-7.93) 3.20 (3.00-3.50) 7.50 (7.00-7.90) 17.8 (16.5-19.2) 8317

 3–5 years 9.43 (8.40-10.6) 4.10 (3.30-5.50) 9.00 (7.80-10.5) 22.8 (18.3-27.8) 427

 6–11 years 9.40 (8.71-10.2) 4.60 (4.10-5.10) 9.10 (8.20-10.1) 20.0 (17.0-22.9) 1006

 12–19 years 7.63 (7.20-8.09) 3.70 (3.40-4.00) 7.50 (7.00-8.00) 15.8 (14.4-17.6) 2199

 20–39 years 7.11 (6.57-7.69) 3.10 (2.80-3.50) 6.80 (6.30-7.50) 17.1 (15.2-19.3) 1707

 40–59 years 7.28 (6.75-7.86) 3.00 (2.70-3.40) 7.10 (6.70-7.80) 17.4 (15.3-19.7) 1459

 60 years and older 7.44 (6.84-8.09) 2.80 (2.50-3.20) 7.70 (7.00-8.30) 18.6 (17.5-19.6) 1519 

Males 

Total, 3 years and older 7.35 (6.96-7.77) 3.14 (2.80-3.40) 7.50 (6.90-7.90) 17.1 (16.0-18.5) 4032

 3–5 years 9.80 (8.43-11.4) 4.20 (3.20-5.60) 9.60 (7.90-11.8) 22.8 (15.6-31.9) 217

 6–11 years 9.63 (8.84-10.5) 5.00 (4.10-5.50) 9.30 (8.40-10.2) 21.2 (16.5-25.9) 503

 12–19 years 7.64 (7.14-8.19) 3.70 (3.30-4.20) 7.50 (7.00-8.10) 15.5 (14.2-17.7) 1085

 20–39 years 7.15 (6.49-7.88) 3.20 (2.80-3.50) 7.10 (6.10-8.00) 16.8 (15.2-19.8) 723

 40–59 years 6.98 (6.57-7.42) 2.90 (2.50-3.30) 7.00 (6.50-7.60) 16.1 (14.6-18.5) 756

 60 years and older 6.64 (6.02-7.31) 2.40 (1.90-2.90) 7.00 (6.00-7.60) 16.7 (15.8-17.7) 748 

Females 

Total, 3 years and older 7.67 (7.23-8.12) 3.40 (3.10-3.50) 7.50 (7.00-7.90) 18.2 (16.7-19.7) 4285

 3–5 years 9.07 (7.79-10.6) 3.90 (3.00-5.30) 8.20 (6.40-10.4) 23.3 (17.3-32.1) 210

 6–11 years 9.15 (8.21-10.2) 4.30 (4.00-4.80) 8.70 (7.80-10.7) 18.4 (16.1-21.6) 503

 12–19 years 7.61 (7.10-8.16) 3.70 (3.40-4.00) 7.50 (7.00-8.00) 16.0 (14.3-17.5) 1114

 20–39 years 7.07 (6.50-7.70) 3.10 (2.60-3.50) 6.70 (6.10-7.50) 17.5 (14.6-19.6) 984

 40–59 years 7.61 (6.88-8.43) 3.10 (2.80-3.50) 7.30 (6.70-8.10) 18.5 (15.4-21.9) 703

 60 years and older 8.10 (7.41-8.86) 3.10 (2.70-3.50) 8.20 (7.40-8.80) 20.1 (18.1-22.7) 771 

Table 2.6.b. Serum beta-cryptoxanthin: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 12.1 (11.1-13.1) 5.10 (4.80-5.70) 12.1 (10.8-13.5) 27.1 (25.0-29.8) 2114

 3–5 years 11.0 (9.50-12.8) 5.20 (4.20-6.70) 10.3 (9.10-12.3) 23.6 (18.8-42.0) 126

 6–11 years 11.9 (10.6-13.3) 6.20 (5.30-7.10) 11.1 (10.0-13.4) 24.1 (19.9-28.7) 290

 12–19 years 9.72 (9.07-10.4) 4.80 (4.20-5.40) 9.70 (9.00-10.5) 19.8 (17.2-21.4) 696

 20–39 years 13.4 (11.9-15.1) 5.60 (4.90-6.80) 14.0 (11.6-15.9) 30.0 (26.9-33.7) 460

 40–59 years 12.2 (10.4-14.3) 4.70 (3.80-5.80) 12.7 (10.4-15.2) 27.3 (23.2-36.9) 287

 60 years and older 11.0 (9.19-13.2) 3.70 (3.20-4.50) 11.1 (9.20-13.4) 28.5 (21.2-37.1) 255 

Males 

Total, 3 years and older 11.8 (10.7-13.1) 5.20 (4.70-5.70) 11.7 (10.4-13.4) 26.6 (23.8-29.9) 1018

 3–5 years 11.1 (8.25-14.8) 5.50† (3.60-6.90) 10.3 (6.80-15.9) 22.8† (14.1-43.1) 62

 6–11 years 11.6 (10.2-13.0) 5.60 (4.90-7.20) 10.9 (9.70-12.6) 24.1 (19.9-28.7) 140

 12–19 years 9.32 (8.39-10.4) 4.70 (3.50-5.50) 9.34 (8.10-10.8) 18.5 (15.2-22.2) 330

 20–39 years 12.9 (11.3-14.8) 5.30 (4.80-7.00) 13.4 (10.6-15.4) 29.8 (24.1-35.1) 213

 40–59 years 12.9 (10.7-15.6) 5.10 (3.20-7.50) 13.1 (9.70-18.4) 28.7 (24.1-38.3) 147

 60 years and older 9.87 (8.17-11.9) 3.50 (2.40-4.40) 10.8 (8.40-13.2) 23.9 (16.7-37.1) 126 

Females 

Total, 3 years and older 12.3 (11.4-13.3) 5.30 (4.90-6.00) 12.2 (10.9-13.9) 27.7 (25.3-32.1) 1096

 3–5 years 11.0 (9.59-12.6) 4.70† (3.20-7.50) 9.90 (7.70-12.7) 25.7† (17.7-44.1) 64

 6–11 years 12.2 (10.7-14.0) 6.80 (5.30-7.30) 11.4 (9.50-14.3) 25.4 (19.1-28.8) 150

 12–19 years 10.2 (9.61-10.8) 5.10 (4.50-5.80) 10.0 (9.40-10.7) 20.8 (18.8-22.5) 366

 20–39 years 13.9 (12.1-16.1) 6.00 (4.80-7.10) 14.6 (11.3-17.6) 32.2 (26.1-37.6) 247

 40–59 years 11.5 (9.71-13.7) 4.50 (3.80-5.80) 11.9 (10.1-13.8) 26.5 (18.8-42.9) 140

 60 years and older 12.0 (9.47-15.3) 4.30 (3.20-6.10) 11.7 (8.50-17.3) 29.7 (21.2-43.4) 129 

† Estimate is subject to greater uncertainty due to small cell size. 

52 52 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 2.6.c. Serum beta-cryptoxanthin: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 8.13 (7.50-8.81) 3.90 (3.40-4.20) 7.90 (7.40-8.50) 18.0 (15.7-20.7) 1987

 3–5 years 10.9 (9.72-12.2) 5.80 (5.30-6.30) 10.2 (8.30-12.7) 20.9 (16.7-23.5) 128

 6–11 years 12.0 (10.7-13.4) 6.50 (5.50-7.90) 11.8 (9.90-13.9) 23.0 (20.4-26.3) 338

 12–19 years 8.94 (8.44-9.47) 4.70 (4.40-5.10) 8.80 (8.30-9.30) 16.6 (14.9-17.6) 670

 20–39 years 7.60 (6.69-8.63) 4.00 (3.60-4.30) 7.00 (6.20-8.20) 15.4 (12.7-21.9) 318

 40–59 years 6.79 (6.35-7.26) 3.10 (2.90-3.50) 6.60 (6.10-7.50) 15.5 (13.2-18.8) 290

 60 years and older 7.89 (6.22-10.0) 3.00 (2.30-3.40) 7.80 (5.70-10.2) 20.5 (15.7-29.6) 243 

Males 

Total, 3 years and older 8.26 (7.59-8.99) 4.00 (3.50-4.30) 8.10 (7.30-9.10) 17.8 (15.7-20.4) 982

 3–5 years 10.7 (9.29-12.3) 5.90† (5.30-6.40) 10.2 (8.70-12.6) 20.1† (16.1-22.7) 64

 6–11 years 12.7 (11.2-14.4) 6.70 (5.60-8.30) 12.8 (10.9-14.2) 23.1 (18.6-30.9) 174

 12–19 years 8.91 (8.29-9.58) 5.00 (4.50-5.40) 8.90 (8.20-9.30) 16.3 (14.4-18.8) 339

 20–39 years 8.00 (6.63-9.67) 4.00 (2.80-5.00) 7.80 (5.70-10.2) 15.9 (13.9-21.9) 132

 40–59 years 6.69 (6.09-7.34) 3.30 (2.90-3.70) 6.50 (5.80-7.30) 14.8 (12.1-19.1) 154

 60 years and older 7.02 (5.69-8.66) 3.10 (2.20-3.50) 6.80 (5.70-8.20) 15.7 (9.30-27.1) 119 

Females 

Total, 3 years and older 8.02 (7.38-8.73) 3.70 (3.30-4.10) 7.80 (7.20-8.30) 18.0 (15.3-21.6) 1005

 3–5 years 11.1 (9.30-13.2) 5.60† (5.00-6.40) 10.6 (7.70-14.9) 20.9† (15.4-53.1) 64

 6–11 years 11.3 (9.47-13.4) 6.30 (4.40-7.70) 11.0 (8.50-13.8) 21.6 (14.7-28.4) 164

 12–19 years 8.97 (8.48-9.49) 4.60 (4.00-5.00) 8.90 (8.60-9.80) 17.0 (15.2-17.7) 331

 20–39 years 7.33 (6.38-8.42) 3.80 (3.40-4.30) 6.30 (6.10-7.30) 15.3 (10.8-24.6) 186

 40–59 years 6.89 (6.31-7.52) 3.20 (2.50-3.70) 6.70 (5.90-7.80) 16.1 (12.9-19.1) 136

 60 years and older 8.55 (6.37-11.5) 2.70 (2.30-4.10) 8.80 (5.10-13.9) 23.0 (16.5-34.7) 124 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 2.6.d. Serum beta-cryptoxanthin: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 6.84 (6.47-7.24) 3.00 (2.70-3.30) 6.80 (6.30-7.20) 15.6 (14.6-16.9) 3552

 3–5 years 8.53 (7.14-10.2) 3.90 (2.80-5.50) 7.90 (6.40-10.4) 19.8 (14.4-31.9) 130

 6–11 years 8.49 (7.67-9.38) 4.20 (3.80-4.90) 8.30 (7.40-9.10) 16.6 (14.6-21.8) 296

 12–19 years 6.87 (6.41-7.36) 3.30 (2.80-3.80) 6.60 (6.10-7.00) 14.3 (12.5-16.6) 651

 20–39 years 6.16 (5.63-6.73) 2.90 (2.60-3.40) 5.90 (5.40-6.50) 13.3 (11.1-16.4) 765

 40–59 years 6.87 (6.39-7.38) 2.90 (2.70-3.30) 6.80 (6.20-7.40) 15.6 (13.9-18.0) 770

 60 years and older 7.14 (6.56-7.76) 2.70 (2.30-3.20) 7.50 (6.70-8.10) 17.6 (16.4-19.1) 940 

Males 

Total, 3 years and older 6.64 (6.31-6.99) 2.90 (2.60-3.30) 6.50 (6.20-7.00) 14.7 (13.8-16.1) 1724

 3–5 years 9.29 (7.45-11.6) 3.80† (2.20-6.10) 8.90 (6.50-11.3) 23.9† (12.1-56.4) 72

 6–11 years 8.68 (7.70-9.77) 4.10 (3.70-5.10) 8.30 (7.40-9.20) 18.4 (13.8-26.3) 155

 12–19 years 6.80 (6.30-7.33) 3.20 (2.80-3.60) 6.60 (6.10-7.40) 14.0 (11.8-16.6) 318

 20–39 years 6.23 (5.54-7.01) 3.10 (2.70-3.50) 6.00 (5.40-6.70) 13.3 (10.8-16.5) 311

 40–59 years 6.50 (6.17-6.84) 2.80 (2.35-3.30) 6.50 (5.90-7.10) 14.3 (12.5-16.0) 402

 60 years and older 6.34 (5.77-6.96) 2.10 (1.90-2.60) 6.80 (5.70-7.60) 16.2 (15.2-17.2) 466 

Females 

Total, 3 years and older 7.04 (6.57-7.55) 3.10 (2.90-3.40) 6.80 (6.30-7.40) 16.4 (14.8-18.4) 1828

 3–5 years 7.73 (5.91-10.1) 3.90† (2.00-5.70) 7.10 (5.30-11.3) 15.0† (11.7-33.0) 58

 6–11 years 8.27 (6.92-9.87) 4.10 (3.50-4.90) 8.20 (6.40-10.9) 15.4 (13.5-18.7) 141

 12–19 years 6.93 (6.33-7.59) 3.50 (3.00-4.00) 6.60 (6.00-7.10) 14.5 (12.7-16.9) 333

 20–39 years 6.09 (5.54-6.70) 2.80 (2.40-3.40) 6.00 (5.40-6.60) 13.5 (10.8-17.8) 454

 40–59 years 7.29 (6.52-8.16) 3.10 (2.90-3.70) 7.00 (6.10-7.90) 17.5 (13.5-22.2) 368

 60 years and older 7.82 (7.06-8.66) 3.20 (2.70-3.60) 8.00 (7.30-8.60) 19.5 (16.9-21.6) 474 

† Estimate is subject to greater uncertainty due to small cell size. 

2 Fat-Soluble Vitamins & Micronutrients 53
Table 2.7.a. Serum lutein/zeaxanthin: Total population 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 13.0 (12.5-13.6) 7.00 (6.60-7.30) 12.8 (12.2-13.5) 25.0 (24.0-25.8) 8353

 3–5 years 12.5 (11.8-13.2) 7.30 (7.00-7.90) 12.5 (12.0-13.4) 20.7 (18.5-22.7) 430

 6–11 years 12.5 (11.9-13.2) 7.60 (7.00-8.20) 12.4 (11.6-13.2) 20.3 (19.1-21.8) 1014

 12–19 years 10.4 (9.91-11.0) 6.10 (5.70-6.60) 10.4 (9.80-11.1) 17.8 (16.5-19.1) 2205

 20–39 years 12.1 (11.5-12.9) 6.30 (6.00-6.80) 12.0 (11.2-12.8) 23.0 (21.7-24.4) 1714

 40–59 years 14.4 (13.6-15.2) 7.70 (7.40-8.30) 14.2 (13.5-15.0) 27.3 (25.5-29.6) 1468

 60 years and older 15.2 (14.3-16.2) 7.60 (7.00-8.30) 15.3 (14.3-16.5) 30.0 (27.3-32.5) 1522 

Males 

Total, 3 years and older 13.0 (12.5-13.5) 7.00 (6.70-7.30) 13.0 (12.4-13.6) 24.9 (23.5-26.0) 4049

 3–5 years 12.2 (11.0-13.5) 7.30 (6.40-8.00) 12.1 (10.8-13.8) 19.5 (18.2-21.8) 217

 6–11 years 12.6 (11.7-13.4) 7.70 (6.40-8.60) 12.5 (11.5-13.5) 21.3 (19.4-24.6) 507

 12–19 years 10.3 (9.71-10.9) 5.90 (5.30-6.30) 10.2 (9.60-10.9) 17.7 (16.5-18.9) 1091

 20–39 years 12.4 (11.7-13.1) 6.70 (6.20-7.10) 12.4 (11.2-13.2) 22.8 (21.6-24.5) 724

 40–59 years 14.5 (13.8-15.3) 7.90 (7.30-8.50) 14.5 (13.7-15.5) 27.6 (25.5-30.4) 761

 60 years and older 14.5 (13.4-15.8) 7.30 (6.30-8.50) 14.7 (13.3-16.4) 28.5 (24.9-32.0) 749 

Females 

Total, 3 years and older 13.1 (12.5-13.7) 6.80 (6.50-7.10) 12.7 (12.2-13.5) 25.0 (24.1-25.9) 4304

 3–5 years 12.8 (11.6-14.1) 7.50 (6.40-8.10) 12.6 (11.8-13.8) 21.4 (17.6-26.5) 213

 6–11 years 12.5 (11.9-13.2) 7.90 (7.00-8.90) 12.2 (11.5-13.3) 19.4 (18.0-20.7) 507

 12–19 years 10.6 (9.95-11.3) 6.50 (5.60-7.00) 10.4 (9.90-11.3) 17.9 (16.5-20.2) 1114

 20–39 years 11.9 (11.1-12.8) 6.20 (5.80-6.90) 11.6 (10.7-12.5) 23.0 (20.8-25.1) 990

 40–59 years 14.2 (13.2-15.2) 7.60 (7.10-8.40) 13.9 (13.0-14.7) 26.8 (24.8-30.2) 707

 60 years and older 15.8 (14.9-16.7) 8.00 (7.10-8.70) 15.7 (14.6-17.5) 32.0 (27.6-33.7) 773 

Table 2.7.b. Serum lutein/zeaxanthin: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 13.7 (13.3-14.1) 7.70 (7.30-8.10) 13.5 (13.1-14.0) 24.1 (23.0-25.1) 2114

 3–5 years 12.5 (11.3-13.9) 7.20 (5.80-9.70) 12.5 (11.8-13.8) 19.1 (16.9-22.5) 126

 6–11 years 12.4 (11.5-13.2) 8.00 (6.40-9.20) 12.2 (11.6-12.8) 19.2 (17.2-21.2) 290

 12–19 years 10.8 (10.4-11.1) 6.70 (6.00-6.80) 10.6 (10.2-11.0) 18.0 (16.7-18.9) 696

 20–39 years 14.4 (13.5-15.4) 8.10 (7.10-8.60) 14.9 (13.8-15.9) 24.4 (23.0-25.7) 460

 40–59 years 15.7 (14.3-17.1) 8.90 (8.20-9.50) 15.5 (13.9-16.7) 28.4 (23.9-32.9) 287

 60 years and older 15.8 (15.0-16.7) 8.00 (6.00-9.70) 16.0 (14.4-17.4) 32.5 (27.3-34.3) 255 

Males 

Total, 3 years and older 14.1 (13.6-14.6) 8.10 (7.40-8.40) 14.2 (13.7-14.6) 24.1 (22.6-26.1) 1018

 3–5 years 12.8 (10.6-15.4) 6.70† (5.30-10.8) 13.1 (11.3-15.4) 19.1† (15.9-25.7) 62

 6–11 years 12.2 (11.2-13.2) 8.20 (6.30-9.30) 12.3 (11.4-12.9) 19.1 (15.7-22.5) 140

 12–19 years 10.7 (10.1-11.3) 6.60 (5.70-7.00) 10.4 (9.60-11.4) 18.2 (15.6-20.1) 330

 20–39 years 15.0 (14.0-15.9) 8.60 (7.30-9.90) 15.8 (14.4-16.5) 23.9 (22.1-26.2) 213

 40–59 years 17.4 (15.7-19.3) 9.50 (8.90-11.4) 17.3 (14.8-19.9) 31.6 (26.6-36.4) 147

 60 years and older 15.3 (14.0-16.6) 7.70 (5.70-9.80) 14.9 (13.4-17.4) 29.5 (25.8-37.9) 126 

Females 

Total, 3 years and older 13.2 (12.8-13.6) 7.40 (6.90-7.70) 13.0 (12.5-13.5) 23.9 (21.9-25.1) 1096

 3–5 years 12.3 (10.8-14.0) 6.70† (5.00-10.0) 12.4 (9.90-14.9) 18.5† (16.0-22.5) 64

 6–11 years 12.6 (11.7-13.6) 8.30 (6.40-9.30) 12.4 (11.6-13.5) 19.2 (16.6-24.2) 150

 12–19 years 10.9 (10.4-11.4) 6.80 (6.10-7.40) 10.9 (10.2-11.3) 17.5 (16.2-19.7) 366

 20–39 years 13.8 (12.7-15.0) 7.30 (6.60-8.20) 13.8 (12.2-15.8) 24.9 (23.8-26.5) 247

 40–59 years 14.0 (12.5-15.6) 8.20 (6.80-9.10) 13.9 (12.3-15.9) 22.7 (18.7-30.8) 140

 60 years and older 16.3 (15.2-17.6) 8.60 (6.00-11.3) 16.0 (13.8-19.0) 32.5 (26.4-34.3) 129 

† Estimate is subject to greater uncertainty due to small cell size. 

54 54 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 2.7.c. Serum lutein/zeaxanthin: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 14.3 (13.2-15.5) 8.10 (7.30-8.80) 14.2 (12.8-15.5) 26.1 (24.1-28.5) 1992

 3–5 years 15.4 (14.0-17.1) 9.80 (8.50-11.2) 15.3 (13.0-18.2) 24.5 (19.6-32.5) 128

 6–11 years 15.3 (14.4-16.3) 9.50 (8.50-10.3) 15.7 (14.7-16.6) 24.7 (22.4-25.3) 340

 12–19 years 12.5 (11.6-13.5) 7.80 (7.20-8.50) 12.5 (11.4-13.7) 19.6 (17.9-22.2) 671

 20–39 years 13.3 (11.9-14.8) 7.50 (6.70-8.10) 12.8 (11.4-14.4) 25.3 (21.8-28.6) 319

 40–59 years 14.9 (13.6-16.4) 8.60 (7.00-9.40) 15.5 (13.2-17.2) 28.2 (24.7-31.2) 291

 60 years and older 17.6 (15.1-20.5) 9.10 (7.30-11.2) 17.7 (14.7-21.5) 33.7 (29.7-36.5) 243 

Males 

Total, 3 years and older 14.5 (13.4-15.7) 8.00 (7.40-9.00) 14.6 (13.4-15.8) 26.2 (24.1-28.5) 984

 3–5 years 15.4 (13.4-17.7) 10.6† (8.50-12.7) 14.5 (13.0-18.4) 21.8† (18.5-34.3) 64

 6–11 years 16.4 (15.2-17.7) 10.1 (8.90-11.4) 16.4 (15.6-17.2) 25.1 (23.9-27.0) 175

 12–19 years 12.3 (11.5-13.0) 7.80 (7.50-8.30) 12.0 (11.4-13.3) 19.6 (18.2-20.8) 340

 20–39 years 13.8 (12.0-15.8) 7.50 (6.80-8.40) 13.5 (11.0-15.6) 25.9 (21.9-29.8) 132

 40–59 years 15.1 (13.5-17.0) 8.60 (7.10-9.70) 15.5 (13.5-17.5) 28.7 (24.2-31.2) 154

 60 years and older 16.1 (14.2-18.1) 7.50 (5.80-10.4) 16.0 (14.7-18.4) 29.6 (22.7-38.9) 119 

Females 

Total, 3 years and older 14.1 (12.9-15.5) 8.10 (7.10-8.80) 13.9 (12.2-15.4) 26.0 (23.3-29.5) 1008

 3–5 years 15.5 (12.9-18.5) 9.40† (7.90-11.8) 15.6 (12.3-18.2) 25.7† (19.3-37.1) 64

 6–11 years 14.2 (12.8-15.9) 8.90 (7.40-10.1) 14.8 (12.3-16.1) 21.8 (19.2-25.3) 165

 12–19 years 12.8 (11.5-14.2) 8.10 (6.80-9.40) 12.8 (11.3-14.4) 20.4 (17.6-24.2) 331

 20–39 years 12.9 (11.4-14.6) 7.10 (6.30-8.10) 12.7 (11.3-14.3) 23.3 (19.5-28.9) 187

 40–59 years 14.7 (13.2-16.3) 8.70 (6.20-9.60) 14.2 (12.5-17.1) 27.4 (22.1-33.3) 137

 60 years and older 18.8 (15.5-22.7) 9.40 (8.00-12.2) 19.3 (14.4-25.4) 35.0 (31.0-36.7) 124 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 2.7.d. Serum lutein/zeaxanthin: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 12.6 (11.9-13.2) 6.80 (6.40-7.10) 12.4 (11.6-13.1) 24.1 (22.5-25.7) 3580

 3–5 years 11.5 (10.8-12.3) 7.20 (6.40-7.60) 11.8 (10.4-12.8) 17.7 (16.9-21.4) 133

 6–11 years 11.7 (10.9-12.6) 7.20 (6.70-7.90) 11.4 (10.8-12.4) 18.7 (17.0-21.8) 301

 12–19 years 9.87 (9.21-10.6) 5.90 (5.20-6.40) 9.80 (9.10-10.5) 16.8 (15.2-19.3) 656

 20–39 years 11.3 (10.6-12.1) 6.00 (5.70-6.50) 11.3 (10.3-12.4) 21.2 (19.3-22.9) 770

 40–59 years 13.8 (13.0-14.8) 7.50 (7.10-7.80) 13.7 (13.1-14.4) 26.3 (24.1-28.5) 777

 60 years and older 14.7 (13.8-15.7) 7.40 (6.80-8.10) 14.9 (13.5-16.4) 28.0 (25.6-31.7) 943 

Males 

Total, 3 years and older 12.5 (11.9-13.1) 6.80 (6.30-7.10) 12.5 (11.7-13.2) 23.9 (22.0-26.0) 1738

 3–5 years 11.2 (9.93-12.6) 7.10† (6.20-7.70) 10.7 (9.00-13.5) 17.1† (15.2-21.7) 72

 6–11 years 11.7 (10.6-13.0) 7.10 (5.70-8.30) 11.3 (10.2-13.0) 19.6 (17.2-25.5) 157

 12–19 years 9.65 (9.05-10.3) 5.50 (4.90-6.20) 9.60 (9.10-10.2) 16.7 (15.5-18.7) 323

 20–39 years 11.6 (10.7-12.6) 6.20 (5.70-6.90) 11.7 (10.6-13.0) 20.7 (17.7-23.7) 312

 40–59 years 13.9 (13.2-14.8) 7.70 (7.10-8.50) 13.9 (13.3-14.9) 26.8 (24.9-28.3) 407

 60 years and older 13.9 (12.8-15.2) 7.30 (6.20-8.10) 14.1 (12.6-16.0) 26.1 (24.2-28.9) 467 

Females 

Total, 3 years and older 12.6 (11.9-13.4) 6.60 (6.20-7.00) 12.2 (11.6-13.0) 24.4 (22.8-25.8) 1842

 3–5 years 11.9 (10.6-13.5) 7.30† (4.30-8.30) 12.6 (10.8-13.8) 18.4† (15.2-23.2) 61

 6–11 years 11.7 (11.0-12.5) 7.50 (6.60-8.10) 11.5 (10.9-12.3) 17.9 (15.5-20.2) 144

 12–19 years 10.1 (9.25-11.0) 6.10 (5.00-6.70) 10.1 (9.10-10.7) 16.8 (14.8-20.8) 333

 20–39 years 11.1 (10.2-12.0) 5.90 (5.60-6.60) 10.6 (9.50-12.0) 21.4 (18.4-23.3) 458

 40–59 years 13.7 (12.6-15.0) 7.40 (6.50-8.00) 13.5 (12.3-14.3) 26.4 (23.4-31.6) 370

 60 years and older 15.4 (14.4-16.4) 7.70 (6.70-8.70) 15.5 (14.0-17.4) 30.4 (25.8-34.3) 476 

† Estimate is subject to greater uncertainty due to small cell size. 

2 Fat-Soluble Vitamins & Micronutrients 55
Table 2.8.a. Serum trans-lycopene: Total population 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 20.5 (19.8-21.1) 10.5 (10.0-11.0) 22.0 (21.2-22.8) 37.5 (36.1-38.6) 8348

 3–5 years 16.1 (15.2-17.1) 7.90 (7.30-8.90) 17.4 (16.2-18.1) 30.7 (28.5-32.8) 427

 6–11 years 21.6 (20.7-22.5) 11.4 (10.4-12.7) 22.7 (21.4-23.7) 36.0 (35.0-37.2) 1012

 12–19 years 21.6 (21.1-22.1) 12.8 (11.9-13.6) 22.3 (21.8-22.8) 36.1 (35.1-37.5) 2205

 20–39 years 22.7 (21.5-23.9) 12.5 (11.7-13.8) 23.7 (22.5-24.8) 39.1 (37.6-41.0) 1714

 40–59 years 21.1 (20.1-22.1) 10.7 (9.80-11.7) 22.6 (21.3-24.1) 38.1 (36.6-39.8) 1468

 60 years and older 15.4 (14.6-16.3) 6.70 (5.70-7.30) 17.1 (15.9-17.9) 33.4 (31.5-34.5) 1522 

Males 

Total, 3 years and older 21.2 (20.5-22.0) 10.8 (10.3-11.3) 23.1 (22.2-24.0) 39.0 (37.4-40.6) 4048

 3–5 years 16.0 (14.9-17.2) 7.80 (7.10-9.00) 17.7 (16.0-19.1) 28.4 (27.1-30.9) 216

 6–11 years 21.7 (20.4-23.1) 11.5 (9.40-13.3) 23.0 (21.2-25.0) 36.4 (34.1-40.1) 507

 12–19 years 22.5 (21.8-23.2) 13.4 (12.4-14.0) 23.5 (22.5-24.5) 37.5 (35.3-39.8) 1091

 20–39 years 24.2 (22.6-25.9) 13.8 (11.7-15.0) 25.0 (23.6-26.3) 42.1 (39.1-45.2) 724

 40–59 years 21.7 (20.4-23.2) 11.1 (9.20-11.9) 23.7 (21.9-25.5) 39.8 (37.5-41.7) 761

 60 years and older 15.2 (14.1-16.4) 6.30 (5.60-7.50) 16.8 (15.5-17.9) 33.2 (30.5-36.0) 749 

Females 

Total, 3 years and older 19.7 (19.1-20.4) 10.3 (9.70-10.9) 21.1 (20.1-21.9) 35.6 (34.3-36.7) 4300

 3–5 years 16.2 (14.6-18.1) 8.00 (6.20-10.3) 16.6 (14.9-18.6) 32.5 (29.1-34.3) 211

 6–11 years 21.5 (20.6-22.4) 10.7 (9.70-13.0) 22.2 (20.6-23.3) 35.5 (34.1-37.3) 505

 12–19 years 20.6 (20.0-21.3) 12.3 (11.5-13.1) 21.4 (20.0-22.2) 34.8 (32.1-36.3) 1114

 20–39 years 21.3 (20.2-22.5) 12.2 (10.5-13.6) 22.3 (21.2-23.6) 36.7 (33.8-39.3) 990

 40–59 years 20.4 (19.4-21.4) 10.7 (9.30-12.1) 21.8 (20.9-22.8) 36.5 (34.4-37.8) 707

 60 years and older 15.6 (14.5-16.9) 6.70 (5.60-7.50) 17.3 (15.7-18.6) 33.3 (30.6-34.5) 773 

Table 2.8.b. Serum trans-lycopene: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 19.7 (18.9-20.5) 10.6 (9.90-11.6) 20.6 (19.8-21.5) 34.6 (33.0-36.0) 2111

 3–5 years 15.0 (12.9-17.4) 7.30 (5.80-9.20) 15.7 (12.5-19.4) 30.4 (23.0-39.8) 124

 6–11 years 19.7 (18.3-21.3) 10.5 (9.20-13.1) 20.5 (18.7-22.5) 33.7 (29.6-36.1) 289

 12–19 years 20.4 (19.4-21.4) 12.3 (11.2-13.4) 20.7 (19.6-22.0) 32.9 (30.4-36.2) 696

 20–39 years 21.4 (20.1-22.8) 12.1 (11.2-13.6) 21.7 (20.6-22.5) 36.0 (33.1-39.9) 460

 40–59 years 19.1 (17.5-20.9) 10.2 (8.70-11.3) 20.0 (17.9-22.3) 34.4 (29.9-39.1) 287

 60 years and older 13.9 (11.7-16.6) 6.20 (2.20-9.60) 15.3 (13.1-17.7) 30.1 (26.6-31.6) 255 

Males 

Total, 3 years and older 20.4 (19.6-21.2) 11.4 (10.2-12.0) 21.3 (20.6-21.9) 35.9 (32.7-39.4) 1018

 3–5 years 15.2 (13.3-17.2) 8.60† (1.80-11.3) 15.7 (12.4-18.1) 28.5† (23.8-33.3) 62

 6–11 years 20.8 (18.5-23.4) 12.6 (8.70-14.7) 20.6 (19.2-24.1) 33.4 (28.4-45.7) 140

 12–19 years 21.1 (20.2-22.0) 12.9 (11.6-13.9) 21.5 (20.4-22.6) 34.6 (30.3-39.4) 330

 20–39 years 22.0 (20.7-23.5) 12.4 (11.2-14.1) 22.2 (20.7-23.6) 39.1 (33.0-43.7) 213

 40–59 years 20.0 (17.9-22.3) 10.2 (8.90-11.8) 20.9 (16.8-24.5) 35.5 (30.2-43.3) 147

 60 years and older 13.0 (10.4-16.3) 5.20 (.800-7.50) 14.2 (10.6-17.7) 27.8 (24.0-31.4) 126 

Females 

Total, 3 years and older 19.0 (18.0-20.0) 10.2 (9.10-11.3) 20.0 (18.6-21.4) 33.7 (31.6-34.9) 1093

 3–5 years 14.8 (11.0-19.8) 6.70† (4.30-9.50) 15.0 (9.50-22.8) 32.7† (20.3-37.9) 62

 6–11 years 18.7 (16.8-20.7) 9.90 (9.10-11.0) 20.0 (16.9-22.9) 33.2 (28.6-35.4) 149

 12–19 years 19.6 (18.4-20.9) 11.7 (10.2-13.6) 19.8 (18.3-21.2) 31.7 (29.7-35.9) 366

 20–39 years 20.6 (18.9-22.5) 11.6 (10.3-13.2) 21.3 (19.0-22.7) 34.8 (30.1-37.6) 247

 40–59 years 18.2 (16.4-20.2) 9.10 (5.30-13.2) 19.3 (17.9-20.8) 30.5 (28.2-36.9) 140

 60 years and older 14.7 (12.1-18.0) 6.80 (1.90-10.3) 15.8 (13.7-20.7) 30.5 (24.4-36.1) 129 

† Estimate is subject to greater uncertainty due to small cell size. 

56 56 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 2.8.c. Serum trans-lycopene: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 21.6 (21.0-22.3) 10.9 (10.1-11.7) 23.4 (22.1-24.2) 40.1 (37.9-42.2) 1992

 3–5 years 20.8 (18.3-23.6) 10.9 (8.90-13.4) 20.8 (18.6-24.9) 40.9 (28.5-54.9) 128

 6–11 years 25.9 (24.1-27.9) 15.0 (13.1-16.8) 27.1 (24.1-29.6) 42.1 (36.7-47.1) 340

 12–19 years 24.7 (23.6-25.8) 13.9 (12.4-16.0) 25.4 (24.0-27.0) 41.0 (38.4-43.0) 671

 20–39 years 24.3 (23.3-25.4) 13.1 (12.4-14.6) 25.2 (23.5-26.8) 41.6 (39.0-46.9) 319

 40–59 years 19.0 (17.7-20.5) 8.70 (6.20-11.3) 20.6 (19.6-22.0) 35.9 (34.4-41.3) 291

 60 years and older 14.1 (12.9-15.4) 5.40 (4.50-7.10) 14.5 (13.3-16.7) 31.4 (28.8-34.1) 243 

Males 

Total, 3 years and older 22.3 (21.4-23.2) 10.7 (9.90-12.4) 23.8 (22.8-24.6) 41.2 (37.4-44.1) 984

 3–5 years 21.6 (18.2-25.5) 9.90† (5.10-15.1) 23.8 (19.3-27.0) 41.7† (30.5-57.7) 64

 6–11 years 27.1 (24.3-30.1) 15.9 (13.0-18.5) 28.0 (23.9-32.2) 44.0 (36.4-49.1) 175

 12–19 years 25.1 (23.9-26.4) 15.2 (13.4-16.7) 25.9 (24.4-27.6) 40.1 (36.8-44.6) 340

 20–39 years 25.6 (24.4-26.9) 14.2 (12.5-16.2) 26.5 (23.8-28.1) 45.3 (37.4-56.2) 132

 40–59 years 19.4 (17.8-21.0) 9.20 (6.20-11.2) 21.3 (19.3-22.7) 35.7 (32.4-41.2) 154

 60 years and older 13.5 (11.8-15.4) 5.40 (4.30-7.10) 14.0 (11.4-16.4) 30.9 (26.2-34.9) 119 

Females 

Total, 3 years and older 21.1 (20.2-22.0) 11.0 (10.1-11.6) 22.6 (20.9-24.2) 39.7 (37.1-41.3) 1008

 3–5 years 20.0 (17.2-23.2) 11.1† (7.60-14.4) 19.6 (15.7-25.5) 40.9† (26.3-44.6) 64

 6–11 years 24.7 (22.7-26.9) 13.8 (11.7-16.8) 25.9 (23.6-28.2) 39.2 (35.2-44.8) 165

 12–19 years 24.3 (22.7-26.0) 12.5 (11.3-15.8) 25.2 (22.7-27.6) 41.0 (38.8-44.4) 331

 20–39 years 23.5 (22.1-25.0) 13.0 (11.8-14.6) 24.4 (22.1-26.6) 39.7 (37.1-46.5) 187

 40–59 years 18.7 (16.9-20.7) 7.90 (5.40-11.9) 19.9 (17.7-22.0) 36.2 (30.9-43.9) 137

 60 years and older 14.5 (12.8-16.5) 5.60 (4.50-8.20) 14.8 (12.5-18.6) 31.4 (28.0-34.1) 124 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 2.8.d. Serum trans-lycopene: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 3 years and older 20.7 (19.9-21.4) 10.8 (10.2-11.4) 22.1 (21.0-23.2) 37.6 (36.3-38.7) 3578

 3–5 years 15.4 (14.0-17.0) 7.90 (6.20-9.30) 16.6 (14.8-17.9) 27.5 (25.3-31.2) 132

 6–11 years 21.5 (20.2-22.9) 11.4 (9.70-13.2) 22.2 (20.6-23.6) 35.8 (33.3-37.8) 300

 12–19 years 21.1 (20.5-21.8) 12.8 (11.5-13.8) 21.9 (20.8-22.6) 35.3 (34.0-36.8) 656

 20–39 years 22.9 (21.3-24.6) 13.1 (11.7-14.2) 24.2 (22.8-25.7) 39.6 (37.7-42.1) 770

 40–59 years 21.9 (20.7-23.1) 11.8 (10.3-13.4) 23.2 (21.3-24.9) 38.5 (36.8-40.0) 777

 60 years and older 16.1 (15.2-17.0) 7.00 (6.20-7.70) 17.8 (16.4-18.6) 33.9 (31.7-35.9) 943 

Males 

Total, 3 years and older 21.4 (20.5-22.4) 11.0 (9.90-11.6) 23.5 (22.3-24.5) 39.5 (37.9-40.9) 1737

 3–5 years 14.4 (12.6-16.5) 7.80† (4.40-9.50) 16.4 (14.3-19.1) 27.4† (24.7-30.9) 71

 6–11 years 21.7 (19.9-23.6) 12.2 (9.40-14.1) 22.2 (20.3-25.2) 36.0 (32.0-40.1) 157

 12–19 years 22.1 (21.2-23.1) 12.9 (11.5-14.0) 23.2 (21.4-24.6) 37.0 (34.3-40.2) 323

 20–39 years 24.8 (22.4-27.3) 13.9 (11.1-16.6) 25.8 (23.9-28.9) 42.4 (38.8-45.6) 312

 40–59 years 22.6 (21.0-24.2) 11.4 (9.20-13.5) 24.5 (22.4-26.9) 40.0 (37.9-42.9) 407

 60 years and older 15.7 (14.6-17.0) 6.90 (5.80-7.70) 17.5 (15.7-18.6) 33.8 (30.6-37.6) 467 

Females 

Total, 3 years and older 19.9 (19.2-20.7) 10.6 (9.90-11.4) 21.1 (20.1-22.1) 35.4 (33.9-36.7) 1841

 3–5 years 16.6 (14.7-18.8) 8.70† (6.20-13.1) 16.6 (14.7-18.9) 26.8† (22.8-31.8) 61

 6–11 years 21.3 (19.8-22.9) 11.0 (9.40-13.8) 21.7 (20.0-23.7) 34.2 (32.5-38.0) 143

 12–19 years 20.2 (19.4-21.0) 12.6 (11.0-13.9) 21.3 (19.4-22.2) 32.4 (28.9-35.8) 333

 20–39 years 21.3 (19.8-23.0) 12.3 (9.40-14.3) 22.4 (20.9-24.1) 36.5 (33.1-39.6) 458

 40–59 years 21.2 (20.2-22.3) 12.6 (10.7-13.7) 22.0 (20.7-23.5) 36.6 (34.0-37.8) 370

 60 years and older 16.4 (15.1-17.7) 6.90 (5.70-8.40) 17.9 (15.9-19.0) 33.8 (31.4-36.1) 476 

† Estimate is subject to greater uncertainty due to small cell size. 

2 Fat-Soluble Vitamins & Micronutrients 57
References 

Agency for Healthcare Research and Quality. Effect of supplemental antioxidants vitamin C, vitamin 

E, and coenzyme Q10 for the prevention and treatment of cardiovascular disease. Evidence Report/ 

Technology Assessment Number 83, 2003. 

Ahuja JK, Goldman JD, Moshfegh AJ. Current status of vitamin E nutriture. Ann N Y Acad Sci. 

2004;1031:387-90. 

Albanes D, Heinonen OP, Taylor PR, Virtamo J, Edwards BK, Rautalahti M, et al. Alpha-tocopherol and 

beta-carotene supplement and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer 

prevention study: effects of base-line characteristics and study compliance. J Natl Cancer 

Inst .1996;88:1560-70. 

Al-Delaimy WK, Ferrari P, Slimani N, Pala V, Johansson I, Nilsson S, et al. Plasma carotenoids as biomarkers 

of intake of fruits and vegetables: individual-level correlations in the European Prospective Investigation 

into Cancer and Nutrition (EPIC). Eur J Clin Nutr. 2005;59:1387-96. 

Ballew C, Bowman BA, Sowell AL, Gillespie C. Serum retinol distributions in residents of the 

United States: third National Health and Nutrition Examination Survey, 1988–1994. Am J Clin Nutr. 

2001;73:586-93. 

Beers MH, editor. Vitamin deficiency, dependency, and toxicity. In: Merck Manual of Diagnosis and 

Therapy. 18th ed. Whitehouse Station, (NJ): Merck & Co., Inc.; 2006 [cited 2008]. Available from: http:// 

www.merck.com/mmpe/sec01/ch004/ch004l.html. 

Boylston T, Nollet LML. Chemical and biochemical aspects of color in muscle foods. In: Perez-Alvarez JA 

and Fernandez-Lopez J, editors. Handbook of meat, poultry and seafood quality. Ames (IA): Blackwell 

Publishing; 2007. p. 25–44. 

Britton G, Liaaen-Jensen S, Pfander H., editors. Carotenoids handbook. Basel (Switzerland): Birkhäuser; 

2004. 

Duewer DL, Kline MC, Sharpless KE, Thomas JB. NIST micronutrients measurement quality assurance 

program: Characterizing the measurement community‘s performance over time. Anal Chem. 

2000;72:4163-70. 

Ford ES, Sowell A. Serum α-tocopherol status in the United States population: findings from the Third 

National Health and Nutrition Examination Survey. Am J Epidemiol. 1999;150:290-300. 

Ford ES. Variations in serum carotenoid concentrations among United States adults by ethnicity and sex. 

Ethn Dis. 2000;10:208-17. 

Ford ES, Gillespie C, Ballew C, Sowell A, Mannino DM. Serum carotenoid concentrations in U.S. children 

and adolescents. Am J Clin Nutr. 2002;76:818-27. 

Ford ES, Schleicher RL, Mokdad AH, Ajani UA, Liu S. Distribution of serum concentrations of alphatocopherol and gamma-tocopherol in the U.S. population. Am J Clin Nutr. 2006;84:375-83. 

Institute of Medicine, Food and Nutrition Board. Dietary reference intakes: vitamin C, vitamin E, 

selenium, and carotenoids. Washington, D.C.: National Academy Press; 2000. 

Institute of Medicine, Food and Nutrition Board. Dietary reference intakes: vitamin A, vitamin K, arsenic, 

boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc. 

Washington, D.C.: National Academy Press; 2001. 

Khachik F, Beecher GR, Goli MB, Lusby WR. Separation and quantitation of carotenoids in foods. Methods 

Enzymol. 1992;213:347–59. 

58 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Krinsky NI, Johnson EJ. Carotenoid actions and their relation to health and disease. Mol Aspects Med. 

2005;26:459–516. 

Lacher DA, Hughes JP, Carroll MD. Estimate of biological variation of laboratory analytes based on the 

Third National Health and Nutrition Examination Survey. Clin Chem. 2005;51:450–2. 

Lichtenstein AH, Appel LJ, Brands M, Carnethon M, Daniels S, Franch HA, et al. Summary of American 

Heart Association diet and lifestyle recommendations revision. Arterioscler Thromb Vasc Biol. 

2006;26:2186–91. 

Moshfegh A, Goldman J, Cleveland L. What we eat in America, NHANES 2001-02: usual nutrient intakes 

from food compared to dietary reference intakes. Beltsville (MD): U.S. Department of Agriculture, 

Agricultural Research Service; 2005 [cited 2008]. Available from: http://www.ars.usda.gov/SP2UserFiles/ 

Place/12355000/pdf/usualintaketables2001-02.pdf. 

Napoli JL. Vitamin A: biochemistry and physiological role. In: Caballero B, Allen L, Prentice A, editors. 

Encyclopedia of human nutrition. 2nd ed. Amsterdam: Elsevier Ltd.; 2006. p. 339–47. 

Redlich CA, Blaner WS, Van Bennekum AM, Chung JS, Clever SL, Holm CT, Cullen MR. Effect of 

supplementation with beta-carotene and vitamin A on lung nutrient levels. Cancer Epidemiol 

Biomarkers Prev. 1998;7:211–14. 

Roodhooft JM. Leading causes of blindness worldwide. Bull Soc Belge Ophthalmol. 2002;283:19–25. 

Thomas, RG, Gebhardt, SE. Nuts and seeds as sources of alpha and gamma tocopherols. ICR/WCRF 

International Research Conference, 2006 Jul 13-14; Washington, D.C. [cited 2008]. Available from: 

http://www.ars.usda.gov/SP2UserFiles/Place/12354500/Articles/AICR06_NutSeed.pdf. 

U.S. Department of Health and Human Services and U.S. Department of Agriculture. Dietary guidelines 

for Americans, 2005. 6th ed. Washington, D.C.: U.S. Government Printing Office; January 2005. 

U.S. Food and Drug Administration. FDA recommendation for pregnant women, T95-56. Washington, 

D.C.: Food and Drug Administration; October 6, 1995 [cited 2008]. Available from: http://www.fda.gov/ 

bbs/topics/ANSWERS/ANS00689.html. 

West Jr, KP. Vitamin A: deficiency and interventions. In: Caballero B, Allen L, Prentice A, editors. 

Encyclopedia of human nutrition. 2nd ed. Amsterdam: Elsevier Ltd.; 2006. p. 348–59. 

2 Fat-Soluble Vitamins & Micronutrients 59 
60 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Fat-Soluble Vitamins & Micronutrients: 

Vitamin D 

Vitamin D (calciferol) comprises a group of fat soluble seco-sterols found 

naturally only in a few foods, such as fish-liver oils, fatty fish, mushrooms, 

egg yolks, and liver. The two major physiologically relevant forms of 

vitamin D are D2

 (ergocalciferol) and D3 (cholecalciferol). Vitamin D3 

is photosynthesized in the skin of vertebrates by the action of solar 

ultraviolet (UV) B radiation on 7-dehydrocholesterol (Fieser 1959). Vitamin D2 

is produced by UV irradiation of ergosterol, which occurs in molds, yeast, 

and higher-order plants. Under conditions of regular sun exposure, dietary 

vitamin D intake is of minor importance. However, latitude, season, aging, 

sunscreen use, and skin pigmentation influence the production of vitamin 

D3

 by the skin (Institute of Medicine 1997). Most of the dietary intake of vitamin 

D comes from fortified milk products and other fortified foods such as 

breakfast cereals and orange juice (Institute of Medicine 1997). Both vitamin D2 

and D3 are used in nonprescription vitamin D supplements, but vitamin D2 

is the form available by prescription in the United States (Holick 2007). 

Vitamin D without a subscript represents either D2

 or D3 or both and is 

biologically inert. Vitamin D from the skin or diet is only short-lived in 

circulation (with a half-life of 1–2 days), as it is either stored in fat cells or 

metabolized in the liver (Mawer 1972). In circulation, vitamin D is bound 

to vitamin D-binding protein and transported to the liver, where it is 

converted to 25-hydroxyvitamin D [25(OH)D] (DeLuca 1984). This major 

circulating form of vitamin D is a good reflection of cumulative effects of 

exposure to sunlight and dietary intake of vitamin D (Haddad 1973; Holick 

1995) and is therefore used by clinicians to determine vitamin D status. To 

be biologically activated at physiologic concentrations, 25(OH)D must be 

converted in the kidneys to 1,25-dihydroxyvitamin D [1,25(OH)2D], which 

is thought to be responsible for most, if not all, of the biologic functions of 

vitamin D (DeLuca 1988; Reichel 1989). The production of 25(OH)D in the liver 

and of 1,25(OH)2

D in the kidney is tightly regulated. In the liver, vitamin 

D-25-hydroxylase is down-regulated by vitamin D and its metabolites, 

thereby limiting any increase in the circulating concentration of 

25(OH)D following intakes or following production of vitamin D after 

exposure to sunlight. In the kidney, in response to serum calcium and 

phosphorus concentrations, the production of 1,25(OH)2

D is regulated 

through the action of parathyroid hormone (PTH) (DeLuca 1988; Reichel 1989). 

2 Fat-Soluble Vitamins & Micronutrients 61 
Active vitamin D functions as a hormone, and its main biologic function in people is 

to maintain serum calcium and phosphorus concentrations within the normal range 

by enhancing the efficiency of the small intestine to absorb these minerals from the 

diet (DeLuca 1988; Reichel 1989). When dietary calcium intake is inadequate to satisfy the 

body’s calcium requirement, 1,25(OH)2

D, along with PTH, mobilizes calcium stores 

from the bone. In the kidney, 1,25(OH)2D increases calcium reabsorption by the distal 

renal tubules. Apart from these traditional calcium-related actions, 1,25(OH)2D and 

its synthetic analogs are increasingly recognized for their potent antiproliferative, 

prodifferentiative, and immunomodulatory activities (Nagpal 2005). 

Vitamin D deficiency is characterized by inadequate mineralization or by 

demineralization of the skeleton. Among children, vitamin D deficiency is a common 

cause of bone deformities known as rickets. Vitamin D deficiency in adults leads to a 

mineralization defect in the skeleton, causing osteomalacia, and induces secondary 

hyperparathyroidism with consequent bone loss and osteoporosis. Potential roles for 

vitamin D beyond bone health, such as effects on muscle strength, the risk for cancer 

and for type 2 diabetes, are currently being studied. The Agency for Healthcare 

Research and Quality recently reviewed the effectiveness and safety of vitamin D on 

outcomes related to bone health (Cranney 2007). The report suggests that vitamin D 

supplementation has positive effects on bone health in postmenopausal women and 

older men. 

Still, what constitutes the optimal intake of vitamin D remains a matter of some 

disagreement. Current recommendations from the Institute of Medicine (1997) call 

for 200 international units (IU) [5.0 micrograms (μg)] of vitamin D daily from birth 

through age 50, 400 IU (10 μg) for those aged 51–70 years, and 600 IU (15 μg) for 

those older than 70 years. According to the Dietary Guidelines for Americans (U.S. 

Department of Health and Human Services and U.S. Department of Agriculture 2005) older adults, 

people with dark skin, and people exposed to insufficient UV B radiation should 

consume extra vitamin D from vitamin D-fortified foods or supplements. The 

American Cancer Society Guidelines on Nutrition and Physical Activity for Cancer 

Prevention echo this recommendation (Kushi 2006). Some experts say that optimal 

amounts for all adults are closer to 800–1000 IU (20–25 μg) daily (Vieth 2007; BischoffFerrari 2006; Dawson-Hughes 2005). The tolerable upper intake level for vitamin D is 2000 IU 

(50 μg) per day in North America and in Europe; however, some scientists are calling 

for an upward revision (Hathcock 2007; Vieth 2006). 

Some clinical laboratories use conventional units for 25(OH)D (nanogram per milliliter 

[ng/mL]) whereas other laboratories use international system (SI) units (nanomole 

per liter [nmol/L]). The conversion factor to SI units is: 1 ng/mL = 2.496 nmol/L. 

No common definition exists for adequate vitamin D status measured as 25(OH)D 

serum concentrations (Dawson-Hughes 2005). The Institute of Medicine (1997) defined 

vitamin D deficiency as serum 25(OH)D concentrations of less than 11 ng/mL (27.5 

nmol/L) for neonates, infants, and young children. Because the lower limit of the 

normal range can be as low as 8 ng/mL (20 nmol/L) and as high as 15 ng/mL (37.5 

nmol/L), depending on the geographic location, vitamin D deficiency has been 

62 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
defined as a concentration of less than 12 ng/mL (mid-range between 8 and 15 ng/ 

mL) for adults (Institute of Medicine 1997). More recently, some scientists have suggested 

that the criteria used to define adequate status should be revised upwards; serum 

25(OH)D concentrations between 20 ng/mL (50 nmol/L) and 32 ng/mL (80 nmol/L) 

have been defined as sufficient (Hollis 2005; Dawson-Hughes 2005; Bischoff-Ferrari 2006; Norman 

2007). A common definition for high serum vitamin D concentrations is also lacking. 

The Institute of Medicine (1997) used serum calcium concentrations greater than 11 

milligrams per deciliter (mg/dL) for assessing the potential for increased risk of harm 

associated with high vitamin D intakes. To date, however, no evidence has surfaced 

of adverse effects with serum 25(OH)D concentrations as high as 56 ng/mL (140 

nmol/L) in healthy individuals (Vieth 1999). 

Different assays measure serum 

25(OH)D, and at times large variations 

occur among methods and even 

between laboratories using the same 

method (Singh 2008; Binkley 2004; Carter 

2004). Standard reference materials 

(SRMs) for serum 25(OH)D are currently 

under development by the U.S. National 

Institute of Standards and Technology 

(U.S. NIST) (http://www.cstl.nist.gov/projects/ 

fy06/food0683904.pdf ). Improvement in the 

agreement between laboratories and 

methods is expected as laboratories 

begin to use the SRMs. 

For more information about vitamin D, 


see the Institute of Medicine’s Dietary 


Reference Intake reports (Institute of 


Medicine 1997), fact sheets from the National Institutes of Health, Office of Dietary 


Supplements (http://ods.od.nih.gov/Health_Information/Information_About_Individual_Dietary_
 

Supplements.aspx), as well as information from the American Society for Nutrition (http://
 

jn.nutrition.org/nutinfo/).
 

Since 1988, NHANES has monitored the vitamin D status of the U.S. population. 


By design, this survey collects information and biological samples in the summer 


from people living at higher latitudes and in the winter from people living at 


lower latitudes. Because the different racial and ethnic groups are not evenly 


distributed across all geographic regions in the United States, the season-latitude 


structure of the survey can affect comparisons by race or ethnicity. In two seasonal 


subpopulations from NHANES III (1988–1994), Looker et al. (2002) showed that in 


the winter and lower latitude subpopulation, 1–5 percent and 25–57 percent had 


25(OH)D concentrations less than 10 ng/mL (25 nmol/L) and less than 25 ng/mL (62.5 


nmol/L), respectively. In the summer and higher latitude subpopulation, 1–3 percent 


and 21–49 percent had 25(OH)D concentrations below these cutoffs. Mean 


Medical technologist checks samples for vitamin D analysis. 

2 Fat-Soluble Vitamins & Micronutrients 63 
25(OH)D concentrations were highest in non-Hispanic whites, intermediate in 

Mexican Americans, and lowest in non-Hispanic blacks. Nesby-O’Dell et al. (2002) 

restricted the analysis of NHANES III data to African-American and white women of 

reproductive age and found the prevalence of hypovitaminosis 

[25(OH)D concentrations < 15 ng/mL (37.5 nmol/L)] to be 42.2 percent among African 

Americans and 4.2 percent among whites. 

Selected Observations and Highlights 

The following sample observations and figures are taken from the tables of 

2001–2002 data contained in this report. Statements about categorical differences 

between demographic groups noted below are based on non-overlapping 

confidence limits from univariate analysis without adjusting for demographic 

variables (e.g., age, sex, race/ethnicity) or other determinants of these blood 

concentrations (e.g., dietary intake, supplement usage, smoking, BMI). A multivariate 

analysis may alter the size and statistical significance of these categorical differences. 

Furthermore, additional significant differences of smaller magnitude may be 

present despite their lack of mention here (e.g., if confidence limits slightly overlap 

or if differences are unobservable before covariate adjustment has occurred). For 

a selection of citations of descriptive NHANES papers related to these biochemical 

indicators of diet and nutrition, see Appendix E. 

General Observations 

•	 Serum 25(OH)D concentrations are similar throughout all age groups, except 

that children 6–11 years of age have higher concentrations than do people in 

other age groups. 

•	 Non-Hispanic whites have higher concentrations of 25(OH)D than do Mexican 

Americans, who themselves have higher concentrations than do non-Hispanic 

blacks. 

•	 Approximately 10 percent of the population has concentrations of 25(OH)D 

that are less than 11 ng/mL. The values at the 10th percentile vary greatly by 

racial-ethnic group, with non-Hispanic blacks having the highest prevalence 

of low 25(OH)D concentrations. 

64 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Highlights 

Because of the current disagreement regarding appropriate criteria by which to 

define adequate status on the basis of serum 25(OH)D concentrations, the figure 

below presents prevalence estimates for older people (≥ 60 years) for three cut-off 

values: 11 ng/mL, 20 ng/mL, and 30 ng/mL. Regardless of the cut-off value, nonHispanic blacks have the highest prevalence of low serum 25(OH)D concentrations 

(Fig. 2.a). 

Figure 2.a 

Prevalence estimates (95 percent confidence intervals) of serum 25-hydroxyvitamin D among U.S. 

persons 60 years and older by race/ethnicity, National Health and Nutrition Examination Survey, 

2001–2002. Prevalence estimates shown here are not part of the tables displayed in this report; 

rather, the data were analyzed separately to generate this figure. 

2 Fat-Soluble Vitamins & Micronutrients 65 
Table 2.9.a. Serum 25-hydroxyvitamin D: Total population 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for the total U.S. population aged 

6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 21.9 (21.0-22.7) 11.0 (11.0-12.0) 22.0 (22.0-23.0) 35.0 (33.0-36.0) 7807 

6–11 years 25.5 (24.2-26.9) 17.0 (16.0-19.0) 26.0 (24.0-27.0) 35.0 (32.0-39.0) 991 

12–19 years 22.0 (21.0-23.1) 13.0 (11.0-14.0) 23.0 (22.0-24.0) 35.0 (33.0-35.0) 2167 

20–39 years 21.6 (20.7-22.6) 11.0 (11.0-12.0) 22.0 (22.0-24.0) 35.0 (33.0-38.0) 1691 

40–59 years 21.6 (20.6-22.6) 11.0 (11.0-13.0) 22.0 (22.0-23.0) 34.0 (32.0-36.0) 1449 

60 years and older 21.0 (20.0-22.1) 12.0 (10.0-12.0) 22.0 (21.0-24.0) 33.0 (32.0-34.0) 1509 

Males 

Total, 6 years and older 22.6 (21.8-23.4) 13.0 (13.0-14.0) 24.0 (23.0-24.0) 34.0 (33.0-36.0) 3782 

6–11 years 26.1 (24.5-27.9) 18.0 (17.0-20.0) 26.0 (24.0-27.0) 38.0 (33.0-44.0) 497 

12–19 years 23.1 (21.9-24.3) 13.0 (11.0-16.0) 24.0 (22.0-25.0) 35.0 (34.0-37.0) 1068 

20–39 years 22.2 (21.4-23.1) 13.0 (11.0-14.0) 23.0 (21.0-24.0) 34.0 (32.0-37.0) 709 

40–59 years 22.3 (21.2-23.5) 12.0 (11.0-14.0) 22.0 (22.0-23.0) 33.0 (32.0-37.0) 762 

60 years and older 21.5 (20.7-22.5) 13.0 (11.0-14.0) 22.0 (21.0-24.0) 32.0 (31.0-33.0) 746 

Females 

Total, 6 years and older 21.2 (20.2-22.2) 10.0 (9.00-12.0) 23.0 (22.0-23.0) 34.0 (33.0-36.0) 4025 

6–11 years 24.9 (23.6-26.3) 17.0 (15.0-19.0) 26.0 (24.0-27.0) 35.0 (32.0-37.0) 494 

12–19 years 21.0 (20.0-22.0) 11.0 (9.00-13.0) 22.0 (20.0-22.0) 33.0 (32.0-35.0) 1099 

20–39 years 21.1 (19.9-22.4) 10.0 (9.00-12.0) 22.0 (21.0-24.0) 37.0 (32.0-40.0) 982 

40–59 years 20.8 (19.6-22.1) 10.0 (9.00-12.0) 23.0 (21.0-24.0) 34.0 (32.0-35.0) 687 

60 years and older 20.6 (19.3-22.0) 11.0 (10.0-12.0) 22.0 (20.0-23.0) 34.0 (33.0-36.0) 763 

Table 2.9.b. Serum 25-hydroxyvitamin D: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for Mexican Americans in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 19.6 (18.5-20.7) 11.0 (10.0-12.0) 20.0 (19.0-22.0) 29.0 (28.0-32.0) 1961 

6–11 years 22.6 (21.7-23.6) 17.0 (15.0-17.0) 22.0 (22.0-24.0) 30.0 (28.0-32.0) 283 

12–19 years 19.7 (18.5-21.0) 12.0 (11.0-14.0) 20.0 (18.0-21.0) 29.0 (27.0-32.0) 687 

20–39 years 19.5 (18.2-20.9) 12.0 (10.0-13.0) 20.0 (18.0-21.0) 31.0 (27.0-33.0) 452 

40–59 years 18.1 (16.5-19.8) 10.0 (8.00-11.0) 20.0 (18.0-21.0) 28.0 (24.0-33.0) 286 

60 years and older 18.3 (15.9-21.1) 10.0 (8.00-11.0) 18.0 (16.0-21.0) 29.0 (24.0-36.0) 253 

Males 

Total, 6 years and older 20.6 (19.4-21.8) 13.0 (11.0-13.0) 21.0 (19.0-22.0) 30.0 (27.0-32.0) 942 

6–11 years 22.8 (21.8-23.9) 17.0 (15.0-18.0) 22.0 (22.0-24.0) 28.0 (26.0-31.0) 138 

12–19 years 21.1 (19.7-22.7) 13.0 (11.0-15.0) 21.0 (19.0-24.0) 29.0 (27.0-33.0) 323 

20–39 years 20.1 (18.7-21.7) 12.0 (10.0-13.0) 20.0 (19.0-22.0) 31.0 (26.0-34.0) 208 

40–59 years 19.9 (18.3-21.7) 12.0 (9.00-14.0) 21.0 (19.0-22.0) 28.0 (25.0-33.0) 148 

60 years and older 19.5 (16.6-22.9) 9.00 (6.00-11.0) 21.0 (16.0-25.0) 31.0 (25.0-39.0) 125 

Females 

Total, 6 years and older 18.6 (17.5-19.7) 10.0 (10.0-11.0) 18.0 (17.0-20.0) 29.0 (27.0-31.0) 1019 

6–11 years 22.4 (21.4-23.5) 17.0 (15.0-18.0) 22.0 (20.0-23.0) 30.0 (28.0-33.0) 145 

12–19 years 18.3 (17.0-19.6) 11.0 (9.00-14.0) 18.0 (17.0-20.0) 26.0 (25.0-28.0) 364 

20–39 years 18.8 (17.3-20.4) 10.0 (9.00-12.0) 18.0 (17.0-21.0) 31.0 (27.0-33.0) 244 

40–59 years 16.3 (14.5-18.3) 8.00 (7.00-10.0) 18.0 (14.0-20.0) 25.0 (22.0-33.0) 138 

60 years and older 17.4 (14.7-20.7) 10.0 (7.00-12.0) 18.0 (16.0-21.0) 27.0 (22.0-30.0) 128 

66 66 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 2.9.c. Serum 25-hydroxyvitamin D: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for non-Hispanic blacks in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 13.0 (12.5-13.6) 7.00 (6.00-7.00) 13.0 (13.0-14.0) 22.0 (22.0-23.0) 1821 

6–11 years 18.7 (17.7-19.8) 11.0 (10.0-14.0) 19.0 (18.0-19.0) 25.0 (24.0-27.0) 334 

12–19 years 13.2 (12.4-14.0) 7.00 (7.00-8.00) 14.0 (13.0-14.0) 22.0 (20.0-23.0) 653 

20–39 years 11.6 (11.0-12.2) 7.00 (6.00-7.00) 12.0 (11.0-12.0) 20.0 (17.0-22.0) 312 

40–59 years 12.2 (11.4-13.0) 5.00 (5.00-6.00) 12.0 (11.0-14.0) 23.0 (21.0-24.0) 285 

60 years and older 14.6 (13.4-15.9) 6.00 (6.00-7.00) 14.0 (13.0-17.0) 28.0 (24.0-29.0) 237 

Males 

Total, 6 years and older 14.2 (13.4-15.0) 7.00 (7.00-8.00) 14.0 (13.0-15.0) 23.0 (22.0-25.0) 898 

6–11 years 19.8 (18.5-21.2) 12.0 (10.0-15.0) 20.0 (18.0-21.0) 27.0 (26.0-29.0) 172 

12–19 years 14.6 (13.5-15.7) 7.00 (6.00-9.00) 14.0 (13.0-16.0) 22.0 (22.0-25.0) 328 

20–39 years 12.7 (11.6-13.8) 7.00 (7.00-8.00) 13.0 (11.0-15.0) 20.0 (19.0-23.0) 127 

40–59 years 13.2 (12.1-14.5) 5.00 (5.00-6.00) 13.0 (11.0-15.0) 23.0 (21.0-24.0) 154 

60 years and older 14.6 (13.7-15.6) 7.00 (6.00-9.00) 15.0 (13.0-17.0) 26.0 (22.0-29.0) 117 

Females 

Total, 6 years and older 12.2 (11.5-12.8) 7.00 (6.00-7.00) 12.0 (12.0-13.0) 22.0 (22.0-24.0) 923 

6–11 years 17.5 (16.1-19.1) 11.0 (9.00-14.0) 18.0 (16.0-19.0) 25.0 (23.0-26.0) 162 

12–19 years 11.9 (11.1-12.8) 7.00 (5.00-7.00) 11.0 (11.0-12.0) 21.0 (18.0-24.0) 325 

20–39 years 11.0 (10.2-11.7) 6.00 (3.00-7.00) 11.0 (10.0-11.0) 19.0 (16.0-23.0) 185 

40–59 years 11.3 (10.2-12.5) 5.00 (5.00-6.00) 10.0 (9.00-12.0) 21.0 (17.0-26.0) 131 

60 years and older 14.6 (12.5-17.0) 6.00 (3.00-7.00) 14.0 (12.0-17.0) 26.0 (21.0-31.0) 120 

Table 2.9.d. Serum 25-hydroxyvitamin D: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for non-Hispanic whites in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 24.3 (23.5-25.2) 15.0 (14.0-16.0) 25.0 (24.0-25.0) 37.0 (34.0-38.0) 3416 

6–11 years 28.5 (26.6-30.5) 21.0 (19.0-22.0) 28.0 (26.0-29.0) 39.0 (33.0-45.0) 294 

12–19 years 25.8 (25.0-26.6) 17.0 (16.0-18.0) 25.0 (25.0-26.0) 36.0 (35.0-38.0) 648 

20–39 years 25.2 (24.4-26.1) 17.0 (15.0-18.0) 26.0 (25.0-26.0) 38.0 (36.0-42.0) 766 

40–59 years 23.7 (22.6-24.9) 13.0 (12.0-15.0) 25.0 (23.0-26.0) 36.0 (33.0-38.0) 768 

60 years and older 22.0 (20.9-23.3) 13.0 (11.0-14.0) 23.0 (21.0-24.0) 34.0 (32.0-34.0) 940 

Males 

Total, 6 years and older 24.8 (23.8-25.8) 15.0 (14.0-17.0) 26.0 (24.0-26.0) 37.0 (34.0-39.0) 1655 

6–11 years 29.1 (26.9-31.4) 22.0 (19.0-24.0) 28.0 (26.0-31.0) 39.0 (35.0-46.0) 152 

12–19 years 26.7 (25.4-28.1) 20.0 (17.0-20.0) 27.0 (25.0-28.0) 38.0 (35.0-41.0) 320 

20–39 years 25.0 (24.0-26.0) 16.0 (14.0-18.0) 25.0 (23.0-26.0) 36.0 (33.0-39.0) 309 

40–59 years 24.2 (22.9-25.7) 14.0 (14.0-16.0) 25.0 (22.0-26.0) 37.0 (33.0-38.0) 406 

60 years and older 22.6 (21.6-23.7) 13.0 (12.0-15.0) 23.0 (23.0-25.0) 33.0 (31.0-34.0) 468 

Females 

Total, 6 years and older 23.9 (23.0-24.9) 13.0 (13.0-15.0) 25.0 (24.0-25.0) 37.0 (34.0-39.0) 1761 

6–11 years 27.8 (25.8-30.0) 21.0 (19.0-22.0) 27.0 (26.0-29.0) 38.0 (33.0-44.0) 142 

12–19 years 25.0 (24.3-25.7) 16.0 (14.0-18.0) 26.0 (24.0-27.0) 36.0 (34.0-38.0) 328 

20–39 years 25.5 (24.1-26.9) 15.0 (14.0-18.0) 25.0 (24.0-27.0) 39.0 (35.0-44.0) 457 

40–59 years 23.1 (22.0-24.2) 12.0 (10.0-13.0) 25.0 (23.0-26.0) 34.0 (33.0-37.0) 362 

60 years and older 21.6 (20.1-23.1) 11.0 (10.0-13.0) 23.0 (21.0-24.0) 35.0 (33.0-36.0) 472 

2 Fat-Soluble Vitamins & Micronutrients 67
References 

Binkley N, Krueger D, Cowgill CS, Plum L, Lake E, Hansen KE, et al. Assay variation confounds the 

diagnosis of hypovitaminosis D: a call for standardization. J Clin Endocrinol Metab. 2004;89:3152-7. 

Bischoff-Ferrari HA, Giovannucci E, Willett WC, Dietrich T, Dawson-Hughes B. Estimation of optimal serum 

concentrations of 25-hydroxyvitamin D for multiple health outcomes. Am J Clin Nutr. 2006;84:18-28. 

Carter GD, Carter R, Jones J, Berry J. How accurate are assays for 25-hydroxyvitamin D? Data from the 

international vitamin D external quality assessment scheme. Clin Chem. 2004;50:2195-7. 

Cranney A, Horsley T, O’Donnell S, Weiler HA, Puil L, Ooi DS, et al. Effectiveness and safety of vitamin D in 

relation to bone health. Evid Rep Technol Assess (Full Rep). 2007;158:1-235. 

Dawson-Hughes B, Heaney RP, Holick MF, Lips P, Meunier PJ, Vieth R. Estimates of optimal vitamin D 

status. Osteoporos Int. 2005;16:713-6. 

DeLuca HF. The metabolism, physiology, and function of vitamin D. In: Kumar R, editor. Vitamin D: basic 

and clinical aspects. Boston (MA): M. Nijhoff Publishers; 1984. p. 1-68. 

DeLuca HF. The vitamin D story: a collaborative effort of basic science and clinical medicine. FASEB J. 

1988;2:224-36. 

Fieser LF, Fieser M. Vitamin D. In: Steroids. 1st ed. New York: Reinhold Publishing Corporation;1959. p. 

90-168. 

Haddad JG, Hahn TJ. Natural and synthetic sources of circulating 25-hydroxy-vitamin D in man. Nature. 

1973;244:515-7. 

Hathcock JN, Shao A, Vieth R, Heaney R. Risk assessment for vitamin D. Am J Clin Nutr. 2007;85:6-18. 

Holick MF. Vitamin D: photobiology, metabolism, and clinical applications. In: DeGroot LJ, editor. 

Endocrinology, Vol 2, 3rd ed. Philadelphia (PA): WB Saunders; 1995. p. 990-1013. 

Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357:266-81. 

Hollis BW. Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for 

establishing a new effective dietary intake recommendation for vitamin D. J Nutr. 2005;135:317-22. 

Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: calcium, phosphorus, 

magnesium, vitamin D and fluoride. Washington, D.C.: National Academy Press; 1997. 

Kushi LH, Byers T, Doyle C, Bandera EV, McCullough M, Gansler T, et al. American Cancer Society 

guidelines on nutrition and physical activity for cancer prevention: reducing the risk of cancer with 

healthy food choices and physical activity. CA Cancer J Clin. 2006;56:254-81. 

Looker AC, Dawson-Hughs B, Calvo MS, Gunter EW, Sayhoun NR. Serum 25-hydroxyvitamin D status of 

adolescents and adults in two seasonal subpopulations from NHANES III. Bone. 2002;30:771-7. 

Mawer EB, Blackhouse J, Holman CA, Lumb GA, Stanbury DW. The distribution and storage of vitamin D 

and its metabolites in human tissues. Clin Sci. 1972;43:413-31. 

Nagpal S, Na S, Rathnachalam R. Noncalcemic actions of vitamin D receptor ligands. Endocr Rev. 

2005;26:662-87. 

68 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Nesby-O’Dell S, Scanlon KS, Cogswell ME, Gillespie C, Hollis BW, Looker AC, et al. Hypovitaminosis D and 

determinants among African American and white women of reproductive age: third National Health 

and Nutrition Examination Survey, 1988–1994. Am J Clin Nutr. 2002;76:187-92. 

Norman AW, Bouillon R, Whiting SJ, Vieth R, Lips P. 13th Workshop consensus for vitamin D nutritional 

guidelines. J Steroid Biochem Mol Biol. 2007;103:204-5. 

Reichel H, Koeffler HP, Norman AW. The role of vitamin D endocrine system in health and disease. N Engl 

J Med. 1989;320:980-91. 

Singh RJ. Are clinical laboratories prepared for accurate testing of 25-hydroxy vitamin D? Clin Chem. 

2008;54:221-2. 

U.S. Department of Health and Human Services and U.S. Department of Agriculture. Dietary guidelines 

for Americans, 2005. 6th ed. Washington, D.C.: U.S. Government Printing Office; January 2005. 

Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. Am J Clin Nutr. 

1999;69:842-56. 

Vieth R. Critique of the considerations for establishing the tolerable upper intake level for vitamin D: 

critical need for revision upwards. J Nutr. 2006;136:1117-22. 

Vieth R. The urgent need to recommend an intake of vitamin D that is effective. Am J Clin Nutr. 

2007;85:649-50. 

2 Fat-Soluble Vitamins & Micronutrients 69 
70 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
71 

3 

Iron-Status Indicators 

•	 Ferritin 

•	 Iron 

•	 Total iron-binding capacity 

•	 Transferrin saturation 

•	 Protoporphyrin 
72 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Iron-Status Indicators
 

Iron functions as a component of proteins and enzymes. Almost twothirds of the iron in the body (approximately 2.5 grams of iron) is found 

in hemoglobin, the protein in red blood cells that carries oxygen to 

tissues, and about 15 percent is in the myoglobin of muscle tissue. The 

average American diet provides 10–15 milligrams (mg) of iron daily 

in the form of heme and nonheme iron. Heme iron is found in animal 

foods that originally contained hemoglobin and myoglobin, such as red 

meat, fish, and poultry. Nonheme iron is found in plant foods, such as 

lentils and beans, and also is provided in iron-enriched and iron-fortified 

foods. Although heme iron is absorbed better than nonheme iron, most 

dietary iron is nonheme iron (Miret 2003). Each day the body absorbs 

approximately 1–2 mg of iron to compensate for the 1–2 mg of iron that 

the (nonmenstruating) body loses (Institute of Medicine 2001). 

Transporting iron from one organ to another is accomplished by the 

reversible binding of iron to the transport protein, transferrin, which 

will then form a complex with a highly specific transferrin receptor (TfR) 

located on the plasma membrane surfaces of cells. Intracellular iron 

availability is regulated through the increased expression of cellular TfR 

concentration by iron-deficient cells. Ferritin is the major iron-storage 

compound: its production increases in cells as iron supplies increase. 

Although all cells are capable of storing iron, the liver, spleen, and bone 

marrow cells are primary iron-storage sites in people (Institute of Medicine 

2001). 

Iron deficiency and iron overload are the two major disorders of iron 

metabolism. Iron-deficiency anemia is the most severe form of iron 

deficiency. It is linked to many adverse consequences of iron deficiency, 

such as reduced physical capacity (Haas 2001) and poor pregnancy 

outcomes (Schorr 1994). Iron deficiency without anemia, however, has 

been linked to negative effects on cognitive development among infants 

and adolescents (Grantham-McGregor 2001; Beard 1999). Iron overload is the 

accumulation of excess iron in body tissues, and it usually occurs as a 

result of a genetic predisposition to absorb iron in excess of normal but 

can also be caused by excessive ingestion of iron supplements or multiple 

blood transfusions (Pietrangelo 2004). In advanced stages of iron overload 

3 Iron-Status Indicators 73 
Medical technologist places samples for ferritin measurement into a clinical 

analyzer. 

disease (hemochromatosis), the iron accumulates in the parenchymal cells of several 

organs, but particularly the liver, followed by the heart and pancreas; this condition 

can lead to organ dysfunction and even death (Pietrangelo 2004). 

The Recommended Dietary Allowance (RDA) for all age groups of men and 

postmenopausal women is 8 mg per day; the RDA for premenopausal women is 18 

mg per day. The Tolerable Upper Uptake Level for adults is 45 mg per day of iron, a 

level based on gastrointestinal distress as an adverse effect (Institute of Medicine 2001). 

Clinical laboratories typically use conventional units for iron-status indicators: 

iron, total iron-binding capacity (TIBC), and erythrocyte protoporphyrin (EPP) are 

calculated in micrograms per deciliter (μg/dL), ferritin in nanograms per milliliter (ng/ 

mL). Conversion factors to international 

system (SI) units are as follows: 1 μg/dL 

= 0.179 micromole per liter (μmol/L) for 

iron and TIBC, 1 μg/dL = 0.01777 μmol/L 

for EPP, and 1 ng/mL = 2.247 picomole 

(pmol)/L for ferritin. 

Several methods are used to measure 

iron and related analytes. Serum iron 

concentration measures the amount 

of ferric iron (Fe3+) bound mainly 

to serum transferrin but does not 

include the divalent iron contained 

in serum as hemoglobin. Serum iron 

concentration is decreased in many 

people with iron-deficiency anemia and 

in people with chronic inflammatory 

disorders. Elevated concentrations 

of serum iron occur in iron-loading 

disorders such as hemochromatosis. 

Serum iron is not, however, a good indicator of iron stores and is not a sensitive 

measure of iron deficiency, partly because of daily fluctuations. For enhanced 

utility, serum iron measurements are used in conjunction with TIBC measurements. 

Normally, because only about one third of the iron-binding sites of transferrin are 

occupied by Fe3+, serum transferrin has considerable reserve iron-binding capacity. 

TIBC is a measurement of serum transferrin after saturation of all available binding 

sites with reagent iron. Concentrations of serum TIBC vary with the type of ironmetabolism disorder. For example, in iron deficiency TIBC is often increased, and 

in chronic inflammatory disorders, malignancies, and hemochromatosis, it is often 

decreased. The ratio of serum iron to TIBC is called transferrin saturation. Low iron 

values in conjunction with elevated TIBC values (or specifically measured transferrin 

concentrations), yielding less than 16 percent transferrin saturation, generally 

indicate iron-deficiency anemia (World Health Organization 2001). Transferrin saturation 

values in excess of 60 percent may be indicative of hemochromatosis or iron overload 

(World Health Organization 2001). 

74 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Ferritin is present in the blood in very low concentrations. Plasma ferritin is 

in equilibrium with body stores, and its concentration declines early in the 

development of iron deficiency. Low serum ferritin concentrations thus are sensitive 

indicators of iron deficiency. Ferritin is also an acute-phase protein; acute and 

chronic diseases can result in increased ferritin concentration, potentially masking 

an iron-deficiency diagnosis. The generally accepted cut-off level for serum ferritin 

below which iron stores are considered to be depleted is 15 ng/mL for people aged 

5 years and older and 12 ng/mL for people younger than 5 years of age (World Health 

Organization 2001). 

Finally, when iron delivery to the bone marrow is not sufficient for maintaining the 

incorporation of iron into newly synthesized globin and porphyrin protein, EPP 

concentrations increase. Yet EPP is not useful to distinguish iron deficiency from 

infection and also elevates in response to lead poisoning (Roels 1975). As a result, 

the measurement of EPP is most useful in settings where iron deficiency levels are 

common and where infections, lead poisoning, and other forms of anemia are rare. 

The generally accepted cut-off level for EPP is 80 μg/dL red blood cells for people 

aged 5 years and older and 70 μg/dL red blood cells for children younger than 5 

years of age (World Health Organization 2001). 

For more information about iron, see the Institute of Medicine’s Dietary Reference 

Intake reports (Institute of Medicine 2001), fact sheets from the National Institutes of 

Health, Office of Dietary Supplements (http://ods.od.nih.gov/Health_Information/Information_ 

About_Individual_Dietary_Supplements.aspx), and information from the American Society 

for Nutrition (http://jn.nutrition.org/nutinfo/). 

Three national health objectives for Healthy People 2010 relate to iron deficiency 

reduction: Objective 19–12 (reduce iron deficiency among young children and 

females of childbearing age), Objective 19–13 (reduce anemia among low-income 

pregnant females in their third trimester), and Objective 19–14 (reduce iron 

deficiency among pregnant females) (U.S. Department of Health and Human Services 2000). 

To address the changing epidemiology of iron deficiency in the United States, CDC 

staff, in consultation with outside experts, developed recommendations in 1998 for 

use by primary health-care providers to prevent, detect, and treat iron deficiency 

(U.S. Centers for Disease Control and Prevention 1998). Since the inception of NHANES in 1971, 

monitoring the iron status of the U.S. population has been an important component. 

To provide the best possible assessment of this element, each NHANES has included 

a battery of hematologic and biochemical indicators of iron status (Looker 1995). 

Since NHANES II (1976–1980), models that employ multiple biochemical iron-status 

indicators have been used to define iron deficiency in the population (Pilch 1984). The 

three-indicator model, using serum ferritin, transferrin saturation, and erythrocyte 

protoporphyrin, was developed in 1980 and applied to NHANES III (1988–1994) as 

well as to the other most recent surveys that became continuous beginning in 1999. 

3 Iron-Status Indicators 75 
Reference data for hematologic and iron-related analytes were published for 

NHANES II (Fulwood 1982) and NHANES III (Hollowell, 2005). Prevalence estimates of iron 

deficiency using the three-indicator model were similar in NHANES III (Looker 1997) and 

in NHANES 1999–2000 (Looker 2002). In NHANES 1999–2000, the estimated prevalence 

of iron deficiency was greatest among toddlers aged 1–2 years (7 percent) and 

adolescent and adult females aged 12–49 years (9 percent to 16 percent). The 

prevalence of iron deficiency was approximately two times higher among nonHispanic black and Mexican-American females (19 percent to 22 percent) than 

among non-Hispanic white females (10 percent). Across all age and sex groups in 

the United States, iron-deficiency anemia has an estimated prevalence of less than 5 

percent. 

Selected Observations and Highlights 

The following example observations and figures are taken from the tables of 

1999–2002 data (for ferritin) and 1999–2000 data (for all other iron-status indicators) 

contained in this report. Statements about categorical differences between 

demographic groups noted below are based on non-overlapping confidence limits 

from univariate analysis without adjusting for demographic variables (e.g., age, sex, 

race/ethnicity) or other determinants of these blood concentrations (e.g., dietary 

intake, supplement usage, smoking, BMI). A multivariate analysis may alter the size 

and statistical significance of these categorical differences. Furthermore, additional 

significant differences of smaller magnitude may be present despite their lack of 

mention here (e.g., if confidence limits slightly overlap or if differences are not 

statistically significant before covariate adjustment has occurred). For a selection of 

citations of descriptive NHANES papers related to these biochemical indicators of diet 

and nutrition, see Appendix E. 

General Observations 

•	 Among all age groups, 1–5 year-old children have the lowest ferritin 

concentrations. Children up to age 11 have lower transferrin saturation levels 

than do adolescents or adults. 

•	 Women 12 years and older are more likely to be defined as iron deficient than 

are men. These women have lower concentrations of serum ferritin, lower 

transferrin saturation, and higher EPP concentrations. 

•	 Mexican Americans have lower serum ferritin and higher EPP concentrations 

than do either non-Hispanic whites or non-Hispanic blacks. 

76 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
•	 Non-Hispanic blacks have lower serum transferrin saturation levels than do 

non-Hispanic whites. 

•	 Mexican-American and non-Hispanic white children (aged 1–5 years) have 

lower serum ferritin concentrations than do non-Hispanic black children. 

•	 Mexican-American children (aged 1–5 years) have higher EPP concentrations 

than do non-Hispanic black or non-Hispanic white children. 

•	 Mexican-American women of childbearing age (aged 20–39 years) have 

lower serum ferritin concentrations than do non-Hispanic white women. 

Concentrations for non-Hispanic black women of childbearing age fall 

between those of Mexican-American and non-Hispanic white women. 

•	 Non-Hispanic black women of childbearing age (aged 20–39 years) have 

lower serum transferrin saturation levels than do non-Hispanic white 

women. Serum transferrin saturation levels for Mexican-American women 

of childbearing age fall between levels for non-Hispanic white and MexicanAmerican women of childbearing age. 

Highlights 

Because children and women have lower serum ferritin and transferrin saturation 

levels than do men and older people (≥ 60 years), children and women are at greater 

risk for iron deficiency. 

Two minority groups, non-Hispanic blacks and Mexican Americans, typically are at 

greater risk for iron deficiency than are non-Hispanic whites. 

At least 5 percent of persons in each age group, except for older people (≥ 60 years), 

have low serum ferritin concentrations (< 12 ng/mL for children younger than 5 years 

and < 15 ng/mL for people aged 5 years and older) that are consistent with depleted 

iron storage. 

At least 10 percent of persons in each age group have low transferrin saturation 

levels (< 16 percent), which are indicative of iron deficiency. 

3 Iron-Status Indicators 77 
Table 3.1.a. Serum ferritin: Total population 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for the total U.S. population aged 

1 year and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 1 year and older 60.2 (58.3-62.1) 9.00 (9.00-10.0) 62.0 (59.0-64.0) 343 (329-359) 16656

 1–5 years 21.5 (20.3-22.9) 6.00 (3.00-8.00) 21.0 (20.0-23.0) 62.0 (53.0-77.0) 1523

 6–11 years 29.8 (28.1-31.5) 11.0 (11.0-13.0) 30.0 (28.0-31.0) 74.0 (67.0-83.0) 1909

 12–19 years 32.8 (31.4-34.3) 8.00 (6.00-9.00) 34.0 (32.0-35.0) 115 (103-125) 4340

 20–39 years 62.2 (58.9-65.6) 8.00 (7.00-10.0) 71.0 (66.0-76.0) 301 (272-321) 3186

 40–59 years 80.8 (76.7-85.0) 9.00 (7.00-11.0) 93.0 (88.0-96.0) 404 (379-433) 2680

 60 years and older 101 (95.5-107) 19.0 (16.0-22.0) 105 (97.0-112) 481 (434-518) 3018 

Males 

Total, 1 year and older 93.0 (89.3-96.8) 16.0 (15.0-17.0) 101 (97.0-107) 416 (391-439) 8142

 1–5 years 20.2 (18.7-21.7) 3.00 (3.00-6.00) 20.0 (19.0-22.0) 62.0 (50.0-79.0) 805

 6–11 years 29.7 (27.3-32.3) 11.0 (9.00-12.0) 31.0 (29.0-32.0) 73.0 (64.0-83.0) 972

 12–19 years 44.3 (41.6-47.1) 15.0 (13.0-17.0) 42.0 (40.0-45.0) 142 (125-154) 2172

 20–39 years 129 (122-137) 41.0 (34.0-46.0) 134 (125-142) 382 (344-406) 1356

 40–59 years 145 (135-157) 32.0 (24.0-42.0) 150 (138-168) 500 (434-574) 1340

 60 years and older 127 (118-136) 21.0 (18.0-24.0) 134 (125-147) 552 (493-623) 1497 

Females 

Total, 1 year and older 39.7 (38.1-41.4) 6.00 (6.00-8.00) 39.0 (37.0-41.0) 213 (198-228) 8514

 1–5 years 23.2 (21.8-24.8) 7.00 (5.00-9.00) 23.0 (22.0-25.0) 69.0 (52.0-88.0) 718

 6–11 years 29.9 (28.2-31.7) 12.0 (10.0-14.0) 30.0 (27.0-31.0) 76.0 (67.0-83.0) 937

 12–19 years 24.0 (22.7-25.3) 5.00 (3.00-7.00) 26.0 (24.0-27.0) 76.0 (70.0-85.0) 2168

 20–39 years 30.4 (28.6-32.4) < LOD 32.0 (30.0-35.0) 126 (110-146) 1830

 40–59 years 45.6 (42.8-48.6) 4.00 (3.00-6.00) 53.0 (46.0-57.0) 228 (201-243) 1340

 60 years and older 84.9 (79.7-90.4) 15.0 (14.0-21.0) 86.0 (80.0-93.0) 391 (349-445) 1521 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

Table 3.1.b. Serum ferritin: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for Mexican Americans in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 1 year and older 46.6 (43.4-50.1) 7.00 (6.00-8.00) 44.0 (40.0-47.0) 298 (265-334) 4946

 1–5 years 19.0 (18.2-19.9) 5.00 (3.00-7.00) 19.0 (18.0-20.0) 48.0 (45.0-54.0) 515

 6–11 years 27.7 (26.1-29.5) 12.0 (10.0-13.0) 27.0 (25.0-28.0) 70.0 (59.0-81.0) 651

 12–19 years 29.9 (28.1-31.8) 6.00 (3.00-7.00) 32.0 (29.0-34.0) 114 (101-122) 1639

 20–39 years 56.8 (51.9-62.2) 6.00 (3.00-8.00) 67.0 (60.0-74.0) 300 (256-336) 867

 40–59 years 76.0 (67.5-85.6) < LOD 97.0 (81.0-111) 463 (409-589) 634

 60 years and older 100 (91.8-110) 18.0 (12.0-24.0) 102 (90.0-120) 433 (342-568) 640 

Males 

Total, 1 year and older 77.1 (72.9-81.6) 14.0 (13.0-16.0) 85.0 (77.0-91.0) 373 (317-408) 2422

 1–5 years 19.0 (18.0-20.0) 5.00 (3.00-7.00) 19.0 (18.0-21.0) 48.0 (42.0-59.0) 268

 6–11 years 28.4 (26.3-30.7) 12.0 (11.0-14.0) 27.0 (25.0-29.0) 70.0 (56.0-88.0) 337

 12–19 years 43.2 (40.5-46.2) 14.0 (10.0-16.0) 42.0 (40.0-46.0) 131 (121-143) 812

 20–39 years 121 (112-131) 39.0 (31.0-51.0) 122 (111-134) 349 (298-395) 383

 40–59 years 160 (142-180) 44.0 (33.0-53.0) 159 (142-177) 646 (457-959) 301

 60 years and older 122 (105-143) 19.0 (13.0-28.0) 136 (102-162) 569 (364-831) 321 

Females 

Total, 1 year and older 26.9 (24.2-30.0) < LOD 27.0 (24.0-29.0) 161 (123-201) 2524

 1–5 years 19.1 (17.6-20.8) 5.00 (3.00-8.00) 20.0 (17.0-20.0) 47.0 (44.0-56.0) 247

 6–11 years 27.0 (24.7-29.6) 12.0 (8.00-14.0) 27.0 (24.0-29.0) 68.0 (59.0-84.0) 314

 12–19 years 20.0 (18.3-21.9) < LOD 22.0 (19.0-24.0) 69.0 (59.0-77.0) 827

 20–39 years 23.3 (20.6-26.3) < LOD 24.0 (22.0-26.0) 98.0 (78.0-144) 484

 40–59 years 35.2 (29.2-42.4) < LOD 38.0 (32.0-44.0) 293 (195-385) 333

 60 years and older 84.6 (76.6-93.4) 17.0 (11.0-24.0) 87.0 (76.0-100) 324 (237-375) 319 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

78 78 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 3.1.c. Serum ferritin: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for non-Hispanic blacks in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 1 year and older 59.2 (55.6-62.9) 8.00 (6.00-10.0) 58.0 (54.0-62.0) 381 (342-423) 3898

 1–5 years 25.9 (23.9-28.1) 8.00 (5.00-10.0) 25.0 (24.0-28.0) 73.0 (62.0-98.0) 415

 6–11 years 36.8 (34.7-39.0) 15.0 (13.0-17.0) 36.0 (34.0-38.0) 86.0 (78.0-91.0) 604

 12–19 years 32.9 (31.3-34.6) 7.00 (6.00-10.0) 33.0 (31.0-36.0) 122 (110-132) 1258

 20–39 years 54.4 (48.0-61.6) < LOD 63.0 (56.0-73.0) 313 (266-368) 592

 40–59 years 96.9 (86.7-108) 7.00 (6.00-12.0) 111 (100-129) 482 (425-642) 543

 60 years and older 133 (118-150) 22.0 (18.0-31.0) 141 (125-162) 613 (509-724) 486 

Males 

Total, 1 year and older 92.8 (87.2-98.8) 17.0 (16.0-19.0) 98.0 (90.0-108) 452 (420-494) 1917

 1–5 years 24.6 (21.8-27.7) 7.00† (3.00-10.0) 24.0 (21.0-27.0) 69.0† (57.0-122) 215

 6–11 years 36.1 (33.6-38.7) 16.0 (13.0-18.0) 34.0 (31.0-38.0) 79.0 (75.0-90.0) 304

 12–19 years 44.1 (42.1-46.1) 14.0 (12.0-16.0) 43.0 (40.0-46.0) 146 (128-171) 642

 20–39 years 137 (126-150) 35.0 (24.0-52.0) 150 (137-161) 381 (325-450) 249

 40–59 years 176 (156-199) 42.0 (30.0-53.0) 178 (157-206) 642 (494-984) 275

 60 years and older 159 (135-186) 26.0 (18.0-34.0) 173 (132-204) 710 (521-851) 232 

Females 

Total, 1 year and older 40.1 (36.5-44.2) 6.00 (3.00-7.00) 40.0 (37.0-42.0) 267 (246-297) 1981

 1–5 years 27.5 (25.0-30.2) 10.0† (7.00-12.0) 26.0 (24.0-30.0) 73.0† (56.0-96.0) 200

 6–11 years 37.6 (34.8-40.6) 16.0 (12.0-17.0) 37.0 (33.0-41.0) 88.0 (73.0-107) 300

 12–19 years 24.5 (22.3-26.8) 3.00 (3.00-6.00) 24.0 (22.0-29.0) 91.0 (78.0-104) 616

 20–39 years 26.6 (22.0-32.2) < LOD 31.0 (24.0-34.0) 142 (102-232) 343

 40–59 years 57.4 (50.1-65.8) 6.00 (3.00-6.00) 61.0 (52.0-75.0) 343 (255-481) 268

 60 years and older 118 (101-138) 21.0 (8.00-30.0) 131 (107-151) 534 (396-613) 254 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 3.1.d. Serum ferritin: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for non-Hispanic whites in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

5th 50th 95th size

Males and Females 

Total, 1 year and older 63.0 (60.4-65.6) 11.0 (10.0-11.0) 65.0 (63.0-69.0) 343 (327-357) 6360

 1–5 years 21.3 (19.2-23.6) 5.00 (3.00-8.00) 21.0 (19.0-23.0) 61.0 (46.0-80.0) 420

 6–11 years 28.4 (26.0-31.1) 10.0 (9.00-12.0) 30.0 (27.0-32.0) 69.0 (59.0-83.0) 496

 12–19 years 32.9 (31.0-34.8) 8.00 (7.00-11.0) 34.0 (31.0-36.0) 107 (95.0-122) 1075

 20–39 years 64.3 (59.6-69.5) 9.00 (7.00-12.0) 74.0 (66.0-81.0) 293 (261-328) 1382

 40–59 years 79.8 (75.7-84.1) 10.0 (9.00-12.0) 91.0 (85.0-96.0) 386 (349-406) 1280

 60 years and older 97.9 (92.2-104) 17.0 (15.0-21.0) 102 (94.0-110) 448 (393-503) 1707 

Males 

Total, 1 year and older 96.0 (91.4-101) 16.0 (14.0-18.0) 107 (99.0-115) 414 (391-435) 3127

 1–5 years 19.4 (17.3-21.8) < LOD 19.0 (17.0-21.0) 61.0 (42.0-79.0) 226

 6–11 years 28.4 (24.8-32.6) 11.0 (9.00-14.0) 29.0 (27.0-33.0) 68.0 (50.0-97.0) 261

 12–19 years 42.9 (39.7-46.4) 14.0 (10.0-17.0) 43.0 (39.0-46.0) 127 (111-143) 536

 20–39 years 131 (121-141) 43.0 (32.0-49.0) 135 (124-144) 382 (331-416) 577

 40–59 years 139 (127-153) 31.0 (18.0-39.0) 144 (132-168) 453 (409-517) 668

 60 years and older 125 (116-135) 20.0 (18.0-25.0) 135 (122-148) 531 (471-601) 859 

Females 

Total, 1 year and older 41.7 (39.5-44.0) 8.00 (6.00-9.00) 41.0 (39.0-44.0) 205 (193-227) 3233

 1–5 years 23.6 (20.9-26.8) 8.00† (5.00-11.0) 24.0 (20.0-26.0) 59.0† (42.0-98.0) 194

 6–11 years 28.4 (25.9-31.2) 10.0 (9.00-14.0) 28.0 (25.0-31.0) 73.0 (56.0-83.0) 235

 12–19 years 24.8 (23.0-26.6) 7.00 (3.00-8.00) 26.0 (25.0-28.0) 71.0 (61.0-85.0) 539

 20–39 years 32.0 (29.1-35.2) 5.00 (3.00-8.00) 34.0 (29.0-40.0) 127 (108-149) 805

 40–59 years 45.2 (41.8-48.8) 6.00 (3.00-8.00) 51.0 (45.0-57.0) 206 (181-235) 612

 60 years and older 80.7 (75.7-86.1) 16.0 (13.0-22.0) 83.0 (77.0-89.0) 353 (296-391) 848 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

3 Iron-Status Indicators 79
Table 3.2.a. Serum iron: Total population 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for the total U.S. population aged 

1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 81.2 (79.5-83.0) 45.0 (42.0-46.0) 85.0 (84.0-87.0) 137 (134-139) 7877

 1–5 years 65.2 (62.0-68.4) 31.0 (27.0-35.0) 70.0 (64.0-79.0) 115 (110-124) 704

 6–11 years 71.5 (68.2-75.0) 39.0 (34.0-41.0) 76.0 (69.0-82.0) 126 (117-131) 887

 12–19 years 82.1 (79.7-84.7) 45.0 (42.0-47.0) 87.0 (83.0-89.0) 141 (133-145) 2127

 20–39 years 84.5 (81.3-87.8) 45.0 (41.0-48.0) 88.0 (86.0-93.0) 146 (139-154) 1470

 40–59 years 83.3 (80.3-86.4) 50.0 (46.0-52.0) 87.0 (83.0-92.0) 135 (131-139) 1199

 60 years and older 82.0 (78.5-85.8) 49.0 (44.0-54.0) 83.0 (80.0-86.0) 132 (126-139) 1490 

Males 

Total, 1 year and older 88.1 (86.1-90.0) 51.0 (49.0-54.0) 92.0 (89.0-94.0) 144 (141-147) 3879

 1–5 years 64.9 (61.3-68.7) 33.0 (26.0-38.0) 67.0 (65.0-73.0) 116 (103-125) 388

 6–11 years 69.6 (65.9-73.5) 38.0 (31.0-41.0) 75.0 (67.0-81.0) 115 (105-129) 463

 12–19 years 92.0 (86.3-98.0) 52.0 (43.0-59.0) 96.0 (91.0-100) 150 (139-161) 1080

 20–39 years 93.8 (91.4-96.3) 60.0 (56.0-63.0) 94.0 (92.0-98.0) 154 (141-163) 632

 40–59 years 93.7 (89.1-98.6) 56.0 (52.0-63.0) 97.0 (92.0-103) 141 (137-148) 570

 60 years and older 86.6 (83.2-90.0) 52.0 (44.0-56.0) 88.0 (85.0-91.0) 145 (137-154) 746 

Females 

Total, 1 year and older 75.1 (73.3-76.9) 39.0 (37.0-43.0) 79.0 (77.0-81.0) 130 (124-135) 3998

 1–5 years 65.5 (58.8-72.9) 30.0 (24.0-37.0) 76.0 (60.0-85.0) 114 (108-128) 316

 6–11 years 73.8 (66.9-81.4) 37.0 (27.0-46.0) 76.0 (67.0-87.0) 133 (111-148) 424

 12–19 years 72.9 (69.0-77.0) 40.0 (36.0-42.0) 77.0 (71.0-81.0) 128 (116-135) 1047

 20–39 years 76.2 (72.0-80.6) 36.0 (33.0-41.0) 82.0 (74.0-87.0) 137 (128-151) 838

 40–59 years 74.7 (71.6-77.9) 44.0 (38.0-48.0) 78.0 (71.0-83.0) 125 (115-134) 629

 60 years and older 78.5 (73.9-83.5) 49.0 (40.0-54.0) 80.0 (76.0-85.0) 125 (114-133) 744 

Table 3.2.b. Serum iron: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for Mexican Americans in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 80.1 (77.7-82.6) 40.0 (38.0-44.0) 84.0 (81.0-87.0) 139 (136-147) 2710

 1–5 years 62.3 (56.6-68.6) 28.0 (21.0-35.0) 70.0 (60.0-79.0) 120 (111-135) 277

 6–11 years 71.2 (65.8-77.1) 41.0 (34.0-45.0) 75.0 (68.0-83.0) 117 (110-133) 361

 12–19 years 83.3 (79.3-87.4) 44.0 (38.0-48.0) 89.0 (83.0-93.0) 143 (138-148) 938

 20–39 years 85.1 (80.1-90.4) 43.0 (37.0-51.0) 88.0 (80.0-97.0) 149 (138-162) 407

 40–59 years 85.1 (81.7-88.6) 47.0 (41.0-52.0) 89.0 (83.0-96.0) 147 (131-162) 344

 60 years and older 82.1 (76.7-87.7) 48.0 (42.0-52.0) 85.0 (77.0-95.0) 134 (130-139) 383 

Males 

Total, 1 year and older 90.0 (86.1-94.1) 49.0 (45.0-55.0) 96.0 (90.0-99.0) 153 (143-162) 1348

 1–5 years 61.6 (54.7-69.4) 28.0 (21.0-35.0) 65.0 (57.0-75.0) 120 (97.0-148) 152

 6–11 years 71.4 (63.3-80.6) 42.0 (32.0-49.0) 74.0 (66.0-84.0) 115 (100-134) 198

 12–19 years 94.1 (90.8-97.6) 53.0 (49.0-58.0) 97.0 (92.0-103) 156 (150-162) 481

 20–39 years 102 (96.5-109) 62.0 (56.0-69.0) 107 (101-111) 162 (150-176) 170

 40–59 years 101 (93.9-108) 62.0 (50.0-76.0) 102 (93.0-112) 151 (133-178) 152

 60 years and older 87.3 (81.9-93.0) 44.0 (30.0-60.0) 95.0 (82.0-102) 141 (130-155) 195 

Females 

Total, 1 year and older 70.8 (67.7-74.1) 36.0 (33.0-38.0) 76.0 (71.0-79.0) 127 (117-132) 1362

 1–5 years 63.3 (56.3-71.1) 26.0 (16.0-37.0) 74.0 (58.0-86.0) 117 (105-138) 125

 6–11 years 71.1 (64.4-78.4) 38.0 (22.0-51.0) 79.0 (70.0-84.0) 118 (110-129) 163

 12–19 years 74.2 (66.6-82.7) 36.0 (30.0-46.0) 79.0 (71.0-87.0) 127 (96.0-144) 457

 20–39 years 69.2 (61.3-78.1) 35.0 (30.0-41.0) 75.0 (66.0-84.0) 124 (111-129) 237

 40–59 years 72.6 (68.4-77.0) 36.0 (27.0-47.0) 73.0 (66.0-83.0) 130 (116-154) 192

 60 years and older 77.4 (70.5-85.1) 48.0 (37.0-57.0) 78.0 (72.0-86.0) 123 (109-137) 188 

80 80 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 3.2.c. Serum iron: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 71.7 (69.0-74.6) 38.0 (35.0-39.0) 75.0 (71.0-80.0) 122 (119-130) 1784

 1–5 years 67.2 (60.0-75.3) 37.0 (30.0-50.0) 69.0 (62.0-80.0) 109 (96.0-125) 172

 6–11 years 71.5 (67.2-76.1) 40.0 (34.0-48.0) 77.0 (73.0-80.0) 117 (103-124) 261

 12–19 years 73.5 (68.0-79.4) 39.0 (33.0-42.0) 79.0 (71.0-84.0) 127 (118-138) 584

 20–39 years 74.1 (70.0-78.5) 35.0 (31.0-41.0) 81.0 (74.0-83.0) 133 (122-147) 274

 40–59 years 71.5 (66.6-76.8) 39.0 (34.0-45.0) 71.0 (66.0-80.0) 126 (112-139) 251

 60 years and older 65.4 (61.5-69.5) 33.0 (30.0-40.0) 67.0 (65.0-72.0) 109 (99.0-119) 242 

Males 

Total, 1 year and older 80.4 (76.3-84.7) 47.0 (39.0-52.0) 82.0 (78.0-85.0) 132 (121-141) 875

 1–5 years 68.4 (60.4-77.6) 37.0† (33.0-40.0) 69.0 (58.0-80.0) 110† (88.0-149) 93

 6–11 years 71.4 (65.7-77.6) 37.0 (28.0-50.0) 79.0 (73.0-84.0) 117 (103-122) 129

 12–19 years 82.2 (77.7-86.9) 46.0 (41.0-54.0) 89.0 (82.0-94.0) 132 (121-138) 301

 20–39 years 88.4 (82.2-95.0) 57.0 (44.0-67.0) 91.0 (82.0-98.0) 137 (120-153) 117

 40–59 years 80.4 (71.8-90.1) 50.0 (31.0-55.0) 80.0 (70.0-94.0) 136 (119-157) 122

 60 years and older 73.0 (66.1-80.5) 35.0 (32.0-54.0) 72.0 (64.0-81.0) 119 (101-141) 113 

Females 

Total, 1 year and older 64.7 (62.1-67.4) 33.0 (30.0-36.0) 67.0 (65.0-70.0) 118 (110-122) 909

 1–5 years 65.8 (56.5-76.7) 33.0† (21.0-54.0) 71.0 (60.0-82.0) 103† (97.0-123) 79

 6–11 years 71.6 (66.3-77.3) 40.0 (27.0-49.0) 76.0 (69.0-80.0) 119 (101-128) 132

 12–19 years 65.3 (57.6-74.1) 34.0 (22.0-40.0) 69.0 (60.0-81.0) 123 (108-135) 283

 20–39 years 63.9 (59.3-68.9) 30.0 (20.0-33.0) 67.0 (61.0-77.0) 123 (112-159) 157

 40–59 years 64.7 (58.2-71.9) 36.0 (31.0-45.0) 67.0 (60.0-71.0) 106 (91.0-115) 129

 60 years and older 60.3 (57.3-63.3) 35.0 (29.0-40.0) 65.0 (58.0-68.0) 103 (86.0-116) 129 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 3.2.d. Serum iron: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 84.0 (81.8-86.2) 47.0 (45.0-51.0) 88.0 (86.0-89.0) 139 (135-141) 2645

 1–5 years 68.5 (63.2-74.3) 35.0 (25.0-44.0) 76.0 (66.0-85.0) 117 (109-132) 170

 6–11 years 72.6 (67.2-78.5) 37.0 (30.0-41.0) 80.0 (66.0-90.0) 131 (113-146) 191

 12–19 years 85.2 (81.2-89.4) 45.0 (40.0-51.0) 89.0 (85.0-91.0) 145 (137-153) 419

 20–39 years 87.3 (81.7-93.3) 46.0 (41.0-56.0) 90.0 (85.0-96.0) 148 (139-158) 609

 40–59 years 85.9 (82.0-90.0) 51.0 (48.0-54.0) 90.0 (85.0-96.0) 135 (129-140) 496

 60 years and older 84.0 (80.4-87.8) 51.0 (47.0-56.0) 86.0 (84.0-90.0) 132 (127-139) 760 

Males 

Total, 1 year and older 89.9 (86.9-92.9) 53.0 (50.0-56.0) 93.0 (90.0-96.0) 146 (141-151) 1315

 1–5 years 67.7 (59.9-76.4) 33.0† (21.0-45.0) 72.0 (64.0-85.0) 118† (100-149) 91

 6–11 years 70.0 (63.9-76.7) 32.0† (29.0-41.0) 79.0 (66.0-87.0) 115† (101-141) 101

 12–19 years 94.4 (85.3-104) 52.0 (42.0-64.0) 97.0 (89.0-108) 161 (145-173) 214

 20–39 years 94.8 (91.7-98.0) 60.0 (52.0-64.0) 95.0 (92.0-101) 154 (141-169) 265

 40–59 years 95.3 (88.6-103) 59.0 (53.0-65.0) 98.0 (92.0-106) 140 (132-147) 254

 60 years and older 87.6 (83.9-91.6) 53.0 (47.0-58.0) 88.0 (85.0-92.0) 146 (136-155) 390 

Females 

Total, 1 year and older 78.5 (76.2-80.9) 43.0 (40.0-46.0) 84.0 (80.0-87.0) 132 (124-141) 1330

 1–5 years 69.5 (62.4-77.5) 35.0† (25.0-40.0) 82.0 (58.0-88.0) 116† (108-132) 79

 6–11 years 75.8 (64.4-89.1) 38.0† (24.0-50.0) 80.0 (60.0-99.0) 136† (118-155) 90

 12–19 years 75.8 (68.3-84.1) 42.0 (36.0-46.0) 80.0 (69.0-87.0) 127 (115-144) 205

 20–39 years 80.4 (72.7-89.0) 41.0 (29.0-47.0) 88.0 (74.0-96.0) 144 (130-161) 344

 40–59 years 77.6 (74.6-80.6) 46.0 (39.0-51.0) 80.0 (72.0-85.0) 126 (113-135) 242

 60 years and older 81.1 (76.2-86.3) 51.0 (43.0-58.0) 83.0 (79.0-87.0) 125 (113-135) 370 

† Estimate is subject to greater uncertainty due to small cell size. 

3 Iron-Status Indicators 81
Table 3.3.a. Serum total iron-binding capacity: Total population 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for the total U.S. population, 

aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 366 (360-371) 297 (292-304) 367 (359-374) 447 (441-453) 7847

 1–5 years 371 (359-383) 309 (286-322) 374 (361-384) 446 (434-454) 699

 6–11 years 369 (361-378) 312 (295-320) 372 (361-380) 438 (423-444) 883

 12–19 years 383 (374-391) 312 (301-328) 385 (377-392) 461 (451-471) 2124

 20–39 years 365 (359-371) 299 (289-306) 363 (357-371) 450 (446-459) 1468

 40–59 years 364 (359-370) 298 (291-305) 364 (354-373) 441 (433-453) 1195

 60 years and older 353 (347-358) 284 (276-290) 355 (347-361) 437 (424-450) 1478 

Males 

Total, 1 year and older 356 (349-364) 294 (287-300) 358 (351-365) 431 (421-438) 3860

 1–5 years 375 (363-387) 306 (276-327) 379 (363-390) 449 (429-477) 385

 6–11 years 364 (351-377) 304 (281-323) 366 (357-381) 426 (408-442) 460

 12–19 years 374 (366-383) 313 (297-329) 379 (367-386) 448 (436-461) 1076

 20–39 years 349 (341-357) 293 (282-298) 350 (342-358) 416 (402-432) 631

 40–59 years 357 (350-364) 294 (289-302) 357 (351-365) 425 (409-436) 567

 60 years and older 345 (337-353) 283 (269-288) 348 (338-357) 431 (409-446) 741 

Females 

Total, 1 year and older 375 (370-381) 305 (298-309) 377 (369-383) 460 (454-465) 3987

 1–5 years 366 (352-381) 307 (271-321) 369 (351-386) 439 (424-447) 314

 6–11 years 375 (367-383) 312 (305-320) 374 (370-387) 441 (427-453) 423

 12–19 years 391 (382-402) 312 (302-335) 393 (383-401) 475 (456-491) 1048

 20–39 years 382 (375-390) 308 (303-316) 383 (374-397) 477 (463-485) 837

 40–59 years 371 (365-378) 300 (290-310) 373 (360-384) 450 (442-466) 628

 60 years and older 359 (354-364) 289 (282-296) 361 (354-371) 439 (424-457) 737 

Table 3.3.b. Serum total iron-binding capacity: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for Mexican Americans in the U.S. 

population, aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 373 (363-384) 303 (288-314) 375 (366-385) 455 (438-478) 2707

 1–5 years 378 (370-387) 316 (303-323) 377 (368-390) 453 (444-476) 274

 6–11 years 379 (371-388) 320 (308-327) 385 (372-395) 441 (433-451) 361

 12–19 years 396 (380-413) 328 (316-336) 395 (386-408) 486 (447-551) 938

 20–39 years 370 (357-384) 299 (277-319) 375 (354-387) 457 (426-485) 407

 40–59 years 365 (359-370) 291 (275-308) 367 (358-372) 439 (431-476) 344

 60 years and older 345 (334-357) 277 (263-290) 350 (338-363) 415 (405-434) 383 

Males 

Total, 1 year and older 365 (356-375) 301 (282-314) 370 (357-380) 437 (427-449) 1345

 1–5 years 382 (370-394) 318 (299-329) 387 (368-396) 456 (436-492) 150

 6–11 years 382 (371-393) 324 (313-337) 386 (366-403) 441 (425-452) 198

 12–19 years 383 (374-392) 319 (304-330) 388 (381-395) 460 (448-469) 480

 20–39 years 359 (344-374) 300 (275-319) 361 (348-380) 428 (411-442) 170

 40–59 years 353 (345-361) 281 (270-305) 357 (347-367) 417 (403-437) 152

 60 years and older 339 (327-352) 276 (250-288) 345 (324-362) 409 (383-434) 195 

Females 

Total, 1 year and older 382 (370-395) 308 (293-318) 384 (373-393) 476 (449-504) 1362

 1–5 years 374 (360-389) 316 (301-334) 368 (355-392) 449 (422-473) 124

 6–11 years 376 (368-384) 315 (305-325) 383 (370-391) 449 (430-456) 163

 12–19 years 409 (383-437) 337 (325-345) 405 (384-428) 529 (436-579) 458

 20–39 years 384 (366-402) 301 (275-325) 383 (371-404) 485 (452-526) 237

 40–59 years 376 (365-388) 299 (284-311) 374 (361-390) 475 (438-496) 192

 60 years and older 351 (337-366) 276 (245-304) 354 (343-365) 421 (408-451) 188 

82 82 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 3.3.c. Serum total iron-binding capacity: Non-Hispanic blacks 

[Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population, aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 354 (349-359) 287 (282-293) 354 (346-360) 435 (427-443) 1774

 1–5 years 370 (363-377) 315 (306-334) 365 (360-375) 435 (415-455) 172

 6–11 years 366 (362-371) 316 (303-327) 367 (360-375) 427 (418-434) 257

 12–19 years 374 (368-379) 312 (301-321) 375 (370-380) 447 (432-460) 582

 20–39 years 356 (346-366) 288 (273-301) 346 (341-360) 444 (428-475) 273

 40–59 years 342 (332-353) 276 (262-286) 346 (331-359) 426 (409-443) 249

 60 years and older 323 (315-331) 259 (242-271) 322 (315-330) 401 (380-435) 241 

Males 

Total, 1 year and older 342 (337-348) 283 (266-291) 344 (340-349) 414 (407-421) 868

 1–5 years 368 (358-378) 320† (295-340) 367 (359-381) 416† (401-435) 93

 6–11 years 365 (358-372) 318 (306-328) 364 (355-374) 423 (409-431) 126

 12–19 years 365 (360-371) 307 (293-317) 369 (360-376) 432 (416-450) 299

 20–39 years 331 (320-342) 265 (253-288) 331 (314-344) 401 (367-428) 117

 40–59 years 333 (319-347) 266 (222-296) 333 (313-362) 405 (384-423) 120

 60 years and older 324 (317-331) 259 (232-282) 325 (313-338) 397 (375-421) 113 

Females 

Total, 1 year and older 364 (359-370) 290 (283-298) 364 (354-375) 447 (441-457) 906

 1–5 years 372 (360-384) 315† (286-334) 362 (351-382) 475† (415-481) 79

 6–11 years 368 (359-376) 311 (295-329) 371 (353-384) 432 (417-443) 131

 12–19 years 382 (374-391) 321 (304-328) 382 (372-390) 456 (433-487) 283

 20–39 years 379 (370-387) 309 (293-319) 379 (362-398) 478 (436-496) 156

 40–59 years 351 (337-365) 275 (262-296) 352 (338-368) 442 (414-448) 129

 60 years and older 323 (310-336) 254 (235-276) 321 (306-333) 406 (375-450) 128 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 3.3.d. Serum total iron-binding capacity: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population, aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 367 (361-373) 300 (294-307) 367 (359-375) 448 (441-454) 2630

 1–5 years 368 (349-387) 305 (265-331) 377 (351-394) 442 (424-451) 168

 6–11 years 372 (363-382) 313 (304-321) 372 (359-388) 442 (413-467) 191

 12–19 years 379 (368-391) 311 (293-328) 384 (374-395) 461 (448-474) 418

 20–39 years 367 (362-371) 299 (291-307) 365 (359-374) 450 (442-463) 608

 40–59 years 369 (362-376) 302 (294-314) 367 (354-379) 444 (433-458) 494

 60 years and older 357 (351-362) 288 (284-293) 358 (349-368) 438 (427-454) 751 

Males 

Total, 1 year and older 358 (350-366) 295 (286-302) 357 (350-366) 433 (419-442) 1306

 1–5 years 370 (355-386) 301† (253-331) 379 (348-398) 446† (411-473) 90

 6–11 years 364 (345-384) 304† (269-326) 367 (352-388) 426† (397-475) 101

 12–19 years 372 (362-384) 310 (285-332) 377 (361-385) 447 (436-464) 213

 20–39 years 351 (342-360) 296 (282-304) 352 (345-362) 418 (401-442) 264

 40–59 years 364 (355-372) 301 (290-319) 362 (352-370) 426 (419-442) 253

 60 years and older 347 (339-356) 284 (271-289) 348 (338-358) 434 (414-447) 385 

Females 

Total, 1 year and older 376 (370-382) 306 (300-311) 378 (370-386) 461 (453-471) 1324

 1–5 years 365 (338-395) 304† (201-336) 372 (334-401) 436† (398-457) 78

 6–11 years 382 (374-391) 317† (313-338) 374 (370-393) 444† (427-467) 90

 12–19 years 387 (375-400) 311 (295-335) 391 (378-403) 471 (450-479) 205

 20–39 years 383 (375-391) 307 (303-316) 383 (367-401) 478 (454-495) 344

 40–59 years 374 (365-384) 302 (289-317) 376 (355-389) 454 (440-479) 241

 60 years and older 365 (360-370) 293 (287-307) 369 (359-376) 450 (424-471) 366 

† Estimate is subject to greater uncertainty due to small cell size. 

3 Iron-Status Indicators 83
Table 3.4.a. Serum transferrin saturation: Total population 

Geometric mean and selected percentiles of serum concentrations (in %) for the total U.S. population aged 

1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 22.2 (21.6-22.9) 12.0 (11.4-12.5) 23.5 (22.8-24.1) 38.8 (37.8-40.4) 7845

 1–5 years 17.6 (16.7-18.6) 8.20 (7.30-9.20) 19.4 (16.8-20.8) 32.9 (29.7-35.3) 697

 6–11 years 19.4 (18.4-20.5) 10.4 (9.40-11.2) 21.1 (18.9-22.4) 34.4 (32.0-35.8) 883

 12–19 years 21.5 (20.6-22.4) 11.3 (10.2-12.3) 22.5 (21.5-23.4) 38.7 (36.0-41.4) 2124

 20–39 years 23.1 (22.2-24.2) 12.3 (11.2-12.7) 24.5 (23.4-25.5) 42.0 (40.0-44.2) 1468

 40–59 years 22.9 (22.0-23.9) 13.1 (12.3-14.1) 23.8 (22.7-25.3) 38.6 (36.4-40.5) 1195

 60 years and older 23.2 (22.2-24.3) 13.3 (12.4-14.3) 24.2 (23.1-25.1) 38.4 (36.8-39.6) 1478 

Males 

Total, 1 year and older 24.7 (23.9-25.6) 14.0 (13.3-14.5) 25.8 (24.8-26.5) 41.8 (40.2-43.8) 3858

 1–5 years 17.4 (16.5-18.3) 8.30 (6.80-9.80) 18.3 (16.6-19.8) 32.4 (29.0-34.6) 383

 6–11 years 19.1 (17.7-20.7) 10.6 (8.80-11.7) 21.2 (18.9-22.4) 32.2 (28.4-35.5) 460

 12–19 years 24.5 (22.9-26.2) 13.3 (11.5-14.5) 25.8 (24.3-26.9) 42.8 (36.3-50.4) 1076

 20–39 years 26.9 (26.1-27.7) 16.3 (14.7-17.4) 27.1 (25.7-28.4) 45.9 (43.7-48.8) 631

 40–59 years 26.2 (24.7-27.8) 16.0 (14.3-17.9) 26.8 (25.4-28.9) 41.6 (39.8-43.2) 567

 60 years and older 25.1 (24.0-26.3) 14.5 (13.3-15.4) 25.9 (24.7-27.3) 41.7 (39.4-43.8) 741 

Females 

Total, 1 year and older 20.1 (19.5-20.7) 10.4 (9.60-11.3) 21.3 (20.9-21.7) 35.8 (33.6-38.4) 3987

 1–5 years 17.9 (15.9-20.1) 7.70 (5.90-10.4) 20.2 (16.2-23.2) 34.1 (29.2-37.1) 314

 6–11 years 19.7 (17.8-21.7) 10.1 (8.30-12.2) 21.1 (17.9-23.8) 36.1 (32.6-38.8) 423

 12–19 years 18.8 (17.6-20.0) 9.90 (9.10-10.9) 19.8 (18.4-20.9) 32.9 (31.0-36.6) 1048

 20–39 years 20.0 (18.8-21.2) 9.00 (7.90-11.1) 21.4 (19.8-23.3) 38.4 (35.0-41.1) 837

 40–59 years 20.2 (19.3-21.1) 11.5 (9.20-13.1) 21.5 (20.5-22.5) 34.8 (32.0-37.6) 628

 60 years and older 21.7 (20.5-23.0) 12.8 (11.1-14.2) 22.3 (21.1-23.6) 35.4 (31.8-37.9) 737 

Table 3.4.b. Serum transferrin saturation: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in %) for Mexican Americans in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 21.5 (20.5-22.5) 10.5 (9.90-11.4) 22.9 (21.6-24.0) 39.3 (37.0-41.2) 2707

 1–5 years 16.6 (14.9-18.4) 7.20 (5.40-9.10) 18.3 (16.5-20.1) 32.9 (28.0-38.8) 274

 6–11 years 18.8 (17.5-20.2) 10.7 (8.70-12.2) 19.9 (18.5-21.4) 30.8 (28.9-33.1) 361

 12–19 years 21.1 (20.2-22.0) 10.6 (9.70-12.0) 22.0 (20.7-22.2) 38.6 (36.4-40.3) 938

 20–39 years 23.0 (21.2-24.9) 12.1 (9.30-13.6) 24.2 (21.9-26.9) 41.2 (38.2-48.1) 407

 40–59 years 23.4 (22.5-24.2) 12.5 (10.4-15.1) 24.7 (23.3-26.4) 41.1 (37.0-44.2) 344

 60 years and older 23.6 (21.9-25.6) 13.2 (11.9-14.9) 24.0 (20.8-27.9) 41.4 (38.0-43.1) 383 

Males 

Total, 1 year and older 24.6 (23.1-26.2) 13.2 (12.1-14.4) 25.8 (24.2-27.5) 43.7 (40.0-48.1) 1345

 1–5 years 16.2 (14.2-18.5) 6.90 (5.10-8.60) 17.0 (15.0-19.8) 32.9 (25.6-41.5) 150

 6–11 years 18.7 (16.8-20.8) 10.8 (8.60-12.9) 19.5 (18.2-21.3) 29.6 (27.4-34.2) 198

 12–19 years 24.6 (23.3-26.0) 13.3 (12.1-14.9) 25.9 (24.3-27.3) 41.0 (38.7-44.1) 480

 20–39 years 28.4 (26.0-30.9) 16.6 (14.6-19.5) 28.6 (25.0-33.0) 49.5 (41.8-56.0) 170

 40–59 years 28.6 (26.8-30.5) 18.4 (14.1-21.2) 28.4 (26.7-30.8) 44.6 (40.9-49.3) 152

 60 years and older 25.6 (23.9-27.5) 13.3 (10.4-16.3) 27.4 (23.2-30.4) 43.8 (38.5-49.0) 195 

Females 

Total, 1 year and older 18.6 (17.5-19.7) 8.90 (8.00-10.0) 20.1 (18.9-21.2) 33.2 (31.0-35.8) 1362

 1–5 years 17.1 (15.5-18.9) 6.80 (5.20-9.70) 19.8 (16.5-22.7) 33.4 (28.0-37.1) 124

 6–11 years 18.9 (17.1-20.9) 10.4 (5.80-13.2) 20.3 (18.8-21.8) 30.8 (29.3-31.7) 163

 12–19 years 18.2 (17.1-19.5) 8.70 (7.50-10.3) 19.7 (18.1-21.3) 33.4 (30.2-36.3) 458

 20–39 years 18.1 (15.9-20.7) 8.10 (6.80-10.4) 19.0 (16.7-21.9) 32.5 (29.5-38.1) 237

 40–59 years 19.3 (18.0-20.7) 8.90 (6.40-12.3) 20.6 (18.5-23.9) 34.1 (31.7-41.0) 192

 60 years and older 21.9 (19.8-24.2) 12.8 (11.8-15.1) 23.0 (19.8-24.2) 35.0 (31.9-41.4) 188 

84 84 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 3.4.c. Serum transferrin saturation: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in %) for non-Hispanic blacks in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 20.3 (19.5-21.2) 9.90 (9.30-10.8) 21.6 (20.5-22.7) 36.5 (34.4-39.0) 1773

 1–5 years 18.3 (16.4-20.3) 10.2 (8.20-12.5) 19.0 (16.1-21.6) 30.7 (26.6-38.1) 171

 6–11 years 19.6 (18.3-21.0) 10.8 (8.60-12.7) 21.3 (19.6-22.3) 31.0 (29.4-34.4) 257

 12–19 years 19.7 (18.2-21.3) 10.0 (8.80-11.3) 21.3 (20.0-22.7) 34.9 (32.2-38.3) 582

 20–39 years 20.8 (19.4-22.4) 8.90 (7.50-10.7) 22.1 (20.4-24.9) 38.4 (35.3-44.2) 273

 40–59 years 20.9 (19.3-22.6) 10.7 (8.50-12.9) 21.4 (19.3-23.2) 37.6 (34.3-42.1) 249

 60 years and older 20.2 (18.9-21.6) 11.4 (9.40-12.9) 21.2 (19.6-22.5) 34.9 (30.6-39.0) 241 

Males 

Total, 1 year and older 23.5 (22.4-24.8) 13.6 (12.5-14.7) 24.5 (22.5-26.1) 39.3 (36.2-41.8) 867

 1–5 years 18.7 (16.6-21.2) 10.4† (9.00-12.4) 19.0 (15.5-22.5) 30.2† (24.6-40.8) 92

 6–11 years 19.7 (17.8-21.7) 10.4 (7.90-13.7) 21.7 (18.9-24.0) 30.1 (28.0-34.3) 126

 12–19 years 22.5 (21.3-23.8) 12.2 (11.1-14.4) 24.2 (22.4-25.6) 36.5 (33.6-39.3) 299

 20–39 years 26.7 (24.8-28.8) 17.4 (14.3-19.8) 27.1 (24.9-30.1) 40.3 (35.7-45.8) 117

 40–59 years 24.2 (21.7-27.0) 13.9 (10.9-16.3) 23.9 (21.4-28.0) 42.2 (37.1-46.8) 120

 60 years and older 22.6 (20.8-24.4) 12.9 (11.4-15.8) 22.4 (20.6-24.3) 38.1 (32.1-41.6) 113 

Females 

Total, 1 year and older 17.8 (16.9-18.7) 8.60 (7.40-9.30) 19.2 (17.9-20.2) 34.3 (31.6-36.0) 906

 1–5 years 17.7 (15.2-20.6) 9.40† (5.30-12.7) 19.4 (14.7-21.8) 29.4† (26.4-38.1) 79

 6–11 years 19.5 (17.8-21.3) 11.5 (6.70-14.1) 21.0 (18.7-22.5) 32.7 (29.4-35.3) 131

 12–19 years 17.1 (14.9-19.5) 8.10 (5.50-10.8) 18.9 (15.5-21.5) 32.3 (28.2-37.0) 283

 20–39 years 16.9 (15.5-18.4) 7.30 (5.40-8.70) 18.0 (15.9-20.1) 37.4 (33.1-41.7) 156

 40–59 years 18.5 (16.3-20.9) 9.90 (6.90-12.0) 19.9 (17.1-21.8) 31.5 (27.1-35.0) 129

 60 years and older 18.6 (17.2-20.0) 9.40 (8.70-11.8) 19.9 (17.8-21.7) 31.3 (28.5-35.0) 128 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 3.4.d. Serum transferrin saturation: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in %) for non-Hispanic whites in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 22.9 (22.0-23.8) 12.6 (11.7-13.2) 24.0 (23.2-24.9) 39.6 (38.3-41.5) 2629

 1–5 years 18.7 (16.9-20.6) 9.20 (6.80-11.4) 20.8 (16.5-23.9) 34.0 (29.2-36.7) 167

 6–11 years 19.5 (17.9-21.2) 9.90 (8.50-11.6) 21.2 (17.0-23.2) 35.7 (32.0-38.8) 191

 12–19 years 22.4 (21.1-23.8) 11.6 (10.2-13.2) 23.2 (21.8-24.1) 41.4 (36.3-44.8) 418

 20–39 years 23.8 (22.3-25.5) 12.7 (10.9-14.6) 25.1 (23.5-26.3) 43.5 (40.9-45.2) 608

 40–59 years 23.4 (22.0-24.8) 14.0 (12.8-15.1) 24.1 (22.8-25.8) 38.6 (35.6-41.5) 494

 60 years and older 23.5 (22.3-24.7) 13.6 (12.4-14.7) 24.5 (23.3-25.6) 38.5 (36.8-39.4) 751 

Males 

Total, 1 year and older 25.1 (23.9-26.4) 14.4 (13.3-15.3) 25.9 (24.5-27.1) 43.0 (40.2-45.2) 1305

 1–5 years 18.5 (16.4-20.8) 9.10† (6.80-12.3) 20.1 (16.5-23.1) 33.2† (28.8-36.7) 89

 6–11 years 19.2 (17.1-21.7) 9.90† (6.10-11.7) 21.6 (17.5-23.4) 32.4† (28.7-36.4) 101

 12–19 years 25.3 (22.8-28.0) 13.4 (11.3-14.5) 26.0 (23.0-29.0) 45.2 (38.4-57.1) 213

 20–39 years 27.0 (26.2-27.9) 16.4 (14.5-18.0) 26.7 (25.2-28.8) 46.3 (44.1-48.9) 264

 40–59 years 26.2 (24.0-28.6) 16.1 (14.1-18.5) 26.2 (24.6-29.2) 40.5 (38.6-43.8) 253

 60 years and older 25.3 (24.0-26.7) 14.2 (13.0-15.9) 26.1 (25.0-27.8) 41.9 (39.2-45.4) 385 

Females 

Total, 1 year and older 20.9 (20.1-21.7) 11.5 (10.4-12.4) 22.0 (21.1-22.9) 36.6 (34.0-39.2) 1324

 1–5 years 19.0 (16.4-21.9) 9.20† (5.10-11.9) 21.1 (15.4-24.5) 34.2† (29.7-41.2) 78

 6–11 years 19.8 (16.8-23.4) 10.2† (6.60-12.8) 21.1 (15.3-26.2) 38.4† (34.7-40.6) 90

 12–19 years 19.6 (17.4-22.0) 10.1 (9.00-13.6) 19.9 (18.1-22.6) 33.0 (30.7-38.7) 205

 20–39 years 21.1 (18.9-23.5) 10.9 (7.80-13.0) 23.0 (19.4-26.3) 39.2 (35.0-42.6) 344

 40–59 years 20.8 (19.9-21.7) 12.4 (10.9-13.8) 21.9 (20.4-22.9) 35.6 (31.5-41.0) 241

 60 years and older 22.1 (20.8-23.5) 13.1 (11.4-14.8) 22.8 (21.3-24.4) 36.1 (31.8-38.4) 366 

† Estimate is subject to greater uncertainty due to small cell size. 

3 Iron-Status Indicators 85
Table 3.5.a. Erythrocyte protoporphyrin: Total population 

Geometric mean and selected percentiles of red blood cell concentrations (in μg/dL) for the total U.S. population aged 1 year 

and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 47.6 (46.7-48.6) 33.0 (32.0-33.0) 46.0 (44.0-47.0) 72.0 (70.0-73.0) 7985

 1–5 years 47.8 (45.9-49.9) 32.0 (31.0-34.0) 45.0 (42.0-48.0) 69.0 (67.0-72.0) 728

 6–11 years 45.2 (42.7-47.8) 31.0 (29.0-34.0) 45.0 (42.0-48.0) 65.0 (60.0-72.0) 905

 12–19 years 46.0 (44.5-47.5) 33.0 (31.0-34.0) 45.0 (43.0-46.0) 70.0 (67.0-73.0) 2139

 20–39 years 46.7 (45.5-47.9) 31.0 (30.0-32.0) 44.0 (42.0-44.0) 72.0 (69.0-76.0) 1477

 40–59 years 48.3 (47.3-49.3) 34.0 (32.0-35.0) 45.0 (44.0-47.0) 71.0 (67.0-75.0) 1217

 60 years and older 51.1 (50.1-52.1) 33.0 (32.0-34.0) 48.0 (48.0-50.0) 76.0 (73.0-80.0) 1519 

Males 

Total, 1 year and older 42.9 (41.9-44.0) 30.0 (30.0-32.0) 41.0 (40.0-43.0) 59.0 (58.0-61.0) 3926

 1–5 years 47.2 (45.0-49.5) 31.0 (30.0-34.0) 46.0 (43.0-49.0) 68.0 (64.0-73.0) 401

 6–11 years 44.1 (41.4-47.0) 31.0 (28.0-33.0) 43.0 (41.0-47.0) 61.0 (54.0-72.0) 473

 12–19 years 41.6 (40.0-43.2) 30.0 (29.0-32.0) 41.0 (39.0-42.0) 56.0 (53.0-59.0) 1082

 20–39 years 40.5 (38.8-42.2) 30.0 (28.0-31.0) 39.0 (37.0-40.0) 58.0 (54.0-61.0) 634

 40–59 years 43.1 (42.2-44.2) 32.0 (30.0-33.0) 41.0 (40.0-42.0) 57.0 (55.0-61.0) 578

 60 years and older 47.2 (46.3-48.1) 32.0 (32.0-34.0) 45.0 (43.0-46.0) 71.0 (66.0-76.0) 758 

Females 

Total, 1 year and older 52.7 (51.5-53.9) 35.0 (34.0-37.0) 49.0 (48.0-51.0) 79.0 (77.0-82.0) 4059

 1–5 years 48.6 (45.3-52.2) 34.0 (31.0-36.0) 45.0 (42.0-50.0) 71.0 (66.0-77.0) 327

 6–11 years 46.4 (43.5-49.4) 32.0 (30.0-35.0) 46.0 (42.0-48.0) 68.0 (62.0-75.0) 432

 12–19 years 51.1 (49.2-53.0) 34.0 (32.0-37.0) 49.0 (47.0-51.0) 76.0 (71.0-81.0) 1057

 20–39 years 53.8 (52.5-55.0) 36.0 (36.0-37.0) 49.0 (49.0-51.0) 83.0 (78.0-89.0) 843

 40–59 years 53.6 (51.3-56.0) 36.0 (34.0-37.0) 51.0 (48.0-52.0) 83.0 (74.0-93.0) 639

 60 years and older 54.4 (52.5-56.5) 37.0 (34.0-38.0) 52.0 (49.0-55.0) 80.0 (75.0-85.0) 761 

Table 3.5.b. Erythrocyte protoporphyrin: Mexican Americans 

Geometric mean and selected percentiles of red blood cell concentrations (in μg/dL) for Mexican Americans in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 52.3 (50.8-53.9) 35.0 (33.0-36.0) 49.0 (48.0-51.0) 84.0 (80.0-88.0) 2741

 1–5 years 53.6 (50.5-56.9) 38.0 (35.0-40.0) 50.0 (48.0-52.0) 79.0 (71.0-94.0) 283

 6–11 years 51.8 (49.6-54.1) 34.0 (33.0-38.0) 49.0 (47.0-53.0) 81.0 (73.0-87.0) 368

 12–19 years 53.9 (50.6-57.5) 35.0 (34.0-37.0) 50.0 (48.0-52.0) 89.0 (73.0-116) 942

 20–39 years 50.6 (47.7-53.7) 32.0 (32.0-36.0) 47.0 (45.0-51.0) 80.0 (71.0-93.0) 410

 40–59 years 53.8 (52.0-55.8) 34.0 (33.0-36.0) 52.0 (48.0-55.0) 88.0 (79.0-94.0) 345

 60 years and older 53.1 (50.8-55.4) 34.0 (33.0-37.0) 51.0 (47.0-54.0) 82.0 (77.0-86.0) 393 

Males 

Total, 1 year and older 46.6 (45.1-48.1) 31.0 (29.0-33.0) 45.0 (43.0-46.0) 69.0 (66.0-71.0) 1361

 1–5 years 55.4 (51.6-59.5) 39.0 (34.0-40.0) 52.0 (47.0-53.0) 84.0 (72.0-120) 156

 6–11 years 50.6 (47.6-53.8) 37.0 (33.0-40.0) 48.0 (46.0-53.0) 73.0 (62.0-90.0) 200

 12–19 years 47.5 (46.1-48.9) 33.0 (31.0-36.0) 45.0 (43.0-46.0) 70.0 (66.0-74.0) 482

 20–39 years 42.7 (40.6-44.8) 31.0 (27.0-34.0) 41.0 (40.0-43.0) 61.0 (54.0-66.0) 172

 40–59 years 45.9 (43.8-48.2) 32.0 (29.0-35.0) 44.0 (41.0-47.0) 66.0 (61.0-78.0) 153

 60 years and older 47.7 (45.4-50.2) 33.0 (29.0-35.0) 46.0 (41.0-49.0) 73.0 (67.0-86.0) 198 

Females 

Total, 1 year and older 59.2 (57.0-61.5) 38.0 (37.0-40.0) 56.0 (54.0-58.0) 96.0 (88.0-108) 1380

 1–5 years 51.4 (47.8-55.3) 37.0 (31.0-41.0) 48.0 (45.0-53.0) 71.0 (64.0-88.0) 127

 6–11 years 53.2 (50.8-55.7) 34.0 (33.0-38.0) 51.0 (48.0-54.0) 86.0 (73.0-89.0) 168

 12–19 years 60.8 (55.0-67.1) 40.0 (38.0-42.0) 57.0 (53.0-61.0) 110 (69.0-127) 460

 20–39 years 61.3 (56.1-67.0) 39.0 (36.0-42.0) 58.0 (52.0-63.0) 101 (81.0-138) 238

 40–59 years 62.5 (60.3-64.8) 37.0 (34.0-41.0) 60.0 (56.0-64.0) 100 (90.0-119) 192

 60 years and older 58.5 (55.6-61.5) 39.0 (36.0-41.0) 56.0 (53.0-59.0) 85.0 (80.0-97.0) 195 

86 86 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 3.5.c. Erythrocyte protoporphyrin: Non-Hispanic blacks 

Geometric mean and selected percentiles of red blood cell concentrations (in μg/dL) for non-Hispanic blacks in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 47.4 (45.8-49.1) 31.0 (30.0-33.0) 44.0 (43.0-47.0) 72.0 (69.0-75.0) 1817

 1–5 years 45.4 (43.1-47.8) 31.0 (28.0-33.0) 45.0 (42.0-48.0) 61.0 (57.0-68.0) 180

 6–11 years 44.9 (42.7-47.2) 30.0 (29.0-31.0) 44.0 (42.0-46.0) 63.0 (58.0-71.0) 270

 12–19 years 45.2 (43.0-47.5) 31.0 (28.0-32.0) 42.0 (40.0-44.0) 67.0 (63.0-75.0) 587

 20–39 years 48.0 (44.9-51.3) 32.0 (29.0-34.0) 45.0 (40.0-49.0) 76.0 (67.0-84.0) 277

 40–59 years 48.3 (46.0-50.7) 32.0 (31.0-34.0) 46.0 (43.0-48.0) 71.0 (62.0-93.0) 255

 60 years and older 51.0 (48.2-54.0) 34.0 (32.0-38.0) 48.0 (45.0-51.0) 78.0 (70.0-86.0) 248 

Males 

Total, 1 year and older 41.9 (40.1-43.9) 29.0 (28.0-32.0) 41.0 (39.0-43.0) 58.0 (56.0-62.0) 890

 1–5 years 45.4 (42.7-48.3) 31.0† (28.0-36.0) 46.0 (39.0-49.0) 61.0† (53.0-68.0) 98

 6–11 years 43.4 (41.6-45.3) 30.0 (27.0-32.0) 43.0 (40.0-45.0) 60.0 (56.0-70.0) 134

 12–19 years 40.5 (39.0-42.1) 29.0 (28.0-31.0) 39.0 (37.0-40.0) 57.0 (51.0-63.0) 301

 20–39 years 39.3 (36.2-42.7) 29.0 (26.0-32.0) 38.0 (34.0-40.0) 54.0 (45.0-67.0) 117

 40–59 years 42.7 (40.7-44.8) 30.0 (27.0-32.0) 42.0 (38.0-43.0) 57.0 (52.0-63.0) 123

 60 years and older 47.5 (43.9-51.4) 32.0 (26.0-36.0) 46.0 (41.0-50.0) 71.0 (62.0-80.0) 117 

Females 

Total, 1 year and older 53.0 (51.1-54.8) 34.0 (33.0-37.0) 50.0 (48.0-53.0) 82.0 (77.0-88.0) 927

 1–5 years 45.4 (42.0-49.0) 31.0† (28.0-33.0) 43.0 (39.0-49.0) 68.0† (58.0-79.0) 82

 6–11 years 46.5 (42.6-50.8) 30.0 (29.0-33.0) 45.0 (41.0-49.0) 72.0 (62.0-76.0) 136

 12–19 years 50.7 (46.2-55.6) 35.0 (32.0-37.0) 46.0 (44.0-50.0) 79.0 (65.0-94.0) 286

 20–39 years 56.6 (52.7-60.7) 37.0 (33.0-39.0) 54.0 (51.0-58.0) 82.0 (71.0-104) 160

 40–59 years 53.6 (49.4-58.3) 34.0 (31.0-37.0) 53.0 (48.0-56.0) 84.0 (70.0-99.0) 132

 60 years and older 53.8 (50.5-57.3) 36.0 (34.0-39.0) 51.0 (46.0-52.0) 82.0 (70.0-105) 131 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 3.5.d. Erythrocyte protoporphyrin: Non-Hispanic whites 

Geometric mean and selected percentiles of red blood cell concentrations (in μg/dL) for non-Hispanic whites in the U.S. 

population aged 1 year and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 1 year and older 46.3 (45.4-47.3) 31.0 (30.0-32.0) 43.0 (43.0-45.0) 68.0 (66.0-70.0) 2674

 1–5 years 45.8 (43.0-48.8) 31.0 (30.0-34.0) 44.0 (40.0-47.0) 67.0 (60.0-72.0) 177

 6–11 years 43.3 (39.7-47.2) 31.0 (27.0-34.0) 43.0 (40.0-46.0) 61.0 (53.0-73.0) 192

 12–19 years 44.2 (42.1-46.3) 32.0 (29.0-33.0) 44.0 (41.0-45.0) 62.0 (58.0-72.0) 423

 20–39 years 45.1 (43.5-46.8) 32.0 (30.0-32.0) 44.0 (42.0-44.0) 69.0 (61.0-73.0) 610

 40–59 years 46.7 (45.8-47.6) 34.0 (32.0-35.0) 45.0 (43.0-46.0) 66.0 (63.0-71.0) 502

 60 years and older 50.3 (49.5-51.0) 34.0 (32.0-34.0) 48.0 (47.0-50.0) 75.0 (72.0-78.0) 770 

Males 

Total, 1 year and older 42.0 (40.8-43.2) 30.0 (30.0-32.0) 41.0 (40.0-42.0) 58.0 (56.0-60.0) 1330

 1–5 years 44.1 (41.3-47.0) 31.0† (28.0-33.0) 44.0 (40.0-47.0) 64.0† (55.0-67.0) 95

 6–11 years 41.9 (37.8-46.5) 29.0† (26.0-33.0) 41.0 (39.0-45.0) 61.0† (49.0-72.0) 103

 12–19 years 40.7 (38.1-43.5) 28.0 (26.0-32.0) 41.0 (37.0-43.0) 54.0 (49.0-59.0) 215

 20–39 years 39.1 (37.5-40.9) 29.0 (25.0-30.0) 37.0 (35.0-39.0) 53.0 (49.0-59.0) 265

 40–59 years 42.7 (41.3-44.2) 32.0 (28.0-34.0) 41.0 (40.0-43.0) 56.0 (52.0-60.0) 258

 60 years and older 46.4 (45.3-47.4) 33.0 (32.0-34.0) 43.0 (42.0-45.0) 67.0 (64.0-74.0) 394 

Females 

Total, 1 year and older 51.0 (49.7-52.3) 35.0 (34.0-37.0) 47.0 (46.0-49.0) 75.0 (73.0-80.0) 1344

 1–5 years 47.9 (42.0-54.7) 34.0† (31.0-36.0) 42.0 (38.0-49.0) 69.0† (60.0-93.0) 82

 6–11 years 45.0 (40.8-49.5) 32.0† (29.0-35.0) 44.0 (39.0-50.0) 60.0† (55.0-77.0) 89

 12–19 years 48.4 (46.0-50.9) 33.0 (32.0-37.0) 47.0 (45.0-50.0) 73.0 (67.0-77.0) 208

 20–39 years 51.9 (49.2-54.8) 36.0 (34.0-39.0) 48.0 (47.0-49.0) 81.0 (72.0-99.0) 345

 40–59 years 51.0 (48.8-53.3) 36.0 (34.0-37.0) 49.0 (45.0-52.0) 74.0 (68.0-83.0) 244

 60 years and older 53.7 (51.8-55.7) 36.0 (34.0-39.0) 52.0 (49.0-56.0) 79.0 (73.0-84.0) 376 

† Estimate is subject to greater uncertainty due to small cell size. 

3 Iron-Status Indicators 87
References 

Beard JL. Iron deficiency and neural development: an update. Arch Latinoam Nutr. 1999;49(3 Suppl 

2):34S-9S. 

Fulwood R, Johnson CL, Bryner JD. Hematological and nutritional biochemistry reference data for 

persons 6 months–74 years of age: United States, 1976–1980. National Center for Health Statistics, Vital 

Health Stat Series 11(232), 1982. 

Grantham-McGregor S, Ani C. A review of studies on the effect of iron deficiency on cognitive 

development in children. J Nutr. 2001;131(2S-2):649S-6S. 

Haas JD, Brownlie T 4th. Iron deficiency and reduced work capacity: a critical review of the research to 

determine a causal relationship. J Nutr. 2001;131:691S-6S. 

Hollowell JG, Van Assendelft OW, Gunter EW. Hematological and iron-related analytes – Reference data 

for persons aged 1 year and over: United States, 1988–1994. National Center for Health Statistics, Vital 

Health Stat Series 11(247), 2005. 

Institute of Medicine, Food and Nutrition Board. Dietary reference intakes: vitamin A, vitamin K, arsenic, 

boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium and zinc. 

Washington, D.C.: National Academy Press; 2001. 

Looker AC, Gunter EW, Johnson CL. Methods to assess iron status in various NHANES surveys. Nutr Rev. 

1995;53:246-54. 

Looker AC, Dallman PR, Carroll M, Gunter EW, Johnson CL. Prevalence of iron deficiency in the United 

States. JAMA. 1997;277:973-5. 

Looker AC, Cogswell ME, Gunter EW. Iron deficiency, United States, 1999–2000. Morb Mortal Wkly Rep. 

2002;51:897-9. 

Miret S, Simpson RJ, McKie AT. Physiology and molecular biology of dietary iron absorption. Annu Rev 

Nutr. 2003;23:283-301. 

Pietrangelo A. Hereditary hemochromatosis – a new look at an old disease. N Engl J Med. 

2004;350:2382-97. 

Pilch SM, Senti FR, editors. Assessment of iron nutritional status of the U.S. population based on data 

collected in the Second National Health and Nutrition Examination Survey, 1976–1980. Bethesda (MD): 

Federation of American Societies for Experimental Biology; 1984. 

Roels HA, Lauwerys RR, Buchet JP, Vrelust M-Th. Response of free erythrocyte porphyrin and urinary 

δ-aminolevulinic acid in men and women moderately exposed to lead. Int Arch Arbeitsmed. 

1975;34:97-108. 

Schorr TO, Hediger ML. Anemia and iron-deficiency anemia: compilation of data on pregnancy outcome. 

Am J Clin Nutr. 1994;59(Suppl):492S-501S. 

U.S. Centers for Disease Control and Prevention. Recommendations to prevent and control iron 

deficiency in the United States. Morb Mortal Wkly Rep. 1998;47(RR-3):1-36. 

U.S. Department of Health and Human Services. Healthy people 2010: understanding and improving 

health. 2nd ed. Washington, D.C.: U.S. Government Printing Office; November 2000. 

World Health Organization (WHO). Iron deficiency anaemia – Assessment, prevention, and control. A 

guide for programme managers. Geneva: World Health Organization; 2001 (WHO/NHD/01.3) [cited 

2008]. Available from: http://www.who.int/nutrition/publications/en/ida_assessment_prevention_ 

control.pdf. 

88 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
4 

Trace Elements
 

•	 Iodine 

•	 Selenium 

89 
90 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Trace Elements: 

Iodine 

Iodine, a trace element found in soil, is an essential component of the 

thyroid hormones involved in regulating the body’s metabolic processes. 

Iodized salt and seafood are the major dietary sources of iodine. In the 

United States, salt is iodized with potassium iodide at 100 parts per million 

(76 milligram [mg] of iodine per kilogram [kg] of salt). Iodized salt is 

chosen by about 50–60 percent of the U.S. population (Institute of Medicine 

2001). Still, most ingested salt comes from processed food (approximately 

70 percent), which is typically not iodized in either the United States or in 

Canada (The Public Health Committee of the American Thyroid Association 2006). 

For the thyroid to synthesize thyroid hormones, iodine is essential. Iodine 

deficiency disorders include mental retardation, hypothyroidism, goiter, 

cretinism, and varying degrees of other growth and developmental 

abnormalities. Iodine deficiency is the most preventable cause of mental 

retardation in the world (World Health Organization 2007). Thyroid enlargement 

(goiter) is usually the earliest clinical feature of iodine deficiency. Thyroid 

hormone is particularly important in the development of the central 

nervous system during the fetal and early postnatal periods. In areas 

where iodized salt is common, iodine deficiency is rare. 

The median intake of iodine from food in the United States is 

approximately 240 to 300 micrograms (μg) per day for men and 190 to 

210 μg/day for women, largely owing to the iodization of salt (Institute of 

Medicine 2001). Iodine deficiency develops when iodide intake is less than 

20 μg/day (Beers 2006). Most dietary iodine absorbed in the body eventually 

appears in the urine; thus, urinary iodine excretion is recommended for 

assessing recent dietary iodine intake worldwide (World Health Organization 

2007). 

Excess iodine intake may also result in goiter, as well as in hyper- or 

hypothyroidism. High iodine intake has also been associated with 

increased risk for thyroid papillary cancer (Institute of Medicine 2001). For most 

people, iodine intake from usual foods and supplements is unlikely to 

exceed the tolerable upper intake level (1,100 μg/day). 

The Institute of Medicine recommends iodine intake at 150 μg per day for 

nonpregnant adults, 220 μg per day for pregnant women and 290 μg per 

day during lactation (Institute of Medicine 2001). 

4 Trace Elements 91
World Health Organization (WHO) categories for median urinary iodine 

concentrations in school-age children and adults (excluding pregnant and lactating 

women) are widely used to define iodine intake and nutrition status for populations 

(World Health Organization 2007) (Table 4.a). An additional adequacy criterion is that not 

more than 20 percent of samples from children and non-pregnant women are below 

50 nanograms per milliliter (ng/mL) of iodine. 

Table 4.a Epidemiological criteria for assessing iodine nutrition based on median urinary iodine 

concentrations of school-age children (≥ 6 years)* 

Median Urinary 

Iodine (ng/mL) 

Iodine Intake Iodine Status 

< 20 Insufficient Severe iodine deficiency 

20–49 Insufficient Moderate iodine deficiency 

50–99 Insufficient Mild iodine deficiency 

100–199 Adequate Adequate iodine nutrition 

200–299 Above 

requirements 

Likely to provide adequate intake for 

pregnant/lactating women but may pose a 

slight risk of more than adequate intake in 

the overall population 

> 300 Excessive Risk for adverse health consequences 

(e.g., iodine-induced hyperthyroidism, 

autoimmune thyroid diseases) 

*Applies to adults but not to pregnant and lactating women 

Note that these categories are useful for classifying population risk but are not 

categories to define individual risk for adverse health outcomes. The large day-to-day 

variations in urine iodine excretion, even among individuals with stable iodine intake, 

tend to offset one another when the sample includes an adequately large number 

(50–100 people per site) of representative individuals (Borak 2005). 

For pregnant women, median urinary iodine concentrations of 150–249 ng/mL 

represent adequate iodine intake (World Health Organization 2007). 

The Public Health Committee of the American Thyroid Association (2006) has 

recommended that until additional physiologic data are available to determine the 

appropriate requirements during pregnancy and lactation, iodine supplementation 

(150 μg/day) is appropriate for these two life stages in the United States and in 

92 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Canada. This decision was based on data for pregnant women from NHANES III 

and NHANES 2001–2002: median urinary iodine concentrations were lower than 

recommended during NHANES III (141 ng/mL) and within the recommended range 

during NHANES 2001–2002 (173 ng/mL), but 95 percent confidence intervals ranged 

from 75 to 229 ng/mL (Caldwell 2005). 

For more information about iodine, 

see the Institute of Medicine’s Dietary 

Reference Intake report (Institute of 

Medicine 2001) as well as information 

from the American Society for Nutrition 

(http://jn.nutrition.org/nutinfo/). 

Since 1971, NHANES has measured 

urinary iodine. The NHANES III 

survey (1988–1994) showed a 

sizable decrease in urinary iodine 

concentrations compared with 

concentrations measured during 

NHANES I (1971–1974) (Hollowell 1998). 

This decline may have been due to 

the dairy industry’s effort in the mid1980s to reduce the iodine residue 

in milk from feed supplements and 

iodophor sanitizing agents (Pennington 

1996). Decreased concentrations of 

iodine in fruit-flavored breakfast 

cereals—the industry’s response 

to a ban on erythrosine (an iodinecontaining food dye)—could also have 

contributed to the decline in urinary 

iodine concentrations (Pennington 1996). Since 2000, urinary iodine has been measured 

in the continuous NHANES survey. CDC uses a new method, involving inductively 

coupled plasma mass spectrometry (ICP-MS), to make these measurements (Caldwell 

2003). This method has been compared with the established Sandell-Kolthoff 

spectrophotometric method used in NHANES III (Pino 1998). The two methods strongly 

correlate (r2 = 0.98), and the average difference between them is not statistically 

significant (Caldwell 2003). When CDC laboratory scientists used this new method to 

measure urinary iodine concentrations in NHANES 2000 (U.S. Centers for Disease Control 

and Prevention 2000) and NHANES 2001–2002 (Caldwell 2005), they found that the U.S. 

median urinary iodine concentration had stabilized since the initial drop that had 

occurred from NHANES I to NHANES III. This finding confirms the stability of the U.S. 

iodine intake and continued adequate iodine nutrition for the country generally. 

Chemist performs maintenance on instrumentation used to measure urinary 

iodine. 

4 Trace Elements 93
Selected Observations and Highlights 

The following example observations and figures are taken from the uncorrected 

tables of 2001–2002 data contained in this report. Statements about categorical 

differences between demographic groups noted below are based on nonoverlapping confidence limits from univariate analysis without adjusting for 

demographic variables (i.e., age, sex, race/ethnicity) or other determinants of these 

urine concentrations (i.e., dietary intake, supplement usage, smoking, BMI). A 

multivariate analysis may alter the size and statistical significance of these categorical 

differences. Furthermore, additional significant differences of smaller magnitude may 

be present despite their lack of mention here (e.g., if confidence limits slightly overlap 

or if differences are not statistically significant before covariate adjustment has 

occurred). For a selection of citations of descriptive NHANES papers related to these 

biochemical indicators of diet and nutrition, see Appendix E. 

General Observations 

•	 Children (aged 6–11 years) have higher urinary iodine concentrations than 

people in any other age group. 

•	 Females have lower urinary iodine concentrations than males. 

Highlights 

After a sharp decline that occurred from 1971–1988, from 1988–2002 median 

concentrations of urinary iodine appear to have stabilized in various population 

subgroups (Fig 4.a). This finding has been shown previously (Caldwell 2005). 

Figure 4.a 

Median concentrations (95 percent confidence intervals) of urinary iodine in the U.S. population, 

aged 6 years and older, and in population subgroups, National Health and Nutrition Examination 

Survey, 1971–2002. Data shown for NHANES 1971–1974 and 1988–1994 are not part of the tables 

displayed in this report but were analyzed separately to generate this figure. 

94 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
4 Trace Elements 95

On the basis of median urinary iodine concentrations, the iodine intake of women 

of childbearing age appears adequate (Fig 4.b). Appropriate consideration should be 

given, however, to the higher intake recommendation for pregnant women (World 

Health Organization 2007). 

Figure 4.b 

Median concentrations (95 percent confidence intervals) of urinary iodine among women of 

childbearing age, National Health and Nutrition Examination Survey, 2001–2002. 
Table 4.1.a. Urinary iodine: Total population 

Geometric mean and selected percentiles of urine concentrations (in ng/mL) for the total U.S. population aged 

6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 162 (152-172) 44.0 (41.0-49.0) 167 (158-176) 503 (466-543) 2837 

6–11 years 235 (208-266) 78.0 (61.0-89.0) 249 (221-289) 682 (571-737) 374 

12–19 years 192 (178-207) 58.0 (42.0-68.0) 206 (189-214) 594 (511-693) 831 

20–39 years 148 (132-166) 49.0 (34.0-58.0) 153 (136-175) 429 (356-482) 627 

40–59 years 140 (121-162) 37.0 (25.0-45.0) 142 (118-169) 478 (403-577) 496 

60 years and older 177 (156-200) 57.0 (49.0-65.0) 173 (152-199) 524 (440-633) 509 

Males 

Total, 6 years and older 192 (178-208) 64.0 (54.0-73.0) 197 (179-209) 542 (478-619) 1333 

6–11 years 250 (213-294) 86.0 (55.0-126) 266 (223-316) 682 (498-864) 185 

12–19 years 238 (214-265) 75.0 (67.0-104) 234 (210-271) 639 (545-896) 386 

20–39 years 176 (155-200) 63.0 (48.0-89.0) 178 (143-213) 425 (345-479) 271 

40–59 years 169 (147-194) 44.0 (35.0-71.0) 172 (149-207) 496 (391-596) 255 

60 years and older 211 (172-258) 75.0 (40.0-102) 202 (163-249) 615 (417-904) 236 

Females 

Total, 6 years and older 137 (127-148) 37.0 (31.0-43.0) 140 (127-157) 458 (421-516) 1504 

6–11 years 220 (182-267) 64.0 (44.0-88.0) 239 (185-293) 638 (524-738) 189 

12–19 years 154 (137-173) 40.0 (28.0-62.0) 174 (148-193) 454 (368-587) 445 

20–39 years 127 (105-153) 34.0 (23.0-53.0) 133 (108-162) 425 (314-507) 356 

40–59 years 115 (93.2-141) 28.0 (22.0-36.0) 111 (78.0-146) 456 (292-695) 241 

60 years and older 155 (135-177) 51.0 (44.0-62.0) 156 (117-189) 440 (349-550) 273 

Table 4.1.b. Urinary iodine: Mexican Americans 

Geometric mean and selected percentiles of urine concentrations (in ng/mL) for Mexican Americans in the U.S. population, age 

6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 176 (163-189) 56.0 (45.0-60.0) 186 (167-205) 487 (442-518) 720 

6–11 years 241 (210-277) 95.0 (62.0-150) 231 (193-297) 621 (487-699) 112 

12–19 years 179 (161-198) 56.0 (40.0-72.0) 190 (160-213) 524 (392-583) 266 

20–39 years 168 (142-198) 50.0 (40.0-66.0) 173 (141-218) 442 (375-534) 166 

40–59 years 156 (124-197) 31.0† (14.0-74.0) 169 (146-215) 472† (380-700) 90 

60 years and older 152 (131-176) 56.0† (36.0-75.0) 156 (115-203) 427† (303-477) 86 

Males 

Total, 6 years and older 201 (173-233) 60.0 (43.0-79.0) 203 (172-236) 524 (442-792) 325 

6–11 years 246 (190-318) 76.0† (42.0-138) 246 (174-374) 677† (469-926) 53 

12–19 years 190 (163-221) 58.0 (33.0-100) 198 (153-226) 511 (344-583) 113 

20–39 years 195 (146-261) 58.0† (28.0-79.0) 197 (137-255) 495† (374-1170) 75 

40–59 years 191 (134-274) 37.0† (15.0-146) 193 (154-311) 453† (346-713) 48 

60 years and older 209 (165-265) 82.0† (13.0-161) 203 (154-345) 455† (324-1210) 36 

Females 

Total, 6 years and older 151 (136-168) 45.0 (31.0-60.0) 169 (137-202) 441 (370-480) 395 

6–11 years 237 (193-290) 107† (79.0-150) 218 (179-297) 510† (370-656) 59 

12–19 years 167 (143-194) 46.0 (32.0-62.0) 189 (146-213) 506 (351-676) 153 

20–39 years 140 (109-179) 40.0† (22.0-69.0) 167 (97.0-247) 331† (294-480) 91 

40–59 years 123 (85.4-178) 22.0† (7.00-58.0) 125 (86.0-178) 433† (186-532) 42 

60 years and older 120 (94.1-154) 51.0† (28.0-61.0) 111 (82.0-158) 299† (158-521) 50 

† Estimate is subject to greater uncertainty due to small cell size. 

96 96 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 4.1.c. Urinary iodine: Non-Hispanic blacks 

Geometric mean and selected percentiles of urine concentrations (in ng/mL) for non-Hispanic blacks in the U.S. population, age 

6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 156 (137-178) 54.0 (45.0-65.0) 143 (124-173) 478 (402-608) 670 

6–11 years 247 (201-302) 97.0 (67.0-138) 257 (175-311) 600 (467-954) 121 

12–19 years 183 (151-221) 62.0 (43.0-78.0) 172 (156-200) 555 (384-695) 248 

20–39 years 145 (117-181) 58.0 (31.0-95.0) 134 (106-169) 398 (306-478) 121 

40–59 years 136 (99.7-185) 44.0† (31.0-57.0) 120 (82.0-197) 627† (275-923) 106 

60 years and older 127 (91.6-176) 40.0† (18.0-64.0) 112 (94.0-129) 268† (213-525) 74 

Males 

Total, 6 years and older 161 (143-181) 55.0 (39.0-68.0) 156 (134-173) 540 (414-681) 325 

6–11 years 259 (201-334) 90.0† (53.0-149) 240 (175-318) 932† (496-1100) 61 

12–19 years 201 (162-249) 65.0 (50.0-101) 186 (161-214) 624 (381-873) 120 

20–39 years 161 (127-204) 69.0† (23.0-126) 149 (127-183) 459† (242-745) 57 

40–59 years 120 (83.6-171) 31.0† (11.0-65.0) 113 (76.0-180) 594† (180-1010) 55 

60 years and older 120 (79.4-183) 45.0† (25.0-99.0) 119 (56.0-232) 320† (156-525) 32 

Females 

Total, 6 years and older 153 (128-182) 53.0 (41.0-60.0) 135 (108-174) 449 (352-608) 345 

6–11 years 234 (177-309) 97.0† (73.0-138) 257 (143-334) 531† (424-744) 60 

12–19 years 167 (134-207) 38.0 (32.0-68.0) 168 (146-186) 487 (366-670) 128 

20–39 years 135 (103-176) 53.0† (47.0-86.0) 121 (92.0-176) 340† (201-471) 64 

40–59 years 152 (104-223) 50.0† (36.0-65.0) 124 (65.0-352) 702† (350-994) 51 

60 years and older 132 (69.1-252) 30.0† (16.0-73.0) 104 (66.0-200) 255† (208-1780) 42 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 4.1.d. Urinary iodine: Non-Hispanic whites 

Geometric mean and selected percentiles of urine concentrations (in ng/mL) for non-Hispanic whites in the U.S. population, age 

6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 163 (150-176) 44.0 (40.0-49.0) 169 (158-179) 511 (468-569) 1222 

6–11 years 229 (195-270) 61.0† (44.0-92.0) 266 (206-327) 682† (516-738) 111 

12–19 years 205 (182-231) 59.0 (41.0-81.0) 214 (192-240) 619 (537-769) 248 

20–39 years 148 (125-176) 47.0 (27.0-63.0) 157 (133-185) 421 (324-507) 280 

40–59 years 139 (115-168) 35.0 (23.0-45.0) 138 (107-169) 480 (387-659) 258 

60 years and older 185 (161-211) 56.0 (48.0-68.0) 186 (163-200) 552 (435-670) 325 

Males 

Total, 6 years and older 199 (180-221) 64.0 (51.0-78.0) 204 (187-219) 548 (470-653) 575 

6–11 years 247 (192-319) 92.0† (37.0-139) 271 (206-320) 682† (389-864) 57 

12–19 years 279 (246-316) 97.0 (67.0-150) 280 (223-344) 696 (586-1020) 116 

20–39 years 179 (149-215) 63.0 (44.0-95.0) 181 (136-247) 407 (323-468) 112 

40–59 years 174 (146-206) 43.0 (35.0-75.0) 172 (141-212) 477 (389-659) 132 

60 years and older 224 (178-282) 80.0 (40.0-107) 212 (168-271) 633 (417-1040) 158 

Females 

Total, 6 years and older 135 (122-149) 35.0 (28.0-43.0) 140 (122-157) 473 (419-569) 647 

6–11 years 211 (153-291) 58.0† (24.0-124) 225 (129-399) 689† (451-895) 54 

12–19 years 153 (126-185) 40.0 (21.0-62.0) 175 (127-194) 454 (323-740) 132 

20–39 years 126 (95.4-166) 28.0 (20.0-53.0) 133 (96.0-169) 425 (303-576) 168 

40–59 years 110 (83.1-144) 28.0 (22.0-36.0) 96.0 (67.0-152) 480 (265-873) 126 

60 years and older 159 (140-181) 52.0 (43.0-65.0) 158 (121-194) 444 (365-634) 167 

† Estimate is subject to greater uncertainty due to small cell size.

 4 Trace Elements 97
Table 4.1.e. Urinary iodine: Total population (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for the total U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 163 (153-173) 64.5 (59.5-68.3) 151 (141-165) 437 (406-470) 2835 

6–11 years 273 (246-304) 116 (101-131) 257 (219-321) 699 (608-817) 374 

12–19 years 149 (137-161) 66.7 (59.9-70.2) 138 (129-146) 364 (297-479) 830 

20–39 years 135 (127-143) 56.7 (51.2-63.7) 128 (116-136) 346 (307-431) 627 

40–59 years 151 (130-175) 59.5 (52.5-66.3) 141 (119-176) 407 (300-478) 496 

60 years and older 216 (192-244) 87.2 (75.8-97.2) 200 (176-230) 518 (452-629) 508 

Males 

Total, 6 years and older 156 (143-171) 59.6 (53.1-69.1) 145 (136-161) 415 (368-501) 1333 

6–11 years 292 (263-325) 123 (92.0-148) 321 (260-359) 774 (533-963) 185 

12–19 years 162 (144-182) 63.8 (58.1-72.5) 151 (136-181) 412 (303-578) 386 

20–39 years 131 (122-141) 57.9 (49.7-65.6) 119 (107-136) 341 (273-470) 271 

40–59 years 133 (112-158) 52.5 (43.9-60.2) 134 (103-162) 315 (269-423) 255 

60 years and older 200 (168-238) 74.8 (57.6-94.9) 190 (145-238) 474 (362-704) 236 

Females 

Total, 6 years and older 170 (161-179) 67.6 (63.1-70.5) 158 (146-169) 449 (426-508) 1502 

6–11 years 254 (213-303) 109 (95.1-119) 220 (195-298) 631 (481-978) 189 

12–19 years 136 (124-149) 66.8 (59.7-71.2) 128 (111-137) 337 (265-434) 444 

20–39 years 139 (127-153) 56.1 (48.6-68.2) 133 (116-144) 359 (299-449) 356 

40–59 years 171 (148-198) 65.4 (56.0-78.4) 155 (133-186) 436 (392-576) 241 

60 years and older 230 (199-265) 96.9 (81.8-113) 207 (179-251) 571 (446-667) 272 

Table 4.1.f. Urinary iodine: Mexican Americans (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for Mexican Americans 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 164 (152-176) 65.4 (61.8-74.5) 154 (140-178) 424 (344-467) 720 

6–11 years 298 (253-350) 135 (104-162) 304 (239-344) 726 (469-939) 112 

12–19 years 144 (132-157) 65.2 (53.5-82.7) 132 (119-149) 314 (255-445) 266 

20–39 years 146 (127-168) 63.0 (54.9-70.8) 143 (109-175) 328 (248-492) 166 

40–59 years 142 (124-164) 62.0† (40.1-83.0) 140 (117-186) 325† (241-479) 90 

60 years and older 200 (170-234) 74.3† (61.9-112) 195 (156-245) 452† (391-765) 86 

Males 

Total, 6 years and older 157 (137-181) 62.2 (53.8-74.4) 150 (125-182) 428 (308-522) 325 

6–11 years 300 (227-395) 141† (93.0-193) 304 (209-375) 766† (459-1090) 53 

12–19 years 133 (116-151) 61.1 (49.3-81.4) 123 (108-146) 282 (182-493) 113 

20–39 years 144 (115-181) 57.3† (49.4-69.3) 143 (102-182) 328† (202-613) 75 

40–59 years 130 (98.3-172) 58.9† (9.93-108) 129 (103-214) 294† (241-405) 48 

60 years and older 193 (130-287) 84.0† (60.9-117) 180 (110-342) 452† (245-765) 36 

Females 

Total, 6 years and older 172 (154-192) 74.1 (63.2-83.7) 159 (139-184) 428 (339-534) 395 

6–11 years 296 (233-375) 130† (90.6-163) 304 (198-373) 726† (428-1070) 59 

12–19 years 157 (136-182) 73.9 (60.8-82.9) 141 (119-168) 364 (255-778) 153 

20–39 years 147 (123-176) 65.4† (42.9-89.7) 145 (108-190) 316† (210-466) 91 

40–59 years 159 (115-218) 70.0† (40.1-119) 143 (95.1-233) 408† (230-705) 42 

60 years and older 204 (158-265) 66.3† (58.5-122) 195 (143-257) 437† (331-1110) 50 

† Estimate is subject to greater uncertainty due to small cell size. 

98 98 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 4.1.g. Urinary iodine: Non-Hispanic blacks (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic blacks 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 113 (103-124) 45.7 (41.3-51.0) 103 (92.5-115) 321 (257-381) 669 

6–11 years 209 (161-273) 89.7 (75.5-110) 206 (121-293) 510 (393-775) 121 

12–19 years 110 (93.7-128) 45.9 (36.8-58.8) 95.5 (87.7-114) 303 (208-406) 247 

20–39 years 94.6 (86.0-104) 42.8 (37.1-55.4) 88.3 (82.4-104) 190 (172-247) 121 

40–59 years 101 (82.3-124) 37.9† (23.6-55.9) 98.7 (69.1-130) 339† (218-441) 106 

60 years and older 122 (93.7-160) 51.3† (38.8-59.3) 102 (93.5-117) 339† (175-394) 74 

Males 

Total, 6 years and older 102 (87.9-119) 37.9 (29.0-48.1) 95.6 (79.1-118) 305 (260-356) 325 

6–11 years 208 (148-292) 84.0† (75.0-107) 204 (109-321) 510† (356-802) 61 

12–19 years 111 (89.6-138) 44.9 (33.7-60.7) 99.1 (80.0-119) 332 (201-479) 120 

20–39 years 90.0 (78.5-103) 37.6† (27.9-53.9) 83.8 (63.3-109) 300† (153-362) 57 

40–59 years 74.7 (54.5-102) 26.9† (7.53-54.1) 73.6 (41.3-148) 188† (116-280) 55 

60 years and older 105 (85.8-129) 50.6† (35.5-67.1) 97.1 (69.5-134) 211† (126-359) 32 

Females 

Total, 6 years and older 123 (111-135) 51.9 (46.3-57.8) 108 (98.7-117) 329 (239-414) 344 

6–11 years 211 (152-293) 101† (33.7-124) 214 (120-328) 478† (297-915) 60 

12–19 years 108 (94.4-124) 45.9 (36.4-62.9) 94.3 (87.7-106) 257 (189-468) 127 

20–39 years 98.2 (82.4-117) 48.6† (37.1-67.5) 90.4 (75.0-115) 184† (157-235) 64 

40–59 years 133 (99.2-178) 48.3† (44.6-65.4) 117 (79.3-162) 441† (303-699) 51 

60 years and older 136 (83.5-222) 51.3† (38.8-71.8) 107 (94.7-115) 270† (120-9060) 42 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 4.1.h. Urinary iodine: Non-Hispanic whites (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic whites 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 2001–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 175 (163-188) 69.2 (64.5-72.4) 164 (151-177) 452 (420-517) 1221 

6–11 years 290 (256-328) 121† (98.2-148) 298 (214-366) 738† (570-857) 111 

12–19 years 159 (145-175) 70.2 (62.5-75.3) 143 (129-175) 353 (297-578) 248 

20–39 years 145 (133-157) 64.5 (52.9-69.7) 133 (121-144) 386 (322-451) 280 

40–59 years 159 (133-191) 62.0 (55.9-69.8) 147 (123-191) 416 (315-562) 258 

60 years and older 232 (203-265) 102 (84.3-116) 211 (188-249) 567 (455-667) 324 

Males 

Total, 6 years and older 167 (149-187) 66.5 (55.6-76.5) 156 (142-175) 432 (371-532) 575 

6–11 years 320 (268-383) 134† (98.2-157) 359 (237-379) 785† (404-1200) 57 

12–19 years 182 (160-206) 67.4 (57.8-89.1) 180 (143-229) 559 (297-710) 116 

20–39 years 139 (122-158) 66.9 (49.7-78.7) 126 (107-145) 352 (228-514) 112 

40–59 years 140 (115-171) 54.7 (43.9-64.8) 137 (99.2-179) 369 (276-439) 132 

60 years and older 215 (175-264) 81.1 (54.1-116) 197 (159-263) 514 (366-830) 158 

Females 

Total, 6 years and older 182 (172-193) 69.6 (65.3-74.3) 169 (158-183) 468 (431-569) 646 

6–11 years 260 (201-336) 106† (85.9-132) 215 (167-368) 631† (449-978) 54 

12–19 years 140 (121-162) 69.2 (59.7-73.5) 131 (103-148) 328 (264-434) 132 

20–39 years 150 (130-172) 62.7 (47.2-69.7) 138 (122-161) 397 (322-451) 168 

40–59 years 182 (150-221) 69.6 (60.7-84.5) 177 (122-231) 437 (387-730) 126 

60 years and older 246 (209-289) 109 (89.4-132) 212 (192-278) 571 (446-700) 166 

† Estimate is subject to greater uncertainty due to small cell size.

 4 Trace Elements 99
References 

Beers MH, editor. Vitamin deficiency, dependency, and toxicity. In: Merck Manual of Diagnosis and 

Therapy. 18th ed. Whitehouse Station (NJ): Merck & Co., Inc.; 2006 [cited 2008]. Available from: http:// 

www.merck.com/mmpe/sec01/ch004/ch004l.html. 

Borak J. Adequacy of iodine nutrition in the United States. Conn Med. 2005;69:73-7. 

Caldwell KL, Maxwell B, Makhmudov A, Pino S, Braverman LE, Jones RL, Hollowell JG. Use of inductively 

coupled plasma mass spectrometry to measure urinary iodine in NHANES 2000: comparison with 

previous method. Clin Chem. 2003;49:1019-21. 

Caldwell KL, Jones R, Hollowell JG. Urinary iodine concentration: United States National Health and 

Nutrition Examination Survey 2001–2002. Thyroid. 2005;15:692-9. 

Hollowell JG, Staehling NW, Hannon WH, Flanders DW, Gunter EW, Maberly GF, et al. Iodine nutrition in 

the United States. Trends and public health implications: iodine excretion data from National Health 

and Nutrition Examination Surveys, I and III (1971–1974 and 1988–1994). J Clin Endocrinol Metab. 

1998;83:3401-8. 

Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: vitamin A, vitamin K, arsenic, 

boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc. 

Washington, D.C.: National Academy Press; 2001. 

Pennington JAT, Schoen SA. Total Diet Study: estimated dietary intakes of nutritional elements, 

1982–1991. Int J Vit Nutr Res. 1996;66:350-62. 

Pino S, Fang SL, Braverman LE. Ammonium persulfate: a new and safe method for measuring urinary 

iodine by ammonium persulfate oxidation. Exp Clin Endocrinol Diabetes. 1998;106 Suppl 3:S22-7. 

The Public Health Committee of the American Thyroid Association. Iodine supplementation for 

pregnancy and lactation — United States and Canada: recommendations of the American Thyroid 

Association. Thyroid. 2006;16:949-51. 

U.S. Centers for Disease Control and Prevention: iodine level, United States, 2000 [cited 2008]. National 

Center for Health Statistics. Available from: http://www.cdc.gov/nchs/products/pubs/pubd/hestats/ 

iodine.htm. 

World Health Organization. Assessment of iodine deficiency disorders and monitoring their 

elimination: a guide for programme managers. 3rd ed. Geneva (Switzerland): World Health 

Organization, 2007 (WHO/NHD/01.1) [cited 2008]. Available from: http://www.whqlibdoc.who.int/ 

publications/2007/9789241595827_eng.pdf. 

100 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Trace Elements: 

Selenium
 

Selenium is a trace mineral essential to good health. The major dietary 

source of selenium is plant foods. Selenium concentrations in plants 

generally reflect the concentration of selenium in soils, but some meats 

and seafood can also contribute dietary selenium; in the United States, 

meats and bread are common sources. Depending on foodstuff origin, 

variation in its selenium content can be between 11- and 72-fold; thus, 

predicting dietary intake by relying on estimates from nutrient databases 

is difficult (Keck 2006). 

Selenium functions through selenoproteins, several of which are 

oxidant-defense enzymes. For example, the selenium-dependent 

glutathione peroxidase defends the body against oxidative stress. Other 

selenium-associated proteins regulate the action of thyroid hormones 

and the oxidation-reduction status of vitamin C and other molecules 

(Institute of Medicine 2000). Most selenium in animal tissues is present as 

selenomethionine or selenocysteine. 

Selenium deficiency in the United States is rare, but it is seen in other 

countries, most notably in China, where the concentration of selenium 

in soil is low. In the United States, most cases of selenium depletion or 

deficiency are associated with severe gastrointestinal problems, such as 

Crohn’s disease, or with the surgical removal of part of the stomach, and 

are therefore a result of impaired selenium absorption (Kuroki 2003; Rannem 

1992; Bjerre 1989). 

By itself, selenium deficiency does not usually cause illness. Rather, it can 

make the body more susceptible to illnesses caused by other nutritional, 

biochemical, or infectious stresses (Beck 2003). Three specific diseases have 

been associated with selenium deficiency. Keshan disease occurs only in 

selenium-deficient children and is associated with an enlarged heart and 

poor heart function. Kashin-Beck disease is a disorder of the bones and 

joints of the hands and fingers, elbows, knees, and ankles of children and 

adolescents. Lastly, myxedematous endemic cretinism, a condition that 

results in mental retardation, occurs in infants born to mothers deficient in 

both selenium and iodine (Institute of Medicine 2000). 

4 Trace Elements 101
Chemists review selenium data. 

Evidence is limited as to whether intakes of selenium 

greater than the amount needed to allow full expression 

of selenoproteins may have chemopreventive effects 

against cancer. Controlled intervention studies are 

needed to adequately evaluate selenium as a cancer 

chemopreventive agent (Institute of Medicine 2000). 

Blood concentrations of selenium greater than 1,000 

nanograms per milliliter (ng/mL) (12.7 micromoles per liter 

[μmol/L]) can result in a condition known as selenosis (Koller 

1986). Manifestations of selenosis include gastrointestinal 

upset, hair loss, white blotchy nails, garlic-breath odor, 

fatigue, irritability, and mild nerve damage (Goldhaber 2003). 

The National Academy of Sciences has established an 

estimated average requirement (EAR) for selenium that 

is based on the amount needed to maximize plasma 

glutathione peroxidase activity and prevent Keshan 

disease. The EAR is the average daily nutrient intake level 

estimated to meet the requirement of half of the healthy 

individuals in a particular life stage and sex group. The EAR 

for selenium for boys and girls 9–13 years old or 14–18 

years old is 35 and 45 micrograms (μg) daily, respectively. 

For healthy children aged 1–3 years or 4–8 years, the 

currently recommended EAR for selenium is 17 and 23 

μg daily, respectively. These values are extrapolated from 

adult values (Institute of Medicine 2000). 

A diagnosis of selenium deficiency is confirmed by measuring concentrations of 

selenium in serum or plasma. Values less than 70 ng/mL or 0.8 μmol/L suggest 

synthesis of selenium-associated proteins has not yet reached a plateau and that 

selenium supplies are limited (Institute of Medicine 2000). 

For more information about selenium, see the Institute of Medicine’s Dietary 

Reference Intake report (Institute of Medicine 2000), the selenium fact sheet from the 

National Institutes of Health, Office of Dietary Supplements (http://ods.od.nih.gov/ 

factsheets/selenium.asp), as well as information from the American Society for Nutrition 

(http://jn.nutrition.org/nutinfo/). 

Using serum selenium concentrations measured in the U.S. population in NHANES 

III (1988–1994), it appears that the diets of most U.S. residents provide the 

recommended amounts of selenium (Niskar 2003). The mean and median serum 

selenium concentrations were 1.58 μmol/L and 1.56 μmol/L, respectively. Serum 

selenium concentrations differed by age, sex, race, ethnicity, poverty-income 

ratio, and geographic region. In NHANES 2001–2002, less than 3 percent of survey 

participants had a dietary intake of selenium below the EAR (Moshfegh 2005). 

102 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Selected Observations and Highlights 

The following example observations are taken from the tables of 1999-2000 data 

contained in this report. Only data for children were available for the NHANES survey 

period covered in this report. Statements about categorical differences between 

demographic groups noted below are based on non-overlapping confidence limits 

from univariate analysis without adjusting for demographic variables (i.e., age, sex, 

race/ethnicity) or other determinants of these blood concentrations (i.e., dietary 

intake, supplement usage, smoking, BMI). A multivariate analysis may alter the size 

and statistical significance of these categorical differences. Furthermore, additional 

significant differences of smaller magnitude may be present despite their lack of 

mention here (e.g., if confidence limits slightly overlap or if differences are not 

statistically significant before covariate adjustment has occurred). For a selection of 

citations of descriptive NHANES papers related to these biochemical indicators of 

diet and nutrition, see Appendix E. 

General Observations 

•	 Younger children (aged 3–5 years) have lower serum selenium concentrations 

than do older children (aged 6–11 years). 

•	 At least 90 percent of 3–11 year-old children have adequate serum 


concentrations of selenium.
 

Highlights 

The majority of U.S. children (> 90 percent) have adequate serum concentrations of 

selenium (≥ 70 ng/mL). No evidence has surfaced of excessive exposure to selenium 

(> 1,000 ng/mL) in U.S. children. 

4 Trace Elements 103
104 104

Table 4.2.a. Serum selenium: Total population 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for the total U.S. population aged 

3 years and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total,3-11 years 112 (110-114) 93.0 (91.0-96.0) 113 (111-114) 130 (127-133) 1186

 3–5 years 107 (104-110) 90.0 (83.0-94.0) 110 (105-112) 128 (124-131) 343

 6–11 years 114 (111-116) 95.0 (93.0-102) 113 (111-116) 130 (128-134) 843 

Males 

Total,3-11 years 113 (110-116) 94.0 (91.0-98.0) 114 (111-116) 134 (129-137) 626

 3–5 years 108 (103-112) 87.0 (64.0-95.0) 108 (104-112) 129 (123-136) 188

 6–11 years 115 (111-119) 96.0 (91.0-104) 114 (110-121) 134 (129-137) 438 

Females 

Total,3-11 years 111 (108-113) 93.0 (90.0-96.0) 112 (110-116) 128 (126-131) 560

 3–5 years 107 (102-111) 89.0 (72.0-96.0) 110 (105-115) 126 (119-131) 155

 6–11 years 112 (109-115) 93.0 (89.0-98.0) 113 (109-117) 128 (126-131) 405 

Table 4.2.b. Serum selenium: Mexican Americans 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for Mexican Americans in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total,3-11 years 110 (107-113) 93.0 (87.0-96.0) 109 (106-113) 126 (123-131) 477

 3–5 years 108 (104-112) 90.0 (83.0-98.0) 107 (103-113) 124 (120-129) 131

 6–11 years 111 (108-114) 95.0 (91.0-100) 111 (107-114) 128 (123-133) 346 

Males 

Total,3-11 years 111 (108-115) 93.0 (85.0-98.0) 111 (108-114) 129 (125-135) 262

 3–5 years 109 (105-113) 87.0† (83.0-99.0) 108 (104-114) 125† (120-135) 71

 6–11 years 112 (109-116) 93.0 (87.0-100) 111 (107-115) 133 (126-135) 191 

Females 

Total,3-11 years 108 (105-112) 95.0 (89.0-98.0) 108 (105-114) 123 (118-126) 215

 3–5 years 106 (100-112) 89.0† (76.0-98.0) 105 (100-112) 123† (116-130) 60

 6–11 years 109 (106-112) 96.0 (87.0-99.0) 111 (105-114) 123 (118-132) 155 

† Estimate is subject to greater uncertainty due to small cell size. 

National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
105

Table 4.2.c. Serum selenium: Non-Hispanic blacks 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for non-Hispanic blacks in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total,3-11 years 107 (104-110) 91.0 (87.0-94.0) 107 (104-111) 124 (120-126) 341

 3–5 years 104 (101-107) 91.0† (84.0-94.0) 104 (102-109) 121† (116-125) 98

 6–11 years 108 (105-112) 92.0 (87.0-94.0) 108 (105-112) 124 (121-130) 243 

Males 

Total,3-11 years 108 (105-112) 91.0 (86.0-94.0) 109 (104-113) 124 (118-130) 173

 3–5 years 104 (99.4-109) 83.0† (50.0-91.0) 105 (103-112) 118† (113-131) 56

 6–11 years 110 (106-115) 92.0 (86.0-101) 110 (105-115) 126 (119-133) 117 

Females 

Total,3-11 years 106 (104-108) 91.0 (87.0-95.0) 107 (103-109) 122 (118-124) 168

 3–5 years 105 (101-109) 93.0† (84.0-96.0) 103 (98.0-112) 120† (112-127) 42

 6–11 years 106 (104-109) 92.0 (87.0-96.0) 106 (103-110) 121 (118-124) 126 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 4.2.d. Serum selenium: Non-Hispanic whites 

Geometric mean and selected percentiles of serum concentrations (in ng/mL) for non-Hispanic whites in the U.S. 

population aged 3 years and older, National Health and Nutrition Examination Survey, 1999–2000. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total,3-11 years 113 (110-116) 94.0 (90.0-102) 116 (112-118) 130 (127-135) 265

 3–5 years 107 (102-113) 87.0† (57.0-103) 114 (105-118) 130† (123-133) 81

 6–11 years 115 (111-119) 94.0 (90.0-104) 116 (111-120) 131 (127-136) 184 

Males 

Total,3-11 years 113 (109-118) 93.0 (91.0-102) 114 (109-121) 134 (128-137) 140

 3–5 years 106 (98.9-114) 87.0† (57.0-99.0) 105 (99.0-122) 125† (123-135) 41

 6–11 years 116 (110-122) 102† (84.0-110) 115 (110-123) 134† (129-139) 99 

Females 

Total,3-11 years 112 (108-117) 94.0 (80.0-102) 116 (111-119) 130 (126-132) 125

 3–5 years 108 (101-117) 80.0† (33.0-107) 114 (107-118) 130† (120-133) 40

 6–11 years 114 (109-119) 93.0† (79.0-105) 118 (110-120) 130† (126-135) 85 

† Estimate is subject to greater uncertainty due to small cell size.

 4 Trace Elements 
References 

Beck MA, Levander O, Handy J. Selenium deficiency and viral infection. J Nutr. 2003;133:1463S-67S. 

Bjerre B, von Schenck H, Sorbo B. Hyposelaemia: patients with gastrointestinal diseases are at risk. J 

Intern Med. 1989;225:85-8. 

Goldhaber SB. Trace element risk assessment: essentiality vs. toxicity. Regul Toxicol Pharmacol. 

2003;38:232-42. 

Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: vitamin C, vitamin E, 

selenium, and carotenoids. Washington, D.C.: National Academy Press; 2000. 

Keck A-S, Finley JW. Database values do not reflect selenium contents of grain, cereals, and other foods 

grown or purchased in the upper Midwest of the United States. Nutr Res. 2006;26:17-22. 

Koller LD, Exon JH. The two faces of selenium-deficiency and toxicity are similar in animals and man. Can 

J Vet Res. 1986;50:297-306. 

Kuroki F, Matsumoto T, Lida M. Selenium is depleted in Crohn’s disease on enteral nutrition. Dig Dis. 

2003;21:266-70. 

Moshfegh A, Goldman J, Cleveland L. What we eat in America, NHANES 2001–2002: usual nutrient 

intakes from food compared to dietary reference intakes. Washington, D.C.: U.S. Food and 

Drug Administration; 2005 [cited 2008]. Available from: http://www.ars.usda.gov/SP2UserFiles/ 

Place/12355000/pdf/usualintaketables2001-02.pdf. 

Niskar AS, Paschal DC, Kieszak SM, Flegal KM, Bowman B, Gunter EW, et al. Serum selenium levels in the 

US population: Third National Health and Nutrition Examination Survey, 1988–1994. Biol Trace Elem Res. 

2003;91:1-10. 

Rannem T, Ladefoged K, Hylander E, Hegnhoj J, Jarnum S. Selenium status in patients with Crohn’s 

disease. Am J Clin Nutr. 1992;56:933-7. 

106 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
5 

Isoflavones & Lignans 


(so-called Phytoestrogens) 

Isoflavones 

•	 Genistein 

•	 Daidzein 

•	 Equol 

•	 O-Desmethylangolensin 

Lignans 

•	 Enterodiol 

•	 Enterolactone 

107 
108 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Isoflavones & Lignans
 

(so-called Phytoestrogens) 

Phytoestrogens are naturally occurring polycyclic phenols found in certain 

plants that may, when ingested and metabolized, have weak estrogenic 

effects. Two important groups of phytoestrogens are isoflavones and 

lignans. The isoflavones considered in this report are daidzein, genistein, 

O-desmethylangolensin (ODMA), and equol. The lignans considered in 

this report are enterodiol and enterolactone. 

Plant sources of isoflavones include legumes, with the largest contribution 

coming from soy-based foods. Since soy flour and soy protein isolates 

may be added to processed meats, meat substitutes, breads, and proteinfood bars, these items can be a major source of isoflavones (Grace 2004; 

Lampe 1999). However, the isoflavone content of soy protein preparations 

can vary widely and is affected by production techniques (Erdman 2004). 

Daidzein and genistein are the main soy isoflavones. Kudzu root, used 

in some dietary supplements, also contains appreciable amounts of 

daidzein. Naringenin, a precursor to genistein, is found in some citrus 

fruits. Formononetin and biochanin A are methylated isoflavones found 

in clovers, which may be used in red clover dietary supplements, and 

they are metabolized in the body to daidzein and genistein, respectively. 

Ingested daidzein is further metabolized to ODMA and to equol by 

intestinal bacteria. Equol, but not ODMA, has estrogenic activity. About 

30 percent of adults produce equol and have higher serum equol 

concentrations after they consume daidzein (Setchell 2003a; Cassidy 2006). 

This ability to produce equol may be related to an individual’s intestinal 

microflora and influenced by dietary habits (Rowland 2000; Setchell 2006). It is 

unclear whether the ability to produce equol results in any health-related 

effects (Vafeiadou 2006). 

Lignans include matairesinol and secoisolariciresinol, which are 

transformed by intestinal bacteria into the estrogenic compounds, 

enterolactone, and enterodiol, respectively (Cornwell 2004; Rowland 2003). 

Enterodiol may also convert into enterolactone and vice versa. Lignans are 

found in flax seeds, whole wheat flour, tea, some fruits, and other cereal 

grains. 

5 Isoflavones & Lignans 109 
Diet is the source of human exposure to phytoestrogens. The absorption and 

metabolism of phytoestrogens varies considerably among individuals, which may 

relate to differences in absorption, enterohepatic circulation, and metabolism by 

intestinal bacteria. Phytoestrogens are ingested in their naturally occurring betaglycosidic forms. The beta-glycosidic forms are hydrolyzed to their aglycones in the 

intestine, absorbed, and then linked in the intestinal wall and liver with glucuronic 

acid to make them more water-soluble, a process known as glucuronidation (Doerge 

2000; Rowland 2003). The glucuronidated metabolites of isoflavones predominate in 

blood and urine (Setchell 2001). 

Isoflavones are excreted from the body within about 24 hours after ingestion, 

mainly in urine and, to a lesser extent, in feces (Setchell 2001). Urinary concentrations 

of daidzein and genistein may not correlate well with the ingested doses, perhaps 

because of the limited absorption of these isoflavones at higher doses (Setchell 2003b). 

In contrast, lignan concentrations in plasma and urine concentrations after flax seed 

consumption increases in a dose-dependent manner (Nesbitt 1999). Equol excretion 

may depend on diet, the type of intestinal bacteria present, and individual genetic 

factors (Rowland 2000; Setchell 2002; Setchell 1999). 

Generally, phytoestrogens are much less potent than endogenously produced 

estrogens, but phytoestrogens can be present in much greater quantities 

(100 to 1000 times the concentration of endogenous estrogens). Additionally, 

phytoestrogens bind less tightly to steroid-hormone serum-transport proteins than 

do endogenous estrogens (Nagel 1998). Equol has more potent estrogen activity than 

its precursor daidzein and has been proposed to be most important in explaining the 

mechanism of action of isoflavones in disease prevention (Setchell 2002). 

In comparison with Western diets, Asian diets typically provide higher intakes of 

soy-based foods. Some have suggested that the higher isoflavone intake in Asian 

diets may account for the lower incidence among Asians of menopause-related 

symptoms and for other associated beneficial health outcomes, such as reduced 

risk for breast, prostate, and colon cancer; cardiovascular health; and modulation of 

osteoporosis. A recent evidence report from the Agency for Healthcare Research and 

Quality (Balk 2005) about the effects of soy on health outcomes reported that there is 

no conclusive evidence of a dose-response effect of either soy protein or isoflavone 

on cardiovascular diseases, menopausal symptoms, endocrine function, cancer, 

bone health, reproductive health, kidney diseases, cognitive function, or glucose 

metabolism. For reducing low-density lipoprotein concentrations, however, soy 

protein could possibly have a dose-response effect. 

Adverse effects on fertility have been observed in animals that graze on red clover. 

Results of chronic feeding studies in pregnant animals suggest that high doses of 

110 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
5 Isoflavones & Lignans 111

phytoestrogens alter the fetal hormonal environment (Cornwell 2004). Infants who 

consume soy-based formula can have plasma concentrations of isoflavones that ar

13,000–22,000 times higher than concentrations of endogenous estrogen in infants

(Setchell 1997). Yet, studies of children who had been fed soy-based formula as infants

and who were followed through adolescence (Klein 1998) and young adulthood (Stro

2001) found no adverse reproductive or endocrine effects. In vitro and animal studie

also suggest that soy isoflavones may have immunologic and thyroid effects (Doerge

2002). The Center for the Evaluation of Risks to Human Reproduction of the National 

Toxicology Program reviewed the developmental and reproductive toxicity of both 

soy formula and genistein and concluded that available data were inadequate to 

determine the effects of soy formula on developmental or reproductive toxicity 

(Rozman 2006a). The expert review panel expressed negligible concern for adverse 

effects in the general population of consuming dietary sources of genistein: under 

current exposure conditions, adults would be unlikely to consume sufficient daily 

levels of genistein to cause adverse reproductive and/or developmental effects 

(Rozman 2006b). 

For more information about soy isoflavones, see the fact sheet from the National 

Institutes of Health, Office of Dietary Supplements (http://ods.od.nih.gov/Health_ 

Information/Information_About_Individual_Dietary_Supplements.aspx). 

e 

m 

s 

Phytoestrogens have been measured in NHANES since 1999. In NHANES 1999–2000, 

CDC scientists detected enterolactone in the highest concentration, and daidzein 

was detected with the highest 

frequency among the six measured 

phytoestrogens (Valentin-Blasini 2005). 

CDC’s Third National Report on Human 

Exposure to Environmental Chemicals 

has presented geometric means 

and selected percentiles (50th, 75th, 

90th, and 95th) for concentrations of 

phytoestrogens by age, sex, and race/ 

ethnicity for participants in NHANES 

1999–2000 and 2001–2002 (U.S. Centers 

for Disease Control and Prevention 2005). 

Chemist verifies sample for phytoestrogen analysis. 
Selected Observations and Highlights 

The following example observations are taken from the uncorrected tables of 

1999–2002 data contained in this report. Statements about categorical differences 

between demographic groups noted below are based on non-overlapping 

confidence limits from univariate analysis without adjusting for demographic 

variables (i.e., age, sex, race/ethnicity) or other determinants of these urine 

concentrations (i.e., dietary intake, supplement usage, smoking, BMI). A multivariate 

analysis may alter the size and statistical significance of these categorical differences. 

Furthermore, additional significant differences of smaller magnitude may be present 

despite their lack of mention here (e.g., if confidence limits slightly overlap or if 

differences are not statistically significant before covariate adjustment has occurred). 

For a selection of citations of descriptive NHANES papers related to these biochemical 

indicators of diet and nutrition, see Appendix E. 

General Observations 

•	 Urinary isoflavone (genistein, daidzein, equol, and ODMA) concentrations are 

generally lower in adults than they are in children and adolescents, whereas 

urinary lignan concentrations either do not differ by age (enterodiol) or show 

a U-shaped age pattern (enterolactone). 

•	 Males and females have similar phytoestrogen concentrations. 

•	 Non-Hispanic whites have higher equol concentrations than non-Hispanic 

blacks and Mexican Americans. Mexican Americans have lower ODMA 

concentrations than non-Hispanic blacks and non-Hispanic whites. 

Highlights 

Urinary isoflavone and lignan concentrations show only small variations by 

demographic variables such as age, sex, or race/ethnicity. 

112 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
5 Isoflavones & Lignans 113
Table 5.1.a. Urinary genistein: Total population 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for the total U.S. population aged 

6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 28.5 (25.5-31.8) 3.27 (2.70-4.17) 28.4 (25.7-30.7) 293 (253-330) 5351 

6–11 years 33.8 (29.3-39.1) 5.80 (4.20-7.05) 31.8 (25.2-37.3) 248 (197-328) 727 

12–19 years 38.0 (32.2-44.7) 5.60 (4.00-8.20) 34.8 (29.0-41.4) 314 (249-365) 1498 

20–39 years 31.3 (26.5-37.0) 3.10 (2.40-4.80) 29.0 (25.8-34.3) 349 (269-437) 1140 

40–59 years 23.7 (19.1-29.3) 2.22 (.900-3.40) 24.4 (21.3-29.4) 298 (202-402) 951 

60 years and older 24.1 (20.8-28.0) 2.90 (2.20-3.95) 24.2 (20.3-29.8) 227 (155-308) 1035 

Males 

Total, 6 years and older 31.1 (26.8-36.2) 3.86 (3.10-5.20) 30.3 (27.6-34.0) 298 (235-341) 2597 

6–11 years 34.6 (27.6-43.3) 5.36 (3.30-7.04) 35.2 (24.3-51.0) 218 (146-348) 368 

12–19 years 36.3 (28.1-46.8) 6.21 (2.62-10.6) 31.0 (25.6-41.4) 299 (204-363) 736 

20–39 years 33.5 (26.5-42.3) 3.16 (2.30-5.39) 30.7 (26.8-35.9) 385 (245-522) 500 

40–59 years 26.5 (19.7-35.6) 3.35 (1.32-5.60) 28.4 (20.1-35.7) 281 (195-383) 480 

60 years and older 29.8 (24.4-36.6) 4.17 (3.10-5.73) 31.1 (23.7-36.6) 233 (141-335) 513 

Females 

Total, 6 years and older 26.1 (23.7-28.8) 2.85 (2.22-3.83) 25.6 (23.5-28.4) 285 (242-353) 2754 

6–11 years 33.1 (26.2-41.9) 5.50 (3.75-7.84) 27.0 (21.8-36.1) 272 (197-426) 359 

12–19 years 39.8 (34.0-46.7) 5.52 (4.00-8.40) 36.8 (31.3-46.3) 321 (247-445) 762 

20–39 years 29.3 (24.0-35.8) 2.99 (1.95-4.86) 27.6 (22.5-36.3) 312 (217-461) 640 

40–59 years 21.2 (17.3-26.1) 1.60 (<LOD-3.00) 22.8 (18.7-26.0) 327 (194-495) 471 

60 years and older 20.5 (17.3-24.3) 2.50 (1.26-3.51) 20.3 (16.4-25.3) 190 (129-290) 522 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

Table 5.1.b. Urinary genistein: Mexican Americans 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for Mexican Americans in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 29.7 (25.4-34.8) 4.07 (3.40-4.60) 27.4 (23.5-32.5) 294 (216-328) 1498 

6–11 years 37.5 (26.3-53.4) 3.78 (1.64-6.00) 42.6 (22.7-63.5) 432 (220-671) 226 

12–19 years 32.4 (26.6-39.4) 3.80 (2.50-5.40) 34.2 (27.7-41.1) 314 (216-367) 543 

20–39 years 30.7 (22.8-41.3) 4.50 (3.40-5.70) 25.8 (18.5-37.5) 302 (201-427) 301 

40–59 years 24.8 (19.7-31.1) 3.60 (2.08-5.62) 25.7 (18.5-34.4) 168 (106-286) 221 

60 years and older 20.3 (16.5-25.0) 2.48 (1.06-4.07) 19.0 (13.7-31.1) 190 (113-489) 207 

Males 

Total, 6 years and older 33.6 (26.0-43.4) 4.28 (3.10-5.40) 31.6 (24.1-45.0) 324 (294-432) 724 

6–11 years 37.7 (23.6-60.3) 3.30 (1.40-7.80) 42.8 (22.4-63.5) 341 (172-830) 117 

12–19 years 34.0 (26.5-43.7) 3.67 (2.09-5.70) 39.7 (26.4-54.2) 324 (216-373) 276 

20–39 years 37.3 (23.9-58.2) 4.50 (2.70-7.05) 32.3 (19.1-72.9) 406 (244-514) 127 

40–59 years 28.7 (20.9-39.4) 4.40† (2.80-8.30) 29.0 (19.5-38.9) 205† (97.3-540) 105 

60 years and older 19.1 (12.5-29.4) 2.48† (<LOD-6.30) 16.9 (11.2-31.1) 125† (57.0-614) 99 

Females 

Total, 6 years and older 26.0 (23.0-29.4) 3.80 (3.18-4.38) 24.4 (20.7-26.9) 220 (193-309) 774 

6–11 years 37.2 (23.9-57.8) 4.60† (<LOD-7.20) 27.4 (19.3-84.7) 523† (220-813) 109 

12–19 years 30.6 (23.4-40.1) 3.94 (2.00-6.11) 30.2 (25.0-38.1) 267 (166-492) 267 

20–39 years 24.3 (19.0-31.2) 4.32 (3.18-6.30) 20.0 (14.6-26.9) 215 (125-349) 174 

40–59 years 21.3 (15.8-28.6) 2.95 (<LOD-5.62) 24.2 (17.0-34.4) 146 (87.3-286) 116 

60 years and older 21.4 (14.9-30.6) 1.90† (<LOD-3.80) 23.5 (10.9-38.9) 213† (128-489) 108 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

114 114 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.1.c. Urinary genistein: Non-Hispanic blacks 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic blacks in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 31.5 (25.2-39.3) 3.73 (2.40-5.00) 33.2 (26.8-41.5) 328 (237-393) 1289 

6–11 years 42.3 (32.8-54.4) 4.70 (3.50-6.90) 43.7 (32.4-58.0) 417 (272-600) 249 

12–19 years 46.7 (37.7-57.9) 7.20 (5.84-10.0) 39.5 (34.4-48.0) 378 (306-467) 451 

20–39 years 31.7 (22.9-43.8) 3.70 (1.60-6.30) 34.9 (25.4-49.1) 301 (164-474) 197 

40–59 years 24.3 (16.3-36.4) 1.90 (<LOD-5.20) 27.9 (18.5-39.7) 246 (114-402) 210 

60 years and older 24.6 (16.8-36.0) 2.79 (1.20-5.40) 23.7 (15.4-34.7) 228 (137-641) 182 

Males 

Total, 6 years and older 33.5 (24.7-45.6) 4.60 (2.30-7.21) 36.9 (28.8-49.1) 257 (178-388) 628 

6–11 years 45.0 (31.5-64.5) 4.96 (3.33-7.05) 49.6 (34.6-73.9) 387 (205-687) 127 

12–19 years 45.8 (36.6-57.4) 7.00 (4.72-10.2) 43.0 (34.6-56.7) 334 (227-445) 212 

20–39 years 30.2 (18.1-50.6) 3.80† (<LOD-8.30) 41.5 (24.0-57.2) 252† (104-513) 91 

40–59 years 26.7 (16.3-44.0) 3.70† (<LOD-10.0) 30.1 (16.6-50.4) 178† (87.4-367) 109 

60 years and older 33.2 (18.3-60.1) 4.70† (<LOD-7.96) 30.3 (15.9-58.6) 276† (108-1120) 89 

Females 

Total, 6 years and older 29.8 (24.0-37.1) 3.00 (2.10-4.40) 30.3 (23.3-38.2) 363 (245-472) 661 

6–11 years 39.4 (29.0-53.6) 4.74 (1.70-9.70) 34.5 (24.7-50.8) 432 (203-600) 122 

12–19 years 47.7 (35.9-63.4) 7.54 (5.90-11.2) 37.4 (29.6-47.6) 394 (233-717) 239 

20–39 years 32.8 (22.5-47.8) 2.99† (<LOD-8.40) 34.4 (21.0-50.7) 346† (161-577) 106 

40–59 years 22.4 (14.0-35.9) 1.50† (<LOD-4.40) 23.3 (17.1-38.6) 285† (106-495) 101 

60 years and older 20.2 (13.1-31.1) 2.30† (<LOD-5.42) 17.4 (10.6-33.3) 228† (105-641) 93 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 5.1.d. Urinary genistein: Non-Hispanic whites 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic whites in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 27.1 (24.2-30.4) 2.96 (2.40-3.91) 26.5 (23.9-29.5) 281 (238-330) 2112 

6–11 years 31.3 (25.2-38.9) 6.40 (4.20-8.15) 28.4 (22.4-37.3) 217 (155-272) 196 

12–19 years 36.4 (29.3-45.3) 5.10 (3.30-9.70) 33.3 (27.9-41.0) 257 (209-331) 375 

20–39 years 30.5 (24.0-38.7) 2.80 (1.92-4.86) 27.9 (23.7-34.0) 387 (254-537) 529 

40–59 years 23.9 (18.6-30.6) 2.14 (<LOD-3.40) 24.3 (19.7-29.5) 335 (214-466) 434 

60 years and older 22.2 (19.0-26.0) 2.74 (1.71-3.98) 22.5 (18.7-27.9) 182 (129-282) 578 

Males 

Total, 6 years and older 30.6 (26.1-35.9) 3.90 (2.80-5.60) 29.5 (26.5-33.1) 293 (226-371) 1038 

6–11 years 31.0 (22.9-42.0) 6.20† (3.10-8.15) 32.9 (20.6-48.3) 190† (104-257) 101 

12–19 years 33.2 (22.9-48.1) 5.09 (2.20-11.5) 28.3 (22.8-38.8) 238 (141-371) 190 

20–39 years 32.2 (23.7-43.8) 2.90 (1.90-5.91) 27.9 (23.7-34.3) 413 (229-734) 231 

40–59 years 29.1 (21.7-39.1) 3.42 (1.32-5.85) 28.7 (21.7-38.7) 298 (195-447) 225 

60 years and older 28.9 (23.0-36.4) 4.17 (3.10-6.00) 29.8 (21.9-36.7) 229 (129-335) 291 

Females 

Total, 6 years and older 24.1 (21.6-27.0) 2.59 (1.50-3.20) 23.7 (20.9-26.1) 268 (226-353) 1074 

6–11 years 31.7 (21.7-46.3) 6.89† (3.51-10.2) 26.7 (17.3-37.9) 256† (131-500) 95 

12–19 years 40.4 (33.6-48.6) 5.10 (3.51-9.13) 37.8 (29.0-53.2) 305 (212-446) 185 

20–39 years 28.9 (21.6-38.8) 2.59 (1.40-4.90) 27.0 (18.7-39.0) 330 (206-626) 298 

40–59 years 19.6 (14.5-26.6) .960 (<LOD-2.87) 18.7 (14.3-24.9) 355 (174-627) 209 

60 years and older 18.1 (14.8-22.1) 2.20 (1.00-3.75) 18.4 (14.1-24.3) 136 (118-202) 287 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 115
Table 5.1.e. Urinary genistein: Total population (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for the total U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 26.6 (23.7-29.8) 3.78 (3.08-4.46) 24.8 (22.5-27.6) 242 (209-274) 5351 

6–11 years 36.7 (31.1-43.4) 6.94 (5.22-8.13) 34.9 (27.6-41.3) 243 (186-292) 727 

12–19 years 27.5 (23.3-32.4) 4.36 (3.68-5.09) 24.4 (20.9-30.8) 192 (153-258) 1498 

20–39 years 25.1 (21.5-29.2) 3.77 (2.96-4.59) 22.8 (19.1-26.3) 244 (202-318) 1140 

40–59 years 23.8 (19.3-29.3) 2.48 (1.17-4.08) 22.3 (18.5-28.7) 270 (196-335) 951 

60 years and older 28.9 (25.4-33.0) 4.48 (3.17-5.31) 26.6 (22.4-32.3) 222 (175-285) 1035 

Males 

Total, 6 years and older 25.0 (21.4-29.3) 4.02 (3.25-4.74) 23.0 (19.8-26.8) 203 (177-265) 2597 

6–11 years 36.5 (28.4-46.8) 6.65 (4.52-8.13) 35.4 (27.1-50.3) 200 (154-286) 368 

12–19 years 25.8 (20.4-32.5) 4.23 (3.54-5.09) 22.2 (18.6-31.7) 164 (115-264) 736 

20–39 years 23.3 (18.4-29.4) 4.01 (1.99-5.04) 19.0 (15.6-24.7) 227 (170-330) 500 

40–59 years 22.0 (16.1-30.0) 3.21 (1.36-4.87) 21.0 (16.1-30.9) 222 (167-334) 480 

60 years and older 28.0 (23.6-33.2) 4.74 (3.44-6.19) 27.1 (22.2-33.1) 177 (143-324) 513 

Females 

Total, 6 years and older 28.1 (25.3-31.3) 3.50 (2.95-4.23) 26.6 (23.8-29.7) 265 (230-308) 2754 

6–11 years 37.0 (28.2-48.6) 7.69 (4.92-9.64) 30.9 (21.9-47.9) 255 (182-488) 359 

12–19 years 29.3 (24.9-34.6) 4.65 (3.09-6.00) 28.2 (23.2-33.2) 216 (162-304) 762 

20–39 years 27.0 (22.4-32.5) 3.32 (3.01-4.41) 25.8 (21.1-30.3) 265 (192-349) 640 

40–59 years 25.6 (21.2-30.8) 2.23 (<LOD-3.81) 24.7 (17.6-36.0) 287 (230-381) 471 

60 years and older 29.7 (24.8-35.5) 4.27 (2.52-5.68) 26.6 (21.6-35.0) 252 (191-319) 522 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

Table 5.1.f. Urinary genistein: Mexican Americans (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for Mexican Americans 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 27.6 (24.1-31.6) 3.85 (3.35-4.65) 24.5 (19.7-30.0) 243 (208-279) 1498 

6–11 years 48.0 (37.4-61.6) 5.98 (3.95-8.12) 42.4 (31.7-62.9) 601 (317-717) 226 

12–19 years 25.5 (21.4-30.4) 3.42 (2.96-4.23) 24.6 (19.7-31.7) 188 (165-254) 543 

20–39 years 25.3 (19.5-32.9) 3.79 (3.16-5.11) 19.1 (14.8-32.6) 215 (181-257) 301 

40–59 years 24.8 (19.9-31.0) 4.01 (2.88-5.44) 25.6 (18.6-32.8) 176 (124-279) 221 

60 years and older 23.4 (18.4-29.6) 3.49 (1.13-5.08) 22.1 (15.8-35.0) 216 (142-329) 207 

Males 

Total, 6 years and older 27.7 (22.5-34.1) 4.01 (3.10-5.17) 25.7 (18.7-34.9) 228 (190-285) 724 

6–11 years 45.3 (30.6-66.9) 4.29 (2.85-9.69) 40.7 (29.1-66.8) 627 (206-776) 117 

12–19 years 25.6 (20.3-32.3) 3.62 (2.22-4.66) 24.7 (18.3-40.4) 185 (165-270) 276 

20–39 years 27.5 (18.7-40.3) 3.99 (2.72-5.71) 19.8 (13.5-41.2) 226 (180-323) 127 

40–59 years 24.1 (17.7-32.8) 4.91† (3.21-6.44) 25.6 (14.8-34.3) 159† (96.9-335) 105 

60 years and older 18.0 (12.2-26.6) 3.05† (<LOD-5.74) 18.5 (10.8-32.4) 135† (50.5-292) 99 

Females 

Total, 6 years and older 27.5 (24.0-31.4) 3.72 (3.27-4.42) 23.8 (19.2-26.2) 253 (195-324) 774 

6–11 years 51.0 (37.5-69.4) 7.40† (<LOD-9.57) 44.0 (25.1-94.3) 537† (253-926) 109 

12–19 years 25.5 (19.4-33.4) 3.42 (2.71-4.65) 24.5 (16.1-36.3) 195 (131-313) 267 

20–39 years 23.0 (18.2-29.1) 3.60 (3.20-4.61) 16.8 (13.8-25.5) 205 (119-325) 174 

40–59 years 25.6 (19.8-33.2) 3.17 (<LOD-5.96) 24.4 (17.5-33.6) 219 (121-324) 116 

60 years and older 29.0 (19.9-42.2) 3.50† (<LOD-11.2) 27.9 (14.7-59.2) 237† (142-408) 108 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

116 116 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.1.g. Urinary genistein: Non-Hispanic blacks (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic blacks 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 21.2 (17.0-26.4) 3.24 (2.52-4.26) 21.1 (17.2-26.1) 192 (154-239) 1289 

6–11 years 39.5 (31.0-50.4) 5.59 (3.92-9.81) 38.5 (28.9-51.2) 279 (203-409) 249 

12–19 years 26.2 (21.4-32.1) 4.25 (3.54-5.18) 24.9 (20.0-30.8) 224 (138-351) 451 

20–39 years 18.0 (12.8-25.3) 2.82 (.344-4.26) 19.0 (13.4-25.6) 186 (95.1-281) 197 

40–59 years 16.4 (11.4-23.7) 2.56 (<LOD-4.68) 16.4 (11.5-23.7) 152 (101-217) 210 

60 years and older 23.1 (17.0-31.5) 4.13 (2.22-5.31) 20.9 (14.9-30.9) 178 (106-384) 182 

Males 

Total, 6 years and older 20.3 (15.1-27.3) 3.24 (1.99-4.68) 20.7 (16.4-28.5) 162 (109-222) 628 

6–11 years 41.8 (29.2-59.7) 5.47 (3.10-12.9) 41.3 (28.5-71.2) 274 (165-450) 127 

12–19 years 25.0 (20.1-31.0) 3.12 (1.84-5.01) 26.1 (20.0-34.8) 176 (114-260) 212 

20–39 years 14.7 (8.72-24.7) 2.82† (<LOD-5.12) 17.2 (10.1-25.6) 103† (53.9-191) 91 

40–59 years 16.3 (10.0-26.5) 2.56† (<LOD-5.14) 18.7 (10.4-30.4) 112† (49.6-236) 109 

60 years and older 24.7 (14.3-42.4) 4.86† (<LOD-7.14) 20.4 (14.7-32.8) 322† (74.5-783) 89 

Females 

Total, 6 years and older 22.1 (17.9-27.1) 3.33 (2.58-4.15) 21.6 (16.5-26.9) 224 (159-317) 661 

6–11 years 37.3 (28.2-49.4) 5.59 (2.77-9.59) 31.6 (21.3-54.0) 344 (185-462) 122 

12–19 years 27.6 (21.0-36.2) 5.14 (4.13-6.43) 22.9 (16.6-32.3) 261 (130-460) 239 

20–39 years 21.2 (14.5-31.1) 3.01† (<LOD-5.56) 23.3 (13.5-30.3) 247† (140-415) 106 

40–59 years 16.5 (10.9-25.0) 2.22† (<LOD-4.89) 14.3 (10.6-25.0) 154† (109-247) 101 

60 years and older 22.1 (15.5-31.6) 3.95† (<LOD-5.45) 20.0 (13.1-33.8) 178† (90.2-446) 93 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 5.1.h. Urinary genistein: Non-Hispanic whites (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic whites 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 27.0 (24.1-30.2) 3.80 (2.98-4.66) 25.6 (22.7-28.8) 242 (207-284) 2112 

6–11 years 34.0 (26.7-43.3) 7.20 (4.92-10.4) 31.7 (23.3-40.8) 186 (145-279) 196 

12–19 years 27.6 (22.0-34.7) 4.76 (2.77-6.72) 24.1 (20.6-33.0) 166 (130-232) 375 

20–39 years 26.6 (21.7-32.5) 3.89 (2.96-4.86) 24.4 (17.5-31.5) 268 (208-348) 529 

40–59 years 25.0 (19.6-31.9) 2.47 (<LOD-4.07) 24.2 (18.1-33.2) 287 (204-367) 434 

60 years and older 27.7 (24.4-31.4) 4.63 (2.98-6.09) 26.0 (21.9-32.0) 185 (150-274) 578 

Males 

Total, 6 years and older 25.9 (22.1-30.4) 4.35 (3.66-5.13) 24.6 (20.6-29.3) 196 (169-284) 1038 

6–11 years 34.1 (24.7-47.1) 6.08† (2.28-11.9) 35.3 (18.9-60.1) 168† (115-279) 101 

12–19 years 25.2 (17.9-35.5) 4.35 (2.76-6.73) 21.0 (17.0-29.6) 124 (95.4-264) 190 

20–39 years 24.5 (18.3-32.7) 4.48 (1.42-5.71) 19.5 (14.8-28.4) 246 (170-365) 231 

40–59 years 24.5 (17.9-33.5) 3.32 (1.55-5.13) 22.0 (16.3-35.8) 271 (167-379) 225 

60 years and older 27.6 (23.4-32.7) 4.85 (3.73-6.59) 26.8 (20.5-34.3) 170 (111-285) 291 

Females 

Total, 6 years and older 28.1 (25.0-31.6) 3.16 (2.45-4.27) 26.6 (22.5-31.3) 274 (230-323) 1074 

6–11 years 33.9 (22.4-51.4) 7.69† (4.25-11.6) 27.6 (17.4-41.1) 200† (140-571) 95 

12–19 years 30.5 (24.3-38.4) 4.74 (2.59-7.08) 29.8 (21.7-40.1) 203 (141-304) 185 

20–39 years 28.8 (22.6-36.7) 3.20 (2.63-4.86) 27.0 (19.6-37.3) 283 (206-357) 298 

40–59 years 25.5 (19.2-34.0) 1.62 (<LOD-4.07) 24.2 (15.6-40.4) 323 (220-480) 209 

60 years and older 27.8 (22.5-34.2) 4.27 (2.00-6.44) 25.9 (19.9-35.0) 222 (155-319) 287 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 117
Table 5.2.a. Urinary daidzein: Total population 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for the total U.S. population aged 

6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 61.0 (55.2-67.3) 6.75 (5.68-8.00) 59.2 (54.0-66.6) 545 (491-642) 5347 

6–11 years 88.1 (78.0-99.4) 15.6 (13.0-19.7) 80.2 (68.2-108) 544 (446-726) 726 

12–19 years 89.7 (73.2-110) 10.9 (7.50-16.5) 87.5 (74.3-103) 786 (569-1090) 1497 

20–39 years 63.7 (55.6-73.1) 6.59 (5.20-8.10) 57.3 (49.9-70.6) 590 (494-781) 1138 

40–59 years 52.3 (43.4-63.1) 5.62 (2.90-7.81) 53.9 (44.2-63.0) 505 (397-725) 951 

60 years and older 44.8 (38.9-51.6) 4.80 (2.00-6.70) 44.6 (38.7-54.2) 394 (300-519) 1035 

Males 

Total, 6 years and older 64.8 (57.2-73.4) 7.29 (5.62-9.40) 63.0 (57.2-70.9) 542 (470-694) 2595 

6–11 years 95.6 (77.5-118) 19.1 (14.4-20.3) 83.6 (56.3-139) 544 (443-745) 368 

12–19 years 87.4 (65.2-117) 12.0 (6.72-18.7) 87.5 (71.0-118) 660 (445-1100) 735 

20–39 years 64.4 (53.6-77.3) 6.50 (4.00-11.4) 57.0 (48.2-69.8) 663 (494-935) 499 

40–59 years 54.8 (43.2-69.4) 5.70 (3.50-7.81) 58.1 (49.5-68.4) 467 (332-774) 480 

60 years and older 54.2 (44.6-65.9) 4.89 (2.60-8.70) 57.9 (43.3-78.7) 414 (300-576) 513 

Females 

Total, 6 years and older 57.5 (51.9-63.7) 6.41 (5.00-8.00) 56.0 (49.3-62.0) 553 (459-702) 2752 

6–11 years 80.7 (66.0-98.8) 13.7 (11.3-19.7) 76.6 (62.3-106) 524 (390-989) 358 

12–19 years 92.1 (75.4-112) 10.4 (6.10-16.5) 89.7 (70.2-115) 922 (642-1330) 762 

20–39 years 63.1 (51.3-77.7) 7.18 (4.70-8.40) 58.1 (48.2-79.2) 517 (411-987) 639 

40–59 years 50.2 (40.5-62.1) 4.40 (1.86-8.22) 46.1 (37.8-61.0) 591 (364-1220) 471 

60 years and older 38.7 (32.8-45.7) 4.40 (1.80-6.97) 37.4 (32.0-43.6) 356 (280-461) 522 

Table 5.2.b. Urinary daidzein: Mexican Americans 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for Mexican Americans in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 55.9 (45.6-68.6) 5.10 (2.41-6.76) 52.5 (43.8-67.4) 618 (513-824) 1495 

6–11 years 81.7 (56.7-118) 10.2 (4.39-14.0) 74.5 (43.4-123) 866 (534-1240) 225 

12–19 years 71.6 (61.0-84.1) 8.50 (6.30-11.4) 74.6 (56.5-98.5) 595 (475-915) 543 

20–39 years 51.9 (36.3-74.2) 3.50 (<LOD-6.82) 47.1 (29.7-68.6) 585 (406-931) 299 

40–59 years 46.8 (35.3-62.2) 3.20 (<LOD-6.90) 53.9 (35.8-71.4) 584 (297-980) 221 

60 years and older 35.1 (24.7-49.8) 1.96 (<LOD-7.99) 36.3 (27.1-47.3) 366 (182-635) 207 

Males 

Total, 6 years and older 62.7 (45.6-86.2) 5.20 (1.80-8.41) 62.9 (45.8-85.0) 745 (515-994) 723 

6–11 years 91.4 (61.1-137) 12.7 (4.37-26.6) 84.3 (50.0-123) 896 (505-1240) 117 

12–19 years 74.9 (57.6-97.4) 7.50 (4.33-11.7) 81.0 (55.8-117) 664 (498-1100) 276 

20–39 years 61.9 (37.0-104) 2.40 (<LOD-9.60) 57.6 (30.1-108) 706 (446-1070) 126 

40–59 years 52.5 (33.6-82.1) 5.03† (<LOD-11.2) 56.0 (33.5-92.5) 872† (331-1090) 105 

60 years and older 29.1 (16.5-51.3) < LOD† 31.6 (18.2-47.3) 284† (106-659) 99 

Females 

Total, 6 years and older 49.4 (41.1-59.4) 5.40 (1.70-7.52) 45.9 (35.7-54.0) 522 (388-682) 772 

6–11 years 72.8 (43.9-121) 6.59† (<LOD-12.5) 60.6 (29.5-195) 824† (514-1420) 108 

12–19 years 68.1 (57.5-80.8) 9.70 (6.30-11.8) 69.0 (48.5-93.2) 541 (299-1440) 267 

20–39 years 42.2 (28.9-61.6) 4.30 (<LOD-10.7) 35.4 (26.3-51.4) 450 (324-669) 173 

40–59 years 41.5 (28.4-60.6) < LOD 50.1 (26.2-71.4) 302 (213-800) 116 

60 years and older 41.0 (25.7-65.5) 2.70† (<LOD-11.2) 37.4 (22.8-76.8) 370† (170-804) 108 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

118 118 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.2.c. Urinary daidzein: Non-Hispanic blacks 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic blacks in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 76.1 (62.0-93.4) 8.10 (5.45-11.1) 88.4 (68.8-106) 628 (491-906) 1288 

6–11 years 120 (95.7-151) 12.5 (8.61-17.9) 135 (99.1-172) 1130 (628-1850) 249 

12–19 years 119 (98.9-144) 15.1 (10.6-20.4) 118 (98.1-148) 950 (660-1370) 450 

20–39 years 77.7 (56.4-107) 9.50 (3.00-12.2) 91.3 (58.1-149) 578 (363-1330) 197 

40–59 years 58.7 (40.0-86.2) 6.05 (<LOD-12.1) 66.1 (41.5-96.3) 529 (393-816) 210 

60 years and older 45.2 (29.3-69.9) 1.90 (<LOD-6.60) 44.7 (26.5-70.9) 556 (377-1140) 182 

Males 

Total, 6 years and older 78.3 (56.9-108) 8.98 (<LOD-14.2) 90.4 (65.6-122) 632 (489-1040) 627 

6–11 years 142 (104-194) 16.4 (11.3-24.2) 161 (94.9-244) 1360 (597-1850) 127 

12–19 years 123 (101-150) 14.9 (10.5-21.1) 142 (104-183) 1030 (650-1320) 211 

20–39 years 74.4 (45.4-122) 8.45† (<LOD-15.0) 86.4 (42.6-198) 582† (305-1340) 91 

40–59 years 52.3 (29.5-92.9) 5.80† (<LOD-16.4) 65.5 (31.2-117) 358† (233-594) 109 

60 years and older 55.7 (28.3-110) < LOD† 58.1 (31.0-104) 519† (377-1960) 89 

Females 

Total, 6 years and older 74.2 (61.5-89.6) 7.70 (3.61-11.3) 85.9 (66.6-103) 611 (473-856) 661 

6–11 years 100 (70.3-144) 10.0 (<LOD-26.2) 107 (79.6-152) 1130 (467-2300) 122 

12–19 years 115 (88.3-151) 15.2 (6.80-24.8) 106 (85.2-129) 805 (545-1840) 239 

20–39 years 80.4 (57.7-112) 9.50† (2.80-14.3) 98.0 (58.7-155) 465† (331-1400) 106 

40–59 years 64.8 (44.8-93.5) 5.70† (<LOD-13.6) 68.8 (37.7-101) 541† (393-1170) 101 

60 years and older 39.4 (23.9-64.8) 2.30† (<LOD-5.45) 33.9 (21.6-61.6) 560† (267-1140) 93 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 5.2.d. Urinary daidzein: Non-Hispanic whites 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic whites in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 58.4 (53.0-64.3) 6.60 (5.33-8.10) 56.2 (51.5-61.0) 505 (439-636) 2112 

6–11 years 83.8 (69.3-101) 16.5 (13.0-20.3) 76.6 (58.9-112) 443 (385-694) 196 

12–19 years 84.2 (62.7-113) 9.60 (4.93-16.9) 85.3 (68.3-119) 755 (493-1310) 375 

20–39 years 62.0 (52.1-73.8) 6.59 (4.00-9.20) 52.1 (44.3-65.5) 601 (437-987) 529 

40–59 years 54.7 (44.4-67.5) 5.70 (3.16-8.00) 54.8 (44.8-62.3) 508 (393-852) 434 

60 years and older 41.5 (35.3-48.9) 5.00 (2.00-7.70) 41.7 (36.9-50.6) 337 (235-416) 578 

Males 

Total, 6 years and older 63.4 (55.9-71.9) 7.77 (5.80-10.1) 59.0 (53.2-69.8) 505 (418-667) 1038 

6–11 years 86.4 (62.7-119) 20.2† (13.0-26.6) 77.7 (43.8-155) 470† (317-694) 101 

12–19 years 79.2 (50.9-123) 11.1 (3.70-19.2) 76.9 (53.0-121) 586 (354-1300) 190 

20–39 years 59.7 (48.0-74.3) 5.30 (2.00-12.0) 48.9 (37.3-66.9) 663 (362-1410) 231 

40–59 years 62.4 (50.6-76.9) 6.30 (5.20-10.1) 58.4 (49.8-71.1) 501 (322-838) 225 

60 years and older 53.1 (42.5-66.3) 5.20 (2.90-10.0) 57.2 (42.3-78.2) 377 (273-570) 291 

Females 

Total, 6 years and older 54.0 (48.2-60.4) 6.20 (3.63-7.77) 52.0 (44.8-59.2) 505 (432-705) 1074 

6–11 years 81.0 (59.0-111) 13.7† (11.6-22.0) 76.6 (58.9-121) 466† (284-1130) 95 

12–19 years 90.3 (67.4-121) 9.30 (3.80-18.9) 90.5 (68.3-140) 922 (566-1410) 185 

20–39 years 64.3 (49.0-84.4) 6.70 (3.63-9.30) 56.2 (43.1-79.2) 530 (369-1300) 298 

40–59 years 48.1 (35.4-65.4) 3.16 (<LOD-10.1) 45.0 (35.4-64.2) 638 (220-1370) 209 

60 years and older 34.3 (27.8-42.3) 3.60 (<LOD-7.08) 34.6 (28.5-41.1) 262 (190-398) 287 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 119
Table 5.2.e. Urinary daidzein: Total population (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for the total U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 56.9 (51.4-63.0) 6.67 (5.54-8.00) 56.3 (50.0-64.0) 536 (460-600) 5347 

6–11 years 95.6 (83.2-110) 18.4 (14.3-21.2) 88.9 (73.4-112) 635 (494-733) 726 

12–19 years 64.8 (52.3-80.3) 8.03 (5.73-10.4) 63.4 (50.0-86.2) 600 (402-797) 1497 

20–39 years 51.1 (44.8-58.3) 5.91 (4.85-7.32) 48.8 (41.2-57.7) 523 (390-624) 1138 

40–59 years 52.6 (43.7-63.2) 5.54 (3.58-7.49) 51.0 (43.3-65.4) 535 (391-689) 951 

60 years and older 53.7 (46.4-62.1) 6.01 (3.90-8.62) 55.5 (43.5-71.3) 389 (308-555) 1035 

Males 

Total, 6 years and older 52.1 (45.8-59.3) 5.96 (5.05-7.39) 51.0 (45.2-59.7) 497 (373-601) 2595 

6–11 years 101 (80.4-127) 22.7 (14.5-30.1) 88.8 (58.6-143) 553 (447-733) 368 

12–19 years 62.0 (47.2-81.5) 9.03 (6.10-10.4) 61.6 (48.6-85.6) 547 (301-921) 735 

20–39 years 44.8 (36.8-54.7) 5.36 (3.66-7.20) 41.2 (33.1-47.9) 497 (268-847) 499 

40–59 years 45.5 (35.9-57.6) 5.05 (3.28-7.38) 45.2 (32.0-65.0) 478 (263-693) 480 

60 years and older 50.9 (41.8-62.0) 4.52 (3.09-7.91) 61.8 (44.2-81.0) 363 (255-659) 513 

Females 

Total, 6 years and older 61.9 (55.4-69.1) 7.18 (5.91-9.10) 61.0 (53.3-70.4) 564 (468-628) 2752 

6–11 years 90.3 (72.6-112) 14.9 (11.9-19.0) 86.3 (70.8-112) 668 (414-838) 358 

12–19 years 67.9 (54.6-84.3) 6.80 (5.25-9.92) 65.1 (48.1-91.9) 628 (478-742) 762 

20–39 years 58.1 (47.6-70.9) 6.74 (3.67-9.55) 56.2 (45.0-78.2) 571 (370-783) 639 

40–59 years 60.3 (48.0-75.8) 6.58 (3.42-9.23) 62.4 (43.2-75.6) 564 (387-950) 471 

60 years and older 56.0 (47.2-66.3) 6.52 (4.52-11.4) 50.9 (39.3-64.8) 451 (312-560) 522 

Table 5.2.f. Urinary daidzein: Mexican Americans (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for Mexican Americans 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 52.0 (43.7-61.9) 4.81 (3.32-7.03) 48.7 (38.2-65.0) 546 (460-645) 1495 

6–11 years 105 (81.0-136) 11.9 (8.98-17.4) 91.1 (65.5-149) 957 (715-1660) 225 

12–19 years 56.5 (47.8-66.8) 7.20 (5.28-9.29) 58.1 (45.6-71.6) 511 (358-684) 543 

20–39 years 43.0 (31.3-59.0) 3.88 (<LOD-6.82) 35.3 (23.2-57.9) 486 (307-608) 299 

40–59 years 46.9 (35.3-62.4) 3.22 (<LOD-6.50) 47.5 (36.0-67.3) 483 (303-708) 221 

60 years and older 40.3 (28.2-57.8) 3.97 (<LOD-8.56) 41.0 (27.1-73.4) 343 (223-638) 207 

Males 

Total, 6 years and older 51.8 (39.5-68.0) 4.77 (2.90-7.95) 51.0 (38.2-72.0) 585 (471-708) 723 

6–11 years 110 (79.0-152) 14.8 (10.2-24.5) 91.1 (57.4-149) 957 (596-1140) 117 

12–19 years 56.4 (43.0-73.9) 5.65 (3.59-9.03) 64.9 (39.8-90.0) 614 (358-837) 276 

20–39 years 45.8 (28.9-72.6) 3.90 (<LOD-7.95) 40.6 (21.8-91.4) 495 (307-641) 126 

40–59 years 44.2 (27.9-69.9) 3.31† (<LOD-9.43) 45.9 (32.2-68.7) 542† (198-1020) 105 

60 years and older 27.4 (15.6-48.1) < LOD† 35.5 (15.0-63.9) 201† (141-458) 99 

Females 

Total, 6 years and older 52.2 (44.0-62.0) 4.81 (3.00-8.02) 43.5 (34.1-65.5) 495 (384-600) 772 

6–11 years 100 (70.6-142) 8.61† (<LOD-15.7) 103 (55.2-201) 1080† (649-2300) 108 

12–19 years 56.6 (47.1-68.0) 8.23 (5.38-9.99) 51.2 (36.9-65.0) 399 (266-684) 267 

20–39 years 39.9 (27.9-57.0) 3.50 (<LOD-10.4) 30.6 (22.1-66.4) 384 (271-517) 173 

40–59 years 50.1 (36.0-69.6) < LOD 49.8 (27.9-102) 474 (245-708) 116 

60 years and older 55.6 (35.9-86.1) 8.02† (<LOD-12.3) 54.0 (28.9-89.9) 479† (258-984) 108 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

120 120 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.2.g. Urinary daidzein: Non-Hispanic blacks (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic blacks 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 51.3 (42.1-62.4) 5.54 (3.95-7.05) 57.1 (46.5-70.5) 447 (306-599) 1288 

6–11 years 113 (91.3-139) 15.4 (10.2-21.8) 109 (83.6-145) 955 (683-1280) 249 

12–19 years 67.0 (56.1-80.1) 9.23 (6.59-10.9) 75.7 (54.8-93.7) 561 (317-975) 450 

20–39 years 44.2 (32.2-60.8) 5.07 (2.92-7.58) 52.1 (38.4-71.7) 348 (207-541) 197 

40–59 years 39.6 (28.3-55.4) 3.95 (<LOD-7.27) 46.5 (26.5-64.1) 272 (215-446) 210 

60 years and older 42.5 (29.7-60.7) 2.34 (<LOD-8.65) 40.4 (27.2-79.3) 488 (249-721) 182 

Males 

Total, 6 years and older 47.3 (34.8-64.3) 5.07 (<LOD-8.50) 54.1 (40.2-70.2) 472 (297-600) 627 

6–11 years 132 (96.4-180) 17.7 (9.66-30.8) 151 (80.0-229) 1050 (661-1300) 127 

12–19 years 67.3 (55.8-81.2) 9.03 (4.93-11.3) 80.8 (61.6-106) 499 (370-650) 211 

20–39 years 36.1 (22.5-57.7) 5.17† (<LOD-8.50) 41.2 (24.5-70.2) 249† (162-541) 91 

40–59 years 31.9 (18.4-55.2) 1.76† (<LOD-10.2) 38.4 (20.4-64.8) 258† (117-696) 109 

60 years and older 41.4 (22.1-77.7) < LOD† 36.0 (23.1-92.3) 562† (214-1370) 89 

Females 

Total, 6 years and older 54.9 (46.3-65.0) 6.20 (3.75-8.65) 62.2 (48.7-77.1) 430 (302-639) 661 

6–11 years 95.0 (71.7-126) 11.9 (<LOD-20.6) 86.3 (69.7-129) 773 (381-1640) 122 

12–19 years 66.7 (51.9-85.8) 9.35 (5.68-12.5) 72.7 (42.1-91.2) 622 (251-1160) 239 

20–39 years 51.9 (37.2-72.6) 4.86† (2.92-7.58) 64.6 (47.0-92.1) 372† (207-639) 106 

40–59 years 47.6 (35.3-64.2) 6.58† (<LOD-11.1) 48.4 (29.1-70.8) 302† (215-802) 101 

60 years and older 43.2 (28.0-66.6) 2.31† (<LOD-10.0) 44.0 (24.3-85.9) 463† (248-828) 93 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 5.2.h. Urinary daidzein: Non-Hispanic whites (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic whites 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 58.1 (52.9-64.0) 6.90 (5.66-9.03) 57.8 (51.0-64.2) 506 (413-601) 2112 

6–11 years 90.9 (75.0-110) 19.0 (14.3-25.4) 88.3 (70.8-112) 494 (324-710) 196 

12–19 years 63.8 (46.5-87.6) 7.18 (4.27-12.2) 63.6 (44.8-96.2) 601 (386-987) 375 

20–39 years 54.0 (47.0-62.1) 6.52 (4.85-8.83) 49.8 (39.7-60.4) 579 (384-847) 529 

40–59 years 57.4 (47.5-69.3) 6.54 (4.23-9.94) 59.0 (44.1-70.2) 548 (377-807) 434 

60 years and older 51.8 (44.0-61.0) 6.01 (3.86-8.87) 53.4 (41.3-69.6) 318 (260-475) 578 

Males 

Total, 6 years and older 53.7 (47.4-60.7) 6.62 (5.39-8.80) 54.1 (45.5-63.3) 464 (336-586) 1038 

6–11 years 95.0 (70.0-129) 24.9† (14.1-31.9) 88.3 (56.2-152) 425† (302-710) 101 

12–19 years 60.2 (39.6-91.4) 9.03 (4.43-12.7) 58.5 (41.9-92.6) 463 (217-1030) 190 

20–39 years 45.4 (36.2-56.9) 5.50 (2.82-8.07) 40.4 (29.1-54.6) 497 (248-850) 231 

40–59 years 52.5 (43.0-64.0) 6.03 (4.60-9.94) 47.0 (34.5-71.5) 502 (276-723) 225 

60 years and older 50.7 (40.7-63.3) 5.14 (3.40-8.87) 61.7 (45.4-80.0) 313 (215-555) 291 

Females 

Total, 6 years and older 62.8 (55.9-70.5) 7.48 (5.49-10.5) 60.8 (52.8-70.4) 564 (423-655) 1074 

6–11 years 86.6 (62.6-120) 16.5† (11.1-21.2) 86.6 (55.2-113) 655† (275-938) 95 

12–19 years 68.2 (48.9-95.0) 6.56 (4.27-9.12) 73.4 (45.1-113) 628 (442-990) 185 

20–39 years 64.0 (51.1-80.2) 8.28 (2.74-14.0) 58.0 (44.1-88.7) 607 (384-852) 298 

40–59 years 62.7 (46.3-84.9) 6.79 (<LOD-12.6) 65.4 (41.0-79.9) 564 (356-1220) 209 

60 years and older 52.6 (42.5-65.1) 6.27 (<LOD-11.3) 49.2 (35.1-66.1) 316 (250-555) 287 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 121
Table 5.3.a. Urinary equol: Total population 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for the total U.S. population aged 

6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 8.77 (7.84-9.81) < LOD 8.28 (7.21-9.50) 38.5 (33.1-45.2) 4976 

6–11 years 11.5 (9.82-13.5) < LOD 13.4 (10.1-16.1) 45.9 (32.3-59.6) 668 

12–19 years 10.4 (9.08-11.9) < LOD 10.5 (8.70-12.1) 43.1 (35.6-53.1) 1401 

20–39 years 8.54 (7.40-9.86) < LOD 8.16 (6.78-9.80) 37.6 (29.5-47.4) 1043 

40–59 years 8.39 (7.24-9.73) < LOD 7.80 (6.20-9.20) 37.1 (28.7-48.7) 909 

60 years and older 7.52 (6.59-8.58) < LOD 6.68 (5.13-8.20) 34.5 (27.9-41.7) 955 

Males 

Total, 6 years and older 9.26 (8.17-10.5) < LOD 8.70 (7.63-10.3) 39.6 (32.7-48.7) 2417 

6–11 years 12.7 (10.1-16.0) < LOD 13.7 (8.95-17.2) 56.0 (38.3-78.9) 347 

12–19 years 10.5 (8.82-12.5) < LOD 10.4 (8.49-12.9) 43.1 (35.2-56.1) 690 

20–39 years 8.68 (7.39-10.2) < LOD 7.90 (6.40-9.40) 38.2 (29.5-48.9) 454 

40–59 years 8.90 (7.47-10.6) < LOD 9.20 (7.10-10.5) 34.4 (27.4-45.2) 454 

60 years and older 8.19 (6.75-9.94) < LOD 6.83 (5.30-9.68) 35.6 (29.8-46.7) 472 

Females 

Total, 6 years and older 8.33 (7.39-9.39) < LOD 7.89 (6.80-9.17) 37.6 (32.2-42.7) 2559 

6–11 years 10.3 (8.60-12.3) < LOD 12.6 (9.40-15.5) 33.5 (28.0-51.0) 321 

12–19 years 10.3 (8.87-11.9) < LOD 10.5 (8.70-12.1) 42.9 (32.1-58.7) 711 

20–39 years 8.40 (6.97-10.1) < LOD 8.60 (6.50-10.9) 37.5 (25.3-50.9) 589 

40–59 years 7.94 (6.53-9.66) < LOD 6.27 (4.70-8.04) 40.3 (28.5-56.6) 455 

60 years and older 7.04 (6.28-7.89) < LOD 6.56 (4.60-8.13) 30.5 (23.5-43.2) 483 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

Table 5.3.b. Urinary equol: Mexican Americans 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for Mexican Americans in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 6.16 (5.59-6.79) < LOD 5.20 (4.44-6.05) 25.0 (19.9-31.0) 1405 

6–11 years 7.70 (6.18-9.60) < LOD 6.51 (5.11-9.20) 29.0 (20.7-48.7) 216 

12–19 years 7.72 (6.95-8.58) < LOD 6.90 (5.70-8.10) 33.0 (25.9-44.4) 507 

20–39 years * < LOD 4.40 (<LOD-5.50) 21.1 (13.7-32.2) 276 

40–59 years 6.06 (5.00-7.34) < LOD 5.10 (4.00-6.44) 21.3 (13.4-39.9) 213 

60 years and older * < LOD 4.07 (<LOD-5.05) 16.9 (12.9-22.8) 193 

Males 

Total, 6 years and older 6.25 (5.48-7.14) < LOD 5.18 (4.20-6.50) 26.2 (19.1-32.9) 676 

6–11 years 8.16 (6.20-10.8) < LOD 8.53 (4.83-12.8) 29.5 (20.3-48.7) 112 

12–19 years 7.31 (6.40-8.35) < LOD 6.50 (5.50-7.67) 31.0 (19.7-48.6) 256 

20–39 years * < LOD 4.20 (<LOD-5.49) 20.5 (13.7-32.1) 117 

40–59 years 6.91 (5.13-9.30) < LOD† 6.50 (3.86-9.48) 22.1† (14.0-42.4) 98 

60 years and older * < LOD† 4.14 (<LOD-5.51) 14.8† (9.20-22.8) 93 

Females 

Total, 6 years and older 6.07 (5.49-6.71) < LOD 5.36 (4.30-6.00) 22.3 (19.1-29.0) 729 

6–11 years 7.25 (5.56-9.44) < LOD† 6.30 (4.96-8.20) 28.6† (18.8-76.3) 104 

12–19 years 8.20 (7.23-9.30) < LOD 7.56 (5.84-8.90) 37.2 (21.3-56.4) 251 

20–39 years 5.51 (4.44-6.85) < LOD 4.99 (3.30-6.60) 16.9 (12.3-35.4) 159 

40–59 years 5.32 (4.29-6.59) < LOD 4.50 (3.50-5.42) 17.3 (10.1-32.7) 115 

60 years and older * < LOD† 3.88 (<LOD-6.08) 19.0† (8.30-160) 100 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

* Not calculated. Proportion of results below limit of detection was too high to provide a valid result. 

122 122 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.3.c. Urinary equol: Non-Hispanic blacks 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic blacks in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 6.89 (6.04-7.86) < LOD 6.09 (4.86-7.50) 28.8 (23.3-34.4) 1196 

6–11 years 8.83 (7.19-10.8) < LOD 9.90 (5.70-13.6) 31.0 (23.5-44.0) 223 

12–19 years 9.45 (8.03-11.1) < LOD 9.90 (7.77-12.0) 40.4 (29.9-51.0) 424 

20–39 years 6.93 (5.62-8.55) < LOD 5.90 (4.40-7.80) 29.6 (21.4-41.4) 178 

40–59 years 6.12 (5.16-7.26) < LOD 5.00 (3.60-7.43) 24.4 (19.4-30.2) 199 

60 years and older * < LOD < LOD 18.9 (11.6-27.6) 172 

Males 

Total, 6 years and older 7.68 (6.62-8.92) < LOD 6.90 (5.10-8.50) 31.4 (26.1-39.8) 588 

6–11 years 9.56 (7.44-12.3) < LOD 9.90 (5.49-13.6) 34.4 (30.2-79.5) 120 

12–19 years 9.68 (7.99-11.7) < LOD 10.6 (6.90-13.6) 40.8 (28.4-51.6) 201 

20–39 years 7.64 (5.88-9.92) < LOD† 5.47 (4.20-9.71) 35.6† (21.5-89.9) 80 

40–59 years 7.30 (6.02-8.84) < LOD† 7.40 (5.05-9.00) 26.0† (19.8-35.3) 104 

60 years and older * < LOD† < LOD 18.9† (7.60-32.0) 83 

Females 

Total, 6 years and older 6.28 (5.36-7.36) < LOD 5.44 (3.70-7.13) 26.2 (18.9-35.4) 608 

6–11 years 8.00 (6.05-10.6) < LOD† 9.48 (4.10-14.7) 26.2† (19.8-31.8) 103 

12–19 years 9.22 (7.50-11.3) < LOD 9.60 (7.20-11.6) 40.8 (29.9-73.4) 223 

20–39 years 6.44 (4.84-8.57) < LOD† 6.17 (3.50-8.30) 22.9† (14.3-43.4) 98 

40–59 years * < LOD† 3.80 (<LOD-6.99) 21.2† (13.4-34.1) 95 

60 years and older * < LOD† < LOD 20.7† (10.5-43.8) 89 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

* Not calculated. Proportion of results below limit of detection was too high to provide a valid result. 

Table 5.3.d. Urinary equol: Non-Hispanic whites 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic whites in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 9.62 (8.32-11.1) < LOD 9.49 (7.73-11.2) 41.3 (35.0-48.9) 1955 

6–11 years 13.7 (10.7-17.6) < LOD 15.2 (11.1-19.4) 53.3 (38.5-68.1) 179 

12–19 years 11.3 (9.28-13.7) < LOD 11.7 (9.74-13.6) 45.5 (36.9-58.8) 350 

20–39 years 9.66 (7.87-11.9) < LOD 9.80 (7.63-12.4) 39.0 (29.2-55.1) 486 

40–59 years 9.34 (7.68-11.4) < LOD 9.00 (6.50-10.8) 41.7 (31.7-60.7) 415 

60 years and older 7.92 (6.81-9.21) < LOD 7.30 (5.58-9.40) 34.5 (27.9-41.7) 525 

Males 

Total, 6 years and older 10.1 (8.58-11.8) < LOD 9.86 (8.00-12.2) 44.0 (35.1-53.8) 965 

6–11 years 14.6 (10.1-21.2) < LOD† 15.2 (8.00-26.3) 59.0† (45.9-85.4) 95 

12–19 years 11.1 (8.64-14.4) < LOD 10.9 (7.90-15.2) 48.1 (36.9-81.5) 179 

20–39 years 9.81 (7.97-12.1) < LOD 9.18 (7.60-12.3) 38.6 (29.5-57.5) 214 

40–59 years 9.51 (7.58-11.9) < LOD 9.82 (6.70-12.5) 39.7 (27.4-53.8) 213 

60 years and older 8.91 (7.00-11.3) < LOD 7.51 (5.52-12.4) 36.8 (30.1-46.7) 264 

Females 

Total, 6 years and older 9.22 (7.83-10.8) < LOD 9.00 (7.40-11.1) 39.7 (34.1-45.8) 990 

6–11 years 12.7 (9.69-16.7) < LOD† 15.1 (11.7-19.4) 36.3† (28.6-53.3) 84 

12–19 years 11.4 (9.19-14.1) < LOD 12.1 (9.90-14.1) 39.4 (25.1-61.5) 171 

20–39 years 9.51 (7.30-12.4) < LOD 10.0 (7.11-13.3) 39.0 (26.2-55.1) 272 

40–59 years 9.18 (6.95-12.1) < LOD 7.80 (5.04-9.80) 42.1 (33.3-93.9) 202 

60 years and older 7.21 (6.46-8.06) < LOD 7.26 (4.97-8.67) 28.5 (22.1-38.4) 261 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 123
Table 5.3.e. Urinary equol: Total population (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for the total U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 8.22 (7.38-9.17) < LOD 7.98 (7.07-9.04) 35.1 (30.3-39.5) 4976 

6–11 years 12.4 (10.5-14.7) < LOD 12.5 (10.3-16.0) 45.6 (33.6-62.8) 668 

12–19 years 7.68 (6.80-8.67) < LOD 7.82 (6.91-8.70) 30.3 (24.3-39.1) 1401 

20–39 years 6.90 (6.03-7.89) < LOD 6.68 (5.68-7.53) 30.3 (25.0-36.3) 1043 

40–59 years 8.40 (7.25-9.73) < LOD 7.88 (6.66-9.16) 37.3 (29.6-46.3) 909 

60 years and older 9.02 (7.98-10.2) < LOD 8.94 (7.32-10.2) 37.8 (27.8-42.4) 955 

Males 

Total, 6 years and older 7.39 (6.53-8.36) < LOD 7.38 (6.30-8.42) 31.1 (27.0-37.8) 2417 

6–11 years 13.3 (10.4-16.9) < LOD 12.7 (8.51-17.5) 48.1 (33.8-93.3) 347 

12–19 years 7.55 (6.50-8.77) < LOD 7.63 (6.45-8.89) 32.2 (25.9-45.3) 690 

20–39 years 5.95 (5.04-7.03) < LOD 5.59 (4.93-6.42) 25.0 (19.7-32.9) 454 

40–59 years 7.30 (6.20-8.59) < LOD 7.53 (6.06-8.81) 27.7 (22.4-39.5) 454 

60 years and older 7.69 (6.43-9.20) < LOD 7.36 (5.50-9.92) 27.9 (22.3-42.4) 472 

Females 

Total, 6 years and older 9.10 (8.09-10.2) < LOD 8.71 (7.60-9.84) 37.8 (32.9-42.5) 2559 

6–11 years 11.5 (9.40-14.0) < LOD 12.3 (10.3-16.3) 37.5 (29.0-50.0) 321 

12–19 years 7.82 (6.72-9.10) < LOD 8.02 (6.97-9.00) 27.0 (23.3-31.7) 711 

20–39 years 7.97 (6.78-9.36) < LOD 7.61 (6.23-9.54) 32.9 (25.6-41.3) 589 

40–59 years 9.57 (7.81-11.7) < LOD 8.63 (6.66-10.0) 46.3 (36.4-67.7) 455 

60 years and older 10.2 (9.23-11.3) < LOD 9.64 (8.27-10.6) 38.8 (27.8-44.8) 483 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

Table 5.3.f. Urinary equol: Mexican Americans (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for Mexican Americans 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 5.77 (5.28-6.31) < LOD 5.68 (4.95-6.39) 26.3 (22.3-28.8) 1405 

6–11 years 9.84 (8.15-11.9) < LOD 9.32 (7.52-11.9) 37.1 (27.6-47.8) 216 

12–19 years 6.19 (5.75-6.65) < LOD 6.02 (5.42-6.85) 23.4 (19.2-30.2) 507 

20–39 years * < LOD 4.46 (<LOD-5.96) 18.9 (15.2-23.6) 276 

40–59 years 6.12 (5.11-7.34) < LOD 5.68 (4.55-7.16) 27.6 (18.7-32.6) 213 

60 years and older * < LOD 5.16 (<LOD-7.14) 21.8 (16.2-33.3) 193 

Males 

Total, 6 years and older 5.24 (4.74-5.79) < LOD 5.05 (4.19-6.31) 21.2 (17.9-24.6) 676 

6–11 years 9.88 (7.79-12.5) < LOD 10.0 (7.61-13.4) 31.4 (22.3-46.6) 112 

12–19 years 5.60 (4.95-6.34) < LOD 5.92 (4.60-6.66) 22.8 (16.2-28.6) 256 

20–39 years * < LOD 3.66 (<LOD-5.72) 15.2 (10.7-19.9) 117 

40–59 years 5.84 (4.35-7.84) < LOD† 5.46 (3.86-7.32) 27.6† (14.9-36.3) 98 

60 years and older * < LOD† 3.76 (<LOD-5.42) 14.7† (7.75-34.2) 93 

Females 

Total, 6 years and older 6.40 (5.66-7.24) < LOD 5.99 (5.19-6.97) 29.2 (25.3-35.3) 729 

6–11 years 9.80 (7.76-12.4) < LOD† 9.00 (6.55-11.4) 43.1† (27.9-106) 104 

12–19 years 6.89 (6.07-7.82) < LOD 6.06 (5.10-7.73) 25.2 (19.1-39.0) 251 

20–39 years 5.13 (4.19-6.30) < LOD 5.17 (3.54-6.64) 24.0 (15.7-39.6) 159 

40–59 years 6.42 (4.80-8.60) < LOD 5.68 (4.55-8.65) 27.9 (18.7-41.1) 115 

60 years and older * < LOD† 6.77 (<LOD-8.26) 25.9† (16.9-51.7) 100 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

* Not calculated. Proportion of results below limit of detection was too high to provide a valid result. 

124 124 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.3.g. Urinary equol: Non-Hispanic blacks (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic blacks 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 4.68 (4.10-5.34) < LOD 4.48 (3.70-5.41) 19.1 (16.5-23.3) 1196 

6–11 years 8.21 (6.66-10.1) < LOD 8.40 (6.92-10.6) 33.6 (20.5-45.4) 223 

12–19 years 5.35 (4.55-6.28) < LOD 5.46 (4.72-6.49) 21.0 (17.2-28.1) 424 

20–39 years 4.02 (3.23-4.99) < LOD 3.56 (2.85-4.96) 15.8 (13.0-23.1) 178 

40–59 years 4.09 (3.31-5.05) < LOD 3.64 (2.99-5.00) 17.1 (11.9-22.7) 199 

60 years and older * < LOD < LOD 18.8 (12.3-25.7) 172 

Males 

Total, 6 years and older 4.66 (3.95-5.50) < LOD 4.48 (3.48-5.49) 19.5 (16.9-25.2) 588 

6–11 years 8.62 (6.68-11.1) < LOD 8.38 (6.11-12.2) 38.3 (25.6-48.1) 120 

12–19 years 5.27 (4.27-6.52) < LOD 5.49 (4.76-7.37) 20.2 (14.0-33.9) 201 

20–39 years 3.82 (2.78-5.23) < LOD† 3.47 (1.97-4.57) 15.8† (10.5-35.3) 80 

40–59 years 4.32 (3.51-5.30) < LOD† 4.07 (3.28-5.42) 17.3† (11.6-27.0) 104 

60 years and older * < LOD† < LOD 12.3† (9.13-22.5) 83 

Females 

Total, 6 years and older 4.69 (4.05-5.45) < LOD 4.48 (3.56-5.75) 18.6 (15.0-24.5) 608 

6–11 years 7.74 (5.98-10.0) < LOD† 8.63 (6.25-10.9) 26.2† (17.1-43.8) 103 

12–19 years 5.42 (4.46-6.59) < LOD 5.44 (4.15-6.94) 24.2 (17.0-32.1) 223 

20–39 years 4.18 (3.16-5.53) < LOD† 3.76 (2.72-5.93) 15.0† (12.3-23.1) 98 

40–59 years * < LOD† 3.05 (<LOD-5.74) 17.1† (9.11-38.0) 95 

60 years and older * < LOD† < LOD 21.2† (12.5-31.3) 89 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

* Not calculated. Proportion of results below limit of detection was too high to provide a valid result. 

Table 5.3.h. Urinary equol: Non-Hispanic whites (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic whites 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 9.61 (8.36-11.0) < LOD 9.30 (7.93-10.6) 38.7 (32.7-46.3) 1955 

6–11 years 14.6 (11.3-18.8) < LOD 15.1 (11.4-21.4) 51.5 (33.8-99.8) 179 

12–19 years 8.77 (7.38-10.4) < LOD 8.89 (7.38-10.2) 31.9 (25.8-47.4) 350 

20–39 years 8.46 (7.10-10.1) < LOD 8.57 (6.85-10.3) 32.9 (28.0-41.4) 486 

40–59 years 9.78 (8.16-11.7) < LOD 8.78 (7.22-10.4) 44.5 (32.3-55.9) 415 

60 years and older 9.85 (8.61-11.3) < LOD 10.0 (8.48-11.6) 38.0 (27.8-42.8) 525 

Males 

Total, 6 years and older 8.44 (7.22-9.86) < LOD 8.48 (7.07-9.94) 35.8 (28.8-43.3) 965 

6–11 years 15.9 (11.1-22.8) < LOD† 15.8 (8.10-27.0) 64.3† (37.4-120) 95 

12–19 years 8.63 (6.94-10.7) < LOD 8.51 (7.06-10.2) 37.3 (26.8-64.3) 179 

20–39 years 7.22 (5.89-8.86) < LOD 7.02 (5.59-9.20) 28.8 (20.5-37.8) 214 

40–59 years 7.97 (6.53-9.72) < LOD 7.97 (6.66-9.70) 30.2 (22.7-42.3) 213 

60 years and older 8.49 (6.91-10.4) < LOD 8.71 (5.85-12.3) 28.9 (22.3-42.8) 264 

Females 

Total, 6 years and older 10.9 (9.38-12.7) < LOD 10.2 (8.63-12.3) 41.8 (36.4-50.0) 990 

6–11 years 13.2 (9.56-18.1) < LOD† 14.7 (11.6-20.7) 43.3† (28.8-60.7) 84 

12–19 years 8.94 (7.23-11.1) < LOD 9.00 (7.33-11.5) 26.0 (21.5-41.7) 171 

20–39 years 9.92 (8.12-12.1) < LOD 9.54 (7.50-12.7) 36.4 (28.0-55.9) 272 

40–59 years 11.9 (9.14-15.5) < LOD 9.71 (7.33-12.5) 65.3 (37.7-94.0) 202 

60 years and older 11.1 (9.88-12.4) < LOD 10.3 (9.38-12.0) 41.0 (27.8-53.2) 261 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 125
Table 5.4.a. Urinary O-desmethylangolensin: Total population 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for the total U.S. population aged 

6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 4.18 (3.65-4.78) < LOD 4.00 (3.40-4.74) 98.7 (75.9-122) 5065 

6–11 years 5.97 (4.69-7.59) < LOD 6.50 (4.63-9.68) 105 (59.6-176) 683 

12–19 years 5.87 (4.59-7.50) < LOD 6.47 (4.47-8.60) 122 (99.0-152) 1411 

20–39 years 3.59 (2.91-4.43) < LOD 3.03 (2.50-4.10) 121 (70.1-189) 1085 

40–59 years 4.67 (3.64-5.98) < LOD 4.30 (3.20-5.50) 111 (66.1-160) 896 

60 years and older 2.94 (2.39-3.62) < LOD 3.01 (1.90-4.12) 63.9 (40.3-73.7) 990 

Males 

Total, 6 years and older 4.24 (3.58-5.01) < LOD 4.22 (3.50-5.29) 102 (74.2-137) 2462 

6–11 years 6.61 (4.59-9.51) < LOD 8.40 (3.96-11.3) 121 (52.7-235) 345 

12–19 years 6.19 (4.51-8.50) < LOD 7.00 (4.22-10.6) 105 (74.1-148) 690 

20–39 years 3.44 (2.53-4.66) < LOD 3.00 (2.00-4.47) 135 (53.9-259) 474 

40–59 years 4.49 (3.45-5.86) < LOD 4.50 (2.80-6.30) 108 (57.3-160) 455 

60 years and older 3.18 (2.56-3.95) < LOD 3.60 (2.43-5.57) 58.4 (36.3-85.2) 498 

Females 

Total, 6 years and older 4.12 (3.55-4.79) < LOD 3.90 (3.00-4.56) 93.3 (70.9-128) 2603 

6–11 years 5.38 (4.06-7.12) < LOD 5.10 (3.43-8.80) 88.5 (59.2-161) 338 

12–19 years 5.56 (4.09-7.55) < LOD 5.69 (3.63-7.80) 137 (85.6-195) 721 

20–39 years 3.75 (2.85-4.95) < LOD 3.11 (2.40-4.90) 94.8 (57.2-228) 611 

40–59 years 4.84 (3.43-6.82) < LOD 4.10 (2.83-5.51) 125 (64.9-233) 441 

60 years and older 2.77 (2.05-3.73) < LOD 2.40 (1.50-4.00) 68.0 (33.8-81.6) 492 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

Table 5.4.b. Urinary O-desmethylangolensin: Mexican Americans 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for Mexican Americans in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 2.43 (1.78-3.34) < LOD 1.80 (1.00-2.84) 86.0 (59.7-105) 1400 

6–11 years 3.17 (2.23-4.49) < LOD 2.84 (1.70-4.04) 61.5 (36.8-129) 212 

12–19 years 3.07 (2.35-4.01) < LOD 2.49 (1.83-3.50) 98.0 (65.2-137) 508 

20–39 years * < LOD 1.40 (<LOD-3.40) 87.8 (44.2-129) 282 

40–59 years * < LOD 1.30 (.700-3.60) 95.2 (36.5-191) 209 

60 years and older * < LOD .420 (<LOD-2.40) 25.2 (16.0-37.9) 189 

Males 

Total, 6 years and older 2.70 (1.77-4.13) < LOD 2.10 (.800-4.70) 90.9 (66.4-129) 686 

6–11 years 3.72 (2.29-6.02) < LOD† 3.75 (1.60-8.50) 60.2† (29.3-140) 111 

12–19 years 3.32 (2.53-4.36) < LOD 3.20 (2.00-5.02) 86.5 (61.0-144) 262 

20–39 years * < LOD 1.31 (<LOD-6.54) 97.6 (59.7-189) 122 

40–59 years 2.49 (1.48-4.19) < LOD† 1.30 (.500-4.70) 122† (28.3-237) 100 

60 years and older * < LOD† .420 (<LOD-3.30) 17.0† (8.73-34.6) 91 

Females 

Total, 6 years and older 2.16 (1.63-2.87) < LOD 1.62 (.880-2.50) 70.9 (40.6-90.1) 714 

6–11 years 2.67 (1.88-3.81) < LOD† 2.28 (1.44-3.30) 55.0† (20.3-129) 101 

12–19 years 2.80 (1.86-4.23) < LOD 2.40 (1.25-3.60) 98.0 (48.2-152) 246 

20–39 years * < LOD 1.39 (<LOD-2.83) 57.4 (25.2-88.3) 160 

40–59 years * < LOD† 1.00 (<LOD-5.20) 86.0† (18.6-191) 109 

60 years and older * < LOD† < LOD 33.2† (18.4-150) 98 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

* Not calculated. Proportion of results below limit of detection was too high to provide a valid result. 

126 126 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.4.c. Urinary O-desmethylangolensin: Non-Hispanic blacks 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic blacks in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 5.54 (4.63-6.64) < LOD 6.40 (5.10-7.98) 116 (95.5-155) 1219 

6–11 years 10.6 (7.78-14.5) < LOD 13.4 (9.40-22.5) 226 (157-303) 235 

12–19 years 10.5 (7.71-14.3) < LOD 13.2 (8.40-17.8) 165 (131-238) 424 

20–39 years 4.69 (2.93-7.51) < LOD 5.55 (2.66-9.30) 103 (52.4-161) 187 

40–59 years 4.42 (2.98-6.55) < LOD 4.67 (2.40-8.71) 87.6 (58.0-114) 199 

60 years and older 3.33 (1.97-5.64) < LOD 3.04 (1.20-5.70) 99.1 (33.4-357) 174 

Males 

Total, 6 years and older 6.36 (4.70-8.59) < LOD 7.20 (4.80-10.2) 143 (105-177) 590 

6–11 years 13.2 (8.14-21.3) < LOD 22.5 (10.1-39.1) 250 (158-355) 121 

12–19 years 12.2 (8.73-17.0) < LOD 14.5 (7.90-20.7) 171 (136-394) 194 

20–39 years 5.91 (3.47-10.1) < LOD† 5.93 (2.60-14.3) 128† (52.4-308) 85 

40–59 years 3.78 (2.07-6.90) < LOD† 3.50 (1.10-9.30) 99.4† (31.4-120) 103 

60 years and older 4.09 (2.10-7.93) < LOD† 5.30 (1.18-7.60) 77.4† (33.7-255) 87 

Females 

Total, 6 years and older 4.94 (4.05-6.02) < LOD 5.69 (4.50-7.90) 100 (73.8-128) 629 

6–11 years 8.38 (5.30-13.2) < LOD 10.4 (5.53-13.6) 147 (64.2-281) 114 

12–19 years 9.07 (5.81-14.2) < LOD 11.8 (6.64-20.1) 141 (95.1-201) 230 

20–39 years 3.92 (2.22-6.93) < LOD† 4.98 (1.40-9.40) 79.7† (26.6-191) 102 

40–59 years 5.04 (2.88-8.81) < LOD† 5.30 (2.10-13.3) 81.6† (40.2-313) 96 

60 years and older 2.89 (1.62-5.16) < LOD† 2.70 (.700-5.31) 99.1† (21.0-502) 87 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 5.4.d. Urinary O-desmethylangolensin: Non-Hispanic whites 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic whites in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 4.25 (3.59-5.04) < LOD 3.98 (3.30-4.80) 98.7 (72.8-135) 2021 

6–11 years 5.98 (4.20-8.50) < LOD 6.97 (3.43-11.5) 88.0 (45.0-191) 181 

12–19 years 6.26 (4.47-8.77) < LOD 6.50 (4.00-10.0) 122 (76.9-172) 360 

20–39 years 3.47 (2.58-4.66) < LOD 2.80 (2.03-4.40) 129 (61.0-228) 511 

40–59 years 5.40 (4.03-7.23) < LOD 4.56 (3.31-6.40) 137 (76.4-202) 405 

60 years and older 2.88 (2.23-3.71) < LOD 2.83 (1.71-4.20) 58.4 (30.2-78.0) 564 

Males 

Total, 6 years and older 4.22 (3.44-5.18) < LOD 4.12 (3.31-5.40) 96.8 (65.7-137) 995 

6–11 years 6.33 (3.52-11.4) < LOD† 7.20 (3.30-15.7) 88.0† (43.4-311) 90 

12–19 years 6.27 (4.21-9.32) < LOD 6.50 (3.60-13.5) 103 (61.6-148) 181 

20–39 years 2.95 (1.95-4.48) < LOD 2.51 (1.20-4.47) 96.0 (25.2-260) 223 

40–59 years 5.35 (4.05-7.06) < LOD 5.28 (3.31-8.00) 111 (58.4-178) 213 

60 years and older 3.27 (2.60-4.12) < LOD 3.60 (1.90-6.00) 58.4 (29.9-98.9) 288 

Females 

Total, 6 years and older 4.29 (3.50-5.25) < LOD 3.98 (2.79-4.98) 106 (70.6-154) 1026 

6–11 years 5.63 (3.55-8.95) < LOD† 5.90 (2.70-14.3) 72.2† (30.5-176) 91 

12–19 years 6.26 (3.92-10.0) < LOD 6.40 (3.50-11.7) 166 (58.3-367) 179 

20–39 years 4.05 (2.76-5.94) < LOD 3.80 (2.05-5.71) 135 (51.2-250) 288 

40–59 years 5.46 (3.47-8.59) < LOD 4.30 (2.36-6.40) 154 (64.9-322) 192 

60 years and older 2.59 (1.81-3.72) < LOD 2.10 (1.21-4.05) 59.9 (17.7-85.1) 276 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 127
Table 5.4.e. Urinary O-desmethylangolensin: Total population 

(creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for the total U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 3.91 (3.38-4.52) < LOD 3.74 (3.09-4.50) 87.6 (69.8-108) 5065 

6–11 years 6.62 (5.15-8.52) < LOD 6.64 (4.63-10.6) 93.7 (65.0-144) 683 

12–19 years 4.28 (3.25-5.65) < LOD 4.45 (3.22-6.51) 76.5 (61.6-102) 1411 

20–39 years 2.89 (2.33-3.59) < LOD 2.63 (1.96-3.66) 87.8 (50.8-126) 1085 

40–59 years 4.67 (3.70-5.90) < LOD 3.87 (2.73-5.68) 112 (71.8-155) 896 

60 years and older 3.51 (2.81-4.37) < LOD 3.19 (2.12-4.95) 64.7 (50.8-76.0) 990 

Males 

Total, 6 years and older 3.43 (2.85-4.12) < LOD 3.51 (2.56-4.45) 75.2 (58.5-96.5) 2462 

6–11 years 7.12 (4.73-10.7) < LOD 6.80 (3.59-17.0) 97.8 (56.2-233) 345 

12–19 years 4.45 (3.20-6.19) < LOD 4.71 (3.41-8.02) 70.2 (48.8-115) 690 

20–39 years 2.40 (1.73-3.33) < LOD 2.05 (1.38-3.06) 88.9 (34.3-151) 474 

40–59 years 3.76 (2.88-4.92) < LOD 3.66 (2.46-5.76) 80.3 (53.1-118) 455 

60 years and older 2.96 (2.35-3.73) < LOD 2.92 (1.84-4.68) 51.7 (35.4-64.2) 498 

Females 

Total, 6 years and older 4.43 (3.76-5.21) < LOD 3.92 (3.15-5.00) 98.3 (70.3-140) 2603 

6–11 years 6.14 (4.67-8.09) < LOD 6.61 (4.42-10.5) 88.0 (52.7-158) 338 

12–19 years 4.12 (2.97-5.71) < LOD 3.87 (2.50-5.90) 89.5 (61.4-111) 721 

20–39 years 3.45 (2.58-4.61) < LOD 3.62 (2.28-4.64) 86.0 (43.2-155) 611 

40–59 years 5.76 (4.18-7.94) < LOD 3.90 (2.69-7.27) 147 (85.2-280) 441 

60 years and older 4.00 (2.93-5.47) < LOD 3.40 (1.92-6.17) 69.8 (56.9-109) 492 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

Table 5.4.f. Urinary O-desmethylangolensin: Mexican Americans 

(creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for Mexican Americans 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 2.26 (1.70-3.00) < LOD 1.69 (1.12-2.67) 58.8 (48.6-87.8) 1400 

6–11 years 4.11 (3.09-5.47) < LOD 3.69 (2.16-7.00) 79.8 (53.6-114) 212 

12–19 years 2.43 (1.85-3.19) < LOD 2.13 (1.55-3.17) 61.5 (47.4-86.3) 508 

20–39 years * < LOD 1.17 (<LOD-2.67) 56.4 (29.9-103) 282 

40–59 years * < LOD 1.56 (.805-3.55) 58.8 (27.8-145) 209 

60 years and older * < LOD 1.03 (<LOD-2.70) 30.4 (21.4-55.3) 189 

Males 

Total, 6 years and older 2.23 (1.52-3.27) < LOD 1.64 (.932-3.90) 61.4 (48.6-93.0) 686 

6–11 years 4.52 (2.88-7.09) < LOD† 4.87 (1.72-8.95) 93.0† (50.2-145) 111 

12–19 years 2.50 (1.87-3.35) < LOD 2.82 (1.54-4.31) 56.1 (37.2-71.2) 262 

20–39 years * < LOD 1.45 (<LOD-4.56) 60.0 (25.8-113) 122 

40–59 years 2.04 (1.26-3.32) < LOD† 1.42 (.661-4.23) 57.2† (19.6-218) 100 

60 years and older * < LOD† .698 (<LOD-3.02) 23.6† (11.1-33.2) 91 

Females 

Total, 6 years and older 2.30 (1.77-2.99) < LOD 1.69 (1.17-2.08) 57.7 (41.7-87.6) 714 

6–11 years 3.73 (2.62-5.29) < LOD† 2.44 (1.68-7.00) 78.3† (27.1-108) 101 

12–19 years 2.35 (1.57-3.52) < LOD 1.78 (1.10-2.78) 68.3 (45.6-115) 246 

20–39 years * < LOD 1.03 (<LOD-2.15) 41.7 (15.5-87.6) 160 

40–59 years * < LOD† 1.77 (<LOD-3.90) 76.8† (29.1-145) 109 

60 years and older * < LOD† < LOD 55.3† (20.9-970) 98 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

* Not calculated. Proportion of results below limit of detection was too high to provide a valid result. 

128 128 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.4.g. Urinary O-desmethylangolensin: Non-Hispanic blacks 

(creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic blacks 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 3.73 (3.08-4.51) < LOD 4.12 (3.20-5.48) 71.9 (54.7-100) 1219 

6–11 years 9.94 (7.43-13.3) < LOD 10.6 (8.27-18.2) 217 (118-305) 235 

12–19 years 5.88 (4.34-7.98) < LOD 7.25 (4.64-10.2) 95.0 (57.0-142) 424 

20–39 years 2.68 (1.70-4.23) < LOD 3.66 (1.67-5.69) 45.4 (26.8-100) 187 

40–59 years 2.95 (2.07-4.19) < LOD 2.93 (1.61-5.48) 60.4 (36.7-81.9) 199 

60 years and older 3.11 (1.99-4.85) < LOD 2.91 (1.64-4.83) 75.6 (47.2-167) 174 

Males 

Total, 6 years and older 3.84 (2.85-5.19) < LOD 4.45 (2.64-7.30) 79.7 (55.2-118) 590 

6–11 years 12.3 (7.52-20.0) < LOD 18.0 (9.43-32.4) 233 (119-363) 121 

12–19 years 6.63 (4.79-9.18) < LOD 7.65 (4.69-11.1) 109 (59.1-198) 194 

20–39 years 2.87 (1.70-4.84) < LOD† 2.95 (1.28-8.61) 42.9† (23.4-100) 85 

40–59 years 2.27 (1.24-4.17) < LOD† 2.18 (.996-5.61) 67.8† (23.2-84.4) 103 

60 years and older 3.05 (1.64-5.69) < LOD† 2.79 (1.12-5.83) 79.7† (26.3-151) 87 

Females 

Total, 6 years and older 3.63 (2.96-4.46) < LOD 4.05 (3.26-5.22) 64.4 (47.0-90.4) 629 

6–11 years 7.89 (5.57-11.2) < LOD 8.27 (4.80-10.9) 104 (62.9-305) 114 

12–19 years 5.24 (3.35-8.21) < LOD 5.83 (3.15-11.1) 71.9 (47.5-142) 230 

20–39 years 2.54 (1.45-4.46) < LOD† 3.36 (1.42-5.69) 42.1† (22.1-185) 102 

40–59 years 3.67 (2.23-6.04) < LOD† 3.61 (1.61-7.58) 54.4† (34.1-147) 96 

60 years and older 3.14 (1.90-5.19) < LOD† 2.91 (1.31-6.30) 75.6† (23.8-359) 87 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 5.4.h. Urinary O-desmethylangolensin: Non-Hispanic whites 

(creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic whites 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 4.24 (3.55-5.07) < LOD 3.78 (3.05-4.95) 97.4 (71.8-125) 2021 

6–11 years 6.69 (4.67-9.58) < LOD 6.80 (3.78-13.6) 85.2 (47.9-190) 181 

12–19 years 4.79 (3.27-7.03) < LOD 4.70 (3.14-8.91) 83.6 (60.3-125) 360 

20–39 years 3.01 (2.28-3.98) < LOD 2.72 (1.89-3.77) 97.4 (50.8-151) 511 

40–59 years 5.67 (4.36-7.37) < LOD 5.32 (2.96-7.96) 136 (71.8-210) 405 

60 years and older 3.56 (2.74-4.64) < LOD 3.17 (1.83-5.45) 64.5 (45.6-83.0) 564 

Males 

Total, 6 years and older 3.60 (2.89-4.49) < LOD 3.51 (2.54-4.68) 76.4 (54.1-102) 995 

6–11 years 7.20 (3.84-13.5) < LOD† 6.80 (2.85-21.3) 90.2† (39.0-407) 90 

12–19 years 4.85 (3.15-7.46) < LOD 4.71 (3.05-13.5) 62.2 (45.9-125) 181 

20–39 years 2.24 (1.48-3.39) < LOD 1.96 (1.27-3.06) 88.2 (23.5-151) 223 

40–59 years 4.56 (3.50-5.94) < LOD 4.91 (2.73-7.08) 96.5 (43.2-161) 213 

60 years and older 3.12 (2.43-4.01) < LOD 3.17 (1.83-5.10) 49.3 (31.6-76.0) 288 

Females 

Total, 6 years and older 4.97 (4.04-6.10) < LOD 4.15 (3.15-6.03) 120 (72.2-153) 1026 

6–11 years 6.19 (4.04-9.49) < LOD† 6.86 (3.85-13.6) 84.7† (37.9-179) 91 

12–19 years 4.74 (2.93-7.67) < LOD 4.64 (2.43-8.27) 98.9 (61.4-292) 179 

20–39 years 4.01 (2.77-5.79) < LOD 4.01 (2.52-5.73) 97.4 (45.6-165) 288 

40–59 years 7.07 (4.69-10.7) < LOD 5.35 (2.45-10.1) 159 (97.6-421) 192 

60 years and older 3.96 (2.70-5.81) < LOD 2.86 (1.64-6.60) 71.5 (49.1-114) 276 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 129
Table 5.5.a. Urinary enterodiol: Total population 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for the total U.S. population aged 

6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 31.1 (28.2-34.3) 4.35 (3.35-5.50) 36.7 (34.2-39.4) 173 (155-189) 5321 

6–11 years 30.2 (25.1-36.5) 5.70 (3.50-7.90) 33.4 (28.3-39.4) 154 (113-219) 723 

12–19 years 32.5 (28.8-36.8) 5.50 (4.40-6.96) 36.8 (31.8-40.7) 165 (134-188) 1488 

20–39 years 31.2 (27.1-35.8) 4.15 (2.50-5.70) 37.6 (34.4-44.2) 170 (140-197) 1139 

40–59 years 31.9 (27.1-37.5) 3.80 (1.72-6.20) 37.7 (33.9-42.6) 191 (167-231) 945 

60 years and older 29.1 (25.5-33.1) 4.20 (2.80-5.50) 33.1 (29.3-37.6) 163 (142-190) 1026 

Males 

Total, 6 years and older 30.3 (26.8-34.2) 3.79 (2.70-5.05) 36.7 (33.2-40.4) 168 (146-187) 2581 

6–11 years 30.1 (24.1-37.6) 5.70 (2.74-9.10) 34.6 (27.0-44.1) 132 (109-162) 366 

12–19 years 28.6 (24.2-33.7) 4.30 (2.70-6.94) 32.7 (27.9-38.0) 140 (111-186) 729 

20–39 years 30.6 (25.9-36.0) 3.60 (2.40-5.13) 37.3 (32.0-46.5) 152 (131-190) 500 

40–59 years 32.7 (26.5-40.4) 3.50 (<LOD-6.66) 40.2 (33.8-48.4) 207 (163-269) 478 

60 years and older 27.0 (22.4-32.7) 3.35 (2.00-4.47) 33.1 (26.5-39.1) 155 (118-197) 508 

Females 

Total, 6 years and older 31.8 (28.9-35.1) 5.01 (3.50-6.40) 37.0 (34.7-39.8) 175 (160-197) 2740 

6–11 years 30.3 (23.2-39.7) 5.85 (2.40-8.53) 33.4 (25.6-40.2) 174 (98.1-279) 357 

12–19 years 37.3 (31.6-44.0) 6.70 (5.01-8.57) 41.7 (34.7-49.8) 171 (148-215) 759 

20–39 years 31.8 (27.3-37.0) 5.30 (1.80-7.40) 38.5 (32.8-45.7) 180 (139-220) 639 

40–59 years 31.1 (25.5-37.9) 3.88 (<LOD-8.50) 36.0 (30.9-41.4) 183 (148-231) 467 

60 years and older 30.7 (26.1-36.2) 5.00 (2.84-7.17) 32.8 (29.3-37.7) 163 (139-209) 518 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

Table 5.5.b. Urinary enterodiol: Mexican Americans 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for Mexican Americans in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 25.8 (23.1-28.8) 2.76 (1.68-4.00) 30.9 (27.5-35.2) 146 (128-169) 1470 

6–11 years 19.4 (16.0-23.6) < LOD 22.3 (18.6-30.2) 120 (92.6-156) 222 

12–19 years 27.2 (22.6-32.8) 3.80 (1.68-5.50) 29.5 (25.4-37.8) 159 (134-213) 533 

20–39 years 28.6 (23.3-35.0) 3.60 (1.60-6.50) 34.3 (26.9-42.4) 143 (110-202) 300 

40–59 years 26.5 (21.5-32.6) 2.38 (<LOD-6.60) 32.4 (26.0-38.7) 173 (141-256) 216 

60 years and older 19.6 (15.3-25.2) 2.13 (<LOD-5.40) 23.8 (20.4-34.6) 92.1 (74.0-143) 199 

Males 

Total, 6 years and older 23.5 (20.0-27.6) 2.04 (<LOD-3.80) 29.5 (23.7-35.0) 137 (105-169) 710 

6–11 years 18.4 (15.3-22.1) < LOD 21.3 (15.1-32.8) 99.2 (79.2-158) 115 

12–19 years 20.9 (16.8-26.0) 1.68 (<LOD-4.53) 24.9 (20.4-29.0) 121 (99.9-159) 269 

20–39 years 26.7 (19.8-36.0) 1.84 (<LOD-6.30) 30.9 (21.3-43.3) 144 (92.5-216) 127 

40–59 years 25.0 (18.6-33.6) 2.36† (<LOD-7.70) 33.0 (19.2-43.3) 115† (75.9-244) 104 

60 years and older 18.4 (12.8-26.4) < LOD† 22.0 (15.7-31.9) 73.1† (43.8-134) 95 

Females 

Total, 6 years and older 28.5 (25.3-32.2) 3.80 (2.21-5.74) 33.4 (28.3-39.0) 168 (141-192) 760 

6–11 years 20.6 (14.6-29.0) 2.01† (<LOD-5.30) 24.2 (16.5-35.3) 120† (92.6-219) 107 

12–19 years 36.2 (29.2-45.0) 5.20 (3.90-9.21) 38.5 (29.3-51.0) 197 (152-282) 264 

20–39 years 31.0 (24.7-38.9) 5.83 (<LOD-9.20) 36.0 (26.9-48.1) 132 (97.3-187) 173 

40–59 years 28.2 (20.9-38.0) 2.21 (<LOD-7.20) 31.3 (20.0-47.2) 197 (159-279) 112 

60 years and older 20.7 (15.1-28.5) 2.21† (<LOD-5.48) 25.5 (16.8-37.9) 101† (63.9-199) 104 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

130 130 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.5.c. Urinary enterodiol: Non-Hispanic blacks 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic blacks in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 30.4 (26.5-34.9) 4.87 (3.30-6.21) 35.4 (31.4-38.4) 168 (140-181) 1289 

6–11 years 30.7 (26.3-35.9) 6.64 (4.46-8.75) 33.7 (27.5-38.7) 132 (112-167) 249 

12–19 years 34.9 (30.9-39.3) 6.11 (3.56-8.33) 41.6 (36.8-47.6) 162 (132-213) 451 

20–39 years 28.8 (22.0-37.7) 5.80 (<LOD-8.67) 35.3 (26.6-41.7) 167 (115-210) 197 

40–59 years 32.3 (25.6-40.9) 4.54 (2.30-10.3) 33.2 (25.7-44.9) 207 (123-278) 210 

60 years and older 25.7 (19.0-34.9) 2.72 (<LOD-4.33) 32.9 (24.4-40.4) 147 (107-219) 182 

Males 

Total, 6 years and older 25.2 (21.6-29.3) 4.00 (1.80-5.97) 29.9 (25.0-34.3) 124 (104-163) 628 

6–11 years 29.5 (23.2-37.5) 5.80 (3.30-8.75) 35.5 (26.2-44.5) 129 (80.3-167) 127 

12–19 years 30.3 (25.8-35.4) 5.70 (3.01-8.57) 34.6 (25.9-42.1) 140 (119-218) 212 

20–39 years 22.8 (16.3-32.0) < LOD† 27.9 (16.6-35.3) 107† (72.4-214) 91 

40–59 years 25.2 (17.8-35.5) 3.50† (<LOD-10.5) 26.0 (20.0-34.9) 123† (75.8-227) 109 

60 years and older 20.3 (14.8-28.0) < LOD† 29.1 (19.3-38.0) 96.3† (65.0-143) 89 

Females 

Total, 6 years and older 35.8 (29.9-42.9) 5.50 (3.30-8.70) 41.7 (35.4-47.0) 180 (154-237) 661 

6–11 years 32.1 (25.6-40.2) 7.34 (4.00-11.4) 33.7 (27.2-38.8) 137 (92.6-230) 122 

12–19 years 40.2 (33.4-48.4) 6.13 (3.20-12.0) 47.0 (38.7-59.2) 171 (125-247) 239 

20–39 years 34.7 (24.7-48.8) 7.80† (<LOD-10.6) 41.7 (32.5-50.4) 176† (115-237) 106 

40–59 years 40.0 (28.9-55.4) 5.50† (2.30-13.1) 37.8 (25.9-63.7) 250† (144-340) 101 

60 years and older 30.1 (18.5-48.8) 2.80† (<LOD-6.25) 36.3 (22.5-49.2) 172† (123-396) 93 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 5.5.d. Urinary enterodiol: Non-Hispanic whites 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic whites in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 32.4 (29.3-35.8) 4.68 (3.50-5.90) 38.5 (36.0-41.7) 173 (152-195) 2110 

6–11 years 32.5 (24.6-42.8) 5.90 (2.40-10.5) 35.7 (28.1-44.8) 152 (106-253) 196 

12–19 years 32.7 (27.6-38.7) 6.10 (3.97-7.80) 35.4 (29.7-43.8) 162 (127-185) 375 

20–39 years 33.4 (28.3-39.5) 4.70 (2.70-6.10) 43.1 (37.4-47.1) 174 (138-214) 529 

40–59 years 33.2 (27.3-40.4) 3.80 (<LOD-7.40) 40.5 (35.8-46.7) 207 (158-254) 433 

60 years and older 29.6 (25.7-34.1) 4.35 (2.74-6.10) 33.4 (29.7-38.7) 160 (139-190) 577 

Males 

Total, 6 years and older 32.7 (28.6-37.4) 4.20 (2.92-5.56) 40.0 (35.4-44.1) 174 (146-198) 1036 

6–11 years 33.7 (24.0-47.3) 7.55† (<LOD-14.6) 37.8 (25.7-50.9) 135† (103-215) 101 

12–19 years 28.6 (22.9-35.7) 4.30 (2.38-7.80) 32.5 (24.3-40.7) 131 (99.1-174) 190 

20–39 years 33.9 (27.3-42.2) 3.79 (<LOD-5.95) 44.2 (34.9-55.1) 174 (132-226) 231 

40–59 years 35.9 (28.1-46.0) 3.65 (<LOD-7.40) 46.7 (37.8-53.2) 213 (167-263) 224 

60 years and older 28.1 (22.8-34.7) 3.35 (2.00-5.30) 33.2 (26.5-40.0) 163 (120-205) 290 

Females 

Total, 6 years and older 32.1 (29.0-35.6) 5.35 (3.53-6.70) 37.6 (35.0-41.1) 171 (148-209) 1074 

6–11 years 31.2 (20.5-47.7) 5.85† (<LOD-12.2) 34.1 (22.3-50.8) 174† (87.0-327) 95 

12–19 years 38.0 (29.5-48.9) 6.87 (3.97-11.2) 43.5 (29.3-58.0) 170 (144-245) 185 

20–39 years 33.0 (26.9-40.4) 5.70 (1.80-7.60) 41.1 (30.1-47.8) 166 (130-220) 298 

40–59 years 30.8 (24.1-39.4) 4.09 (<LOD-10.4) 36.2 (27.8-42.5) 195 (127-259) 209 

60 years and older 30.8 (25.6-37.2) 5.18 (2.74-7.50) 32.9 (29.2-39.8) 160 (127-209) 287 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 131
Table 5.5.e. Urinary enterodiol: Total population (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for the total U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 29.0 (26.5-31.7) 4.17 (3.19-5.13) 33.6 (31.1-36.8) 150 (136-163) 5321 

6–11 years 32.8 (27.6-39.0) 5.61 (3.48-7.95) 36.2 (30.8-42.7) 188 (140-244) 723 

12–19 years 23.5 (21.1-26.3) 4.27 (2.64-5.42) 26.6 (24.1-30.4) 102 (93.2-117) 1488 

20–39 years 25.0 (21.6-28.9) 3.52 (2.52-5.12) 28.2 (25.3-32.7) 124 (108-156) 1139 

40–59 years 32.0 (27.7-36.9) 3.50 (2.54-5.86) 39.1 (33.2-44.8) 162 (140-197) 945 

60 years and older 34.9 (31.1-39.2) 5.13 (4.30-7.13) 41.3 (35.6-46.2) 174 (157-194) 1026 

Males 

Total, 6 years and older 24.3 (21.7-27.4) 3.17 (2.52-4.34) 28.8 (25.2-31.7) 129 (111-152) 2581 

6–11 years 31.8 (25.1-40.2) 4.62 (2.80-8.38) 34.8 (28.3-43.7) 172 (112-244) 366 

12–19 years 20.3 (17.2-23.9) 3.27 (1.98-4.96) 23.9 (20.5-28.1) 94.1 (81.5-111) 729 

20–39 years 21.3 (18.3-24.8) 2.84 (2.15-4.03) 24.6 (21.2-28.1) 111 (96.4-130) 500 

40–59 years 27.2 (22.4-33.0) 3.19 (<LOD-5.80) 31.7 (28.3-41.9) 160 (121-201) 478 

60 years and older 25.5 (20.5-31.7) 2.96 (2.04-4.74) 30.2 (23.8-35.4) 138 (105-179) 508 

Females 

Total, 6 years and older 34.2 (31.2-37.5) 5.26 (4.20-7.08) 39.9 (36.6-43.8) 162 (148-178) 2740 

6–11 years 33.9 (26.8-42.8) 6.64 (3.93-8.55) 37.3 (28.6-50.1) 193 (108-304) 357 

12–19 years 27.5 (24.0-31.5) 5.26 (3.66-7.26) 30.0 (26.2-34.9) 115 (100-132) 759 

20–39 years 29.2 (24.7-34.6) 4.73 (2.54-7.41) 33.5 (28.1-40.6) 141 (108-182) 639 

40–59 years 37.3 (31.0-44.9) 4.11 (<LOD-9.07) 44.6 (39.0-53.0) 165 (140-217) 467 

60 years and older 44.4 (38.2-51.7) 7.53 (5.23-12.3) 51.4 (44.8-58.8) 188 (164-222) 518 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

Table 5.5.f. Urinary enterodiol: Mexican Americans (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for Mexican Americans 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 23.8 (21.5-26.3) 3.21 (2.34-4.32) 27.6 (25.2-30.2) 134 (116-158) 1470 

6–11 years 24.8 (20.1-30.6) < LOD 32.4 (23.9-40.2) 140 (105-182) 222 

12–19 years 21.7 (18.2-25.7) 3.35 (1.53-5.17) 23.9 (19.0-30.4) 115 (99.3-134) 533 

20–39 years 23.6 (19.5-28.6) 2.78 (1.62-5.36) 27.1 (22.4-30.1) 127 (91.4-181) 300 

40–59 years 26.0 (21.3-31.6) 4.20 (<LOD-6.80) 30.6 (21.5-42.2) 157 (126-192) 216 

60 years and older 22.7 (17.8-28.9) 2.26 (<LOD-7.79) 31.3 (25.7-38.1) 110 (80.0-149) 199 

Males 

Total, 6 years and older 19.4 (16.9-22.2) 2.48 (<LOD-4.32) 21.9 (18.9-26.1) 117 (87.5-141) 710 

6–11 years 21.9 (17.5-27.5) < LOD 26.9 (19.9-39.3) 129 (83.7-188) 115 

12–19 years 15.9 (12.6-20.2) 1.99 (<LOD-3.66) 18.3 (15.2-22.5) 85.9 (73.8-115) 269 

20–39 years 19.6 (14.9-25.9) 2.34 (<LOD-5.83) 20.0 (15.7-27.8) 117 (82.1-179) 127 

40–59 years 20.9 (15.9-27.5) 4.92† (<LOD-6.91) 23.5 (13.6-36.6) 120† (59.6-192) 104 

60 years and older 17.5 (12.0-25.7) < LOD† 22.7 (17.0-36.2) 74.3† (49.3-179) 95 

Females 

Total, 6 years and older 29.8 (26.5-33.6) 4.68 (2.71-7.01) 34.4 (29.6-38.8) 154 (127-193) 760 

6–11 years 28.1 (20.5-38.7) 2.82† (<LOD-6.25) 37.3 (25.1-48.1) 144† (98.7-279) 107 

12–19 years 30.3 (25.3-36.3) 6.40 (3.13-9.44) 31.6 (24.0-43.4) 156 (112-195) 264 

20–39 years 29.3 (23.8-36.0) 5.23 (<LOD-9.41) 31.0 (27.1-38.8) 133 (93.6-193) 173 

40–59 years 32.7 (24.9-43.0) 4.56 (<LOD-10.1) 44.8 (27.0-59.4) 183 (141-235) 112 

60 years and older 28.2 (20.3-39.3) 3.80† (<LOD-8.93) 34.5 (28.6-42.2) 130† (78.9-213) 104 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

132 132 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.5.g. Urinary enterodiol: Non-Hispanic blacks (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic blacks 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 20.5 (17.5-24.0) 3.30 (2.47-4.03) 23.3 (19.7-26.6) 118 (97.4-138) 1289 

6–11 years 28.7 (24.0-34.4) 5.03 (4.02-7.59) 31.1 (26.1-38.8) 126 (95.2-168) 249 

12–19 years 19.6 (17.2-22.3) 3.48 (2.11-4.47) 23.5 (19.7-27.2) 86.8 (72.7-116) 451 

20–39 years 16.4 (12.2-22.0) 2.15 (<LOD-4.41) 19.3 (14.1-23.8) 96.0 (68.6-128) 197 

40–59 years 21.8 (16.9-28.2) 3.57 (2.35-5.11) 23.3 (16.2-31.4) 145 (94.5-187) 210 

60 years and older 24.2 (17.8-32.8) 2.94 (<LOD-5.25) 27.0 (22.7-38.6) 146 (88.0-241) 182 

Males 

Total, 6 years and older 15.2 (12.9-18.0) 2.40 (1.44-3.12) 18.0 (14.6-21.0) 84.6 (65.9-108) 628 

6–11 years 27.3 (20.5-36.4) 4.14 (2.52-9.49) 30.8 (25.6-42.5) 106 (77.7-168) 127 

12–19 years 16.5 (14.0-19.5) 2.23 (1.22-4.05) 20.0 (15.1-24.3) 82.9 (61.4-103) 212 

20–39 years 11.1 (7.62-16.1) < LOD† 12.9 (10.3-18.0) 70.4† (30.6-154) 91 

40–59 years 15.3 (11.1-21.3) 2.65† (<LOD-5.24) 15.9 (12.8-21.0) 72.6† (41.9-155) 109 

60 years and older 15.1 (11.2-20.4) < LOD† 24.0 (13.9-30.2) 66.1† (45.5-97.2) 89 

Females 

Total, 6 years and older 26.5 (21.6-32.5) 4.41 (3.40-5.50) 30.1 (23.5-37.7) 138 (112-180) 661 

6–11 years 30.3 (24.4-37.7) 6.64 (4.20-8.88) 33.8 (23.2-41.8) 134 (93.9-209) 122 

12–19 years 23.2 (19.3-28.0) 3.96 (2.30-6.55) 26.2 (22.6-30.0) 106 (71.7-145) 239 

20–39 years 22.4 (15.8-31.8) 4.87† (<LOD-7.83) 26.6 (18.2-41.9) 99.4† (68.6-138) 106 

40–59 years 29.4 (20.0-43.3) 4.32† (2.35-8.07) 34.8 (22.6-48.1) 158† (118-321) 101 

60 years and older 33.0 (20.2-53.7) 3.35† (<LOD-9.66) 33.3 (22.7-54.5) 229† (123-590) 93 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 5.5.h. Urinary enterodiol: Non-Hispanic whites (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic whites 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 32.3 (29.5-35.3) 5.15 (3.94-6.23) 37.4 (33.7-41.4) 158 (140-174) 2110 

6–11 years 35.3 (27.5-45.2) 6.62 (3.23-9.63) 40.3 (29.4-50.4) 188 (132-281) 196 

12–19 years 24.8 (21.2-29.0) 5.02 (2.36-7.01) 28.1 (24.3-33.6) 99.5 (91.3-121) 375 

20–39 years 29.1 (24.9-34.2) 4.84 (2.92-6.99) 31.3 (27.2-37.6) 140 (109-182) 529 

40–59 years 34.9 (29.3-41.5) 3.68 (<LOD-7.14) 43.4 (37.7-52.9) 165 (135-208) 433 

60 years and older 37.0 (32.4-42.2) 5.89 (4.17-7.67) 44.0 (36.7-50.3) 179 (155-209) 577 

Males 

Total, 6 years and older 27.7 (24.5-31.3) 3.53 (2.80-5.38) 31.9 (28.0-36.9) 138 (114-170) 1036 

6–11 years 37.0 (25.9-52.8) 6.62† (<LOD-14.2) 42.2 (21.7-60.2) 202† (105-290) 101 

12–19 years 21.7 (17.2-27.5) 4.74 (1.98-6.23) 24.7 (20.8-33.1) 94.1 (71.7-119) 190 

20–39 years 25.8 (21.2-31.4) 3.41 (<LOD-6.26) 28.0 (24.0-34.9) 121 (100-167) 231 

40–59 years 30.2 (24.4-37.5) 3.13 (<LOD-6.83) 38.0 (30.0-51.0) 160 (114-216) 224 

60 years and older 27.0 (21.1-34.5) 3.19 (2.17-5.13) 31.1 (23.8-40.0) 138 (104-189) 290 

Females 

Total, 6 years and older 37.4 (34.2-40.9) 7.08 (4.81-7.92) 43.1 (38.7-48.7) 168 (151-196) 1074 

6–11 years 33.4 (23.1-48.3) 6.28† (<LOD-10.0) 35.5 (27.5-60.6) 150† (87.0-325) 95 

12–19 years 28.7 (23.3-35.3) 6.14 (3.02-7.64) 32.1 (26.2-38.8) 112 (90.2-146) 185 

20–39 years 32.8 (27.1-39.8) 6.46 (3.12-10.7) 34.9 (27.8-47.5) 166 (107-235) 298 

40–59 years 40.1 (32.3-49.8) 6.00 (<LOD-14.4) 48.7 (39.0-58.5) 165 (129-224) 209 

60 years and older 47.2 (39.4-56.7) 8.54 (6.23-14.9) 53.0 (46.4-65.3) 189 (157-225) 287 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 133
Table 5.6.a. Urinary enterolactone: Total population 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for the total U.S. population aged 

6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 249 (227-273) 23.6 (19.6-29.5) 330 (303-370) 1710 (1500-1960) 5342 

6–11 years 297 (251-352) 55.1 (41.1-73.7) 340 (288-412) 1420 (1250-2050) 727 

12–19 years 256 (223-294) 31.5 (22.1-48.0) 317 (266-377) 1560 (1250-1900) 1490 

20–39 years 237 (203-276) 20.3 (13.0-28.0) 317 (255-380) 1850 (1420-2320) 1139 

40–59 years 231 (190-280) 15.9 (11.0-25.3) 334 (272-399) 1810 (1510-2240) 951 

60 years and older 276 (245-311) 32.9 (17.9-50.3) 362 (303-417) 1680 (1330-2170) 1035 

Males 

Total, 6 years and older 258 (234-285) 21.7 (17.5-25.3) 349 (310-389) 1890 (1600-2280) 2594 

6–11 years 322 (267-387) 55.3 (35.8-102) 363 (309-456) 1380 (1120-1810) 368 

12–19 years 246 (212-287) 29.6 (19.4-41.7) 318 (252-391) 1560 (1250-1820) 733 

20–39 years 249 (208-299) 19.2 (11.2-30.9) 337 (258-389) 2050 (1650-2540) 500 

40–59 years 246 (194-312) 16.6 (12.7-25.3) 360 (278-438) 1940 (1580-2530) 480 

60 years and older 274 (228-330) 19.9 (12.9-43.2) 361 (291-458) 1790 (1410-2470) 513 

Females 

Total, 6 years and older 241 (215-270) 25.9 (18.1-38.7) 321 (281-359) 1500 (1300-1810) 2748 

6–11 years 273 (203-368) 55.5 (24.0-83.6) 325 (236-420) 1520 (847-2280) 359 

12–19 years 267 (218-326) 37.2 (20.1-59.1) 314 (259-383) 1500 (1040-2130) 757 

20–39 years 225 (181-279) 21.4 (9.30-38.4) 312 (239-381) 1450 (991-2000) 639 

40–59 years 217 (164-288) 15.8 (7.30-44.9) 311 (227-399) 1510 (1180-1810) 471 

60 years and older 277 (231-333) 43.4 (18.9-66.5) 362 (282-419) 1490 (1190-2140) 522 

Table 5.6.b. Urinary enterolactone: Mexican Americans 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for Mexican Americans in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 236 (198-280) 32.0 (17.7-40.2) 316 (266-354) 1550 (1230-1890) 1492 

6–11 years 209 (155-282) 31.4 (17.7-50.6) 265 (192-375) 913 (796-1420) 226 

12–19 years 272 (238-312) 36.6 (29.5-61.7) 314 (253-370) 1650 (1350-1990) 538 

20–39 years 262 (203-340) 34.5 (8.76-49.8) 346 (280-424) 1840 (1280-2620) 300 

40–59 years 192 (149-249) 12.9 (8.00-35.8) 245 (200-347) 1390 (929-2060) 221 

60 years and older 197 (137-285) 23.0 (6.66-50.5) 296 (180-415) 967 (825-1490) 207 

Males 

Total, 6 years and older 253 (200-320) 32.7 (15.7-46.3) 346 (266-416) 1640 (1000-2380) 722 

6–11 years 236 (170-328) 35.1 (24.7-55.1) 316 (171-476) 972 (815-1800) 117 

12–19 years 236 (210-266) 34.3 (21.7-55.3) 293 (210-357) 1510 (950-1900) 274 

20–39 years 317 (225-446) 39.6 (6.81-79.5) 455 (280-628) 2380 (1280-3560) 127 

40–59 years 166 (104-265) 10.4† (4.10-38.8) 238 (148-389) 1030† (647-2120) 105 

60 years and older 266 (176-402) 37.2† (6.66-99.7) 374 (248-488) 967† (679-2570) 99 

Females 

Total, 6 years and older 218 (167-285) 30.2 (11.9-53.2) 279 (228-344) 1380 (980-1840) 770 

6–11 years 184 (106-319) 16.8† (<LOD-80.4) 236 (170-375) 847† (745-1550) 109 

12–19 years 319 (241-422) 56.1 (19.5-105) 352 (258-473) 1710 (1290-2530) 264 

20–39 years 209 (134-328) 17.3 (2.91-77.7) 308 (183-414) 1100 (790-2580) 173 

40–59 years 224 (159-316) 19.1 (3.44-58.0) 245 (193-392) 1480 (980-2200) 116 

60 years and older 154 (96.7-246) 11.3† (<LOD-43.0) 231 (148-322) 920† (524-1490) 108 

< LOD means less than the limit of detection, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

134 134 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.6.c. Urinary enterolactone: Non-Hispanic blacks 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic blacks in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 272 (230-322) 26.3 (17.6-43.6) 392 (339-441) 1500 (1270-1890) 1286 

6–11 years 369 (297-457) 75.1 (41.0-99.1) 470 (391-521) 1520 (1220-2160) 249 

12–19 years 351 (315-391) 53.9 (34.8-87.3) 428 (385-479) 1850 (1450-2340) 448 

20–39 years 239 (167-344) 12.0 (5.40-49.4) 342 (248-504) 1680 (993-2300) 197 

40–59 years 254 (202-320) 23.1 (14.5-45.9) 366 (283-479) 1350 (1050-1920) 210 

60 years and older 237 (179-312) 15.2 (7.90-44.9) 399 (296-502) 1270 (1020-1960) 182 

Males 

Total, 6 years and older 266 (215-329) 20.9 (12.0-36.5) 416 (339-497) 1630 (1250-2080) 627 

6–11 years 362 (304-430) 65.4 (21.5-107) 487 (341-524) 1370 (1070-1720) 127 

12–19 years 330 (266-409) 38.6 (26.3-77.1) 422 (363-484) 1770 (1360-2440) 211 

20–39 years 261 (163-417) 17.7† (4.49-116) 416 (260-596) 1670† (1000-2500) 91 

40–59 years 235 (160-345) 16.6† (4.20-34.6) 401 (184-559) 1350† (741-2580) 109 

60 years and older 183 (119-281) 6.00† (3.30-19.5) 267 (155-488) 1290† (1000-1980) 89 

Females 

Total, 6 years and older 278 (235-327) 39.1 (18.9-53.2) 360 (314-427) 1500 (1190-1870) 659 

6–11 years 376 (259-547) 75.8 (28.7-130) 416 (299-664) 1740 (1050-2410) 122 

12–19 years 374 (325-431) 87.3 (39.1-136) 441 (378-521) 1870 (1320-2260) 237 

20–39 years 224 (152-330) 9.10† (3.10-49.7) 314 (219-499) 1500† (854-2140) 106 

40–59 years 272 (218-340) 43.4† (15.2-71.6) 358 (246-469) 1270† (842-1540) 101 

60 years and older 281 (197-401) 32.6† (9.50-102) 438 (307-565) 1270† (900-2210) 93 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 5.6.d. Urinary enterolactone: Non-Hispanic whites 

Geometric mean and selected percentiles of urine concentrations (in μg/L) for non-Hispanic whites in the U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 259 (230-291) 23.9 (18.1-33.1) 344 (301-387) 1810 (1580-2100) 2112 

6–11 years 308 (244-388) 57.5 (35.8-103) 331 (262-412) 1600 (1290-2310) 196 

12–19 years 249 (203-306) 29.6 (17.5-58.1) 310 (242-384) 1620 (1200-2420) 375 

20–39 years 235 (196-281) 19.1 (11.1-33.1) 317 (240-383) 1780 (1300-2180) 529 

40–59 years 249 (195-319) 16.4 (9.30-34.1) 387 (278-424) 2030 (1610-2750) 434 

60 years and older 297 (256-345) 44.8 (19.9-73.6) 372 (303-424) 1730 (1340-2260) 578 

Males 

Total, 6 years and older 272 (240-308) 22.9 (17.2-33.1) 360 (310-400) 1970 (1620-2450) 1038 

6–11 years 336 (257-441) 70.2† (35.8-152) 348 (283-474) 1390† (881-2600) 101 

12–19 years 242 (192-306) 23.2 (10.6-64.4) 316 (222-445) 1560 (1150-2180) 190 

20–39 years 236 (185-300) 19.2 (11.0-32.3) 258 (209-389) 2000 (1300-2620) 231 

40–59 years 290 (218-386) 17.3 (12.7-39.6) 424 (307-555) 2400 (1710-3540) 225 

60 years and older 296 (236-372) 29.6 (12.9-62.1) 377 (292-492) 1750 (1310-2730) 291 

Females 

Total, 6 years and older 246 (212-286) 25.4 (15.8-43.7) 328 (280-383) 1490 (1290-2010) 1074 

6–11 years 279 (185-420) 47.3† (15.7-117) 325 (224-427) 1530† (719-2900) 95 

12–19 years 257 (189-349) 45.4 (17.5-62.1) 286 (222-403) 1800 (944-2950) 185 

20–39 years 234 (176-310) 17.4 (7.50-43.7) 323 (238-431) 1310 (980-1970) 298 

40–59 years 214 (148-310) 13.0 (5.28-46.1) 347 (206-418) 1660 (1010-2750) 209 

60 years and older 298 (245-363) 53.0 (19.4-78.0) 348 (265-418) 1700 (1190-2240) 287 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 135
Table 5.6.e. Urinary enterolactone: Total population (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for the total U.S. 

population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 233 (213-254) 21.2 (17.4-24.5) 309 (286-335) 1500 (1380-1630) 5342 

6–11 years 323 (277-375) 69.3 (41.1-91.9) 375 (305-423) 1490 (1190-1780) 727 

12–19 years 185 (163-211) 23.4 (15.2-31.9) 231 (206-256) 1110 (908-1330) 1490 

20–39 years 190 (163-221) 14.0 (10.4-20.9) 278 (240-304) 1290 (1110-1520) 1139 

40–59 years 232 (194-277) 16.3 (11.7-24.2) 315 (267-377) 1630 (1380-1940) 951 

60 years and older 331 (286-383) 37.6 (20.3-65.1) 437 (380-492) 1860 (1540-2040) 1035 

Males 

Total, 6 years and older 208 (190-227) 17.4 (13.9-21.6) 279 (254-303) 1360 (1210-1540) 2594 

6–11 years 339 (283-408) 76.0 (49.3-101) 397 (291-480) 1580 (1130-2120) 368 

12–19 years 175 (152-201) 19.0 (12.9-29.6) 226 (200-247) 1090 (907-1310) 733 

20–39 years 174 (143-210) 15.1 (10.4-22.6) 240 (206-276) 1180 (872-1530) 500 

40–59 years 204 (165-253) 12.3 (8.16-24.2) 282 (243-350) 1420 (1150-1850) 480 

60 years and older 257 (208-318) 18.2 (11.4-35.3) 380 (282-486) 1590 (1210-1940) 513 

Females 

Total, 6 years and older 259 (232-290) 27.9 (18.6-32.9) 342 (307-379) 1590 (1440-1800) 2748 

6–11 years 306 (237-394) 55.4 (30.2-126) 343 (263-401) 1400 (1110-1610) 359 

12–19 years 197 (163-237) 25.9 (16.2-36.8) 243 (198-306) 1150 (850-1490) 757 

20–39 years 207 (165-259) 13.9 (8.20-27.9) 302 (259-360) 1370 (1120-1800) 639 

40–59 years 261 (204-335) 18.7 (9.02-39.1) 355 (267-447) 1850 (1450-2300) 471 

60 years and older 401 (339-474) 60.5 (30.9-103) 472 (404-562) 2020 (1590-2250) 522 

Table 5.6.f. Urinary enterolactone: Mexican Americans (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for Mexican Americans 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 219 (191-252) 24.2 (18.6-33.2) 283 (258-328) 1270 (1030-1490) 1492 

6–11 years 268 (200-359) 41.3 (20.8-64.7) 348 (240-437) 1190 (871-1980) 226 

12–19 years 215 (185-250) 33.0 (18.7-49.5) 257 (215-296) 1110 (955-1310) 538 

20–39 years 217 (174-270) 24.2 (9.46-37.2) 281 (242-398) 1410 (995-1730) 300 

40–59 years 193 (146-254) 18.1 (6.78-23.3) 277 (214-371) 1220 (1020-1430) 221 

60 years and older 227 (160-323) 25.3 (10.0-60.4) 334 (231-450) 1200 (985-1800) 207 

Males 

Total, 6 years and older 208 (169-257) 22.6 (14.9-36.1) 264 (227-328) 1270 (946-1730) 722 

6–11 years 284 (191-421) 41.3 (12.9-83.0) 355 (217-504) 1840 (898-2790) 117 

12–19 years 178 (152-208) 19.9 (14.6-43.8) 233 (184-281) 939 (716-1150) 274 

20–39 years 233 (171-318) 26.9 (9.46-54.1) 280 (206-444) 1570 (868-2190) 127 

40–59 years 140 (90.5-216) 8.37† (3.50-22.6) 213 (126-282) 1030† (597-1430) 105 

60 years and older 251 (161-390) 26.8† (3.62-67.2) 298 (206-503) 1390† (989-2520) 99 

Females 

Total, 6 years and older 231 (193-277) 24.2 (11.1-58.9) 308 (273-366) 1280 (1070-1440) 770 

6–11 years 252 (166-382) 28.5† (<LOD-97.1) 319 (223-455) 1010† (786-1490) 109 

12–19 years 266 (208-339) 50.2 (18.0-87.9) 282 (225-373) 1400 (1030-1630) 264 

20–39 years 199 (138-286) 13.3 (2.46-70.4) 280 (179-409) 1220 (981-1650) 173 

40–59 years 270 (189-387) 21.9 (7.00-73.6) 394 (233-611) 1480 (1170-2140) 116 

60 years and older 209 (135-324) 21.1† (<LOD-63.0) 333 (154-422) 1070† (773-1500) 108 

< LOD means less than the limit of detection for the uncorrected urine value, which may vary for some compounds by year. See Appendix D for LOD. 

† Estimate is subject to greater uncertainty due to small cell size. 

136 136 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999–2002 
Table 5.6.g. Urinary enterolactone: Non-Hispanic blacks (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic blacks 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 183 (153-220) 17.9 (12.0-29.9) 269 (219-309) 1090 (911-1230) 1286 

6–11 years 345 (285-417) 76.0 (48.1-108) 429 (331-495) 1170 (972-1650) 249 

12–19 years 197 (176-221) 32.3 (14.1-53.4) 244 (215-273) 931 (804-1180) 448 

20–39 years 136 (92.9-199) 7.64 (3.17-26.6) 197 (138-288) 888 (628-1590) 197 

40–59 years 172 (134-220) 15.8 (7.07-28.9) 251 (181-318) 1010 (678-1230) 210 

60 years and older 222 (167-295) 15.7 (6.74-56.4) 341 (252-439) 1390 (872-1690) 182 

Males 

Total, 6 years and older 161 (128-202) 12.0 (7.64-31.9) 236 (197-278) 1010 (850-1220) 627 

6–11 years 335 (272-413) 60.3 (38.6-112) 409 (329-507) 1100 (937-1570) 127 

12–19 years 180 (147-221) 20.1 (11.8-45.1) 217 (186-271) 931 (728-1250) 211 

20–39 years 126 (78.3-204) 7.64† (1.31-32.6) 177 (125-242) 1100† (556-1590) 91 

40–59 years 143 (97.7-209) 9.30† (2.81-28.1) 252 (152-319) 820† (615-1420) 109 

60 years and older 136 (86.0-215) 7.45† (1.61-15.7) 220 (128-344) 885† (705-1470) 89 

Females 

Total, 6 years and older 205 (172-245) 28.9 (17.0-37.7) 298 (241-340) 1090 (911-1390) 659 

6–11 years 356 (270-468) 88.1 (59.4-126) 431 (279-552) 1180 (972-1670) 122 

12–19 years 216 (187-250) 50.3 (24.3-69.9) 262 (221-298) 911 (686-1300) 237 

20–39 years 144 (96.1-217) 12.1† (2.05-37.2) 218 (142-326) 888† (622-1670) 106 

40–59 years 200 (157-256) 28.4† (7.07-51.5) 247 (184-354) 1060† (604-1440) 101 

60 years and older 308 (214-443) 41.0† (17.0-90.6) 428 (302-549) 1460† (869-2020) 93 

† Estimate is subject to greater uncertainty due to small cell size. 

Table 5.6.h. Urinary enterolactone: Non-Hispanic whites (creatinine corrected) 

Geometric mean and selected percentiles of urine concentrations (in μg/g creatinine) for non-Hispanic whites 

in the U.S. population aged 6 years and older, National Health and Nutrition Examination Survey, 1999–2002. 

Geometric mean 

(95% conf. interval) 

Selected percentiles (95% conf. interval) Sample 

10th 50th 90th size

Males and Females 

Total, 6 years and older 257 (229-289) 22.6 (17.1-27.9) 338 (308-377) 1630 (1460-1880) 2112 

6–11 years 334 (277-402) 76.1 (48.9-108) 378 (291-435) 1580 (1220-2020) 196 

12–19 years 189 (155-229) 22.8 (15.9-29.6) 238 (192-288) 1240 (900-1720) 375 

20–39 years 205 (172-243) 14.5 (9.83-22.6) 296 (268-323) 1370 (1160-1640) 529 

40–59 years 261 (210-326) 16.4 (10.2-29.9) 362 (282-444) 1850 (1410-2490) 434 

60 years and older 371 (310-443) 44.3 (20.3-96.7) 468 (386-570) 1920 (1570-2200) 578 

Males 

Total, 6 years and older 230 (206-257) 21.2 (14.6-25.2) 308 (276-336) 1520 (1290-1690) 1038 

6–11 years 370 (282-484) 82.0† (69.3-123) 435 (247-601) 1780† (1180-2940) 101 

12–19 years 184 (146-233) 19.7 (7.43-31.9) 238 (189-287) 1210 (900-1880) 190 

20–39 years 179 (141-227) 14.0 (9.83-24.7) 251 (201-309) 1270 (755-1630) 231 

40–59 years 244 (189-316) 16.0 (8.16-29.9) 327 (254-433) 1630 (1240-2490) 225 

60 years and older 283 (220-364) 19.6 (13.0-44.7) 424 (301-576) 1590 (1170-1980) 291 

Females 

Total, 6 years and older 287 (247-333) 27.9 (16.9-37.7) 370 (327-418) 1850 (1520-2020) 1074 

6–11 years 299 (215-416) 55.2† (25.1-142) 342 (249-401) 1400† (847-1800) 95 

12–19 years 194 (147-256) 21.7 (13.8-36.8) 241 (172-344) 1250 (783-1800) 185 

20–39 years 233 (174-311) 14.0 (6.11-30.6) 322 (280-424) 1410 (1180-2010) 298 

40–59 years 279 (204-383) 16.9 (6.44-48.4) 378 (281-532) 1930 (1450-2560) 209 

60 years and older 457 (377-553) 76.3 (30.9-151) 513 (404-681) 2040 (1620-2580) 287 

† Estimate is subject to greater uncertainty due to small cell size. 

5 Isoflavones & Lignans 137
References 

Balk E, Chung M, Chew P, Raman G, Kupelnick B, Tatsioni A, et al. Tufts-New England Medical Center 

Evidence-based Practice Center. Effects of soy on health outcomes. Summary. Rockville (MD): Agency for 

Healthcare Research and Quality; July 2005. Evidence Report/Technology Assessment No. 126. Contract 

No. 290-02-0022.) AHRQ Publication No. 05-E024-1. 

Cassidy A, Brown JE, Hawdon A, Faughnan MA, King LJ, Millward J, et al. Factors affecting the 

bioavailability of soy isoflavones in humans after ingestion of physiologically relevant levels from 

different soy foods. J Nutr. 2006;136:45-51. 

Cornwell T, Cohick W, Raskin I. Dietary phytoestrogens and health. Phytochemistry. 2004;65:995-1016. 

Doerge DR, Chang HC, Churchwell MI, Holder CL. Analysis of soy isoflavone conjugation in vitro and in 

human blood using liquid chromatography-mass spectrometry. Drug Metab Disp. 2000;283:298-307. 

Doerge DR, Sheehan DM. Goitrogenic and estrogenic activity of soy isoflavones. Environ Health 

Perspect. 2002;110(Suppl 3):349-53. 

Erdman JW Jr, Badger TM, Lampe JW, Setchell KDR, Messina M. Not all soy products are created equal: 

caution needed in interpretation of research results. J Nutr. 2004;134:1229S-1233S. 

Grace PB, Taylor JI, Low Y, Luben RN, Mulligan AA, Botting NP, et al. Phytoestrogen concentrations 

in serum and spot urine as biomarkers for dietary phytoestrogen intake and their relation to breast 

cancer risk in European prospective investigation of cancer and nutrition—Norfolk. Cancer Epidemiol 

Biomarkers and Prev. 2004;13:698-708. 

Klein KO. Isoflavones, soy-based infant formulas, and relevance to endocrine function. Nutr Rev. 

1998;56:193-204. 

Lampe JW, Gustafson DR, Hutchins AM, Martini MG, Li S, Wahala K, et al. Urinary isoflavonoid and lignan 

excretion on a western diet: relation to soy, vegetable and fruit intake. Cancer Epidemiol Biomarkers and 

Prev. 1999;8:699-707. 

Nagel SC, vomSaal FS, Welshons WV. The effective free fraction of estradiol and xenoestrogens in human 

serum measured by whole cell uptake assays: physiology of delivery modifies estrogenic activity. Proc 

Soc Exp Biol Med. 1998;217:300-9. 

Nesbitt PD, Lam Y, Thompson LU. Human metabolism of mammalian lignan precursors in raw and 

processed flaxseed. Am J Clin Nutr. 1999;69:549-55. 

Rowland IR, Wiseman H, Sanders TAB, Adlercreutz H, Bowey EA. Interindividual variation in metabolism 

of soy isoflavones and lignans: influence of habitual diet on equol production by the gut microflora. 

Nutr Cancer. 2000;36:27-32. 

Rowland I, Faughnan M, Hoey L, Wahala K, Williamson G, Cassidy A. Bioavailability of phyto-estrogens. 

Br J Nutr. 2003;89(Suppl 1):S45-S58. 

Rozman KK, Bhatia J, Calafat AM, Chambers C, Culty M, Etzel RA, et al. NTP-CERHR expert panel 

report on the reproductive and developmental toxicity of soy formula. Birth Defects Res. (Part B) 

2006a;77:280-397. 

Rozman KK, Bhatia J, Calafat AM, Chambers C, Culty M, Etzel RA, et al. NTP-CERHR expert panel report on 

the reproductive and developmental toxicity of genistein. Birth Defects Res. (Part B) 2006b;77:485-638. 

Setchell KD, Zimmer-Nechemias L, Cai J, Heubi JE. Exposure of infants to phyto-oestrogens from soybased infant formula. Lancet. 1997;350:23-7. 

138 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Setchell KD, Cassidy A. Dietary isoflavones: biological effects and relevance to human health. J Nutr. 

1999;129:758S-67S. 

Setchell KD, Brown NM, Desai P, Zimmer-Nechemias L, Wolfe BE, Brashear WT, et al. Bioavailability of 

pure isoflavones in healthy humans and analysis of commercial soy isoflavone supplements. J Nutr. 

2001;131(4 Suppl):1362S-75S. 

Setchell KD, Briwb NM, Lydeking-Olsen E. The clinical importance of the metabolite equol: a clue to the 

effectiveness of soy and its isoflavones. J Nutr. 2002;132:3577-84. 

Setchell KDR, Brown NM, Desai PB, Zimmer-Nechimias L, Wolfe B, Jakate AS, et al. Bioavailability, 

disposition, and dose-response effects of soy isoflavones when consumed by healthy women at 

physiologically typical dietary intakes. J Nutr. 2003a; 133:1027-35. 

Setchell KDR, Faughnan MS, Acades T, Zimmer-Nechemias L, Brown NM, Wolfe BE, et al. Comparing 

the pharmacokinetics of daidzein and genistein with the use of 13C-labeled tracers in premenopausal 

women. Am J Clin Nutr. 2003b;77:411-9. 

Setchell KD, Cole SJ. Method of defining equol-producer status and its frequency among vegetarians. J 

Nutr. 2006;136:2188-93. 

Strom BL, Schinnar R, Ziegler EE, Barnhart KT, Sammel MD, Macones GA, et al. Exposure to soy-based 

formula in infancy and endocrinological and reproductive outcomes in young adulthood. JAMA. 

2001;286:807-14. 

U.S. Centers for Disease Control and Prevention. Third National Report on Human Exposure to 

Environmental Chemicals. Atlanta (GA): CDC; 2005. 

Vafeiadou K, Hall WL, Williams CM. Does genotype and equol-production status affect response to 

isoflavones? Data from a pan-European study on the effects of isoflavones on cardiovascular risk markers 

in post-menopausal women. Proc Nutr Soc. 2006;65:106-15. 

Valentin-Blasini L, Sadowski MA, Walden D, Caltabiano L, Needham LL, Barr DB. Urinary phytoestrogen 

concentrations in the U.S. population (1999–2000). J Exposure Anal Environ Epidemiol. 2005;15:509-23. 

5 Isoflavones & Lignans 139 
140 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Appendices 

Appendix A NHANES Reports Related to Nutritional Status 

Appendix B References for Analytical Methods for 

Biochemical Indicators 

Appendix C Confidence Interval Estimation for Percentiles 

Appendix D Limit of Detection Table 

Appendix E Selected References of Descriptive NHANES 

Papers on Biochemical Indicators of Diet and 

Nutrition 

141 
142 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Appendix A: 

NHANES Reports Related to Nutritional Status 

National Center for Health Statistics (NCHS) Series 11 Reports 

http://www.cdc.gov/nchs/products/pubs/pubd/series/ser.htm#sr11 

Hollowell JG, van Assendelft OW, Gunter EW, Lewis BG, Najjar M, Pfeiffer C. Hematological and 

iron-related analytes—Reference data for persons aged 1 year and over: United States, 1988–1994. 

National Center for Health Statistics. Vital Health Stat Series No. 11(247), 2005. 

Bialostosky K, Wright JD, Kennedy-Stephenson J, McDowell M, Johnson CL. Dietary intake of 

macronutrients, micronutrients, and other dietary constituents: United States 1988–1994. National 

Center for Health Statistics. Vital Health Stat Series No. 11(245), 2002. 

Ervin RB, Wright JD, Kennedy-Stephenson J. Use of dietary supplements in the United States, 

1988–1994. National Center for Health Statistics. Vital Health Stat Series No. 11(244), 1999. 

Wright JD, Bialostosky K, Gunter EW, Carroll MD, Najjar MF, Bowman BA, Johnson CL. Blood folate and 

vitamin B12: United States, 1988–1994. National Center for Health Statistics. Vital Health Stat Series 

No. 11(243), 1998. 

Fulwood R, Johnson CL, Bryner JD, Gunter EW, McGrath CR. Hematological and nutritional 

biochemistry reference data for persons 6 months–74 years of age: United States, 1976–1980. 

National Center for Health Statistics. Vital Health Stat Series No. 11(232), 1982. 

National Center for Health Statistics (NCHS) Series 2 Reports 

http://www.cdc.gov/nchs/products/pubs/pubd/series/ser.htm#sr2 

Looker AC, Gunter EW, Cook JD, Green R, Harris JW. Comparing serum ferritin values from different 

population surveys. National Center for Health Statistics. Vital Health Stat Series No. 2(111), 1991. 

National Center for Health Statistics (NCHS) Advance Data Reports 

http://www.cdc.gov/nchs/about/major/nhanes/advancedatas.htm 

Advance Data No. 349. Prevalence of leading types of dietary supplements used in the Third National 

Health and Nutrition Examination Survey, 1988–94. 

Advance Data No. 341. Dietary intake of selected minerals for the United States population: 

1999–2000. 

Advance Data No. 339. Dietary intake of selected vitamins for the United States population: 

1999–2000. 

Advance Data No. 334. Dietary intake of ten key nutrients for public health, United States: 1999–2000. 

Appendices 143 
Life Sciences Research Office (LSRO) Reports 

Pilch SM. Assessment of the vitamin A nutritional status of the U.S. population based on data 

collected in the Health and Nutrition Examination Surveys. Bethesda (MD): Federation of American 

Societies for Experimental Biology; 1985. 

Senti FR, Pilch SM. Analysis of the folate nutritional status of the U.S. population based on data 

collected in the Second National Health and Nutrition Examination Survey, 1976–1980. Bethesda 

(MD): Federation of American Societies for Experimental Biology; 1984. 

Pilch SM, Senti FR. Assessment of iron nutritional status of the U.S. population based on data collected 

in the Second National Health and Nutrition Examination Survey, 1976–1980. Bethesda (MD): 

Federation of American Societies for Experimental Biology; 1984. 

Pilch SM, Senti FR. Assessment of zinc nutritional status of the U.S. population based on data collected 

in the Second National Health and Nutrition Examination Survey, 1976–1980. Bethesda (MD): 

Federation of American Societies for Experimental Biology; 1984. 

144 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Appendix B: 

References for Analytical Methods for Biochemical 

Indicators 

Detailed Laboratory Procedure Manuals for Analytical Methods 

•	 NHANES 1999–2000: 

http://www.cdc.gov/nchs/about/major/nhanes/lab_methods99_00.htm 

•	 NHANES 2001–2002: 

http://www.cdc.gov/nchs/about/major/nhanes/lab_methods01_02.htm 

Additional Useful Analytical Method References 

Water-Soluble Vitamins & Related Biochemical Compounds 

Life Sciences Research Office. Assessment of folate methodology used in the Third National Health 

and Nutrition Survey (NHANES 1988–1994). Washington, D.C.: Center for Food Safety and Applied 

Nutrition, Food and Drug Administration, Department of Health and Human Services; 1994. 

Gunter EW, Bowman BA, Caudill SP, Twite DB, Adams MJ, Sampson EJ. Results of an international 

round robin for serum folate and whole-blood folate. Clin Chem. 1996;42:1689-94. 

Pfeiffer CM, Twite D, Shih J, Holets-McCormack SR, Gunter EW. Method comparison for total plasma 

homocysteine between the Abbott IMx analyzer and an HPLC assay with internal standardization. Clin 

Chem. 1999;45(1):152-3. 

Pfeiffer CM, Huff DL, Smith SJ, Miller DT, Gunter EW. Comparison of plasma total homocysteine 

measurements in 14 laboratories: an international study. Clin Chem. 1999;45(8):1261-8. 

Pfeiffer CM, Caudill SP, Gunter EW, Bowman BA, Jacques PF, Selhub J, et al. Discussion of critical issues 

related to the comparison of homocysteine values between the Third National Health and Nutrition 

Examination Survey (NHANES) and NHANES 1999+. J Nutr. 2000;130:2850-4. 

Pfeiffer CM, Smith SJ, Miller DT, Gunter EW. Comparison of serum and plasma methylmalonic acid 

measurements in 13 laboratories: an international study. Clin Chem. 1999;45:2236-42. 

Fat-Soluble Vitamins & Micronutrients 

Sowell AL, Huff DL, Yeager PR, Caudill SP, Gunter EW. Retinol, alpha-tocopherol, lutein/zeaxanthin, 

beta-cryptoxanthin, trans-lycopene, alpha-carotene, trans-beta-carotene, and four retinyl esters in 

serum determined simultaneously by reversed-phase HPLC with multi-wavelength detection. Clin 

Chem. 1994;40:411-6. 

Appendices 145 
Trace Elements 

Paschal DC, Kimberly MM. Automated direct determination of selenium in serum by electrothermal 

atomic absorption spectroscopy. At Spectrosc. 1986;7:75-8. 

Caldwell KL, Maxwell CB, Makhmudov A, Pino S, Braverman LE, Jones RL, et al. Use of inductively 

coupled plasma mass spectrometry to measure urinary iodine in NHANES 2000: comparison with 

previous method. Clin Chem. 2003;49:1019-21. 

Iron-Status Indicators 

Blanck HM, Pfeiffer CM, Caudill SP, Reyes R, Gunter EW, Imperatore G, et al. Serum iron and ironbinding capacity: a round-robin interlaboratory comparison study. Clin Chem. 2003;49:1672-5. 

Looker AC, Gunter EW, Johnson CL. Methods to assess iron status in various NHANES surveys. Nutr 

Rev. 1995;53:246-54. 

Isoflavones & Lignans 

Valentin-Blasini L, Blount BC, Rogers HS, Needham LL. HPLC-MS/MS method for the measurement of 

seven phytoestrogens in human serum and urine. J Expo Anal Environ Epidemiol. 2000;10:799-807. 

Kuklenyik Z, Ye X, Reich JA, Needham LL, Calafat AM. Automated on-line and off-line solid 

phase extraction methods for measuring isoflavones and lignans in urine. J Chromatogr Sci. 

2004;42:495-500. 

146 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Appendix C: 

Confidence Interval Estimation for Percentiles 

A common practice to calculate confidence intervals from survey data is to use large-sample normal 

approximations. Ninety-five percent confidence intervals on point estimates of percentiles are often 

computed by adding and subtracting from the point estimate a quantity equal to twice its standard 

error. This normal approximation method may not be adequate, however, when estimating the 

proportion of subjects above or below a selected value (especially when the proportion is near 0.0 or 

1.0 or when the effective sample size is small). 

In addition, confidence intervals on proportions deviating from 0.5 are not theoretically expected to 

be symmetric around the point estimate. Further, adding and subtracting a multiple of the standard 

error to an estimate near 0.0 or 1.0 can lead to impossible confidence limits (i.e., proportion estimates 

below 0.0 or above 1.0). 

We used the method of Korn and Graubard (1998) to compute Clopper-Pearson 95 percent 

confidence intervals about percentile estimates. We describe the method below, using SAS Proc 

Univariate and SUDAAN. SAS code for calculating these confidence intervals can be downloaded from 

http://www.cdc.gov/exposurereport. 

Procedure to calculate confidence intervals about percentiles 

Step 1: Use SAS (SAS Institute Inc., 1999) Proc Univariate to obtain a point estimate of the percentile 

of a chemical’s results for the demographic group of interest (e.g., the 90th percentile of blood 

lead results for children aged 1–5 years). Use the Freq option to assign the correct sample 

weight for each chemical result. 

Step 2: Use SUDAAN (SUDAAN Users Manual, 2001) Proc Descript with Taylor Linearization DESIGN = 

WR (i.e., sampling with replacement) and the proper sampling weight to estimate the 

proportion (p) of subjects with results below the percentile estimate obtained in Step 1 and 

to obtain the standard error (sep

) associated with this proportion estimate. Compute the 

degrees-of-freedom adjusted effective sample size 

n =((t /t )2

)p(1 - p)/(se 2) (1) df num denom p 

where t and t are 0.975 critical values of the Student’s t distribution with degrees of num denom

freedom equal to the sample size minus 1 and the number of PSUs minus the number of 

strata, respectively. Note: the degrees of freedom for t can vary with the demographic denom

subgroup of interest (e.g., males). 

Appendices 147 
 

Step 3: After obtaining an estimate of p (i.e., the proportion obtained in Step 2), compute the 

Clopper-Pearson 95 percent confidence interval (P (x,n ), P (x,n )) as follows: L df U df 

P (x,n ) = v F (0.025)/(v + v F (0.025)) & P (x,n ) = v F (0.975)/(v + v F (0.975)) (2) L df 1 v1,v2 2 1 v1,v2 U df 3 v3,v4 4 3 v3,v4

where x is equal to p times n , v = 2x, v = 2(n - x + 1), v = 2(x + 1), v = 2(n - x), and F (β) df 1 2 df 3 4 df d1,d2

is the β quantile of an F distribution with d1 and d2 degrees of freedom. (Note: If ndf is greater 

than the actual sample size, or if p is equal to zero, then the actual sample size should be 

used.) This step will produce a lower and an upper limit for the estimated proportion 

obtained in Step 2. 

Step 4: Use SAS Proc Univariate (again using the Freq option to assign weights) to determine the 

chemical values that correspond to the proportion obtained in Step 2 and the lower and 

upper limits on this proportion obtained in Step 3. 

Example: 

To estimate the 75th percentile, use SAS Proc Univariate with the Freq option to get a weighted point 

estimate of the chemical value that corresponds to the 75th percentile. Then use SUDAAN to estimate 

the weighted proportion of subjects with results below the 75th percentile (which should be very 

near 0.75). Next, obtain a confidence interval on this proportion by computing the weighted ClopperPearson 95 percent confidence limits using the degrees-of-freedom adjusted effective sample size. 

Suppose these confidence limits are 0.67 and 0.81, then use SAS Proc Univariate with the Freq option to 

determine the chemical values corresponding to the weighted 67th and 81st percentiles. These point 

estimates are the lower and upper confidence limits on the 75th percentile. 

References 

Korn EL, Graubard BI. Confidence intervals for proportions with small expected number of positive 

counts estimated from survey data. Survey Methodology. 1998;24:193-201. 

148 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Appendix D: 

Limit of Detection Table 

The table below presents the analytical limit of detection (LOD) for each of the different indicators. 

The LOD is the level at which the measurement has a 95 percent probability of being greater than 

zero (Taylor 1987). For the same indicator, LOD values may change over time as a result of changes to 

analytical methods. This was the case for urinary phytoestrogens. We used the higher of the two LOD 

values for the analysis of the combined four-year data. 

Indicator Units 1999–2000 2001–2002 

Water-Soluble Vitamins & Related Biochemical Compounds 

Serum folate ng/mL 0.1 0.1 

Red blood cell (RBC) folate ng/mL RBC 20 20 

Serum vitamin B12 pg/mL 20 20 

Plasma homocysteine μmol/L 0.35 0.35 

Plasma methylmalonic acid μmol/L 0.05 0.05 

Fat-Soluble Vitamins & Micronutrients 

Serum vitamin A μg/dL 1.03 1.03 

Serum vitamin E μg/dL 40.7 40.7 

Serum gamma-tocopherol μg/dL 10.7 10.7 

Serum alpha-carotene μg/dL 0.7 

Serum trans-beta-carotene μg/dL 0.8 

Serum beta-cryptoxanthin μg/dL 0.9 

Serum lutein/zeaxanthin μg/dL 2.4 

Serum	trans-lycopene μg/dL 0.8 

Serum vitamin D, 25-hydroxy ng/mL 1.5 

Iron-Status Indicators 

Serum ferritin ng/mL 1.1 1.1 

Serum iron μg/dL 2 

Serum total iron-binding capacity μg/dL 6 

Serum transferrin saturation % n/a 

Erythrocyte protoporphyrin μg/dL RBC 1 

Trace Elements 

Urinary iodine ng/mL 1.0 

Serum selenium ng/mL 8 

Isoflavones & Lignans 

Urinary genistein μg/L 0.3 0.8 

Urinary daidzein μg/L 0.5 1.6 

Urinary equol μg/L 3.0 3.3 

Urinary O-desmethylangolensin μg/L 0.2 0.4 

Urinary enterodiol μg/L 0.8 1.5 

Urinary enterolactone μg/L 0.6 1.9 

Appendices 149 
References 

Taylor JK. Quality assurance of chemical measurements. Chelsea (MI): Lewis Publishing; 1987. 

150 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002
 
Appendix E: 

Selected References of Descriptive NHANES Papers on 

Biochemical Indicators of Diet and Nutrition 

Water-Soluble Vitamins & Related Biochemical Compounds 

Bentley TGK, Willett WC, Weinstein MC, Kuntz KM. Population-level changes in folate intake by age, 

gender, and race/ethnicity after folic acid fortification. Am J Public Health. 2006;96:2040-7. 

Boulet SL, Yang Q, Mai C, Mulinare J, Pfeiffer CM. Folate status in women of childbearing age by 

race/ethnicity—United States 1999–2000, 2001–2002, and 2003–2004. Morb Mortal Wkl Rep. 

2007;55(51):1377-80. 

Dietrich M, Brown CJP, Block G. The effect of folate fortification of cereal-grain products on blood 

folate status, dietary folate intake and dietary folate sources among adult non-supplement users in 

the United States. J Am Coll Nutr. 2005;24:266-74. 

Ganji V, Kafai MR. Trends in serum folate, RBC folate, and circulating total homocysteine 

concentrations in the United States: analysis of data from National Health and Nutrition Examination 

Surveys, 1988–1994, 1999–2000, and 2001–2002. J Nutr. 2006;136:153-8. 

Ganji V, Kafai MR. Population reference values for plasma total homocysteine concentrations in US 

adults after the fortification of cereals with folic acid. Am J Clin Nutr. 2006;84:989-94. 

Ganji V, Kafai MR. Population references for plasma total homocysteine concentrations for US children 

and adolescents in the post-folic acid fortification era. J Nutr. 2005;135:2253-6. 

Ganji V, Kafai MR. Serum total homocysteine concentration determinants in non-Hispanic white, nonHispanic black, and Mexican-American populations of the United States. Ethn Dis. 2004;14:476-82. 

Ganji V, Kafai MR. Demographic, health, lifestyle, and blood vitamin determinants of serum total 

homocysteine concentrations in the Third National Health and Nutrition Examination Survey, 

1988-1994. Am J Clin Nutr. 2003;77:826-33. 

Morris MS, Jacques PF, Rosenberg IH, Selhub J. Elevated serum methylmalonic acid concentrations are 

common among elderly Americans. J Nutr. 2002;132:2799-2803. 

Must A, Jacques PF, Rogers G, Rosenberg IH, Selhub J. Serum total homocysteine concentrations in 

children and adolescents: results from the Third National Health and Nutrition Examination Survey 

(NHANES III). J Nutr. 2003;133:2643-9. 

Pfeiffer CM, Osterloh JD, Kennedy-Stephenson J, Picciano MF, Yetley EA, Rader JI, Johnson CL. Trends 

in circulating concentrations of total homocysteine among US adolescents and adults: findings 

from the 1991–1994 and 1999–2004 National Health and Nutrition Examination Surveys. Clin Chem. 

2008;54:801-13. 

Appendices 151 
Pfeiffer CM, Johnson CL, Jain RB, Yetley EA, Picciano MF, Rader JI, Fisher KD, et al. Trends in blood folate 

and vitamin B12 concentrations in the United States, 1988–2004. Am J Clin Nutr. 2007;86:718-27. 

Pfeiffer CM, Caudill SP, Gunter EW, Osterloh J, Sampson EJ. Biochemical indicators of B vitamin status 

in the U.S. population after folic acid fortification: results from the National Health and Nutrition 

Examination Survey 1999–2000. Am J Clin Nutr. 2005;82:442-50. 

Selhub J, Jacques PF, Rosenberg IH, Rogers G, Bowman BA, Gunter EW. Serum total homocysteine 

concentrations in the Third National Health and Nutrition Examination Survey (1991–1994): 

population reference ranges and contribution of vitamin status to high serum concentrations. Ann 

Intern Med. 1999;131:331-9. 

U.S. Centers for Disease Control and Prevention. Folate status in women of childbearing age, by race/ 

ethnicity — United States, 1999–2000. Morb Mortal Wkl Rep. 2002;51:808-10. 

Wright JD, Bialostosky K, Gunter EW, Carroll MD, Najjar MF, Bowman BA, Johnson CL. Blood folate and 

vitamin B12: United States, 1988–1994. National Center for Health Statistics. Vital Health Stat Series 

No. 11(243), 1998. 

Yang Q-H, Carter HK, Mulinare J, Berry RJ, Friedman JM, Erickson JD. Race-ethnicity differences in 

folic acid intake in women of childbearing age in the United States after folic acid fortification: 

findings from the National Health and Nutrition Examination Survey, 2001–2002. Am J Clin Nutr. 

2007;85:1409-16. 

Fat-Soluble Vitamins & Micronutrients 

Ford ES, Schleicher RL, Mokdad AH, Ajani UA, Liu S. Distribution of serum concentrations of 

α-tocopherol and γ-tocopherol in the U.S. population. Am J Clin Nutr. 2006;84:375-83. 

Ford ES, Ajani UA, Mokdad AH. Brief communication: the prevalence of high intake of vitamin E from 

the use of supplements among U.S. adults. Ann Intern Med. 2005;143:143-5. 

Ford ES, Liu S, Mannino DM, Giles WH, Smith SJ. C-reactive protein concentration and concentrations 

of blood vitamins, carotenoids, and selenium among United States adults. Eur J Clin Nutr. 

2003;57:1157-63. 

Gillespie C, Ballew C, Bowman BA, Donehoo R, Serdula MK. Intraindividual variation in serum retinol 

concentrations among participants in the Third National Health and Nutrition Examination Survey, 

1988–1994. Am J Clin Nutr. 2004;79:625-32. 

Gruber M, Chappell R, Millen A, LaRowe T, Moeller SM, Iannaccone A, et al. Correlates of serum lutein 

+ zeaxanthin: findings from the Third National Health and Nutrition Examination Survey. J Nutr. 

2004;134:2387-94. 

152 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Knutsen SF, Fraser GE, Linsted KD, Beeson WL, Shavlik DJ. Comparing biological measurements 

of vitamin C, folate, alpha-tocopherol and carotene with 24-hour dietary recall information in 

nonhispanic blacks and whites. Ann Epidemiol. 2001;11:406-16. 

Looker AC, Dawson-Hughes B, Calvo MS, Gunter EW, Sahyoun NR. Serum 25-hydroxyvitamin D status 

of adolescents and adults in two seasonal subpopulations from NHANES III. Bone. 2002;30:771-7. 

Nesby-O’Dell S, Scanlon KS, Cogswell ME, Gillespie C, Hollis BW, Looker AC, et al. Hypovitaminosis D 

prevalence and determinants among African American and white women of reproductive age: third 

National Health and Nutrition Examination Survey, 1988-1994. Am J Clin Nutr. 2002;76:187-92. 

Stimpson JP, Urrutia-Rojas X. Acculturation in the United States is associated with lower serum 

carotenoid levels: third National Health and Nutrition Examination Survey. J Am Diet Assoc. 

2007;107:1218-23. 

Zadshir A, Tareen N, Pan D, Norris K, Martins D. The prevalence of hypovitaminosis D among US adults: 

data from the NHANES III. Ethn Dis. 2005;15(4 Suppl 5):S5-97-101. 

Iron-Status Indicators 

Brotanek JM, Gosz J, Weitzman M, Flores G. Iron deficiency in early childhood in the United States: risk 

factors and racial/ethnic disparities. Pediatrics. 2007;120:568-75. 

Looker AC, Cogswell ME, Gunter EW. Iron deficiency—United States, 1999–2000. Morb Mortal Wkly 

Rep. 2002;51:897-9. 

Looker AC, Dallman PR, Carroll M, Gunter EW, Johnson CL. Prevalence of iron deficiency in the United 

States. JAMA. 1997;277:973-5. 

Looker AC, Gunter EW, Johnson CL. Methods to assess iron status in various NHANES surveys. Nutr 

Rev. 1995;53:246-54. 

Looker AC, Gunter EW, Cook JD, Green R, Harris JW. Comparing serum ferritin values from different 

population surveys. National Center for Health Statistics. Vital Health Stat Series No 2(111), 1991. 

Michels Blanck H, Cogswell ME, Gillespie C, Reyes M. Iron supplement use and iron status among 

US adults: results from the Third National Health and Nutrition Examination Survey. Am J Clin Nutr. 

2005;82:1024-31. 

Ramakrishnan U, Frith-Terhune A, Cogswell M, Kettel Khan L. Dietary intake does not account for 

differences in low iron stores among Mexican American and non-Hispanic white women: third 

National Health and Nutrition Examination Survey, 1988–1994. J Nutr. 2002;132:996-1001. 

Appendices 153 
Trace Elements 

Caldwell KL, Jones R, Hollowell JG. Urinary iodine concentration: United States National Health and 

Nutrition Examination Survey 2001–2002. Thyroid. 2005;15:692-9. 

Hollowell JG, Staehling NW, Hannon WH, Flanders DW, Gunter EW, Maberly GF, et al. Iodine nutrition in 

the United States. Trends and public health implications: iodine excretion data from National Health 

and Nutrition Examination Surveys I and III (1971–1974 and 1988–1994). J Clin Endocrinol Metab. 

1998;83:3401-8. 

Semba RD, Ricks MO, Ferrucci L, Xue QL, Guralnik JM, Fried LP. Low serum selenium is associated with 

anemia among older adults in the United States. Eur J Clin Nutr. In press 2008. 

Vogt TM, Ziegler RG, Patterson BH, Graubard BI. Racial differences in serum selenium concentrations: 

analysis of US population data from the Third National Health and Nutrition Examination Survey. Am J 

Epidemiol. 2007;166:280-8. 

Isoflavones & Lignans 

U.S. Centers for Disease Control and Prevention. Third National Report on Human Exposure to 

Environmental Chemicals. Atlanta (GA): CDC; 2005. 

Valentin-Blasini L, Sadowski MA, Walden D, Caltabiano L, Needham LL, Barr DB. Urinary phytoestrogen 

concentrations in the U.S. population (1999–2000). J Expo Anal Environ Epidemiol. 2005;15:509-23. 

Valentin-Blasini L, Blount BC, Caudill SP, Needham LL. Urinary and serum concentrations of 

seven phytoestrogens in a human reference population subset. J Expo Anal Environ Epidemiol. 

2003;13:276-82. 

154 National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population 1999-2002 
Appendices 155
 
Centers for Disease Control and Prevention 

National Center for Environmental Health 

Division of Laboratory Sciences 

Mail Stop F-20 

4770 Buford Highway, NE 

Atlanta, Georgia 30341-3724 

Telephone (toll-free): 1-800-CDC-Info (1-800-232-4636) 

Email: CDCINFO@cdc.gov 

Web site: www.cdc.gov/nutritionreport