a

s“

Diet and Iron

Status, A Study

of Relationships:

United States,

1971-74

.

This reporl presents findings of the first

National Health and Nutrition Examination

Survey on the iron status of the U.S.

population 1-74 years of age during

1971-74. The relationship between several dietary, health, and socioeconomic variables and iron status also are presented

in this report for selected population

groups.

Data From the National Health

Survey

Series 11. No. 229

DHHS Publication No. (PHS) 83-1679

U.S. Department of Health and Human

Services

Public Health Service

National Center for Health Statistics

Hyattsvil Ie, Md.

December 1982

National Center for Health Statistics

ROBERT A. ISIWEL, Acting Director

JACOB J. FELDMAN, Ph. D., Associate Director for

Analysis and Epidemiology

GAIL F. FISHER, Ph. D., Associate Director for the

Cooperative Health Statistics System

GARRIE J. LOSEE, Associate Director for Data

Processing and Services

ALVAN O. ZARATE, Ph. D., Assistant Director for

Itzternational Statistics

E. EARL BRYANT, Associate Director for Interview

and Examination Statistics

ROBERT L. QUAVE, Acting Associate Director for

Management

MONROE G. SIRKEN, Ph. D., Associate Director for

Reseawh and Methodology

PETER L. HURLEY, Associate Director for Vital and

Health Care Statistics

ALICE HAYWOOD, Information Oficer

Interview and Examination Statistics Program

E. EARL BRYANT, Associate Directtir

MARY GRACE KOVAR, Special Assistant for

Policy and Analysis

Division of Health Examination Statistics

ROBERT S. MURPHY, Director

Data

SIDNEY ABIWHAM, ChieJ Nutrition Statistics

Branch

JEAN ROBERTS, Chief Medical Statistics Branch

KURT R. MAURER, ChieJ Survey Planning and

Development Branch

Data Processing and Services Program

GARRIE J. LOSEE, Associate Director

ALAN K. KREGER, ChieJ Computer Users Stay

Division of Data Services

JAMES C. JACKS, Ph. D., Director

PHILLIP R. BEATTIE, Deputy Director

DAVID L. LARSON, ChieJ Health Examination Field

Operation Branch

Cooperation of the U.S. Bureau of the Censu~

Under the legislation establishing the National Health Survey, the Put,lic

Health Sewice is authorized to use, insofar as pnssible, the services or facilities

of other Federal, State, or private agencies. In accordance with specifications

established by the National Center for Health Statistics, the U.S. Bureau ,Df the

Census participated in the design and selectinn of the sample and carried out

the household interview stage of the data colkclion and certain parts of the

statistical processing.
Foreword and

acknowledgments

The National Health and Nutrition Examination

Survey is the only source of general U.S. population

data that provides a direct link between indicators of

health and nutritional status and reported dietary

intake information. Congress provided resources in the

“Departments of Labor, Health and Human Services,

and Related Agencies Appropriation Bill, 1980” to the

National Center for Health Statistics to fund an

initiative to undertake more detailed analyses of

nutrition-related health problems measured in the first

National Health and Nutrition Examination Survey.

As part of this initiative, the Division of Health

Examination Statistics and the Division of Nutrition,

Center for Health Promotion and Education, Centers

for Disease Control, funded a contract (no.

233-79–209 1) with Abt Associates, Inc. in Cambridge,

Mass., to examine relationships among dietary intake

of iron and measures of anemia and to relate the

prevalence of anemia to various socioeconomic and

demographic variables.

The approach and depth of analysis presented in

this report differ from most reports from the Division

of Health Examination Statistics. This report is based

on a statistical rather than a descriptive presentation of

the data.

Cognizant that the underlying assumptions of

traditional statistical analyses are violated to some

extent, the degree of which is unknown, the authors

and National Center for Health Statistics staff jointly

determined that the assumptions made in the analyses

presented in this report are reasonable in light of

present knowledge. In addition, the authors have

presented material throughout the text and technical

appendix that concerns appropriate qualifications

readers should consider in interpreting the results and

conclusions presented.

Analyses for this report were undertaken by the

staff of Abt Associates, Inc., with the assistance of

several consultants in the fields of nutrition, hematology, and biochemistry. Dr. Linda Meyers, Dr. JeanPierre Habicht, and D. Yvonne Jones of Cornell

University investigated relationships between socioeconomic status and iron status. Drs. Meyers and Habicht

also helped to select appropriate definitions of anemia

and to clarify the overall process of iron metabolism.

Dr. James Cook of the University of Kansas Medical

Center was instrumental in developing an algorithm

when applied to dietary intake data-estimated available iron. Dr. Peter Dallman of the University of

California, San Francisco, School of Medicine contributed especially to the knowledge of pediatric hematology, prevalence of anemia, and racial differences in

iron status. In addition, Dr. Jack Smith of the

Swanson Center for Nutrition, Omaha, Neb., provided

overall technical guidance, particularly in the area of

biochemistry. All of these consultants also helped to

select variables to be investigated and to determine

subgroups on which to focus the analyses. Their

assistance throughout the investigation is greatly

appreciated.

Several Abt Asociates, Inc. staff members also

gave invaluable support. In particular, Catharine

Barclay directed the data processing and performed

analyses for children ages 1–3 years; Dr. Barbara

Dillon Goodson provided statistical support and performed analyses for menstruating women ages 12–54

years; and Dr. Patricia Granahan undertook a review

of the literature as well as analyses for elderly persons

ages 65–74 years. Additional computer support was

provided by Dr. Charles Cole, who developed a

program to estimate absorbable iron. Dr. John Himes

and Mary Kay O’Neill Fox helped to prepare and

review the final manuscript and tables. The support of

these persons was instrumental to the successful

completion of the project.

A very special acknowledgment goes to Ms. Penny

Spingam, who provided invaluable assistance in the

substantive editing and revising of this report.

Robert S. Murphy

Director

Division of Health Examination Statistics

...

Ill
Contents

Foreword and acknowledgments ...................................................................................................................................................

Introduction ......................................................................................................................................................................................

Highlights ..........................................................................................................................................................................................

Background—Review of the literature ...........................................................................................................................................

Anemia and iron status ............................................................................................................................................................

Iron nutrition in the individual ..................................................................................................................................................

Groups at risk of iron deficiency and anemia .........................................................................................................................

Preschool children ............................................................................................................................................................

Women of childbearing age .............................................................................................................................................

The elderly ........................................................................................................................................................................

Methodology Sources and limitations of the data ........................................................................................................................

Survey procedure .....................................................................................................................................................................

Biochemical determinations ....................................................................................................................................................

Assessment of iron status .......................................................................................................................................................

Calculation of dietary intake and absorbable iron .................................................................................................................

Relational analyses: Analytical subgroups, independent variables, and tests of statistical significance .........................

Hndings ............................................................................................................................................................................................

Iron status .................................................................................................................................................................................

Age and sex ......................................................................................................................................................................

Race ..................................................................................................................................................................................

Pregnancy .........................................................................................................................................................................

Iron intake and iron status .......................................................................................................................................................

Age, sex, and race ............................................................................................................................................................

Pregnancy .........................................................................................................................................................................

Relational anaIyses ..................................................................................................................................................................

Children ages 1-3 years ..................................................................................................................................................

Menstruating women ages 12-54 years .........................................................................................................................

Elderly persons ages 65-74 years ..................................................................................................................................

Dscussion ........................................................................................................................................................................................

Iron status in the United States ................................................................................................................................................

Diet ........................................................................................................................................................................ ....................

Socioeconomic, demographic, and health factors ................................................................................................................

References .......................................................................................................................................................................................

List of detailed tables ......................................................................................................................................................................

.,.

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iv
Appendixes

1. Statistical notes ................................................................................................................................................ ......................... ..

H. Definitions of terms ........................................................................................................................................................ .............

List of text figures

1. Prevalence of low hemoglobin levels, by sex and age: United States, 1971.74 ................................................................

2. Prevalence of low hemoglobin levels among males, by race and age: United States, 1971-74 ......................................

3. Prevalence of low hemoglobin levels among females, by race and age: United States, 1971 -74 ...................................

4. Prevalence of low transferring saturation levels, by sex and age: United States, 1971-74 ................................................

5. Prevalence of low transferringsaturation levels among males, by race and age: United States, 1971-74 .......................

6. Prevalence of low transferringsaturation levels among females, by race and age: United States, 1971–74 ....................

7. Prevalence of low hemoglobin and low transferring saturation levels, by sex and age: United States, 1971 -74 .............

8. Prevalence of low hemoglobin and low transferring saturation levels among males, by race and age: United States,

1971-74. . ...................................................................................................................................................... ............... .............

9. Prevalence of low hemoglobin and low transferring saturation levels among females, by race and age: United States,

1971.74 ....................................................................................................................................................................................

10. Mean iron intake for males ages 1-74 years, by age and hemoglobin levels: United States, 1971 -74 ............................

11. Mean iron intake for females ages 1-74 years, by age and hemoglobin levels: United States, 1971 –74 ........................

12. Mean iron intake for males ages 1-74 years, by age and transferring saturation levels: United States, 1971 -74 ............

13. Mean iron intake for females ages 1-74 years, by age and transferring saturation levels: United States, 1971 -74 ........

List of text tables

A. Age- and sex-specific hemoglobin reference standards ........................................................................................................

B. Z-statistics for comparison of iron intake for low and adequate iron status for pregnant women 1844 years, with

mean, and standard error of the mean, by iron status indicator and race: United States, 1971 -74 ...................................

75

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Symbols used in tables

. . . Data not available

. . . Categow not applicable

Quantity zero

0.0 Quantity more than zero but lessthan

0.05

z Quantity more than zero but lessthan

500 where numbers are rounded to

thousands

●

Figure does not meet standards of

reliability or precision

# Figure suppressed to comply with

confidentiality requirements
Diet and Iron Status, A

Study of Relationships

by Judith D. Singer, M.A., Patricia Granahan, SC.D., Nancy

N. Goodrich, Ed.D., Abt Associates, Inc., Linda D. Meyers,

Ph.D., Cornell University and Clifford L, Johnson, M.S,P.H.,

Division of Health Examination Statistics

Introduction

This report presents the results of a study of iron

statusand selected dietary, health, socioeconomic, and

demographic correlates. Findings are based on data

from the first National Health and Nutrition Examination Survey; the CataZog of Publications of the National

Center for Health Statistical should be consulted if

previous reports are of interestto the reader.

The first National Health and Nutrition Examination Survey was one in a series of related programs

carried out by the National Center for Health Statistics under authorization by Congress in the National

Health Survey Act of 1956. The programs characteristically are national in scope, based on probability

sampling, and used to collect a broad range of

morbidity data and related health information. The

essential differentiating characteristic of the health

examination surveys is their primary concern with

health-related data obtained only (or at least optimally) from specially standardized direct medical examinations, including tests and other procedures used in

clinical practice. Examinations given to persons selected in the scientific sample permit estimates of the total

prevalence of specifically defined diseases in the U.S.

population. They also permit estimation of the distribution within the population of a broad variety of

health-related measurements, including physical measurements, such as height, weight, and various skinfolds

as well as physiological measurements, such as diastolic blood pressure, serum cholesterol level, and psychological measurements.

The first National Health and Nutrition Examination Survey and earlier examination studies conducted

by the Center are unique in that specially designed and

constructed mobile examination centers were moved to

the selected sample areas so that standard physical

examinations could be given under standard conditions. The team of interviewers and examiners also

moved with the examination centers.

Standard physical examinations of a probability

sample of the population have several advantages over

other means of collecting data about the health of the

population:

The examination can be designed to focus upon

specified conditions and furnish more reliable

estimates of the total prevalence of the conditions

than can be obtained by interview. Cases unknown

to the examinee can be identtied, and the criteria

for diagnoses can be specified carefidly.

The use of mobile examination centers and a small

team of specially trained personnel reduces the

variability that is found in studies using local

facilities and personnel.

The instruments are recalibrated, and interviewing

and examining are monitord so the only variance

should be the person examined.

The probability design reduces the potential bias

that might be found in populations selected for

other specific purposes.

The first National Health and Nutrition Examination Survey was conducted from April 1971 to June

1974 and included medical, dermatological, and dental

examinations; body measurements; dietary interviews;

medical histories; and demographic interviews of a

national probability sample. A detailed description of

the specific content and plan of operation of the

survey, inclu~ing the sample design and forms used to

collect the dap has been published. 2

In this rep@t, data from the biochemical determinations were used to determine the prevalence of three

categories of iron status—low hemoglobin, low percent

transfernn saturation, and low hemoglobin combined

with low percent transferringsaturation. The dietary

interviews provided data to investigate the iron intake

of persons in these,categories. Other analyses explored

the association between selected demographic, health,

and dietary characteristics and the three categories of

iron status defined in this report.

1
Highlights

The analyses of the data from this national survey

by various subpopulations showed that:

Iron-deficiency anemia, measured by the combination of low hemoglobin and low transferring saturation levels, is not widespread in the United States.

The prevalence of low hemoglobin is most common in young children, pregnant women, elderly

men, and the black population.

The prevalence of low hemoglobin, low transferring

saturation, and the combination of these two

measures is marked among children ages 1–3

years.

Of the three measures of iron status, low transferring saturation, which indicates that iron status is

less than optimal but has not necessarily deteriorated to the point of causing anemia, is the most

prevalent. It is most common in young children

and women of childbearing age.

Reported iron intake is below recommended allowances for many subpopulations. The relationship between reported dietary iron intake and the three iron

status categories was examined for persons ages 1–74

years and was analyzed by age, race, sex, and pregnancy status.

●

●

●

Except among young children, there is no strong

relationship between reported iron intake and iron

status as measured by hemoglobin levels or transferring saturation levels.

Among children ages 1–3 years, for whom reported iron intake and iron status are associated, mean

iron intake and an estimate adjusted for availability were examined, and the adjustment for availability did not affect the association.

Failure to find associations between reported iron

intake and iron status may be due to problems in

the method used to collect dietary information or

to problems inherent in the use of reference

standards to classify persons into iron status

categories. Only a small portion of ingested iron is

absorbed, which may compound the problems.

Dietary, health, socioeconomic, and demographic

characteristics that may affect iron status in three

high-risk groups-children ages 1–3 years, menstruating women ages 12–54 years, and persons ages 65–74

years—were examined in multivariate logistic ar[alyses.

●

●

Two socioeconomic variables, a poverty index and

low education of the head of household, are

associated with poor iron status.

Low iron intake is significantly associated with low

hemoglobin levels among children ages 1–3 years.

Previous pregnancy and diagnosis of anemia are

associated with poor iron status among menstruating women; the use of oral contraceptives is

associated with adequate iron status. None of’ the

variables related to dietary habits is associated ‘with

any of the iron status categories for this group.

Poor general health and trouble eating are the

variables most associated with poor iron status

among persons ages 65–74 years. However, the

association was not consistent in all categories, No

variables related to dietary habits are associated

with iron status in this population.

Cross-sectional survey data cannot be interpreted

as showing cause and effect relationships. However,

the analyses between iron status and the selected

dietary, socioeconomic, and health variables indicated

factors in addition to reported iron intake that should

be investigated further.
Background—Review of the

literature

Anemia and iron status

Anemia generally is believed to be the major

nutritional deficiency problem in the United States

today.3-s However, estimates of the prevalence of

anemia vary widely;~ for example, estimates of the

prevalence of anemia range from 17 to 44 percent

among preschool children’ and from 5 to 25 percent

among women ages 1544 years. X-lI Problems in

assessing anemia as a public health problem arise from

two causes: (1) there is no general agreement on a

definition of anemia and (2) the commonly used

criteria do not necessarily reveal the cause of anemia.

Generally, anemia is a condition in which an

inadequate amount of oxygen is delivered to cells

throughout the body. Lack of oxygen at the cellular

level creates metabolic slowdown, causes muscles

(such as the heart) to operate less effectively, and

places stress on the circulatory system as it tries to

oxygenate tissues. The physiological symptoms of

anemia tend to be nonspecific, making the condition

difficult to isolate. Mild unemia, for example, may be

associated with dizziness, weakness, fatigue, and irritability. A person with iron-deficiency anemia may

experience breathlessness, tachycardia, dysphagia, and

palpitation on exertion. A diagnosis of anemia usually

is based on a biochemical determination of the

capacity of an individual’s red blood cells to carry

oxygen throughout the body and make it available to

cells.

The only parts of the red blood cell to which

oxygen can be attached und transported are the ironcontaining porphyrin complexes within the protein

hemoglobin. Thus hemoglobin levels reflect anemia

and iron status.

The hemoglobin level represents a relationship

between the production of red blood cells and their

destruction or loss. Low hemoglobin concentrations

may result if red blood cell synthesis is decreased or if

destruction or loss increases, and these conditions are

influenced in turn by several factors. Dietary components such as iron, folic acid, and vitamin BIz tiect the

rate of synthesis and successful maturation of red

blood cells. The most common cause of red blood cell

loss is hemorrhage from trauma, surgery, childbirth,

or internal bleeding. Genetic diseases such as sickle

cell disease, thalassemia, and gIucose-6-phosphatase

dehydrogenase deficiency can cause red blood cell

destruction. A low hemoglobin level may result from

any of these factors, but the major cause is iron

deficiency.l,d

Although determination of low hemoglobin concentration or hematocrit (volume of packed red blood

cells) may indicate an anemic condition reflecting a

variety of factors involved in the synthesis, destruction, or loss of red blood cells, more specific tests can

be used to look at the critical factor of iron status. Free

erythrocyte protoporphyrin measures the portion of

the hemoglobin molecule to which iron could be

attached; thus free erythrocyte protoporphyrin levels

will rise proportionally as the amount of iron in

hemoglobin declines. Iron is also transported in blood

plasma. Serum iron, total iron-binding capacity, and

percent transferring saturation are measures of this

“circulating iron.’’3,J Iron stores are found in other

body tissues, such as the liver, spleen, and bone

marrow. These iron reserves can be measured by

determining levels of iron storage proteins—marrow

hemosiderin or serum ferritin.

When iron intake satisfies body needs in a healthy

individual, circulating iron is maintained at an optimal

level. However, when iron needs are not met by dietary

iron, the body’s iron stores become progressively

depleted, circulating iron levels are affected and,

ultimately, hemoglobin levels drop because the iron is

insufficient to support the proper synthesis of red

blood cells. Thus iron status is a point on a continuum

that ranges from adequate tissue levels and stores to

depleted tissue levels and stores.

Three stages generally are identified in the process

of iron depletion. In the first stage, iron stores are

reduced, measured by a decrease in marrow hemosid3
erin and serum ferritin. During this stage, the absorption of dietary iron may become more efficient, as the

body tries to compensate for increased iron losses or

increased demands for iron.

The second stage involves a severe reduction in

iron stores and impaired red blood cell production.

Serum iron levels generally decline, and the body

compensates by increasing the amount of transferring,

the protein that transports serum iron. Thus the ratio

of serum iron to iron-binding capacity, or transferring

saturation, decreases markedly. In this stage, levels of

free erythrocyte protoporphyrin increase, but hemoglobin levels are in the normal range.

It is diilicult to monitor this second stage of iron

depletion because serum iron and total iron-binding

capacity are affected by several factors, not just by

iron. For example, serum iron levels exhibit diurnal

variation, with the highest values usually found in the

morning and the lowest in the evening. Infection alters

serum iron and total iron-binding capacity levels. Both

of these conditions could result in a lower percent

transferringsaturation that might be interpreted as iron

deficiency. .

In the third stage of iron depletion, circulating iron

levels decline, and iron stores may be depleted. This is

reflected by lower hemoglobin concentrations, lower

hematocrit values, and lower percent transferringsaturation.

km nutrition in the individual

Each individual’s iron nutrition is a state of

balance between the body’s supplies of iron and needs

for iron. Iron supplies are affected by diet and health;

iron requirements change with age and physiological

conditions such as pregnancy and illness.

Dietary sources of iron include foods, iron supplements, and unintentional sources, such as iron from

cast-iron pots. The amount and chemical form of iron

ingested as well as the individual’s iron needs affect the

body’s capacity to absorb iron.

The average American diet contains 6 milligrams

(mg) of iron per 1,000 kilocalories.’’’” In general, daily

iron intake is about 3 mg in infancy and increases

steadily until adolescence. For males, intake remains

stable at 18 mg throughout adulthood, but females’

intake declines from 15 mg among adolescents to 11

mg among adults. This pattern suggests that total iron

intake is related directly to total caloric intake.14

These figures for daily iron intake do not indicate

how much iron is absorbed. Iron occurs in two forms,

which differ in their availability to the body. Readily

absorbable “heme iron” comes from animal tissues,

such as meat, fish, and poultry. As the name implies, it

is the organic iron bound to myoglobin in muscle

tissues. “Nonheme iron,” which is less available to the

body, also is found in animal products, such as eggs,

and foods from nonanimal origin such as grains,

vegetables, and legumes.

The estimated heme iron intake is only 1–3 mg per

day in the United States.1S17Nevertheless, heme iron

is an important contribution to iron statusbecause :27

to 37 percent of the heme iron ingested is absorbed. 16,1‘Jg Moreover, heme iron is absorbed directly

into the mucosal cells of the small intestine, which take

up the entire complex without releasing the iron frclm

its bound form.20,21Once inside the mucosal cell, heme

iron is released. Other dietary factors are not known to

affect heme iron absorption.5

Nonheme iron is the more abundant dietary

form.’z Because nonheme iron is bound in inorganic

forms and iron-protein compounds, it must be released

and reduced from a ferric to the more soluble ferrous

form by substances in the intestines before it can be

absorbed.zo,” In addition, the absorption of nonheme

iron is affected greatly by other components of the

meal in which it is consumed. Thus it is difficult to

estimate or predict what portion of ingested nonherne

iron is absorbed.16,24

At least two factors enhance the uptake of nonheme iron by as much as fourfold. These are the “meat

factor” and vitamin C.12116,24,Z5 Iron absorption tests in

which adult females ate a typical mixed Americrm

meal revealed that beef, lamb, chicken, pork, and fish

had identical enhancing effects on iron absorption.5

Therefore, animal tissue is doubly valuable because it

provides highly available heme iron and also contributes an enhancing factor that improves the availability

of nonheme iron. This enhancing factor has not belen

identified specifically, although studies to date have

ruled out protein or animal protein.17,26There is some

evidence that individual amino acids present in larger

amounts in animal tissue protein than in vegetable

protein may be responsible.15 Animal protein from

eggs and dairy products does not have an enhancing

effect and may lower the availability of ingested iron

by as much as 60 to 80 percent.s,lz,lg

Vitamin C (ascorbic acid), the other dietamy

constituent known to enhance nonheme iron absorption, acts by maintaining iron in a reduced, soluble

form that is absorbed readily. Vitamin C also enhances

iron uptake by forming a chelate with iron that

remains soluble (and thus more absorbable), even in

the basic environment of the small intestine.~,ZAThe

enhancing effect of vitamin C appears to be limited to 4

hours after iron ingestions It has been suggested that

the effects of animal tissue and vitamin C consumed

together are additive and that 1 gram (g) of meat and 1

mg of ascorbic acid may produce roughly equivalent

effects.‘A

Other dietary factors may enhance iron absorption, but most have not been studied sufficiently to

permit an assessment of their effects.s’ls-lTOn the other

hand, there are several known inhibiting factors,

including tannic acid in tea, which appears to create

4
insoluble iron complexes. ~’ Egg yolk phosvitin,’7 antacids, lb calcium and phosphate salts,28 bran,29 and

ethylene diamine tetraacetic acid (EDTA)30 also have

been shown to inhibit iron uptake.

Absorption of heme and nonheme iron also is

affected by an individual’s iron status. As iron stores

become depleted, absorption increases; as more iron is

stored, absorption decreases.l@J~4 Iron status, in turn,

varies according to an individual’s iron requirements.

Iron requirements are determined primarily by the

amount of iron lost in the normal turnover of body

cells, the amount lost from normal and abnormal

losses of blood, and the amount needed to make new

cells and tissues, which may vary during the life cycle.

Normal iron loss in the adult male has been estimated

to be about 1 mg per day.~1 This loss occurs mainly in

the gastrointestinal tract-O.4 mg as red blood cells,

0.2 mg from bile, and less than 0.1 mg through

exfoliated cells. 15JZDaily losses also include about 0.2

mg through skin as exfoliated cells and in sweat and

about 0.1 mg in urine.j~

Females require additional iron to compensate for

that lost in menstrual blood and to meet the needs of

pregnancy. An average of 0.5 mg per day of additional

iron is required to replace that lost in menstrual

blood.]z Full-term pregnancy places an additional

demand for 700 to 1,000 mg of iron on the mother, a

need that generally cannot be met without

~~~u Body size and blood volume supplementation. 1---0-

also cent ribute to differences in normal iron losses and

average iron requirements among individuals and

between males and females.~~

Another factor that affects iron requirements,

especially among adults, is blood loss. A blood

donation of 450 milliliters entails a loss of 225 mg of

iron, the equivalent of a loss of about 0.6 mg per day

over 1 year. }3Surge~, accidents, and chronic illnesses

such as ulcers and hemorrhoids also account for

sizable iron losses.

Drugs may increase or decrease iron loss, either

directly or through their effects on blood 10SS. Oral

contraceptives, for example, reduce menstrual blood

loss.~’J7 Other drugs, such as aspirin, act as gastric or

enteric irritants and increase blood 10SS.38

The dietary and health factors that affect an

individual’s iron status often are influenced by social,

cultural, and economic conditions. People with limited

financial resources may not be able to purchase many

iron-rich foods such as meat or foods rich in vitamin

C, such as fresh fruits and vegetables. Inadequate

medical care, which is at least partially a function of

income level, may increase the occurrence or duration

of diseases associated with low iron stores or blood

loss. People with limited education may have trouble

choosing a diet that provides enough iron. Studies have

shown, for example, that mothers’ educational level is

positively correlated with the quality of their children’s

diets.~’,w Cultural practices associated with geographic

regions or ethnic goups also may affect iron status.

Pica, the eating of nonfood items (such as clay or

laundry starch), can inhibit iron absorption by binding

available iron and forming insoluble complexes, and

this practice is more common in some cultural and age

groups than in others.

Race is a factor that may be associated with iron

nutrition and anemia. Several large surveys have

reported a higher prevalence of low hemoglobin

among black persons than among white persons. MLAZ These differences may be a result of

differences in cultural eating patterns or in income.

However, there is increasing evidence that differences

persist even when iron status measured by percent

transfernn saturation4M8 and socioeconomic status4WS

are taken into account.

Groups at risk of iron deficiency and

anemia

Because so many dietary, health, and socioeconomic factors interact in determining iron intake, iron

requirements, and iron loss, there is great individual

variation in iron status. Despite this variation, it is

reported commonly in the literature that several

population groups—preschool children, adolescents,

women of childbearing age (including pregnant women), and the elderly—are most likely to develop iron

deficiency and anemia.20’49 The analyses of iron status

derived from NHANES I data directed attention to

three of these groups: children ages 1–3 years,

menstruating women ages 12–54 years, and persons

ages 65–74 years.

Preschool children

The level of iron endowment at birth varies widely.

It generally is believed that most infants are born with

stores sufficient only for the first 4 to 6 months of life,

at which time they become dependent upon dieta~ or

supplemental iron to maintain body stores and meet

the demands imposed by growth.jo

Several factors make it difficult for very young

children to develop and maintain adequate iron status.

Human milk and cow’s milk, the major foods in the

first year of life, are poor sources of iron, although

breast milk at least supplies iron in a form that is

absorbed easily and may thus afford some protection

against development of iron-deficiency anemia.j Ironfortified formulas and dry cereals have been used

increasingly in the past 10 years in an effort to boost

the iron in the daily diet of infants. Nonetheless, by the

time they reach the age of 1 year, many children may

have inadequate iron status.so

Children over 1 year old whose diet is composed

almost entirely of cow’s milk are at particular risk of

iron deficiency not only because milk is very low in

iron but also because it may be substituted for other

5
foods that are better sources of iron. In addition, milk

may interfere with iron absorption through the formation of insoluble iron complexes. It may even promote

iron loss by causing gastrointestinal bleeding (often

called cow’s milk anemia).3,51

Women of childbearing age

The combination of menstrual blood loss, increased iron needs in pregnancy, and eating habits,

including dieting, place women of childbearing age at a

high risk of iron deficiency and anemia.

As a continual cause of blood loss, menstruation is

responsible for an average daily iron loss of 0.5 mg,

added to the average normal physiological iron loss of

1.0 mg per day. Some women average daily iron losses

from menstrual flow of as much as 1.4 mg per day,

bringing their total average monthly loss to 2.4 mg per

day.~z

Assuming that only 10 percent of dietary iron is

absorbed, women would need to eat 18 mg of iron

daily to meet their physiological needs, and many find

this difficult to achieve. It would take approximately

3,000 calories to provide a daily intake of 18 mg of

iron, far beyond the recommended dietary allowance

for calories for women. As a result, even if a woman

has adequate iron stores when she attains menarche,

the continual additional demand for iron to replace

that loss during her reproductive years through

menstruation may place her at risk of iron deficiency

or anemia.

In addition, pregnancy often exacerbates this

cumulative iron loss by increasing the iron needs of a

woman who may be bordering on iron deficiency.

Increased demands for iron arise from a 25-percent

increase in maternal hemoglobin mass and the need to

provide tissue iron and develop iron stores in the fetus.

Because the iron needs of the fetus will be met before

those of the mother, a pregnant woman may experience further drain on her iron stores and may not be

able to compensate for this loss after giving birth.52-SO

The elderly

With increasing age, people are more prone to

health problems. Many chronic conditions, such as

arthritis, which are more prevalent in the elderly and

result in disability or discomfort, may influence eating

patterns.ss Dental and other impairments that may

influence diet are also more prevalent among older

persons. For example, the percent of persons ages

65–74 years without natural teeth is higher (about 45

percent), than that of persons ages 18–64 years,5band

the rate of visual and paralytic impairments is much

higher among persons ages 65 years and over than

among younger people. STA study of NHANES I data

showed that a higher proportion of persons ages 65--74

years with natural teeth, ingested foods that are

sources of iron, vitamin C, and protein at levels at or

above the NHANES standards than persons of similar

ages without natural teeth or whose teeth were

indicated for extraction did.SE

Studies have reported that many senior citizens

have iron intakesbelow recommended allowances, that

iron intake decreases with increasing age, and that

protein sources may change from red meats to less

expensive nonmeat substitutes.sg,wLow-cost, high-energy foods such as cereals, pastas, and legumes have

lower iron content and lessavailable forms of iron than

animal protein foods. A slight decrease in iron intake

and lower meat consumption have been documented

from the NHANES I data for persons ages 65--74

years.b1,b2

The dietary habits of this group, as with all

subpopulations, are influenced by many social, cultural, and economic conditions .bJ,64
Methodology: Sources and

limitations of the data

Suwey procedure

Medical and demographic data were collected for

NHANES I from April 1971 to June 1974. Teams of

interviewers and examiners moved with specially

designed and constructed mobile examination centers

to each of the 65 selected sample areas so that standard

physical examinations could be given under standard

conditions. Of the 28,043 persons ages 1-74 years who

were selected in the national probability sample,

20,749 (74 percent) were examined.’

Information available from this sample included

information from general medical, dermatological, and

dental examinations; medical history questionnaires;

dietary interviews consisting of a 24-hour recall and a

food frequency questionnaire; and laboratory analyses

of blood and urine samples. Body measurements were

taken by trained technicians, and demographic data

were obtained by interviewers from the U.S. Bureau of

the Census. In addition, a detailed component of the

survey consisting of a general medical history supplement, supplements for arthritisand for respiratory and

cardiovascular conditions, a health care needs questionnaire, a general well-being questionnaire, and more

extensive medical and laboratory examinations was

administered to a subsample of 3,854 adults ages

25–74 years. The analyses mesented in this reDort . are

based & the 20,749 ex-&nin~dpersons.

Biochemical determinations

Blood specimens were obtained by venirmncture

for adults %d by venipuncture or ‘finger~tick for

children ages 1–3 years.b Hemoglobin levels were

determined in the mobile examination centers using a

Coulter Hemoglobinometer, which employs a beam of

‘Appendix I inchsdex a more detailed account of the selection of the

national probability sample.

%e method used to obtain the blood specimen for each child was not

recorded.

light and a photoelectric measuring device to compare

a measured reference solution to the blood sample. The

hemoglobinometer was checked daily with commercially available hemoglobin reference solutions. Hemoglobin concentration was computed automatically and

displayed in grams per deciliter (g/dI). The test was

run twice and samples had to agree within 0.2 g/all.

Readings of less than 11.0 g/all or more than 18.5 g/all

were retested for accuracy and then called to the

attention of a physician.

Serum samples were frozen and sent to the

Nutrition Biochemistry Laboratory at the Centers for

Disease Control, where serum iron and total ironbinding capacity were measured using a modification

of the automated Technicon AAII 25 method.bs The

technique involved measuring the intensity of the

violet-colored complex formed in the reaction between

Ferrozine and Fe(II) in pH 5.0 buffer at 562 nm. Total

iron-binding capacity was determined by diluting

serum specimens and quality control samples with an

iron-saturating solution, removing excess iron, centrifuging, and analyzing the supematent for iron using

the serum iron method. Determinations were repeated

for serum iron below 50 and above 250 p.g/dl and for

total iron-binding capacity below 250 and above 500

pg/dl. Percent transferringsaturation then was calculated. A more detailed description

methods used to obtain these data

Iished.bs

Assessment of iron status

The biochemical determinations

of biochemical

has been pubavailable from

NHANES I included three measurements that commordy are used to assess iron status—hemoglobin

concentration, serum iron, and total iron-binding

capacity.’ They were used to create three classifications of iron status—low hemoglobin (low Hb),

‘3-Iematocrit was also determined, but it was not used in this study because

it is highly correlated with hemoglobin levels.

7
Table A. Age- and sex-specific hemoglobin reference standards!

Age Sex Hemoglobin value

(g/all)

1-5 years ............................

6-11 years ..........................

12-14 years ........................

12-14 years ........................

15-17 years ........................

15-17 years ........................

16-74 years ........................

18-74 years ........................

Male and female

Male and female

Male

Female

Male

Female

Male

Female

11.0

11.5

12.5

12.0

13.0

12,0

14.0

12.0

~See references66 and67.

low percent transferringsaturation (low TS), and low

hemoglobin combined with low percent transferring

saturation (low Hb/TS) in this report.

Hemoglobin levels are the most widely used

measure of anemia. In this study, persons with

hemoglobin levels below the reference standard for

their age and sex (table A), were classified as low Hb.

This category describes persons who are below a

generally accepted cutoff point for anemia. The hemoglobin levels could reflect the presence of several

factors that affect the synthesis, maturation, destruction, and loss of red blood cells.

As serum iron levels decline, the capacity to

transport iron, or total iron-binding capacity (TIBC),

increases as the body attempts to compensate by

creating more iron-carrying transferringproteins. Thus

the ratio of serum iron to TIBC, called percent

transfernn saturation (TS), declines markedly. Percent

transferringsaturation is widely considered a better

indicator of circulating iron status than serum iron or

TIBC alone.bg However, in chronic infections, TS

decreases but TIBC does not increase and may even

decrease slightly. Thus to exclude from the analyses

persons with low TS values due to infection, this study

used TS and TIBC to categorize persons with low

circulating iron. Persons with a TS below 16 percent

and a TIBC above 250 pg/dl were classified as low TS.

Persons with hemoglobin levels below the standard

for their age and sex in conjunction with low circulating iron (defined as transferringsaturation below 16

percent and total iron-binding capacity above 250

p.g/dl) were placed into the third category, low

Hb/TS. Instead of a reading of low hemoglobin alone,

this category reflects an anemic condition that can be

attributed to lack of iron or iron-deficiency anemiam6S,69

Persons not in these categories were referred to as

having adequate Hb, adequate TS or adequate Hb/TS.

However, “adequate” cannot be interpreted as a

clinical judgfnent of iron status. The categories of iron

status used in this report are defined according to

reference standards, which is only one approach to

determining an anemic condition.

Above all, although the measurements used to

classify the data were chosen to reflect stages of

general anemia, iron deficiency, and iron-deficiency

anemia, they do not represent the prevalence of disease

but rather the prevalence of biochemical levels that are

below the chosen reference standards, Because individual iron requirements vary widely, analyses reporting

that a certain number of persons are in the low Hb

category do not mean that this number of cases of

anemia exist, nor does the statement that a certain

number of persons have adequate Hb mean that none

of these persons could be diagnosed as anemic. For

example, a 30-year-old female with a hemoglobin level

of 12.0 g/all, the reference standard for her age, may

not have a sufficient iron supply to meet her bc~dy’s

needs, while another female of the same age with a

hemoglobin level of 11.5 g/all may not need or even be

able to absorb additional iron. A further consequence

of using this approach to classify iron status is that the

prevalence estimates calculated in this study are

dependent on the reference standards used. Revising

the standards would alter the prevalence estimates,

although the conditions measured by the biochemical

determinations do not change.

Other approaches-clinical trials (response to iron

therapy intervention), multiple iron parameters, and

distribution analysis—have been used to estimate the

prevalence of anemia in populations. The first approach was not applicable to this survey data, and the

second approach was of limited use because only some

of the iron-related determinations were done in

NHANES I. The third method, distribution anal!ysis,

has been used to look at the iron status of women ages

1844 years.qj However, the large sample sizes required by this approach made it less desirable for use

in this general study. ,Therefore, the use of cu~toff

values was the most appropriate method for the study

of iron status using NHANES I data.

Calculation of dietary intake and

absorbable iron

Dietary intake and food consumption patterns

were determined for each examinee using two methods: (1) a 24-hour recall questionnaire and (2) a fc)od

frequency questionnaire. Interviews were conducted by

trained staff who had bachelor’s degrees in food amd

nutrition or who were registered dietitians.

The recall covered the 24-hour period ending at

midnight the day before the examination. Examinations were performed Tuesday through Saturday, so

that weekends, when eating patterns may be different,

were excluded. The examinee (or parent of a child

under age 12) was asked to report all foods, beverages,

and supplements consumed on a meal-by-meal basis

(breakfast, lunch, supper, snack). To help the examinee estimate portion size, three-dimensional fc~od

models were used. The data were coded, edited, amd

computer analyzed at NCHS for nutrient value per

100-gram portion of food. A computer model to

8
analyze the types of foods consumed in each ingestion

period was designed and implemented at Abt Associates, Inc.

The food frequency questionnaire, which was used

to collect information on how often different types of

foods were consumed during the preceding 3 months,

was administered after the 24-hour recall. In addition

to providing data about usual food consumption

patterns, the food frequency questionnaire helped the

interviewer determine whether the foods consumed on

the day reported were typical of those consumed over a

longer period. The frequency questionnaire also helped

the interviewer identify and clarify inconsistent responses.

Both of these instruments have methodological

problems. The 24-hour recall is limited to one day;

however, intake for any one day may be neither usual

nor representative of a person’s overall diet. Moreover,

the 24-hour recall is designed to provide an estimate of

the quantities of food consumed, and individuals vary

greatly in their ability to remember what they ate.

People also err in estimating the amounts of food they

ate. Finally, error is introduced into the 24-hour recall

because methods of food preparation vary greatly

among respondents, and it is difficult to determine the

nutrient content of many commercial or mixed dishes.

Thus the available nutrient breakdowns provide only

rough estimates of the nutritive value of the foods

reported.

The food frequency questionnaire is subject to the

same limitations as the 24-hour recall because the

respondents must remember and report the wide

variety of foods and beverages consumed over a 3-

month period, as well as estimate how frequently each

item was consumed. Because the quantities consumed

are not reported, nutrient intake cannot be calculated

accurately from the food frequency questionnaires.

Therefore, data from the food frequency questionnaires were not included in the analyses for this report.

Mean iron intake values, which are the most

widely used estimates of dietary iron intake, were

computed from the 24-hour recall data to examine the

relationship between iron intake and the iron status

categories investigated in the prevalence analysis.

However, mean iron intake does not represent accurately the amount of iron available to or absorbed by

the individual. In the relational analyses, which also

considered iron intake as one factor contributing to

iron status, iron intake from the 24-hour recall data

was adjusted according to an experimental method

developed by Monsen and Cook. M-17

This calculation of absorbable iron took into

account the consumption of heme iron, two facilitators

(the meat factor and vitamin C), and one inhibitor

(tea). Meals were calculated separately and totalled for

the 24-hour period. A two-stage classification system

was employed.

First, the iron ingested was classified into a low,

medium, or high availability category according to

enhancing and inhibiting factors in the meal, as

follows:

Low availability-Meals that contained less than

24 mg of vitamin C or less than 6 g of protein from

meat, fish, or poultry.

Medium avai/abili~Meals that contained more

than 25 mg but less than 75 mg of vitamin C or more

than 6 g but less than 18 g of protein from meat, fish,

or poultry.

High availabili~—Meals that contained more than

75 mg of vitamin C or more than 18 g of protein from

meat, fish, or poultry or from 25–75 mg of vitamin C

plus from 6-18 g of protein from meat, fish, or poultry.

If more than 225 g of tea was consumed during the

ingestion period, the iron intake was dropped one

category unless it was classified as low availability.

The Monsen algorithm on which this step is based

employed grams of meat, fish, and poultry rather than

g-rams of protein. In this model, it was assumed that

lean meat contains approximately 25 percent protein;

thus 6 grams of protein corresponds to approximately

25 grams of meat, fish, or poultry.

In the second step, iron intake was divided into its

heme and nonheme components. It was assumed that

40 percent of the total iron present in meat, fish, and

poultry was heme iron. The availability category

determined in step one, according to the enhancing or

inhibitory nature of the meal, affected the percent of

heme and nonheme iron that would be absorbed. For

example, it was assumed that only 3 percent of

nonheme iron would be absorbed in a low availability

meal, but 8 percent would be absorbed in a high

availability meal. lA,lT.~

Low availability meal: Absorbable iron = (heme

iron x O.110) + (nonheme iron X 0.030)

Medium availability meal: Absorbable iron =

(heme iron X O.122) + (nonheme iron X 0.050)

High avaiIabiiip meal: Absorbable iron = (heme

iron X O.14) + (nonheme iron X 0.080)

Relational analyses: Analytical

subgroups, independent variables, and

tests of statistical significance

The relational analyses were designed to examine

associations between iron status and dietary, health,

socioeconomic, and demographic variables. Separate

but parallel analyses were performed on three

groups-children ages 1–3 years, women ages 12-54

years between menarche and menopause, and persons

ages 65–74 years. These groups generally are ccmsidered to be at risk of iron deficiency and anemia. They

also were chosen for closer study because analyses of

9
the NHANES I data revealed a sufficient prevalence of

low Hb, low TS, or low Hb/TS to suggest that there

might be a public health problem in these groups and

because the sample ,sIzeswere large enough to draw

meaningful statisticalconclusions.

The subpopulation of children ages 1–3 years

comprised black and white children and both sexes.

The group of menstruating women was composed of

black and white women who had attained menarche

and had not reached menopause (ages 12–54 years),

excluding pregnant women and women who had been

pregnant within the past year. The elderly subpopulation was defined as persons ages 65–74 years, male and

female and black and white. Adults with a history of

ulcers, who might be suffering from large blood losses,

or have diabetes, were excluded from the analyses.

These groups were excluded because of the known

association of the condition with iron status or dietary

intake status. As noted earlier, the sample sizes within

each subgroup varied because of missing data for some

of the independent variables,

For each group, relationships between iron status

and an extensive set of independent variables were

considered. Approximately 200 independent variables,

hypothesized to be associated with iron status or iron

intake, were selected for study from the available

NHANES I data tapes. Preliminary statisticalanalyses

were conducted to collapse these variables into a

smaller set of analytical constructs for use in subsequent bivariate and multivariate analyses. Variables

that had a high proportion of missing data, did not

vary across the sample, or were not easily quantified

were set aside. The food frequency questionnaire data,

for example, were eliminated for the last reason. In

addition, variables that addressed the identical construct were collapsed into a single variable; for

example, several questions about aspirin were collapsed into a single measure of regular aspirin use.

Many other potential variables were excluded on the

basis of low frequency (e.g., leukemia), the expectation

of little relationship to iron status (e.g., dermatology

exam), or poor measurement properties (e.g., physical

activity).

The resulting set of “core variables” to be tested

was composed of the 21 variables listed below. The

definitions of these variables are presented in appendix

H.

Total iron intake (mg)

(log) Total iron intake (log mg)

Total animal tissue iron intake (mg)

Total non-animal tissue iron intake (mg)

Total protein intake (mg)

Total animal tissue protein intake (mg)

Total non-animal tissueprotein intake (mg)

Estimated available iron (mg)

Estimated available iron with tea (mg)

Vitamin C intake (mg)

Pica

Regular vitamin use

Regular mineral use

Regular vitamin and mineral use

Regular aspirin use

Age

Poverty income ratio (a poverty index)

Estimated family income

Number of persons in the household

Age of head of household

Years of education of head of household

In addition, a few variables of particular interest

within each age group were added to the appropriate

subpopulation. For children ages 1–3 years, additicmal

variables included history of breastfeeding and variables related to the child’s birth. The analyses for

menstruating women and the elderly included variables dealing with general health, reproductive history,

and two additional demographic -

scribed below.

Children ages 1–3 years

Ever breast-fed

Mother’s age at child’s birth

Whether child was the firstborn

Child’s birthweight

Whether child was premature

Whether child is presently ill

Women ages 12–54 and persons

Special diet

Age menstruation began

Ever pregnant

Ever diagnosed as anemic

Any trouble eating

variables, as deages 65–74 years

General findings on the general medical exam

Ever had abdominal surgery

Married

Education of examinee

Current or recent use of oral contraceptives

(women ages 12-54 years only)

For each group, bivariate analyses were conducted

to examine the relationship between iron status amd

each variable in the appropriate core set. Two-tailed

Z-tests with a significance level of 0.05 were conducted

taking into account the complex survey design (see

appendix I).

As a further step to understanding the relationship

of these dietary, health, socioeconomic, and demographic variables to iron status, a limited set of

variables was placed into a multivariate logistic framework, These multivariate analyses were designed to

determine which combination of variables was most

associated with the various iron status categories in

each subgroup, This approach was concerned with

discerning associations that might warrant closer

study and does not show cause-and-effect relationships

between any variable and iron status.

As a general guideline, the dietary and health

variables that were significantly associated with iron

10
status in the bivariate analyses were chosen for the

multivariate analyses. As a final test of iron intake,

however, (log) mean iron intake and estimated absorbable iron were placed in the multivariate framework,

regardless of the results of the bivariate test. In

addition, a few variables of special interest—those

common in a particular age group or those holding

general theoretical interest—were included in the

multivariate set.

Furthermore, the socioeconomic and demographic

variables included in the core bivariate set could not be

examined simultaneously in a single multivariate

model because many of them were highly correlated. A

series of logistic analyses was conducted to select a

smaller set of these variables that were relatively

unconfounded and related to iron status. These analyses were designed to assess whether the logarithmic

transformation of a poverty index called the poverty

income ratio (PIR), was a better variable than PIR

itself and whether any additional demographic variables (other than age, race, and sex of the examined

person) contributed to the analyses when used in

conjunction with PIR. (The poverty index and how it

is calculated are discussed in appendix IL) The

analyses, conducted simultaneously for all three

groups for each iron status category, showed that the

logarithmic transformation of PIR did not predict iron

status better than PIR. In addition, the only socioeconomic variable that had a significant effect when

entered with PIR was years of educaton of the head of

the household. Because these results were consistent

across all three analytic groups and for all measures of

iron status, PIR and years of educaton of the head of

household were entered as socioeconomic covariates in

all multivariate analyses.

Initially, a simple forward stepwise solution to the

logistic model was obtained without taking into

account the complex sample design. If any variable

was not included because of collinearity between it and

the remaining variables in the model, the variable was

tested without including its collinear measures. Twotailed t-tests with a significance level of 0.05 were

conducted. Each variable that was significant under

this approach (t > 1.96) was retained for the final

model. If at that point, dietary iron intake was not

entered in the model, it was “forced in, ” to yield a final

test of its significance in relation to iron status when

controlling for all other significant variables. (A

detailed presentation of the statistical approach is

included in appendix I.)

11
Findings

Iron status

The mean values and distribution of the measures

of iron status collected in NHANES I (hemoglobin,

hematocrit, serum iron, total iron-binding capacity,

and percent transferring saturation) are shown in tables

1-1o.

These measures were used as described in the

preceding section to calculate prevalence rates for

three categories of iron status—low Hb, low TS, and

low Hb/TS. Prevalence estimates for various age

groups, males and females, and black and white

persons are presented in tables 11–13 and summarized

in figures 1–9. Z-statistics for selected comparisons of

prevalence of iron status are presented in table 14.

Prevalence rates for pregnant and nonpregnant women

and Z-statistics are presented in table 15. Differences

with a Z-value greater than 1.96 (p < .05) are noted as

“significant” in the text.

Age and sex

The prevalence of low Hb decreased rapidly from

infancy through the preschool years, from a peak of

19.3 percent for males and 12.6 percent for females at

age 1 to 1.7 percent and 1.9 percent by ages L%5years

(table 11 and figure 1). A brief rise in prevalence

occurred for children entering adolescence (ages 6-11

years), which continued for males into ages 12–14

years. The prevalence was higher for boys ages 12–14

years (7.6 percent) than for girls of similar ages (3.4

percent), although the difference was not statistically

significant.

Prevalence rates of low Hb were relatively constant at approximately 5 percent for adults (ages 18–54

years) of both sexes. With advancing age, however, the

prevalence rate rose markedly for males, beginning at

ages 55–64 years. At ages 65–74 years, males had a

prevalence of 14.9 percent and females only 4.3

percent, a difference that is statistically significant.

The prevalence of iron deficiency, as defined by

percent transferring saturation and total iron-binding

capacity, generally was higher than that of low

hemoglobin, except among adult males. LOIW TS

peaked at age 1 with a prevalence of 50.8 percent for

males and 38.3 percent for females (table 12 and figure

4). During the childhood years, the prevalence decreased rapidly for both sexes, dropping to 8,6 percent

for boys and 13.1 percent for girls ages 12–14 years.

Beginning in adolescence, values for females rose

slightly and reached 16.4 percent for ages 1844 years,

while the prevalence rate for males dropped to 3.6

percent. This difference is statistically significant.

Beginning at the age group 45–54 years, ]prevalence rates for males and females became similalr and

decreased to approximately&7 percent by ages 65-74

years.

The combination of low Hb and low TS showed

the lowest prevalence of the three categories. Ex~ept at

age 1, when it was especially marked (17.7 percent for

males and 9.9 percent for females), the prevalence of

low Hb/TS for any age and sex group never exceeded

4 percent (table 13 and figure 7). Within this low level,

however, the pattern was similar to that obserwed for

the other two categories of iron status.

Race

In many instances, the prevalence of low Hb was

significantly higher for black than for white persons

among males and females and at all ages. Exclept at

ages 55–64 years among males and ages 45 years

among females, the prevalence of low Hb was 2 to 10

times as high among black persons. For example, the

prevalence among white women ages 1844 years was

3.4 percent; it was almost five times as high (15.8

percent) among black women of the same ages (table

11 and figures 2 and 3).

Differences between black and white persons generally were not as great for low TS and low Hb/TS nor

were the rates for black persons consistently higher

(tables 12 and 13, figures 5 and 6, and figures 8 and 9).

Furthermore, although black persons tended tal have

slightly higher prevalence rates in both categories,

most differences were not statistically signi:licant.

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21
These findings are consistent with previous

research,4145 which indicates that a racial variation in

iron status appears to be prominent for low hemoglobin but not for other indicators of iron status.

Pregnancy

Because iron status measures may change during

pregnancy, pregnant women were analyzed as a

separate sample. Table 15 shows that pregnant women

ages 1844 years were six times as likely to have low

hemoglobin as women in this age range who are not

pregnant. This significant difference was observed

among black women and white women; the prevalence

of low hemoglobin for pregnant women was three

times and eight times as high. No significant

differences between pregnant and nonpregnant women

were found for the low TS or low Hb/TS categories.

Iron intake and iron status

Mean iron intakes (mg per day) of persons in two

of the iron status categories analyzed by age, sex, and

race, are presented in tables 16 and 17. Results for the

total sample classified as low or adequate Hb and low

or adequate TS are shown in figures 10-13. These

figures are presented to show the overall relationship.

Selected subgroups have small sample sizes that

account for large variability in the mean iron intakes.

(Mean iron intakes for pregnant women are presented

in table B.) Associations with a Z-statistic of greater

than 1,96 are noted as “significant” in the text.

Age, sex, and race

In general, males with low hemoglobin levels had

mean iron intakes similar to males with adequate

hemoglobin levels. Similar findings were observed for

females with low and adequate hemoglobin levels.

With one exception, the differences in mean iron

intake for males classified as low and adequate TS were

nonsignificant. No significant differences were found

for females.

One marked difference between the sexes was that

females’ iron intake decreased between the ages 12 and

17 years, while males’ intake increased. This pattern

was found in all the low and adequate Hb and TS

categories of iron status, although it was most pronounced in the low TS group. Too few individuals

were classified as low Hb/TS to present findings about

their iron intake.

Similarly, the sample sizes for black persons were

too small to substantiate any racial pattern of

differences in iron intake. In general, the iron intiake of

black persons in the various iron status categories was

similar to that of the total sample.

Overall, mean daily iron intakes were lower than

the recommended allowances for each age and sex. 12

Pregnancy

As shown in table B, no statistically significant

differences were found in the iron intake of pre,gnant

and nonpregnant women for low and adequate hemoglobin levels. Although the difference for black women

was larger, the small sample sizes precluded testing the

difference for statistical significance.

The difference in iron intake of pregnant and

nonpregnant women with low and adequate transferring

saturation levels was significant for all races combined

and for white women. For black women, the difference

was in the same direction, but small sample sizes again

led to unreliable estimates. Too few pregnant women

had low hemoglobin combined with low transferring

saturation values to present findings for this iron status

indicator.

Relational analyses

For each subpopulation-children ages 1–3 :years,

menstruating women ages 12–54 years, and persons

ages 65–74 years—bivariate analyses were conducted

on a core set of dietary, health, socioeconomic and

Table B. Z-statistics for comparison of iron intake for low and adequate iron statusl for pregnant women 1844 years, with mean, and

standard error of the mean, by iron status indicator and race: United States, 1971–74

Low Adequate

Iron status indicator and race Number of Standard Number of Standard

examined Mean error of

Z-staifistic

examined Mean error of

persons mean persons mean

Hemoglobm

All racesz ..... ...... ...... ...... ....... ...... ...... ...... 63 11.1 0.67 133 10.9 0.46 0.2!5

White , ..... ..... . . . . . . .. . . .. . .. . 39 11.4 0.85 113 10.6 0.49 0.E12

Black ....................................................................... 22 “10.3 ‘1.11 14 *13.7 ●1.66 . . .

Transfernn saturation

All racesz ..... .... ...... ....... ....... ....... ........ ........ 40 9.0 0.66 155 11.5 0.43 -3.10

White ....................................................................... 30 8.6 0.77 117 11.4 0.48 -3.09

Black ....................................................................... 9 ‘10.4 ●1.40 31 12.7 1.13 .,, .

I Lowandadequatslevels as defined in this report.

zIncludes data for races which are not shown as separate categories.

NOTE: Estimatss preceded by an asterisk do not meet this report’s standards of reliability (i.e., the number of examined persons is less than 25).

22
18

17

16

15

14

13

12

11

10

9

8

7

— Adequate hemoglobin

---- Low hemoglobin

–H”

J,,,,,,

6

5

0

I I I I

1 2-34-5 6-11 12-1415-17 16-44 45-54 55-64 65-74

Age in years

Figure 10. Mean iron intake for males ages 1-74 years, by age and hemoglobin levels: United States, 1971-74

demographic variables. Multivariate logistic analyses

also were conducted on a smaller set of these variables.

Because data were missing on some of these independent variables for certain sample persons, the

sample sizes in the analyses vary within the subgroups.

All associations discussed in the text are significant at

a value of 1.96 (p < .05), unless specifically noted as

“not statistically significant.”

Children ages 1-3 years

Analyses examining the relationship between iron

statusand a core set of dietary, health, socioeconomic,

and demographic variables were performed only for

children classified as having low or adequate hemoglobin, because about 45 percent of the serum iron and

total iron-binding capacity data were missing from

NHANES I for this age group. Appendix I discusses

some of the reasons this large amount of blood data

were missing in this survey. Males and females were

not analyzed separately because sexual differences in

iron status are not noted until adolescence, when

menstruation begins in females, and both sexes experience growth spurts.TO

Bivariate analyses were conducted for 27 variables,

and results for the total sample (table 19) showed 16

statistically significant associations. Many of these

associations were for dietary variables-most of the

iron intake variables, animal protein intake, vitamin C

intake, and regular vitamin and mineral use. Two

variables related to dietary habits also were significant;

37.5 percent of the children in the low Hb category

had a history of pica compared with 18.3 percent of

the children in the adequate Hb category. In addition,

only 16.9 percent of the children with low Hb had been

breastfed, compared with 26.5 percent of those with

adequate Hb.

The only health variable for which differences were

significant was “presently ill,” but there were four

significant findings for the socioeconomic and demographic variables. Children with low Hb were younger,

with a mean age of 2.19 years compared with 2.58

years for the children with adequate Hb. Low hemoglobin also was associated with a lower poverty index

ratio, more people in the household, and lower

educational level of the head of household.

Tables 20 and 21 present the results of analyses

conducted for black children and white children.

Among white children with low compared with

adequate Hb, significant differences were found for the

23
18 r — Adequate hemoglobin

t

---- Low hemoglobin

17

14 1-

%

-Ic, ,~,

: 13

.-&

= 12

T

g 11

.-

: 10

. 1- -\. \.4md.4. e.--= ------------- =---

9 ,/”

.-.-

.-m

\

8

9%.

\

“w

7 i

6 ,/’

?

5

0

12-3 4-5 6-11 12-14 15-17 18-44 45-54 55-64 65-74

Age in years

Figure 11. Mean iron intake for females ages 1-74 years, by age and hemoglobin levels: United States, 1971-74

same variables that were simificant in the total samrde, variables that were significantly associated with hamo- .-

except for vitamin C intake, breastfeeding, and presently ill, and with the addition of total animal tissue

iron intake. The same trends were evident for black

children as well, although the only statistically significant difference was for age, This may be due to the

small sample sizes for black persons. In the white

population, 105 children had low Hb, and 960 children

had adequate Hb; in the black population the sample

sizes were 72 children with low Hb, and 285 children

with adequate Hb. Because standard errors were

substantially higher for the estimates for the black

population than for the white population, a difference

that was statistically significant for white children may

not be significant for black children. When results for

the sample of black children were examined for each of

the seven variables found to be significantly associated

with low hemoglobin in the analyses for the total

sample and the white sample, the differences between

means for each variable were quite consistent. This

also suggests that the lack of statistical significance

within the analyses of black children was due primarily to higher standard errors associated with the small

number in the sample.

Three of the socioeconomic and demographic

globin status in the b~variate a~alyses for the total and

white samples were chosen for analysis in the multivariate framework—PIR, years of education of the

head of household, and age. Most dietary variables

that were significant in the bivariate analyses were

correlated with iron intake, so (log) total iron intake

and estimated available iron were retained for multivariate analysis, with vitamin and mineral use and -

pica. Race was the eighth variable included in the

mutivariate analysis.

The results of the multivariate approach (table 22) “

showed that age, race, PIR, and education of the hlead

of household still were significantly associated with

low hemoglobin. Children who were younger, black,

from poorer homes, and from homes in which the head

of the household had fewer years of education were

more likely to have low hemoglobin.

When these socioeconomic and demographic

effects were taken into account, pica and iron intake

also were associated with low hemoglobin, indicating

that two factors related to diet—adequate iron intake

and the absence of pica—make it more likely that a

child’s iron status will be adequate regardless of

socioeconomic situation. The contributions of (log)

24
18

17

16

15

14

B

7

— Adequate transferringsaturation

i’”x.

- — -- Low transferringsaturation

i ‘.N.

i ‘\. \-

--------------

.\* \

●\. \

-+ ●-. +. -

—#’

J,, , ,,

6

5

0

I I I I

1 2-3 4-5 6-11 12-14 1517 16-44 45-54 55-64 65-74

Aga in years

Figure 12. Mean iron intake for males ages 1-74 yeare, by age and transferring saturation levels: United States, 1971-74

total iron intake and estimated available iron were

about equal in the final logistic equation, suggesting

that adjusting iron intake for bioavailability does not

offer any advantage in explaining low hemoglobin in

children.

Memtruating women ages 12-54 years

Because of cumulative iron losses due to menstruation and pregnancy, women of childbearing age have

been considered particularly susceptible to iron

deficiency and anemia.lz The prevalence estimates

calculated from NHANES I data suggest that these

conditions may not be as widespread as has been

postulated; however, they are prevalent enough to

warrant closer examination.

A large sample with complete data permitted

analyses of possible correlates of all three iron status

categories for menstruating women ages 12-54 years.

Bivariate analyses of 31 variables were conducted for

each category for the total sample of women and for

black women and white women separately. Results are

presented in tables 23-31.

The bivariate analyses for the total sample (tables

23–25) produced few significant associations. Only age,

previous pregnancy, and years of education of the head

of household were associated with all three iron status

categories. Analyses of the sample of white women

(tables 26-28) yielded similar statistical results; analyses of the sample of black women (tables 29–31)

showed differences that were similar in magnitude but

were not statistically significant, probably because of

small sample sizes. Women who were older, had ever

been pregnant, and came from homes where the head

of the household had less education, were more likely

to have poor iron status measured by Hb, TS, or both.

Several other variables were significantly associated with two iron status categories. The dietary

variable of vitamin and mineral supplementation was

associated with TS or Hb combined with TS for the

total sample and for white women. Previous diagnosis

of anemia, which often is related to previous pregnancy, was associated with low Hb or low Hb combined

with low TS for the same two samples. Women who

reported using oral contraceptives, which may reduce

iron losses by reducing menstrual blood flow, were

more likely to be in the adequate TS and adequate

Hb/TS categories; this association was signiikant for

the total, white, and black samples. Of the demographic variables, age of the head of household was

25
18

— Adequate transferring saturation

17 ---- Low transferring saturation

16

15

14

-a

E 13 m

.—s—= 12

E

~

11

m

E

.-

C 10 ~------ ------- ---

0L

9

“\.

8

\,

7

6 –i

5

/ 5

0’ I I I I I I I —

1 2-3 4-5 6-11 12-14 15-17 18-44 45-54 55-64 65-74

Age in years

Figure 13. Mean iron intake for females ages 1-74 years, by age and transferring saturation levels: United States, 1971-74

associated with Hb or Hb combined with TS in the

total and white samples. In addition, a few variables

showed significant associations with only one iron

status category (tables 23–3 1).

Twelve variables were selected for examination in

the multivariate framework. Two demographic variables—age and years of education of the head of

household—that were consistently significant in the

bivariate analyses were retained for the multivariate

analyses. Race also was included, as was PIR. Of the

dietary variables, regular vitamin use was a significant

correlate in the bivariate analyses; (log) total iron

intake and estimated available iron were automatically

included; and pica was included for theoretical interest. The health variables chosen were previous pregnancy, previous diagnosis of anemia, and oral contraceptive use, which were significantly associated with

iron status in the bivariate analyses, and age of

menarche, which showed a high correlation.

Because this set of variables was larger and

contained more intercorrelated variables than the set

of variables chosen for multivariate analysis for children, the analytic strategy was more complex. First, a

series of models was tested to (1) examine the

significance of the individual independent variables, (2)

ascertain which variables were confounded, and (3)

identify the combination of variables that was most

associated with iron status, These analyses yielded a

final model of seven variables that were consistently

and significantly associated with iron status, as slhown

in tables 32–34.

These seven variables included the four socioeconomic and demographic variables that were significant

correlates of iron status in children—PIR, education

of the head of household, age, and race. Persons from

poorer homes and homes where the household head

had less education were more likely to have low Hb.

Black women were six times more likely to have low

Hb and almost three times more likely to have low

Hb/TS than white women. The older a woman was,

the more likely she was to have poor iron status as

measured by Hb, TS, or both.

The health variables were the other major falctors

affecting iron status over and above socioeconomic

status, age, and race. Women who were using oral

contraceptives were only half as likely to have low Hb,

low TS, or low Hb/TS as women who did not use oral

contraceptives. On the other hand, women whcl had

ever been pregnant were more likely to be in the low

Hb or low TS categories, and women who had been

26
diagnosed as anemic were twice as likely to have low

Hb or low Hb/TS as women who had never been

diagnosed as anemic. Most diagnoses of anemia had

been made during or immediately after pregnancy,

which further suggests that pregnancy has long-term

effects on iron status.

In fact, it is difficult in this approach to separate

the effects of previous pregnancy, previous diagnosis

of anemia, and age. Women who have been pregnant

are more likely to have been diagnosed as anemic, and

they also are generally older than women who have

never been pregnant. When all three variables are

entered in one model, only one or two remain

significant. Therefore, it was concluded that the

configuration of these variables is associated with iron

status.

Elderly persons ages 65-74 years

The sample of the elderly included only a few

persons who were classified as low Hb\TS, so the

analyses of the relationship between iron status and

possible correlates focused on low Hb and low TS.

Bivariate analyses of 30 variables revealed few

significant differences between persons in the low or

adequate Hb and low or adequate TS categories (tables

35 and 36). Low hemoglobin was significantly associated with lower PIR, more people in the household,

and less education for both the examinee and the head

of household in the analyses for the total sample.

Significant health variables were previous diagnosis of

anemia and, for women, previous pregnancy. Use of

vitamin and mineral supplements was associated with

Hb and vitamin C intake with TS. Low TS also was

associated with aspirin use and with age of the head of

household.

Separate analyses conducted for white persons and

black persons yielded similar results (table 37-40). In

most cases, the magnitude of the differences between

groups was similar, but the differences usually were

not significant within the racial groups because of the

small sample sizes.

A set of 12 variables was selected for multivariate

analysis. This set included five socioeconomic and

demographic varibles (PIR, years of education of the

head of household, age, race, and sex) and four dietary

and health variables that were significant correlates in

the bivariate analyses (regular vitamin use and regular

vitamin and/or mineral use, previous diagnosis of

anemia, and previous pregnancy). Estimated available

iron and (log) total iron intake were included automatically. Two health variables that were reported by

many people in the elderly subgrou~findings on the

general medical examination and trouble eating—were

included in the multivariate analysis, although they

were not significant correlates in the bivariate analyses.

In the multivariate approach, six variables were

significantly associated with low Hb, including race

and sex; black persons were six times more likely to

have low Hb than white persons, and men were seven

times more likely to have low Hb than females. As was

found in the analyses for menstruating women, the

health variables were associated with hemoglobin, but

dietary factors were not. Elderly persons who had a

history of anemia, who said they had trouble eating,

and who had health problems noted on their general

medical exams were two to three times more likely to

have low hemoglobin than persons without these

difficulties.

Only one variable, years of education of the head

of household, was associated with low TS in the elderly

subgroup. However, this association was not significant in the bivariate analyses, nor were the associations between trouble eating and findings on the

medical exam and low hemoglobin. Although the

multivariate analyses indicated that socioeconomic

and health factors are important contributors to iron

status among the elderly, this approach did not reveal

any clear-cut relationships.

27
Discussion

Iron-deficiency anemia is believed to be the major

nutritional deficiency problem in the United States

today s-s Estimates of the prevalence vary, but there is

general agreement that the populations at greatest risk

are infants, adolescents, females during the reproductive years, and pregnant women. IZ.Z0,19The primary

cause of anemia usually is attributed to nutrition, that

is, the increased physiological need for iron either to

support growth or to compensate for iron losses that

exceed intake and absorption.qq Small-scale and national nutrition studies have shown that iron intake is

below recommended levels for the American population in general and for these high-risk groups i!n

particular. 1r6111,71

The results of this study generally support the

previous research on iron status and iron intake. Two

somewhat unexpected findings emerged, however.

First, the study shows that iron deficiency as

measured by low transferringsaturation levels is the

most prevalent of the three measures of iron status in

the United States. The prevalence of iron-deficiency

anemia, in which the condition can be attributed to

iron lack based on a combination of low transferring

saturation and low hemoglobin levels, is limited; this

iron-deficiency anemia appears to be a problem only

among very young children.

Second, although the dietary iron intake of children with low hemoglobin is significantly lower than

that of children with adequate hemoglobin, there is no

strong relationship between iron intake and iron status

in the population asa whole,

Iron status in the United States

Low hemoglobin, perhaps the most widely used

indicator of iron status, is most common in young

children, pregnant women, older men, and the black

population. At age 1, the prevalence of low hemoglobin in the total sample population is 19.3 percent for

males and 12.6 percent for females, and at ages 2–3

years, it is approximately 9 percent for both sexes.

After early childhood, the prevalence rarely exceeds 5

percent, except for males ages 65–74 years, when it

rises to almost 15 percent. At all ages, however, black

males and females are 2 to 10times more likely to have

low hemoglobin than white persons. Approximately 32

percent of the pregnant women in NHANES I had low

hemoglobin, with a prevalence of 28.4 percent among

white women and 52.9 percent among black women.

These findings are in general agreement with the

results of other more limited studies. The Ten-State

Nutrition Survey,8 the Preschool Nutrition Sw-vey,72

and the Nutrition Surveillance System of the Centers

for Disease ControlTs all found low hemoglclbin in

children ages 1–3 years. The presence of low hemoglobin among pregnant women has been reportedl widely,52-54

The high proportion of males ages 55–74 years

who have low hemoglobin also has been repo]led in

other studies, notably in the Ten State NZJtrition

Survey.8 However, although men of this age lhave a

high prevalence of low hemoglobin, no other evidence

relates these levels to iron lack. It has been suggested

that the phenomenon is attributable to changes in

testosterone levels occurring with advancing age,74in

which case the reference standard used to define

hemoglobin status might be inappropriate for elderly

men.

A high prevalence of low hemoglobin among black

males and females of all ages also has been repolrtedin

many recent studies of iron status. In the Ten-State

Nutrition Survey, a consistent 1 g/all difference in mean

hemoglobin levels between black persons and white

persons of both sexes was found regardless of age,

income, or region. ~ Mean hemoglobin levels of black

children in the Preschool Nutrition Survey were 0.5

g\dl lower than mean values for white children, even

after controlling for transferringsaturation.~,1’ Other

studies, including the collaborative perinatal project,12

the Bogalusa heart study,% and several sma~ll-scale

studies,45~8found persistent differences in mean,hemoglobin levels and hence, prevalence rates of low

28
hemoglobin between black persons and white persons,

using the same reference standards.

Although it is clear that the true prevalence of

anemia is higher in the black population, differences in

hemoglobin levels between black persons and white

persons are evident among healthy Persons.ds Several

researchers have suggested that lower mean hemoglobin values found for black persons are normal healthy

iron status.a Because little difference in the TS values

of black persons and white persons was found in this

study and in others, the problem may lie with applying

hemoglobin cutoff values traditionally used for white

subjects to data obtained from black subjects.

In contrast to low hemoglobin, which was not

common throughout the population, low circulating

iron measured by transferringsaturation and total ironbinding capacity is widespread and is equally prevalent

among black persons and white persons. Groups

identified in this study as at the greatest risk of iron

deficiency are children ages 1–5 years, adolescents ages

12–14 years, and women ages 1844 years.

The finding that low TS is more prevalent than low

hemoglobin is in agreement with earlier studies.

Prasad, for example, cites six studies that reported low

TS without low Hb, and he states that iron deficiency

is two to three times more common than irondeficiency anemia.zo

Despite the high prevalence of low transferring

saturation (iron deficiency), iron-deficiency anemia

(low Hb/TS) is not widespread according to

NHANES I data. Although the condition seems to be

a problem among l-year-old children, only a small

proportion of individuals over age 2 were classified as

low Hb/TS. Apparently, iron intake adequately meets

the iron needs associated with growth in adolescence

and with menstrual blood loss during the female

reproductive years, although the low values found for

transferringsaturation and total iron-binding capacity

indicate that iron nutrition is not optimal.

Diet

The recommended di~’ary allowances (RDAs) for

iron intake are set at ,U mg/day for infants up to 6

months of age, children ages +10 years, males ages 19

and over, and post-menopausal women ages 50 and

over. A higher intake of 15 mg/day is recommended

for children 6 months to 4 years of age. An intake of

18 mg/day is recommended during adolescence (ages

11–18 years) and the female reproductive period (ages

18–50 years).lz

Previous analyses of NHANES I data showed that

iron intakes are well below RDAs for much of the U.S.

population. 1,2Groups whose intakes most often are

deficient include those at greatest risk of anemia and

iron deficiency-infants and preschoolers, adolescents,

and females during their reproductive period. This

study shows that low hemoglobin and low circulating

iron are common in these groups, which suggests a

clear association between iron intake and iron status.

However, a comparison of mean dietary iron intake

and iron status did not support that hypothesis; there

was a significant association between low iron intake

and poor iron status only among children ages 1–3

years.

The study did not detect relationships between

iron intake and iron status. Although such relationships may not exist or may be confounded by other

factors, the 24-hour recall method used to collect

dietmy intake data may have been inaccurate or

unreliable or individuals may have been misclassified

as to their iron status.

The 24-hour recall is a method used to collect

information about a single day’s dietary intake. It may

not reliably reflect daily dietay intake52,73nor intake

over a longer period. The relationship between iron

intake and iron status may not lie with dietary iron

intake alone, but with a more refined measure (perhaps

estimates adjusted for bioavailability). Yet when iron

intake was adjusted experimentally in the multivariate

analyses, the adjusted estimate was not a better

predictor of low hemoglobin in children than (log)

total mean iron intake.

Misclassification of persons with adequate iron

status into low iron status categories may have tiected

the ability to uncover a relationship between iron

intake and iron status. If, for example, the reference

standard for hemoglobin were inappropriate, it would

be difficult to differentiate anemic and nonanemic

groups. Even if this reference standard did identify

correctly the majority of healthy individuals (a highly

specific diagnosis), dilution of the anemic group could

occur if the prevalence of low hemoglobin was low, as

it was in this study. Thus the unreliability of the

dependent variable-iron status—may have diminished the power to detect effects.

The measures of iron status also maybe too broad.

Although hemoglobin and transferringsaturation measurements can reflect the presence of iron deficiency,

neither gives any clue to the cause—whether iron

deficiency results from decreased iron intake or increased iron requirements. Yet iron loss due to

bleeding has different implications from other causes

of increased requirements, because bleeding losses

often cannot be covered by dietary iron intakes.

Finally, the consistent relationship between reported iron intake and iron status among young children

may reflect a greater real association between iron

intake and iron status. This may be due to several

factors associated with this age group-increased iron

needs due to growth, maternal awareness and control

over what the child eats, or a more limited diet.

Socioeconomic, demographic, and

health factors

The multivariate logistic analyses were designed to

point to associations between iron status and selected

29
dietary, socioeconomic, demographic, and health factors. In this approach, race, age, and sex are all

correlates of iron status. Race was significantly associated with iron status in three high-risk groups—

children ages 1–3 years, menstruating women ages

12–54 years, and persons ages 65–74 years. Age was a

significant correlate for children and women, and sex

was a significant correlate for the elderly.

Two socioeconomic factors were significant even

when dietary and health variables, race, age, and sex

were taken into account. Women and children from

poor homes, as measured by the poverty income ratio,

are most likely to have poor iron status. The education

of the head of the household was significantly associated with iron status in all three groups.

Educational attainment generally is regarded as

associated with income, and years of education of the

head of household was correlated with iron status.

However, the relationship of education to iron status is

not simply a function of income. Even when PIR was

taken into account in multivariate analysis, years of

education of the head of household had a distinct

significant association with iron status.

Several health variables also were associated with

iron status among adults in this study. For menstruating women ages 12–54 years, oral contraceptive use,

reproductive history, and prior diagnosis of anemia all

were important. Individuals who have ever been

diagnosed as anemic were more likely to have poor

iron status later in life. Anemia routinely is treated

with oral iron preparations, but after the treatment

period is over, the dietary or health conditions that

contributed to anemia may exert their effect again. The

role of oral contraceptives in reducing blood losses and

of pregnancy in draining iron stores are welll established as factors affecting iron status.52

For persons ages 65–74 years, findings on the

general medical examination and problems related to

eating were associated with iron status in the multivariate approach used in this study. However, these

associations did not occur across all analyses, so the

conclusions for the elderly are less certain.

These multivariate analyses are only one approach

to looking at correlates of iron status in the United

States. They are not designed to show any cause-andeffect relationships, but the findings for the socioeconomic, demographic, and health variables did indicate

that other factors besides iron intake should be

investigated in future studies of iron status.

30
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32
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Exhibit L (rev.).

33
List of detailed tables

1.

2.

3.

4,

5,

6.

7.

&

Hemoglobin levels for males 1-74 years, with mean, standard

error of the mean, and selected percentiles, by race and age:

United States, 1971.74 .................................................................. 36

Hemoglobin levels for females 1-74 years, with mean, standard error of the mean, and selected percentiles, by race and

age: United States, 1971.74 .......................................................... 37

Hematocrit levels for males 1–74 years, with mean, standard

error of the mean, and selected percentiles, by race and age:

United States, 1971-74 .................................................................. 38

Hematocrit levels for females 1-74 years, with mean, standard

error of the mean, and selected percentiles, by race and age:

United States, 1971.74 .................................................................. 39

Serum iron levels for males 1–74 years, with mean, standard

error of the mean, and selected percentiles, by race and age:

United States, 1971.74 .................................................................. 40

Serum iron levels for females 1–74 years, with mean, standard

error of the mean, and selected percentiles, by race and age:

United States, 1971.74 .................................................................. 41

Total iron binding capacity levels for males 1-74 years, with

mean, standard error of the mean, and selected percentiles, by

race and age: United States, 1971–74 .......................................... 42

Total Iron binding capacity levels for females 1-74 years, with

mean, standard error of the mean, and selected percentiles, bv

race and age: United States, 1971 -74 .......................................... 43

9. Transferringsaturation levels for males 1–74 years, with mean,

10,

11,

12,

13.

14.

15.

34

standard error of the mean, and selected percentiles, by race

and age: United States, 1971–74 .................................................. 44

Transferring saturation levels for females 1–74 years, with

mean, standard error of the mean, and selected percentiles, by

race and age: United States, 1971-74 .......................................... 45

Percent and standard error of percent of persons ages 1-74

years, with low hemoglobin levels, by sex, race, and age:

United Statesl 1971-74 .................................................................. 46

Percent and standard error of percent of persons ages 1-74

years, with low transfernn saturation levels, by sex, race, and

age: United States, 1971.74 .......................................................... 47

Percent and standard error of percent of persons ages 1-74

years with the combination of low hemoglobin and low

transferring saturation levels, by sex, race, and age: United

States, 1971-74 .............................................................................. 48

Z-statistics for comparison of percent of persons with low iron

status indicators for sex within age and race within sex and age

comparisons: United States, 1971-74 .......................................... 49

Percenf and standard error of the percent for women 18-44

years with low hemoglobin, low transferringsaturation, and the

combination of low hemoglobin with low transferringsaturation,

with Z-statistic for comparison of pregnancy status, by race:

United States, 1971.74 .................................................................. 50

16.

17.

10.

19.

20.

21.

22.

23.

24.

25.

26.

27.

2a.

Iron intake for persons 1-74 years, with mean, and standard

error of the mean, by sex, hemoglobin status, race, and age:

United States, 1971.74 .................................................................. 51

Iron intake for persons 1-74 years, with mean, and standard

error of the mean, by sex, transferringsaturation status, race,

and age: United States, 1971-74 ..................................................

Z-statistics for comparison of iron intake for persons wit!h low

or adequate hemoglobin and for persons with low or adequate

transferringsaturation, by specied age and sex-race categories:

United States, 1971.74 ..................................................................

Z-statistics for comparison of low and adequate hemoglobin

status for children 1-3 years, with statistic and standard error

of the statistic, by selected characteristics: United States,

1971.74 ...........................................................................................

Z-statistics for comparison of low and adequate hemoglobin

status for white children 1–3 years, with statistic and standard

error of the statistic, by selected characteristics: United States,

1971.74 ...........................................................................................

Z-statistics for comparison of low and adequate hemoglobin

status for black children 1–3 years, with statistic and standard

error of the statistic, by selected characteristics: United States,

1971.74 ............................................................................................

Logit analysis statistics showing the relationship between

selected characteristics and hemoglobin status for children

1-3 years: United States, 1971.74 .................................................

Z-statistics for comparison of low and adequate hemoglobin

status for menstruating women ages 12-54 years, with statistic

and standard error of the statistic, by selected characteristics

United States, 1971-74 ......................................................... ........

Z-statistics for comparison of low and adequate transferring

saturation status for menstruating women ages 12-54 years,

with statistic and standard error of the statistic, by sefected

characteristics: United States, 1971-74 .............................. ........

Z-statistics for comparison of low and adequate hemoglobin

combined with transferring saturation status for menstruating

women ages 12–54 years, with statistic and standard error of

the statistic, by selected characteristics: United States,

1971.74 ...........................................................................................

Z-statistics for comparison of low and adequate hemoglobin

status for whhe menstruating women ages 12-54 years, with

statistic and standard error of the statistic, by selected

characteristics: United States, 1971-74 .......................................

Z-statistics for comparison of low and adequate hemoglobin

status for black menstruating women ages 12-54 years, with

statistic and standard error of the statistic, by selected

characteristics: United States, 1971-74 .......................................

Z-statistics for comparison of low and adequate transferring

saturation status for white menstruating women ages 12-54

years, with statistic and standard error of the statistic, by

52

53

54

55

56

57

57

58

59

60

61

selected characteristics: United States, 1971 -74..., .................... 62
29. Z-statistics for comparison of low and adequate transferring

saturation status for black menstruating women ages 12-54

years, with statistic and standard error of the statistic, by

selected characteristics: United States, 1971 –74 ........................ 63

30. Z-statistics for comparison of low and adequate hemoglobin

combined with transferringsaturation status for white menstruating women ages 12–54 years, with statistic and standard

error of the statistic, by selected characteristics: United States,

1971.74 ........................................................................................... 64

31. Z-statistics for comparison of low and adequate hemoglobin

combined with transferringsaturation status for black menstruating women ages 12-54 years, with statistic and standard

error of the statistic, by selected characteristics: United States,

1971.74 ........................................................................................... 65

32. Logit analysis statistics showing the relationship between

selected characteristics and hemoglobin status for menstruating women ages 12–54 years: United States, 1971 -74 ............... 66

33. Logit analysis statistics showing the relationship between

selected characteristics and transferring saturation status for

menstruating women ages 12-54 years: United States,

1971-74 ........................................................................................... 66

34. Logit analysis statistics showing the relationship between

selected characteristics and hemoglobin and transferringsaturation status for menstruating women ages 12–54 years

United States, 1971–74 . ........... ........ ................ ........ ............... 66

35. Z-statistics for comparison of low and adequate hemoglobin

status for persons ages 65-74 years, with statistic and

standard error of the statistic, by selected characteristics:

United States, 1971.74 .................................................................. 67

36. Z-statistics for comparison of low and adequate transferring

saturation status for persons ages 65-74 years, with statistic

and standard error of the statistic, by selected characteristics:

United States, 1971.74 .................................................................. 68

37. Z-statistics for comparison of low and adequate hemoglobin

status for white persons ages 65-74 years, with statistic and

standard error of the statistic, by selected characteristics:

United States, 1971.74 .................................................................. 69

36. Z-statistics for comparison of low and adequate hemoglobin

status for black persons ages 6S74 years, with statistic and

standard error of the statistic, by selected characteristics:

United States, 1971.74 .................................................................. 70

39. Z-statistics for comparison of low and adequate transferring

saturation status for white persons ages 65-74 years, with

statistic and standard error of the statistic, by selected

characteristics: United States, 1971-74 ..... .......... ...................... 71

40. Z-statistics for compa;son of low and adequate transferring

saturation status for black persons ages 65-74 years, with

statistic and standard error of the statistic, by selected

characteristics: United States, 1971-74 ....................................... 72

41. Logit analysis statistics showing the relationship between

selected characteristics and hemoglobin status for persons

ages 65-74 years: United States, 1971 -74...............................,.. 73

42. Logit analysis statistics showing the relationship beWeen

selected characteristics and transferring saturation status for

persons ages 65-74 years: United States, 1971 -74 ................... 73

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Table 11. Percent and standard error of percent of persons ages 1–74 years, with low hemoglobin Ievels,l by sex, race, and age:

United States, 1971-74

Male Female z

Race and age Number of Estimated Standard Number of Estimated Standard

examined population Percent error of the examined population Percent error of the

persons in thousands percent persons in thousands percent

All racess

1 year ......................................

2-3 years, ...............................

4-5 years, ...............................

6-11 years ..............................

12–”4 years,,, .........................

15-17 years, ...........................

18-44 years, ...........................

45–54 years ............................

55-64 years ............................

65–74 years ............................

White

1 year ......................................

2-3 years ................................

4-5 years ................................

6-11 years ..............................

12-14 years ............................

15–17 years ............................

18–44 years.., .........................

45–54 years, ...........................

55-64 years, ...........................

65–74 years ............................

Black

1 year, .....................................

2–3 years ................................

4-5 years ................................

6–11 years ..............................

12–14 years .,,.........................

15-17 years ............................

18-44 years ............................

45-54 years .,.....,,,......,,.......,,.

55-64 years, ...........................

65-74 years ............................

272

577

549

974

519

487

2,128

740

569

1,501

199

425

419

734

396

373

1,786

607

484

1,293

70

138

127

229

121

108

307

126

77

270

1,692 19.3

3,538 8.7

3,379 1.7

11,913 3.0

6,348 7.6

6,196 2.3

35,425 5.2

11,156 5.3

8,993 13.1

5.495 14.9

1,401 14.9

2,991 7.4

2,857 0.9

10,070 1.6

5,434 4.0

5,297 1,1

31,376 4.5

10,045 4.6

8,195 12.9

4,969 12.4

281 42.1

473 18.7

495 6,4

1,732 11,5

877 30.2

009 8.6

3,529 12.0

1,059 12.0

707 17.0

482 40.4

3.59

1.76

0.83

0.62

1.65

1.02

0.72

1.24

2.12

1.34

3.79

1.91

0.69

0.69

1.40

0.81

0.74

1.28

2.29

1.37

0.85

4.98

3.26

3,16

6.26

4,05

2.78

4.34

6.42

4.4a

254

535

571

974

534

457

4,613

788

639

1,728

179

401

418

734

401

357

3,679

665

531

1,426

70

120

148

234

128

98

065

118

105

294

1,625

3,390

3,301

11,455

6,043

5,932

36,998

12,159

10,054

7,275

1,328

2,857

2,777

9,630

5,146

5,132

32,243

10,876

9,115

6,600

260

501

506

1,745

831

775

4,354

1,235

868

651

12.6

8.3

1.9

3.2

3.4

4.9

4.9

4.7

2.0

4.3

10.5

7.2

1.7

2.1

2.2

3.4

3.4

4.2

0.7

3.1

21.8

15.3

2.8

9,1

11.5

14.8

15.8

9.1

12.4

16.6

3.12

1.79

0.86

0.05

1.18

1.51

0.48

1.13

0.83

0.73

3,44

1,94

0,95

0,,79

1,,10

1,“44

0,,45

1,,17

0,,54

0,,69

7,40

4,77

2,03

2.82

4.23

5.38

1.66

3.97

4.02

3,26

! Age- and sex-speclflc hemoglobin standards are shown m table A.

2 Does not include data for pregnant women,

3 Includes data for races which are not shown as separate categories

46
Table 12. Percent and standard error of percent of persons ages 1-74 years, with low transferring saturation Ievels,’by sex, race, and age:

United States, 1971-74

Male Femalez

Race and age Number of Estimated Standard Number of Estimated Standard

examined population Percent error of the examined population Percent

persons

error of the

in thousands percent pareons in thousands percent

All racesa

1 year ......................................

2-3 years ................................

4-5 years ................................

8-11 years ..............................

12-14 years ............................

15-17 years ............................

13-44 years ............................

45-54 years ............................

55-64 years ............................

6%74 years ............................

White

1 year ......................................

2-3 years ................................

4-5 years ................................

6-11 years ..............................

12-14 years ............................

15-17 years ............................

1644 years ............................

45-54 years ............................

55-64 years ............................

65-74 years ............................

Black

1 year ......................................

2-3 years ................................

4-5 years ................................

6-11 years ..............................

12-14 years ............................

15-17 years ............................

1844 years ............................

45-54 years ............................

55-64 years ............................

65-74 years ............................

113

342

552

979

526

485

2,126

715

556

1,545

87

251

411

719

393

360

1,753

579

464

1,232

26

82

130

250

131

119

337

130

05

294

724

2,203

3,372

11,925

6,260

6,248

35,449

11)137

8,990

5,496

625

1,B77

2,859

10,086

5,343

5,354

31,398

10,026

8,192

4,969

99

275

488

1,738

883

813

3,519

1,073

715

488

50.8

27.0

23.1

16.9

8.6

6.3

3.6

7.2

7.7

4.2

47.7

27.5

22.2

17.6

7.9

6.8

3.6

7.4

7.9

4.3

70.9

24.3

27.3

13.2

12.9

3.7

4.2

5.7

5.5

3.0

7.05

3.60

2.69

1.80

1.83

1.65

0.61

1.45

1.70

0.77

8,03

4.23

3.27

2.13

2.04

1.99

0.67

1.63

1.88

0.87

13.36

7.10

5.69

6.87

4.39

2.60

1.64

3.05

3.71

1.49

77

313

571

988

535

462

4,661

789

632

1,701

56

233

405

720

389

350

3,637

658

514

1,375

20

76

161

262

141

110

956

126

115

318

505

2,070

3,295

11,433

8,036

5,980

37,052

12,165

10,037

7,283

438

1,793

2,758

9,625

5,133

5,160

32,290

10,880

9,103

6,606

59

264

515

1,735

818

796

4,373

1,243

848

656

38.3

24.2

18.0

12,8

13.1

16.3

16.4

9.5

8.1

7.1

37.1

21.0

17.3

12.7

12.4

16.3

15.8

9.1

7.2

6.9

‘53.0

43.9

22.9

12.9

16.4

17.2

20.7

13.1

17.6

9.4

8.31

3.63

2.41

1.59

2.19

2.58

0.81

1.57

1.63

0.93

9.68

4.00

2.82

1.86

2.51

2.96

0.91

1.68

1.71

1.03

.

8.54

4.97

3.11

4.68

5.40

1.97

4.51

5.33

2.45

I Persons with a transfernn salutation below 16.0 percent snd a TIBC above 250 ~g/dl were classified as low treneferrin saturation.

ZDoes not include data for pregnant women.

3Includes data for races which are not shown as separate categories.

NOTE Asterisks indicate estimates that do not meet this report’s slandards of reliability.

47
Table 13. Percent and standard error of percent of persons ages 1-74 years, with the combination of low hemoglobin and low tra(nsferrin

saturation Ievels,l bv sex, race, and acre: United States, 1971–74

Male Femalez

Race and age Number of Estimated Standard Number of Estimated Standard

examined population Percent error of the examined population Percent error (of the

persons in thousands percent persons in thousands percent

AH races3

1 year ......................................

2-3 years .... . .............. .......

4-5 years ................................

6–1 1 years ..............................

12–14 years...,, .......................

15–17 years..., ........................

18-44 years ............................

45-54 years ............................

55–64 years .,, .........................

65-74 years, ...........................

White

1 year ......................................

2–3 years ................................

4–5 years ................................

6–1 1 years ..............................

12–14 years ............................

15–17 years ............................

18-44 years..., ........................

45–54 years ............................

55-64 years...,,, ......................

65-74 years...,, .......................

Black

1 year ......................................

2-3 years ................................

4-5 years ................................

6–1 1 years ..............................

12-14 years ............................

15–17 years.., .........................

18-44 years.,, .........................

45–54 years.,, .........................

55-64 years .,, .........................

65-74 veals ............................

109

333

524

927

497

2,013

690

527

1,469

84

247

394

6B9

374

342

1,672

558

443

1,181

25

77

127

228

121

108

306

126

77

270

722

2,177

3,372

11,924

6,295

6,237

35,501

11,142

9,059

5,495

623

1,864

2,850

10,083

5,379

5,339

31,452

10,032

0,261

4,969

99

264

497

1,745

881

810

3,540

1,074

718

483

17.7

1.6

0.9

0.5

1.5

0.2

0,1

1.3

2.2

1.8

17.0

0.9

0.7

0,4

0.9

0.0

0.1

1.3

2.4

1.0

22.2

6.4

2.0

1.5

5.3

1.2

0.3

0.8

0.8

1.5

5.49

1.04

0.61

0.34

0,82

0.31

0.10

0.65

0.96

0.52

6.15

0.90

0.63

0.36

0.73

0.00

0.12

0.72

1.09

0.58

12.47

4.18

1.86

1.21

3.06

1.57

0.47

1.19

1.52

1.11

72

296

547

931

510

431

4,397

741

602

1,607

53

227

395

691

377

331

3,469

618

494

1,305

18

65

148

234

128

98

863

118

105

294

479

2,015

3,303

11,446

6,056

5,947

36,969

12,161

9,968

7,279

421

1,750

2,780

9,621

5,157

5,152

32,206

10,876

9,034

6,601

49

252

509

1,746

813

772

4,401

1,241

843

655

9.9

3.3

0.3

0.6

1.0

2.0

2.8

2.4

0.8

1.6

11.2

1.3

0.3

0,4

0.6

1.6

2.2

2.4

0.6

1.3

‘0.0

17,3

0.2

1.4

3.1

4,1

7.4

2.0

2.7

4.1

5,;~B

1.!56

0.:35

0.:38

0.66

1.01

0.:37

0.84

0.!54

0.47

6.!50

1.”13

0.41

0.:36

0.[30

1.03

0.:37

().92

0.!52

0.47

.

7.04

O.!js

1.”15

2.:30

3.00

1.34

1.{)3

2.:?7

1.73

~Age- and sex-speclflc hemoglobin stendards are found in Table A. Persons with a transferring saturation below 16.0 percent and a TIBC above 250 ~g/dl were classified as

low transferring saturation.

ZDoes not include data for pregnant women.

3Includes data ~orraces which are not shown as separate categories,

NOTE: Asterisks indicate estimates that do not meet this raport’s standards of reliability.

48
Table 14. Z-statisticsi for comparison of percent of persons with low

iron status indicators for sex within age and race within sex and age

com~arisons: United States. 1971-74

Iron status indicator

Low

Comparisons Low Low hemoglobin

transferring hemoglobin saturation and low

transferring

saturation

Males versus females

1 year .................................

2-3 years ...........................

4-5 years ...........................

6-11 years .........................

12-14 years .......................

15-17 years .......................

18-44 years .......................

45-54 years .......................

55-64 years .......................

65-74 years .......................

Black males versus

white males

1 year..., .............................

2-3 years ...........................

4-5 years ...........................

6-11 years .........................

12-14 years .......................

15-17 years .......................

1B44 years .......................

45-54 years .......................

55-64 years .......................

65-74 years .......................

Black females versus

white females

1 year .................................

2-3 years ...........................

4-5 years ...........................

6-11 years .........................

12-14 years .......................

15-17 years .......................

16-44 years .......................

45-54 years .......................

55-64 years .......................

65-74 veals .......................

1.41

0.16

-0.17

-0.17

2.00

-1.42

0.35

0.36

4.87

6.93

-2.63

-0.75

-1.65

-3.06

4.07

-1.02

-2.61

-1.63

-0.60

-5.98

-1.38

-1.57

-0.49

-2.39

-2.13

-2.05

-6.40

-l.l B

-2.41

+.06

Z-statistics

1.15

0.55

1.41

1.59

-1.58

-3.26

-12.62

-1.00

-0.17

-2.10

-1.49

-0.85

-0.79

1.07

-1.03

0.95

-0.34

0.49

0.58

0.75

*

-2.43

-0.98

-0.06

-0.75

-0.15

-2.26

4.83

-1.86

-0.63

1.02

-0.91

0.84

-0.19

0.48

-1.70

-6.96

-1.03

1.27

0.59

-0.37

-1.29

-0.66

-0.87

-1.40

-0.76

-0.41

0.36

0.05

0.24

*

-2.24

0.15

-0.03

-1.05

-0.79

-3.75

0.19

-0.66

4.78

I Significant values are z & 1.96 based on two-tailed test (P=o.05).

NOTE Asterisks indicate statisl!cs that do not meat this report’s standards of

reliability,

49
Table 15. Percent and standard error of the percent for women 16-44 years with low hemoglobin,l low transferringsaturation,z and the cornbioation of

low hemoglobin with low transferringsaturation, with Z-statistic for comparison of pregnancy status, by race: United States, 1971-74.

Pregnant Non-pregnant

Race and iron status indicators Number of Standard Number of Standard

examined Percent

Z-statistic

error of the examined Percent error of the

persons percent persons percent

All racesa

Low hemoglobin ...................................................... 196 31.9 4.99 4,613 4.9 0.48 !j.as

Low transferringsaturation ...................................... 195 22.1 4.46 4,661 16.4 O.B1 1.26

Low hemoglobin and low transferring

saturation ................................................................ 1B5 6.5 2.72 4,397 2.8 0.37 ‘1.35

White

Low hemoglobin ...................................................... 152 28.4 5.49 3,679 3.4 0.45 4.54

Low transferringsaturation ...................................... 147 21.7 5.10 3,637 15.8 0.91 ‘1.14

LOW hemoglobin and low transferring

saturation ................................................................ 141 7.0 3.22 3,469 2.2 0.37 ‘1.40

Black

Low hemoglobin ......................................................

Low transferringsaturation ......................................

Low hemoglobin and low transferring

saturation ................................................................

36 52.9

40 27.6

36 5.0

12.48

10.60

5,45

865 15.8 1.86 ,2.94

956 20.7 1.97 10.64

863 7.4 1.34 10.43

1Age. and sex-specific hemoglobin standards are found in table A.

ZPersons with a transferringsaturation below 16.0 percent and a TIBC above 250 pg/dl were classified as having low transferringsaturation.

3Includes data for races which are not shown as separate categories.

50
<=g

c1w

“%

fi

91

T-.=$.

?1

gig!

akii

51
*mwowmr-wmr-

@Y1-*u-Jl-mcu*cYel

I-I?’Jlommcqu)w !--

.-

0000.CWF--7

~lqo-)~mlq-qm.u-)o

mmawm.momw

,

>

m

r

r

l-d.
N*

●

<:

=:.ucau

-i m

T

~,,

al

L?E

-a .

53
Table 19. Z-statistics for comparison of low and adequate hemoglobin statusl for children 1-3 years, with statistic and standard error of

the statistic, by selected characteristics: United States, 1971-74

Low hemoglobin Adequate hemoglobin

Characterktics Number of Standard Number of Standard

examined Statistic

Z!-statistic

error of the examined Statistic error of the

persons statistic persons sta fistic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .... . ....

Total nonanimal tissue iron intake (mg) ...........

Total protein intake (mg) ...... ....... . ........ ...... . .

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) ........................ ....

Estimated available iron with tea (mg) .............

Vitamin C (mg) .......................)..............................

Socioeconomic

Age of mother at child’s birth (years) ....... ......

Birth weight (pounds) ...........................................

Age (years) .............................................................

Poverty income ratio (index) ...................... ........

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Other2

Pica ..........................................................................

Regular vitamin use ..............................................

Regular mineral use..............................................

Regular vitamin and mineral use .......................

Ever breastfed .......................................................

Is child the first born ...........................................

Premature birth ......................................................

Present illness........................................................

Regular aspirin use, ..............................................

177

177

177

177

177

177

177

177

177

177

173

175

177

173

173

177

177

173

177

177

177

177

177

142

175

159

177

Mean Mean

6.20

73.63

1.50

4.70

49.13

11.95

37.16

0,65

0.65

60.04

24.01

7.17

2.19

1.57

4,253.93

5.74

32.42

10.72

Percent

37.49

30.26

10.15

42.46

16.90

16.43

7.67

45.44

41.00

0.49

2.78

0.19

0.41

2.23

1.20

1.82

0.06

0.06

7.49

0.56

0.13

0.09

0.11

297.53

0.29

1.02

0,37

1,245

1,245

1,245

1,245

1,245

1,245

1,245

1,245

1,245

1,245

1,232

1,229

1,245

1,227

1,226

1,245

1,244

1,201

7.47

82.55

1.85

5.61

52.51

14.68

37.82

0.82

0.82

76.93

25.23

7.31

2.56

2.22

3,877.03

4.76

31.77

11.94

Percent

0.21

0.94

0.08

0.20

0.93

0.55

0.68

0.03

0.03

3.47

0.24

0.05

0.04

0.06

111.17

0.06

0.37

0.14

-2.39

-3.05

-1.73

-2.02

-1.40

-2.06

-0.33

-2.63

-2.66

-2.05

-1.94

-0.10

4.15

-5.21

1.19

3.25

0.60

-3.12

5.46

5.18

3.42

5.57

4.23

4.67

3.02

5.92

5.55

1,245

1,245

1,245

1,245

1,241

936

1,241

1,072

1,245

16.27

44.56

20.71

52.93

26.50

17.70

7.16

32.95

32.07

1.64

2.11

1.72

2.12

1.88

1.67

1.10

2.15

1.98

3.37

-2.56

–2.76

-1.61

-2.06

-0.25

0.16

1.98

1.52

! Age-and sex-specific hemoglobin standards are found in table A.

ZStatistics [or Ihese characteristics represent only those persons who answered yes on the questionnaire.

54
Table 20. Z-statistics for comparison of low and adequate hemoglobin statusl for white children 1-3 years, with statistic and standard error

of the statistic, by selected characteristics: United States, 1971-74

Low hemoglobin Adequate hemoglobin

Characteristics Number of Standard Number of Standard Z-sfatistic

examined Statistic error of the examined Statistic error of the

persons statistic persons sta fistic

Dietaty intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (mg) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age of mother at child’s birth (years) ..............

Birth weight (pounds) ...........................................

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Otherz

Pica ..........................................................................

Regular vitamin use ..............................................

Regular mineral use..............................................

Regular vitamin and mineral use .......................

Ever breastfed .......................................................

Is child the first born ...........................................

Premature birth ......................................................

Present illness........................................................

Regular aspirin use ...............................................

105

105

105

105

105

105

105

105

105

105

102

105

105

103

103

105

105

102

105

105

105

105

105

84

105

93

105

5.91

73.14

1.30

4.61

49.65

10.95

38.70

0.60

0.59

61.86

24.11

7.40

2.19

1.73

4,268.04

5.62

31.78

10.92

Percent

37.63

30.67

9.79

45.76

18.00

13.52

4.75

43.35

45.41

Mean

0.45

3.20

0.20

0.37

2.89

1.46

2.36

0.06

0.06

10.52

0.69

0.14

0.11

0.15

391.63

0.36

1.24

0.49

7.09

6.76

4.35

7.29

5.62

5.60

3.11

7.71

7.29

960

960

960

960

960

960

960

960

960

960

951

951

960

948

949

960

960

925

960

960

960

960

957

719

951

815

960

7.49

82.77

1.60

5.69

52.87

14.36

38.51

0.81

0.81

78.77

25.44

7.39

2.59

2.36

3,909.25

4.63

31.38

12.22

Percent

18.06

45.82

21.39

56.07

28.20

18.04

5.72

31.74

32.16

0.25

1.06

0.08

0.23

1.06

0.61

0.76

0.03

0.03

4.06

0.27

0.06

0.04

0.06

128.74

0.08

0.39

0.16

1.86

2.41

1.99

1.97

2.18

2.15

1.13

2.45

2.26

-3.10

-2.86

-2.36

-2.46

–1 .05

-2.16

0.06

-3.00

-3.33

–1 .50

–1 .80

0.07

-3.42

-3.87

0.87

2.70

0,31

–2.51

2.67

-2.08

-2.43

-1.37

–1 .69

-0,75

-0.29

1.44

1.16

1Age- and sex-specific hemoglobin standards are found in table A.

ZStatistics for these characteristics represent only those persons who answered yes on the questionnaire.

55
Table 21. Z-statistics for comparison of low and adequate hemoglobin status’ for black children 1-3 years, with statistic and standard error

of the statistic, by selected characteristics: United States, 1971-74

Low hemoglobin Adequate hemoglobin

Characteristics Number of Standard Number of Standard Z-statistic

examined Statistic error of the examined Statistic error of the

persons statistic persons sta fistic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ...... ................ ..

Total animal tissue iron intake (mg) .. ... .

Total nonanimal tissue iron intake (mg) ....... .

Total protein intake (ma) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .. .

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) . .........

Vitamin C (mg) ......................................................

Socioeconomic

Age of mother at child’s birth (years) ..............

Broth weight (pounds) ...........................................

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Otherz

Pica ... ...... ...... ...... ...... ........ ....... . . .... .

Regular vitamm use,, ............................................

Regular mineral use..............................................

Regular vitamin and mineral use...,, ..................

Ever breastfed .......................................................

Is child the first born ...........................................

Premature bifih ......................................................

Present illness........................................................

72

72

72

72

72

72

72

72

72

72

71

70

72

70

70

72

72

71

72

72

72

72

72

50

70

66

72

Mean

7.04

75.02

2.10

4.94

47.65

14.86

32.77

0.02

0.82

54.76

23.74

6.50

2.19

1.13

4,212.49

6.10

34.27

10.10

Percent

37.09

28.51

11.18

32.89

13.90

24.76

16.26

51.56

28.23

1.19

5.52

0.39

1.00

3.51

2.12

2.63

0.12

0.12

8.29

1.02

0.24

0.15

0.12

445.46

0.52

1.83

0.48

8.54

7.98

5.57

8.31

6.12

8.50

6.61

9.23

,7.96

265

2B5

265

285

205

285

2B5

285

285

285

281

278

285

279

279

285

284

276

285

285

285

285

2B4

217

278

257

Regular aspirin use...,, .......................................... 285

Mean

7.32

81.14

2.18

5.14

50.18

16.70

33.41

0.86

0.86

65.13

23.87

6.80

2.52

1.31

3,664.61

5.61

34.27

10.16

Percent

19.67

36.52

16.30

39.24

15.30

15.50

16.56

40.07

31.46

0.39

2.12

0.18

0.28

2.18

1.25

1.49

0.07

0.07

5.78

0.58

0.13

0.07

0.10

202.35

0.23

0.98

0.28

3.53

4.28

3.26

4.34

3.20

3.69

3.35

4.59

4.13

-0.22

--1.03

--0.18

--0.19

-4.61

--0.78

-0.21

-0.28

--0.28

--1.03

--0.11

--1.09

--2.01

-1.14

1.12

0.87

0.00

-0.14

1.80

.4.88

-0.79

.4.68

-0.20

1.00

-0.04

1.12

-0.36

IAge- andsex-specifichemoglobmstandardsare foundintable A

ZStatisticsforthese characteristicsrepresentonlythosepersonswhoansweredyes onthe questionnam

56
Table 22. Logit analysis statistics showing the relationship between selected characteristics and hemoglobin status for children 1-3 years:

United States, 1971-74

Characteristics

bgit analysis statistics

Coefficierrt Sfandard error t-fesf stafisfic 1 Odds rafio 2

Constant ............................................................................................. 1.494 0.672

Race ...................................................................................................

. . . . . .

0.891 0.249 3.580 2.45

Age ...................................................................................................... -0.505 0.097 -5.216 0.60

Poverty income ratio........................................................................ -0.243 0.104 -2.336 0.78

Education of head of household (years) ..................................... -0.036 0.018 -2.018 0.96

Hca ..................................................................................................... 0.712 0.211 3.376 2.05

Log total iron intake ........................................................................ -0.015 0.004 -3.664 0.98

10nly characteristicswitha f-test statistic > 1.96 (p < .05) are shown.

~See appendixI fordiscussionofoddsratios.

Table 23. Z-statistics for comparison of low and adequate hemoglobin status! for menstruating women ages 12-54 years, with statistic and

standard error of the statistic, by selected characteristics: United States, 1971–74

Low hemoglobin Adequate hemoglobin

Characteristics Number of Standard Number of Sfandard Z-stafistic

examined Statisfic error of the examined Statistic error of the

persons sta fistic persons sfatistic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (mg) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

Marriedz ............................................ ......................

Otherz

Pica ..........................................................................

Regular vitamin use ..............................................

Regular mineral use............................................l.

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet .............................................................

Oral contraceptive usage in pasf 6 months ....

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General fintings .....................................................

Abdominal operations ................... ......................

Acte beaan menstruating Wears) .......................

259

259

259

259

259

259

259

259

259

246

240

259

259

253

250

220

259

259

259

259

259

259

259

259

259

259

258

259

Mean

9.50

95.16

3.59

5.91

63.26

31.19

32.07

1.34

1.30

68.15

31.10

2.30

3,908.12

4.64

4,234

10.1B

11.01

Percent

65.30

1.85

21.73

13.43

36.94

49.38

5.76

15.60

63.70

37.70

29.10

0.83

24.50

Mean

12.85

0.42

1.87

0.29

0.27

2.80

2.17

1.58

0.08

0.08

6.88

1.10

0.13

248.43

0.23

1.12

0.35

0.27

4.69

1.26

3.04

3.18

6.06

4.66

2.17

3.30

4.48

4.52

4.23

0.85

4.01

0.13

3.646

3,646

3,646

3,646

3,646

3,646

3,646

3,646

3,646

3,646

3,646

3,542

3,542

3,646

3,645

3,569

3,627

3,117

3,646

3,646

3,646

3,646

3,646

3,646

3,646

3,646

3,646

3,646

3,639

3,646

Mean

9.99

96.09

3.75

6.23

65.09

31.02

34.06

1.41

1,36

80.27

27.72

2.67

3,687.13

4.28

39.39

11.67

11.55

Percent

65.70

1.23

26.91

19.98

48.99

46.37

7.05

22.41

53.96

25.72

33.00

0.89

20.73

Mean

0.12

0.52

0.08

0.06

0.76

0.63

0.45

0.02

0.02

2.22

0.27

0.04

65.34

0.05

0.29

0.08

0.07

1.28

0.27

1.13

0.99

1.70

1.24

0.67

1.04

1.24

1.09

1.17

0.23

1.01

3,646 12.61 0.04

-1.12

-0.48

-0.54

-1.12

-0.62

0.06

-1.21

-0.66

-1.00

-1.68

2.98

-2.63

0.86

1.56

2.56

-4.72

-1.94

-0.08

0.46

-1.79

-1.97

-1.91

0.62

-0.92

-1.93

2.09

2.56

-0.91

-0.07

0.91

1.73

t Age-andsex-specifichemoglobinstandardsare foundintableA.

2Statisticsforthese characteristicsrepresentonlythosepersonswhoansweredyes onthe questionnaire.

57
Table 24. Z-statistics for comparison of low and adequate transferring saturation statusl for menstruating women ages 12–54 years, with

statistic and standard error of the statistic, by selected characteristics: United States, 1971-74

Low transferringsaturation Adequate transferringsaturation

Characteristics Number of Standard Number of Standard

examined Statistic

Z-statistic

error of the examined Statistic error of the

persons statistic r3ersons sta fistic

Dietary intake

Total iron intake (mg) ................ ........ ........ ......

Log total iron intake (log mg) ............ ...... .......

Total animal tissue iron intake (mg) . .. . .

Total nonanimal tissue iron intake (mg) ..........

Total protein intake (mg) ........... ................. ......

Total animal tissue protein intake (mg) . ....... ..

Total nonanimal tissue protein intake (mg) .. ..

Estimated available iron (mg) . ..... ....... ........ .

Estimated available iron with tea (mg) ........ ..

Vitamin C (mg) . ...... ......................... ...................

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ........ ........ .............

Estimated family income (dollars) ...... ....... .....

Number of persons in household (units) ..........

Age of head of household (years) ... ...... ........

Education of head of household (years) ..........

Education of examinee (years) ......... ........ .......

Marriedz ...................................................................

Otherz

Pica ............,,,,....,.,........................ ...... ....... ....... ,.

Regular vitamin use,, ............................................

Regular mineral use., ............................................

Regular vitamin and mineral use ......................

Regular aspirin use ...............................................

Special diet .............................................................

Oral contraceptive usage in past 6 months...,

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findings .....................................................

Abdominal operations ................. .............. ........

Age began menstruating (years) .... ...... ....... ...

664

664

664

664

664

664

664

664

664

664

664

648

648

664

663

640

662

571

664

664

664

664

664

664

664

664

664

664

662

664

664

Mean

9.51

94.57

3.55

5.96

61.80

2,940

32.40

1.33

1.30

73.75

29.24

2.45

3,727.55

4.61

40.42

11.05

11.23

Percent

64.00

2.11

21.36

15.68

39.23

46.38

8.53

14.08

60.85

30.72

34.08

5.39

23.55

Mean

12.61

0.27

1.19

0.17

0.20

1.66

1.33

1.03

0.05

0.05

5.07

0.65

0.09

152.99

0.12

0.67

0.20

0.15

3.01

0.84

2.39

2.12

4.02

2.90

1.63

2.03

2,84

2.69

2,76

1.32

2.47

0.08

3,241

3,241

3,241

3,241

3,241

3,241

3,241

3,241

3,241

3,241

3,241

3,142

3,142

3,241

3,241

3,174

3,223

2,774

3,241

3,241

3,241

3,241

3,241

3,241

3,241

3,241

3,241

3,241

3,235

3,241

3,241

Mean

9.99

96.11

3.76

6.24

65.58

31,07

34.51

1.41

1.38

80.81

27.70

2.67

3,670.17

4.23

39.40

11.96

11.59

Percent

0.13

0,55

0.09

0,09

0.84

0.68

0.48

0.02

0.02

2.34

0.29

0,04

69.34

0.05

0.30

0.08

0.07

65.60

1.07

30.51

20.79

50.67

47.22

7.76

23.10

53.17

25.64

33.03

1.57

20.71

Mean

1.35

0.27

1.21

1.07

1.89

1.32

0.70

1.11

1.31

1.15

1.24

0.33

1.07

12.63 0.04

-1.62

-1.17

-1.07

-1,26

-2.01

-1.12

-1.86

-1.49

-1.51

-1.26

2.14

-2.28

0.34

2.81

1.39

-4.17

-2.22

LO.48

1.18

43.42

–’2.15

-2.57

-0.26

13.43

-:3.91

,2.45

1.74

13.35

2.82

1.06

-0.23

~Persons with a transferringsaturation below 16,0 percent and a TI BC value above 250 pg/dl were classified ae having a low transferringsaturation,

ZStatistics for these characteristics represent only those persons who answered yes on the questionnaire.

58
Table 25. Z-statistics for comparison of low and adequate hemoglobin combined with transferring saturation status’ for menstruating women

ages 12-54 years, with statistic and standard error of the statistic, by selected characteristics: United States, 1971 –74

Low hemoglobirr/ Adequate hemoglobin/

transfemn saturation tran.sferrin saturation

Characteristics Number of Standard Number of Standard Z-statistic

examined Statisfic error of the examined Statistic error of the

persons statistic persons statistic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (mg) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units), .........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

Married~ ...................................................................

Other~

Pica ..........................................................................

Regular vitamin use ..............................................

Regular mineral use....................... ......................

Regular vitamin and mineral use ......................

Regular aspirin use ...............................................

Special diet .............................................................

Oral contraceptive usage in past 6 months ....

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .......................... ......................

General findings.....................................................

Abdominal operations ...........................................

Age began menstruating (years) .......................

143

143

143

143

143

143

143

143

143

143

143

139

139

143

143

139

143

133

143

143

143

143

143

143

143

143

143

143

142

143

143

Mean

9.73

96.55

3.69

6.04

61.74

31.01

30.78

1.37

1.31

62,02

34.41

2.33

3,903.79

4.04

44.54

9.11

10.75

Percent

47.60

2.30

14.60

11.00

27.00

47.90

7.50

9.10

72.30

38.70

34.00

0.00

23.40

Mean

0.61

2.57

0.44

0.39

4.15

3.35

1.90

0.12

0.11

7.50

1.44

0.17

339.39

0.31

1.44

0.50

0.37

6.49

18.69

4.43

3.93

7.35

6.27

3.30

3.61

5.61

6.11

5.95

0.00

5.32

13.08 0.18

3,762

3,762

3,762

3,762

3,762

3,762

3,762

3,762

3,762

3,762

3,762

3,651

3,651

3,762

3,761

3,683

3,742

3,212

3,762

3,762

3,762

3,762

3,762

3,762

3,755

3,762

3,762

3,762

3,75!5

3,762

3,762

9.95

95.97

3.74

6.21

65.17

31.04

34.14

1.41

1.37

79.85

27.67

2.66

3,678.21

4.28

39.44

11.85

11.54

Percent

62.40

1.20

20.90

19.80

40.90

47.20

7.80

22.40

53.80

25.90

32.80

0.90

20.90

Mean

12.61

0.12

0.51

0.08

0.09

0.76

0.61

0.44

0.02

0.02

2.18

0.27

0.04

64.25

0.05

0.28

0.08

0.06

1.20

0.27

1.11

0.98

1.75

1.22

0.65

1.02

1.22

1.07

1.15

0.23

0.99

0.03

-0.35

0.22

-0.11

-0.42

-0.80

-0.01

-1.72

-0.34

-0.52

-2.28

4.59

-1.91

0.65

1.81

3.46

-5.47

-2.10

-2.24

0.06

-3.13

-2.18

-2.90

0.11

-0,09

-3.54

3.22

2.06

0.20

-3.91

0.46

2.54

~Age- and sex-apeclflc hemoglobin standards are found in table & persons with a iransfemn saturation below 16.0 percenl and TIBC value above 250 ~g/dl were classn7ed

as having a low transferringsaturation

~statistics for these charactenst(cs represent only those persons who anewered yes on the questlonnare.

59
Table 26. Z-statistics for comparison of low and adequate hemoglobin status’ for white menstruating women ages 12-54 years, with

statistic and standard error of the statistic, by selected characteristics: United States, 1971-74

Low hemoglobin Adequate hemoglobin

Characteristics Number of Standard Number of Standard Z-stlatistic

examined Statistic error of the examined Statistic error of the

persons statistic persons statistic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (ma) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units) ..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

Marriedz ...................................................................

Otherz

Pica ..........................................................................

Regular vitamin use ..............................................

Regular mineral use ..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet .............................................................

Oral contraceptive usege in past 6 months ....

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findngs .....................................................

Abdominal operations ...........................................

Age began menstruating (years) ........................

133

133

133

133

133

133

133

133

133

133

133

125

125

133

133

131

132

119

133

133

133

133

133

133

133

133

133

133

133

133

133

Mean Mean

9,88

97.70

3.64

6.04

66.85

32.44

34.41

1.41

1.35

70.88

33.28

2.66

3,939.53

4.35

42.40

10.42

11.12

76,10

0.00

22.92

14.76

37.23

50.49

5.35

15.73

67.10

45.13

29.63

0.00

26.96

12,86

0.59

2.50

0.45

0.34

4.16

3.37

2.07

0.12

0.11

10.07

1.55

0.17

362,92

0.27

1.54

0.50

0.36

5.66

0.00

5.47

4.61

6.44

6.50

2.93

4.74

6.11

6.47

5.94

0.00

5.77

0.17

3,024

3,024

3,024

3,024

3,024

3,024

3,024

3,024

3,024

3,024

3,024

2,939

2,939

3,024

3,024

2,963

3,010

2,615

3,024

3,024

3,024

3,024

3,024

3,024

3,024

3,024

3,024

3,024

3,024

3,024

3,024

10.06

96.56

3.76

6,29

65.69

30.98

34.72

1.42

1.36

81.12

27.86

2.77

3,636.44

4.18

39.32

12.05

11.65

Percent

67.60

0.60

30.50

20.69

50.69

47.40

6.14

22.28

53.36

25.61

32.69

0.90

21.39

Mean

12.60

0.13

0.56

0.09

0.10

0.85

0.69

0.50

0.03

0.03

2.44

0.30

0.04

71.96

0.05

0.31

0.09

0.07

1.37

0.21

1.26

1.11

1.97

1.36

0.75

1.14

1.36

1.19

1.26

0.26

1.12

0.04

-0.30

CI.44

C1.le

41.71

11.27

CI.42

41,14

41.08

~1.26

41.99

3.44

-0.52

0.02

0.62

1.96

-3,20

-1.36

1,41

-2.85

-1.35

-1.29

-1.55

0.47

-0.92

-1.35

2.19

2.94

-0.50

-3.51

0.95

1,55

~Age- and sex-specific hemoglobin standards are found in table A.

2Statistics for thase characteristics represent only those persons who answerad yes on tha questionnaire.

60
Table 27. Z-statistics for comparison of low and adequate hemoglobin statusl for black menstruating women ages 12-54 years, with

statistic and standard error of the statistic, by selected characteristics: United States, 1971-74

Low hemoglobin Adequate hemoglobin

Characteristics Number of Standard Number of Standard Z-statistic

examined Statistic error of the examined Statistic error of the

persons statistic persons statistic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (mg) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units) ..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

126

126

126

126

126

126

126

126

126

126

126

123

123

126

126

122

126

109

126

126

126

126

126

126

126

126

126

126

125

126

126

Mean

0.74

90.06

3.00

5.66

56.03

28.6B

27.35

1.21

1.19

62.65

26.70

1.58

3,847.99

5.25

42.22

9.68

10.78

Percent

Marriedz ...................................................................

Otherz

Pica ..........................................................................

Regular vitamin use ..............................................

Regular mineral use ..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet .............................................................

Oral contraceptive usage in past 6 months ....

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findings .....................................................

Abdominal operations ...........................................

Age began menstruating (years) ........................

43.60

5.57

19.33

10.76

36.36

47.15

6.59

15.33

56.86

22.77

28.04

2.50

19.54

Mean

12.84

0.57 622

2.76 622

0.28 622

0.46 622

3.63 622

2.24 622

2.40 622

0.09 622

0.09 622

8.75 622

I .3a 622

0.15 603

326.07 603

0.39 621

1.63 621

0.46 606

0.37 617

Mean

9.34

92.18

3.61

5.73

59.99

31.37

28.62

1.34

1.33

73.04

26.52

1.78

4,105.14

5.15

39.98

10.34

10.70

Percent

7.13 502

3.06 622

5.28 622

4.14 622

8.72 622

6.67 622

3.31 622

4.82 622

6.62 622

5.60 622

6.00 622

2.09 621

5.30 622

48.00

6.47

15.5a

12.33

34.75

41.17

5.16

23.45

58.97

24.93

41.17

0.60

15.20

Mean

0.22 622 12.74

0.30

1.41

0.19

0.21

1.90

1.49

0.96

0.05

0.05

5.33

0.65

0.09

151.28

0.16

0.73

0.10

0.16

3.35

1.48

2.18

1.98

4.00

2.96

1.33

2.55

2.96

2.60

2.96

0.47

2.16

0.10

-0.94

-0.60

–1 .58

-0.14

-0.97

-1.00

-0.49

-1.26

–1 .34

-1.01

0.12

-1.13

-0.72

0.26

1.25

-1.34

0.20

4.66

-0.26

0.66

4.34

0.17

0.02

0.40

-1.49

-0.29

-0.35

-1.96

0.89

0.76

0.41

1Age- and sex-specific hemoglobin standards ara found in table A.

zStatistics for these characteristics represent only those pereons who answered yes on the questionnaire.

61
Table 28. Z-statistics for comparison of low and adequate transferring saturation status! for white menstruating women ages 12-54 years,

with statistic and standard error of the statistic, by selected characteristics: United States, 1971–74

Low transferring saturation Adequate transferring saturation

Characteristics Number of Standard Number of Standard Z-statistic

examined Statistic error of the examined Statistic error of the

persons sfa tistic persons statistic

Dietary intake

Total iron retake (mg) ..........................................

Log total iron intake (log mg) ..... ........ ...... . ..

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (mg) ..... ....

Total protein retake (mg) .... ...... ........ ........ ....

Total animal tissue protein intake (mg) ... ........

Total nonanimal tissue protein intake (mg) ....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ....... ..............................................

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units) ..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

Marriedz ...................................................................

Otherz

Pica ...... . ................................ .............................

Regular vitamin use ..............................................

Regular mineral use ..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet .............................................................

Oral contraceptive usage in past 6 months ....

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findings .....................................................

Abdominal operations ...........................................

Age began menstruating (years) ........................

505

505

505

505

505

505

505

505

505

505

505

492

492

505

505

497

504

Mean

9.52

94.67

3.58

5.94

62.55

29.45

33.10

1.33

1.29

73.09

29.34

2,50

3,696,64

4.46

40.17

11.22

11.34

Percent

0.31

1.36

0.20

0.23

1.95

1.54

1.19

0.06

0.06

5.70

0,75

0,10

177.41

0.14

0.77

0.23

0.17

437

505

505

505

505

505

505

505

505

505

505

504

505

67.30

1.28

22.85

16.25

39.78

46,47

9,04

14.41

59.79

30.93

34.44

2.78

24.14

Mean

3,37

0.75

2.80

2.46

4.63

3.33

1,91

2.34

3.27

3.09

3.17

1.10

2.86

505 12.60 0.09

2,652

2,652

2,652

2,652

2,652

2,652

2,652

2,652

2,652

2,652

2,652

2,572

2,572

2,652

2,652

2,597

2,638

2,297

2,652

2,652

2,652

2,652

2,652

2,652

2,652

2,652

2,652

2,652

2,647

2,652

2,652

Mean

10.11

96.74

3.79

6,32

66,34

31.14

35.20

1.43

1.39

.92.19

27.85

2,79

3,625.26

4.13

39.29

12.18

11.69

67.70

0,40

32.16

21.88

52.41

47.90

7.94

23,04

52.62

25.68

32.50

1.64

21.30

Mean

12.62

0.14

0.60

0.10

0.10

0.93

0.75

0.53

0.03

0.03

2.61

0.32

0.05

76.92

0.06

0.33

0.09

0.08

1.46

0.10

1.36

1.20

2.09

1.46

0.79

1.23

1.45

1.27

1.36

0.37

1.19

0.04

-1.73

-1.39

-0.92

-1.50

-1.76

-0.99

-1.61

-1.44

-1.62

‘-1.45

1.83

-1.91

0.37

2.26

1.05

-3.88

-1.91

--0.11

1.14

--2.99

--2.05

--2.48

-0.39

0.53

--3,26

2.00

1.57

0.56

0.98

0.92

-0.21

TPersons with a transferringsaturation below 16,0 percent and TIBC value above 250 pg/dl were classified as having a low transferring saturation.

ZStatistic for these characteristics represent only those persons who answered yes on the questionnaire.

62
Table 29. Z-statistics for comparison of low and adequate transferring saturation statusf for black menstruating women ages 12-54 years,

with statistic and standard error of the statistic, by selected characteristics: United States, 1971–74

Low transferringsaturation Adequate transfemin saturation

Characteristics Number of Standard Number of Standard Z-statistic

examined Statistic error of the examined Statistic error of the

persons statistic persons sta tisk

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (ma) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (ma) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age (yearn) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

MarriedZ ...................................................................

Otherz

Pica ..................................................... ....................

Regular vitamin use ..............................................

Regular mineral use..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet .............................................................

Oral contraceptive usage in past 6 months ....

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findings.....................................................

Abdominal operations ...........................................

Age began menstruating (years) ........................

159

159

159

159

159

159

159

159

159

159

159

156

156

159

158

151

158

134

159

159

159

159

159

159

159

159

159

159

158

159

159

Mean Mean

9.46

93.96

3.40

6.06

57.12

29.10

28.02

1.34

1.31

77.93

28.56

1.63

3,921.41

5.55

41.95

9.92

10.52

Percent

43.50

7.33

12.05

12.05

35.79

45.79

5.36

11.97

67.53

29.38

31.83

0.20

19.82

Mean

0.50

2.48

0.31

0.41

3.14

2.53

1.93

0.08

0.08

11.53

1.30

0.14

289.41

0.30

1.34

0.37

0.30

6.43

3.10

3.87

3.87

8.01

5.93

2.68

3.86

5.57

1.85

5.54

0.54

4.74

589

589

589

589

509

5B9

589

589

589

589

570

570

589

509

577

585

477

589

509

589

589

589

509

509

5B9

589

5B9

588

509

12.73 0.18 589

9.13

90.89

3.51

5.62

59.40

30.50

28.90

1.30

1.29

69.55

26.40

1.69

4,032,33

5.50

40,26

10.16

10.75

Percent

47.00

6.57

17.04

11.90

36.39

41.64

6.32

23.59

57.63

25.20

37.33

1.07

15.84

Mean

12.73

0.31

1.47

0.19

0.22

1.95

1.47

1.03

0.06

0.06

5,00

0.67

0.09

156.19

0,17

0.76

0.19

0.17

3.43

1.53

2.32

2.00

4.19

3.05

1.50

2.62

3.05

2.69

3.00

0.64

2.26

0.10

0.56

1.07

-0.31

0.95

-0.62

-0.48

-0.40

0.40

0.20

0.67

1.48

-0.36

-0.34

0.14

1.10

-0.57

-0.67

-0.48

0.22

-1.10

0.03

-0.07

0.62

-0.31

-2.49

1.56

1.26

-0.87

-1.04

0.76

0.00

1Personswitha transferringsaturationbelowt 6.0 percentandTIBCvalueabove250 pg/dl were classifiedas havinga lowtransferringsaluralion,

ZStatisticsforthesecharacterishcsrepresentonlythosepersonswhoansweredyes onlhs questionnaire.

63
Table 30. Z-statistics for comparison of low and adequate hemoglobin combined with transferring saturation status~ for white menstruating

women ages 12-54 years, with statistic and standard error of the statistic, by selected characteristics United States, 1971-74

Low hemoglobin/ Adequate hemoglobin/

transferring saturation transferring saturation

Characteristics Number of Standard Number of Standard Z-statistic

examined Statistic error of the examined Statistic error of the

persons statistic persons statistic

Oietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (mg) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ....... .

Total nonanimal tissue protein intake (mg) .. .

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .......... .

Vitamin C (mg) ......................................................

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units) ..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

MarriedZ ...................................................................

Otherz

Pica ........................................................ ....... .......

Regular vitamin use ..............................................

Regular mineral use ..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet .............................................................

Oral contraceptive usage in past 6 months ....

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findngs .....................................................

Abdominal operations ...........................................

88

8B

88

88

80

88

88

88

88

88

88

84

04

80

88

87

88

82

80

08

88

88

88

88

88

88

80

80

88

88

88

Mean

10.20

99.45

4.06

6.14

65.76

33.36

32.40

1.46

1.40

59.92

35.75

2.56

4,054.37

4.61

44.73

9.21

10.68

Percent

0.78

3.14

0.60

0.44

5.53

4.59

2.30

0.16

0.03

9.19

1.62

0.21

451.19

0.36

1.90

0.64

47.81

56.90

0.00

15.30

11.00

25.80

45.00

6.60

10.50

72.20

44.60

34.10

0.00

24.30

Mean

Age began menstruating (years) ........................ 13.04

8.20

0.00

5.76

5.01

9.19

7.96

4.03

4.89

7.16

7.96

7.56

0.00

6,86

0.20

3,069

3,069

3,069

3,069

3,069

3,069

3,069

3,069

3,069

3,069

3,069

2,980

2,980

3,069

3,069

3,007

3,054

2,652

3,069

3,069

3,069

3,069

3,069

3,069

3,069

3,069

3,069

3,069

3,063

3,069

3,069

Mean

10.03

96.46

3.76

6.27

65.77

30.97

34.80

1.42

1.36

81.02

27.82

2.78

3,629.19

4.26

39.35

12.05

11.65

Percent

63.10

0.58

30.60

20.60

50.60

47.80

8.00

22.30

53.30

25.90

32.40

0.90

21.50

Mean

12.60

0.13

0.55

0.09

0.10

0.84

0.68

0.49

0.02

0.02

2.42

0,30

0.04

71.40

0.05

0.31

0.09

0.07

1.41

0.21

1.25

1.10

1.95

1.35

0.74

1.13

1.35

1.19

1.27

0.26

1.11

0.04

0.21

0.94

0.46

-0.29

-0.00

0.52

-1.02

0.25

0.53

-2.22

4.29

–1 .01

0.93

0.90

2.80

-4.43

-0.02

-0.75

-2.83

-2.60

-1.91

-2.64

4.35

-0.29

-2.35

2.59

2.35

0.22

-3.53

0.40

2.15

1Age- and sex-specific hemoglobin standards are found in table A persons with a transferring saturation below 16.0 percent and TIBC value above 250 pg/d! were classified

as having a low transferring saturation.

ZStatistics for these characteristics represent only those persons who answered yes on the questionnaire.

64
Table 31. Z-statistics for comparison of low and adequate hemoglobin combined with transfemin saturation statusl for black menstruating

women ages 12-54 years, with statistic and standard error of the statistic, by selected characteristics United States, 1971-74

Low hemoglobin/ Adequate hemoglobirrl

iransferrin saturation fransfem”n saturation

Characteristics Number of Standard Number of Standard Z-statistic

examined Statistic error of the examined Statistic error of the

persons statistic persons statistic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (ma) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age (yearn) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

Marned2 ...................................................................

Otherz

Pica ..........................................................................

Regular vitamin use ..............................................

Regular mineral use..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet.............................................................

Oral contraceptive usage in past 6 months ....

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General tindings.....................................................

Abdominal operations ...........................................

55

55

55

55

55

55

55

55

55

55

55

55

55

55

55

52

55

51

55

55

55

55

55

55

55

55

55

55

54

55

55

Mean

8.18

06.90

2.40

5.71

48.61

23.23

25.38

1.06

1.03

69.03

29.98

1.61

3,424.23

5.58

43.89

8.76

11.01

Percent

14.90

9.80

12.50

11.00

30.80

57.40

9.70

4.50

72.60

18.40

33.60

0.10

20.60

Mean

0.91

4.11

0.39

0.84

4.65

3.36

3.30

0.13

0.13

13.43

2.17

0.23

464.43

0.56

2.09

0.76

0.56

7.48

6.01

6.70

6.33

12.52

10.01

5.97

4.19

9.02

7.77

9.55

0.06

8.19

693

693

693

693

693

693

693

693

693

693

693

671

671

693

692

676

560

693

693

693

693

693

693

693

693

693

693

692

693

Age began menstruating (years) ...... ................. 13.22 0.39 693

9.30

92.06

3.61

5.70

60.44

31.55

28.89

1.34

1.32

70.73

26.48

1.74

4,058.45

5.09

40.17

10.24

10.72

Percent

55.80

6.00

16.00

12.10

35.90

42.10

5.60

23.30

57.90

25.40

36.00

0.90

15.70

Mean

12.71

0.28

1.33

0.17

0.20

1.79

1.37

0.93

0.05

0.05

4.87

0.62

0.08

143.27

0.15

0.70

0.17

0.15

3.15

1.36

2.09

1.86

3.83

2.B2

1.31

2.41

2.82

2.48

2.74

0.54

2.07

0.09

-1.17

-1.19

-2.62

0.01

-2.37

-2.29

-1.02

-2.02

-2.06

4.12

1.55

-0.53

-1.30

0.64

1.69

-1.90

0.50

-5.04

0.62

-0.50

-0.17

-0.39

1.47

0.67

-3.09

1.56

0.66

-0.24

-1.40

0.56

1.27

1Ag+ andsex-specifichemoglobinslandardsare foundintableA personswith a Iranafeminasturationbelow16.0 percent and TleC value above 250 pg/dl were classified

as having a low Iranslemn aalwahon.

ZStatistics for these characteristics represent only those persons who answered yes on the questionnaire.

65
Table 32. Logit analysis statistics showing the relationship between selected characteristics and hemoglobin status for menstruating women

ages 12–54 years: United States, 1971-74

Characteristics

Logit analysis statistics

Coefficient Standard error t-test statistic Odds ratio 2

Constant ............................................................................................. -1.901 0.674 . . . . . .

Poverty Income ratio ........................................................................ -0.164 0.057 –2.878 o.i95

Race ..:................................................................................................ 1.818 0.179 10.148 6.:34

Education of head of household .................................................. -0.060 0.016 -3.091 0.’94

Oral contraceptive usage in past 6 months ............................... -0.548 0,284 -1.930 0.:56

Age ...................................................................................................... 0.023 0.018 2.269 1.ID2

Ever been anemic ............................................................................ 0.561 0.188 2.966 1.76

Ever been pregnant ......................................................................... 0.025 0.301 0.083 1.(D3

~Only characteristics with a t-test statstic > 1.96 (p < .05) are shown.

2See appendix I for discussion of odds ratios.

Table 33. Logit analysis statistics showing the relationship between selected characteristics and transferring sat;;ation status for

menstruating women ages 12-54 years: United States, 1971-74

Logit ana/ysk statistics

Characteristics

Coefficient Standard error t-test statistic 1 Odds ratio z

Constant ............................................................................................. 0.535 0.427 . . . . . .

Poverty Income ratio........................................................................ -0.175 0.040 =$.325 0.04

Race ..:................................................................................................ 0.495 0.171 2.696 1.65

Education of head of household ..................................................

-0.032 0.010 -3.304 0.97

Oral contraceptive usage m past 6 months ...............................

-0.379 0.142 -2.663 0.68

Age ...................................................................................................... 0.003 0.007 0.424 1.00

Ever been anemic ............................................................................ 0.059 0.143 0.416 1.06

Ever been pregnant ......................................................................... 0.609 0.177 3.436 1.84

10nly characteristics with a t-test statistic > t .96 (P < .05) are shown.

Z. Seeappendix I for discussion of odds ratios.

Table 34. Logit analysis statistics showing the relationship between selected characteristics and hemoglobin and transferring saturation

status for menstruating women ages 12–54 years: United States, 1971–74

Characteristics

Logit analysis statistics

Coefficient Standard error t-test statistic Odds ratio z

Constant ............................................................................................. 0.977 0.886

Poverty income ratio ........................................................................

. . . ,,. .

0.205 0.079 -2.592 0.61

Race ................................................................................................... 1.017 0.236 4.307 2.70

Education of head of household .................................................. 0.073 0.020 -3.655 0.93

Oral contraceptive usage in past 6 months ...... ....... ............... 0.929 0.404 -2.297 0.38

Age ...................................................................................................... 0.033 0.013 2.510 1.04

Ever been anemic ............................................................................ 0.595 0.280 2.129 1.81

Ever been pregnant ......................................................................... 0.437 0.427 1.023 1.57

10nly characteristics with a f-test statistic > 1.96 (p < .05) are shown.

2~e appendix I for discussion of odds ratios.

66
Table 35. Z-statistics for comparison of low and adequate hemoglobin statusl for persons ages 65-74 years, with statistic and standard

error of the statistic, by selected characteristics: United States, 1971-74

Low hemoglobin Adequate hemoglobin

Characteristics Number of Standard Number of Standard

examined Statistic

Z-statistic

error of the examined Statistic error of the

persons statistic persons statistic

Oietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (ma) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age (years) .............................................................

Poverly income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

Married2 ...................................................................

0ther2

Pica ...................................................... ...................

Regular vitamin use ..............................................

Regular mineral use..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet.............................................................

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findings.....................................................

Abdominal operations ...........................................

Age began menstruating (years) ........................

249

249

249

249

249

249

249

249

249

249

249

237

237

249

249

235

245

249

247

249

249

249

249

247

63

249

249

247

247

57

Mean

11.20

99.42

3.73

7.47

64.81

30.21

34.60

1.59

1.54

06.47

69.29

2.20

3,534.00

2.45

67.46

8.58

8.41

Percent

65.50

0.85

25.78

19.19

30.81

45.02

17.91

21.90

25.25

68.91

2.53

48.96

Mean

13.44

0.77

2.30

0.43

0.56

3.01

2.23

1.69

0.14

0.14

9.05

0,28

0.18

210.95

0.17

0.83

0.41

0.40

4.52

0.88

4.16

3.74

5.15

4.73

3.66

7.82

4.12

4.40

1.50

4.77

0.33

1,987

1,987

1,987

1,987

1,987

1,987

1,987

1,987

1,987

1,987

1,987

1,898

1,898

1,987

1,987

1,840

1,966

1,982

1,986

1,987

1,987

1,987

1,987

1,986

1,123

1,987

1,987

1,975

1,986

1.081

Mean

10.26

97.47

3.19

7.08

60.64

26.86

33.78

1.38

1.34

94.34

68.89

2.5e

3,915.00

2.02

68.54

9.85

9.90

Percent

0.17

0.68

0.11

0.12

0.99

0.77

0.59

0.03

0.03

2.81

0.10

0.07

78.54

0.04

0.22

0.13

0.13

61.70

0.41

34.57

17.97

48.11

41.74

14.29

47.63

16.64

61.80

1.72

51.33

Mean

13.64

1.64

0.22

1.60

1.29

2.22

1.66

1.18

2.24

1.25

1.63

0.44

1.68

0.08

1.20

0.81

1.21

0.68

1.32

1.42

0.46

1.44

1,38

-0.83

1.34

-2.01

-1.69

2.49

-1.26

–2.92

-3.53

0.79

0.49

–1 .97

0.31

-3.09

0.65

0.94

-3.16

2.00

1.51

0,52

-0.47

-0.59

IAge andsex-specifichemoglobinstandardsare foundin table A.

ZStatistics for these characteristics represent only those persons who answered yea on the questionnaire

57
Table 36. Z-statistics for comparison of low and adequate transferring saturation statusl for persons ages 65-74 years, with statistic and

standard error of the statistic, by selected characteristics: United States, 1971-74

Low transferrirr saturation Adequate transferringsaturation

Characteristics Number of Standard Number of Standard Z-statistic

examined Statistic error of the examined Statistic error of the

persons statistic persons statistic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) ... .............

Total nonanimal tissue iron intake (mg) ..... .....

Total protein intake (ma) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) ....

Estimated available iron (mg) ........................ ....

Estimated available iron with tea (mg) .............

Vitamin C (mg) ............ ....... ........ ................. . ....

Socioeconomic

Age (years) .............................................................

Poverly income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ................. .........

MarriedZ ...................................................................

Otherz

Pica .................................................. ..... ..... . .....

Regular vitamin use ..............................................

Regular mineral use..............................................

Regular vitamin and mineral use .... ..................

Regular aspirin use..., ...........................................

Special diet .............................................................

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findngs .....................................................

Abdominal operations ................................. ........

Age began menstruating (years) ..... ....... ....... .

126

126

126

126

126

126

126

126

126

126

126

121

121

126

126

120

124

126

125

126

126

126

126

125

79

126

126

126

125

74

Mean

9.93

93.94

2.99

6.93

59.52

26.71

32.61

1.27

1.22

72.24

68.86

2.13

3,429.00

2.44

66.94

9.01

8.91

Percent

56.40

1.47

35.10

20.30

40.00

59.10

21.50

55.30

23.60

64.10

5.40

57.30

Mean

13.54

0.77

3.17

0.44

0.56

4.28

3.48

2.44

0.12

0.12

9.33

0.40

0.21

307.36

0.26

0.88

0.50

0.48

6.63

1.62

6.39

5.37

8.34

6.56

5.51

8.39

5.67

6.68

3.02

6.64

0.36

2,110

2,110

2,110

2,110

2,110

2,110

2,110

2,110

2,110

2,110

2,110

2,014

2,014

2,110

2,110

1,995

2,087

2,106

2,100

2.110

2,110

2,110

2,110

2,108

1,107

2,110

2,110

2,096

2,108

1.064

10.36

97.83

3.27

7.09

61.27

27.33

33.93

1.40

1.36

93.02

66.90

2.52

3,906.00

2.03

68.47

9.73

9.75

Percent

62.60

0.24

34.20

18.30

46.90

42.10

14.10

44.60

17.20

63.00

1.60

50.90

13.64

0,17

0.67

0.11

0.13

0.96

0.75

0.57

0.03

0,03

2.72

0.09

0.06

76.31

0.03

0.22

0.13

0.13

1.59

0.16

1.55

1.26

2.13

1.61

1.14

2.24

1.23

1.50

0.41

1.63

0.09

-0.55

-1.20

-0.62

-0,27

-0.40

-0.17

-0.45

0.55

-1.24

-2.14

-0.10

-1.76

-1.51

1.54

-2.19

-1.42

-1.69

-0.91

0.76

0.14

0.36

-0.80

2.51

1.31

1.23

1.10

0.16

1.25

0.94

-0.27

1Personswitha Iransfeninsaturationbelow16.0 percentandTIBCvalueabove250 Wg/dlwareclassifiedse havinga lowtransferringsaturation.

zStatisticsforthese characteristicsrepresentonly those pereonswhoansweredyesonthe questionnaire.
Table 37. Z-statistics for comparison of low and adequate hemoglobin statusl for white persons ages 65-74 years, with statistic and

standard error of the statistic, by selected characteristics: United States, 1971-74

Low hemoglobin Adequate hemoglobin

Characteristics Number of Standard Number of Standard

examined Statistic

Z-sfatistic

error of the examined Statistic error of the

Persons statistic oersons statistic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (ma) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

Marriedz ...................................................................

Olherz

Pica ..........................................................................

Regular vitamin use ..............................................

Regular mineral use..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet.............................................................

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findings.....................................................

Abdominal operations ...........................................

Aae began menstruating (years) ........................

145

145

145

145

145

145

145

145

145

145

145

140

140

145

145

136

143

145

144

145

145

145

145

144

35

145

145

143

144

34

Mean Mean

10.61

99.45

3.48

7.13

63.92

29.11

34.02

1.40

1.43

89.20

69.33

2.59

3,780.00

2.30

67.10

10.00

9.77

Percent

73.00

1.03

30.08

21.00

33.09

45.45

20.95

22.17

28.83

69.17

2.30

52.10

Mean

13.48

0.67

2.72

0.40

0.46

3.55

2.5B

2.06

0.12

0.12

9.74

0.36

0.25

285.75

0.21

1.20

0.45

0.44

5.48

1.27

5.71

5.07

6.83

6.20

5.09

10.62

5.61

5.75

1.B8

6.25

0.44

1,683

1,683

1,683

1,683

1,683

1,683

1,683

1,683

1,683

1,683

1,683

1,611

1,611

1,683

1,683

1,565

1,670

1,680

1,682

1,683

1,683

1,683

1,683

1,682

941

1,683

1,683

1,673

1,682

919

10.38

98.06

3.22

7.16

61.09

26.87

34.22

1.39

1.35

94.61

68.91

2.67

3,966.00

1.99

68.57

10.11

10.12

Percent

62.00

0.38

35.38

18.59

48.63

41.27

14.30

47.43

16.69

61.25

1.69

52.59

Mean

13.67

0.18

0.73

0.11

0.14

1.07

0.83

0.64

0.03

0.03

2.98

0.11

0.07

85.62

0.04

0.23

0.14

0.14

1.77

0.23

1.75

1.42

2.41

1.80

1.28

2.44

1.36

1.76

0.47

1.83

0.09

0.33

0.49

0.63

-0.06

0.76

0,83

0.28

0.71

0.64

-0.53

1.12

-0.31

-0.62

1.87

-1.20

-0.23

-0.76

2.05

0.51

-0.69

0.46

-2.04

0.65

1.25

-2.31

2.10

1.32

0.31

-0.08

-0.43

1Age- andsex-specifichemoglobmstandardsare foundintableA.

2Statisticsfor these characteristics represent only those persons who answered yes on the questionnaire.

69
Table 3EI. Z-statistics for comparison of low and adequate hemoglobin status’ for black persons ages 65-74 years, with statistic and

standard error of the statistic, by selected characteristics: United States, 1971 –74

Low hemoglobin Adequate hemoglobin

Characteristics Number of Standard Number of Standard

examined Statistic

Z-statistic

error of the examined Statistic error of the

persons sfa tistic persons sta fistic

Dietary intake

Total iron intake (mg) ................ ........ ...... .......

Log total iron intake (log mg) . .................. ......

Total animal tissue iron intake (mg) ....... ........

Total nonanimal tissue iron intake (mg) ...........

Total protein, intake (mg) ................................... .

Total animal tissue protein intake (mg) .. ..... ...

Total nonanimal tissue protein intake (mg) .,.,.

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) ......... ...

Vitamin C (mg) ................... .............................. ...

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units) ..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

MarriedZ ...................................................................

Otherz

Pica ................................................................... ......

Regular vitamin use ..............................................

Regular mineral use ..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet .............................................................

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findings .....................................................

Abdominal operations ............................... ........ ..

Age began menstruating (years) ........................

104

104

104

104

104

104

104

104

104

104

104

97

97

104

104

99

102

104

103

104

104

104

104

103

28

104

104

104

103

23

Mean Mean

12.66

99.33

4.35

B.31

67.00

32.94

34.06

1.85

1.83

79.72

69.20

1.16

2,074.00

2.64

68.35

5.23

5.00

Percent

45.20

0.37

15.17

14.71

23.21

43.96

10,13

19.90

17.67

68.24

3.10

40.92

1.80

4.29

1.00

1.37

5.62

4.26

3.01

0.34

0.34

16.78

0.47

0.12

265.62

0.30

0.87

0.59

0.58

7.33

0.09

5.28

5.21

7.60

7.30

4.46

11.32

5.61

6.85

2.55

7.27

304

304

304

304

304

304

304

304

304

304

304

287

267

304

304

275

296

302

304

304

304

304

304

304

162

304

304

302

304

0.90

90.45

2.76

6.13

55.34

26.74

28.61

1.20

1.17

91.06

68.57

1.54

3,302.00

2.32

68.19

6.86

7.15

Percent

57.20

0.74

24.91

10.65

41.95

47.40

13.23

49.99

16.11

69.34

2.10

36.26

Mean

●13.34 *

162 13.35

0.38

1.91

0.26

0.27

2.65

2.34

1.30

0.07

0.07

9.01

0.23

0.10

182.22

0.12

0.60

0.36

0,35

4.27

0.74

3.72

2.65

5.86

4.30

2.92

5.56

3.16

3.97

1.24

4.14

0.19

2.04

1.89

1.54

1.56

1.88

1.27

1.66

1.89

1.92

-0.54

1.21

-2.49

-1.33

0.99

0.15

-2.36

--3.17

--1.42

-0.32

--1.51

0.69

--1.95

--0.41

-4.58

--2.39

0.24

-0.14

0.35

0.56

0.02

j Age- and sex-specific hemoglobin standards are found in table A.

2Statistics for these characterfstice represent only those persons who answered yes on the questionnaire.

70
Table 39. Z-statistics for comparison of low and adequate transferring saturation status! for white persons ages 65-74 years, with statistic

and standard error of the statistic, by selected characteristics: United States, 1971-74

Low hemoglobin Adequate hemoglobin

Characteristics Number of Standard Number of Standard Z-statistic

examined Sfatistic error of the examined Sfatistic error of fhe

persons stafisfic persons sfa tisfic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (mg) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) .....

Estimated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) ....................

Education of head of household (years) ..........

Education of examinee (years) ...........................

Marriedz ...................................................................

Otherz

Pica ..........................................................................

Regular vitamin use ..............................................

Regular mineral use ..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special det .............................................................

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findings.....................................................

Abdominal operations ...........................................

101

101

101

101

101

101

101

101

101

101

101

97

97

101

101

97

101

101

101

101

101

101

101

101

63

101

101

101

101

61

Mean

9.93

94.22

2.71

7.23

58.24

24.55

33.69

1.23

1.19

76.70

68.79

2.19

3,408.00

2.36

66.99

9 +7

9.11

Perce,rW

60.90

1.50

30.40

22.20

37.80

60.10

23.60

58.10

25.30

63.60

2.80

56.20

Mean

Age began menstruating (years) ........................ 13.53

0.85

3.47

0.39

0.67

4.38

3.28

2.80

0.12

0.12

10.78

0.43

0.24

334.46

0.28

1.26

0.54

Q-.52

7.28

1.79

7.25

6.21

0.76

7.31

6.34

9.32

6.49

7.18

2.46

7.40

0.40

1,727

1,727

1,727

1,727

1,727

1,727

1,727

1,727

1,727

1,727

1,727

1,654

1,654

1,727

1,727

1,604

1,712

1,725

1,725

1,727

1,727

1,727

1.727

1,725

913

1,727

1,727

1,715

1,725

892

Mean

10.44

98.38

3.29

7.15

61.66

27.32

34.34

1.41

1.37

93.60

60.92

2.63

3,979,00

2.01

68.49

10.06

10.06

Percent

63.30

0.23

35.20

18.90

48.10

41.60

14.10

45.00

17.30

62.30

1.60

52.50

Mean

13.67

0.18

0.72

0.11

0.13

1.06

0,81

0.64

0.03

0.03

2.92

0.10

0.07

84.68

0.04

0.24

0.14

0.13

1.74

0.17

1.73

1.41

2.36

1.78

1.26

2.47

1.36

1.75

0.46

1.81

0.09

-0.59

-1.17

-1.41

0.12

-0.76

-0.82

-0.23

-1.40

-1.42

-1.51

-0.30

-1.76

-1.66

1.24

-1.17

-1.59

-1.77

-0.32

0.71

0.43

0.52

-1.14

2,46

1.47

1.36

1.21

0.18

0.48

0.49

-0.34

I Personswitha transferringsaturationbelow16.0 percentand TIBC value above 250 pg/dl were classified as having a low tranferrin saturation.

ZStatistics for these characteristics represent only those persons who answered yes on the questionnaire.

71
Table 40. Z-statistics for comparison of low and adequate transferring saturation statusi for black persons ages 65-74 years, with statistic,

and standard error of the statistic, by selected characteristics United States, 1971-74

Low transferringsaturation Adequate transferringsaturation

Characteristics Number of Standard Number of Sfandard

examined Statistic

Z-stiatistic

error of the examined Statistic error of the

persons statistic persons sta fistic

Dietary intake

Total iron intake (mg) ..........................................

Log total iron intake (log mg) ............................

Total animal tissue iron intake (mg) .................

Total nonanimal tissue iron intake (mg) ...........

Total protein intake (mg) .....................................

Total animal tissue protein intake (mg) ............

Total nonanimal tissue protein intake (mg) ....

Est~mated available iron (mg) .............................

Estimated available iron with tea (mg) .............

Vitamin C (mg) ......................................................

Socioeconomic

Age (years) .............................................................

Poverty income ratio (index) ...............................

Estimated family income (dollars) ......................

Number of persons in household (units)..........

Age of head of household (years) .... .......... ....

Education of head of household (years) ..........

Education of examinee (years) ...........................

MarriedZ ...................................................................

Otherz

Pica .......... ....... ....... ......... ... ...... .................

Regular vitamin use ..............................................

Regular mineral use..............................................

Regular vitamin and mineral use .......................

Regular aspirin use ...............................................

Special diet .............................................................

Ever been pregnant ..............................................

Ever been anemic .................................................

Any trouble eating .................................................

General findings .....................................................

Abdommal operations ...........................................

Age began menstruating (years),, ......................

25

25

25

25

25

25

25

25

25

25

25

24

24

25

25

23

23

25

24

25

25

25

25

24

16

25

25

25

24

13

Mean

9.88

91.91

5.09

4.79

68.85

42.42

26,43

1.53

1.40

39.57

69.41

‘1 .57

‘3,607.00

3.08

66.62

●7.79

“6.9B

Percent

1.87

8.12

1.74

0.62

13.80

12.74

3.58

0.41

0.35

10.50

1.11

●

*

0.73

2.74*

●

23.30

‘ 1.60

10.60

6.70

56.60

52.30

‘3.70

‘34.70

10.70

68.20

24.40

●66.70

Mean

12.69

●

9.24

7.53

24.93

15.00

*

*

9.27

13.98

12.87

●

‘13.66 ●

383

383

383

383

383

383

383

303

383

383

383

360

360

383

383

351

375

381

383

383

383

383

303

383

194

383

383

381

303

172

Mean

9.57

92.06

3.07

6.50

57.16

27.47

29.69

1.31

1.30

87.20

68.63

1.40

3,128.00

2.33

68.28

6.35

6.52

Percent

55.30

0.04

23.70

12.10

34.60

47.20

13.20

41.00

15.80

69.50

0.80

34.50

Mean

13.29

0.50

1.84

0.33

0.36

2.41

1.99

1.24

0.10

0.10

8.17

0.21

0.08

156.06

0.11

0.50

0.33

0.32

3.82

0.49

3.26

2.50

4.73

3,83

2.60

5.30

2.80

3.53

0.68

3.64

0.18

0.16

-0.02

1.14

-2.38

0.83

1,16

-0.86

0.52

0.28

-3.58

0.69

0.46

0.57

1.01

-0.60

1.13

0,38

-2,,41

0,,41

-1 ,“34

-0.68

0,,87

0,33

-1,50

-0,34

4,53

-0.09

1.83

2.16

0.51

1Personswitha transferrmsaturationbelow16.0 percentanda TIBC above250 pg/dl were classifiedas havinglowtransfarrinsaturation.

ZStatlshcsforthese characteristicsrepresentonly those persons who answered yes on the questionnaire.

72
Table 41. Logit analysis statistics showing the relationship between selected characteristics and hemoglobin status for persons ages 65-74

years United States, 1971-74

Characteristics

Logit analysis ststisfics

Coehkient Standard error t-test statistic 1 Odds ratio 2

Constant ............................................................................................. -0.159 0.778 . . .

Race ..................................................................................................-

. . .

1.903 0.301 6.317 6.33

Sex ...,.................................................................................................. -1.939 0.236 -6.220 0.14

Education of head of household .................................................. -0.042 0.018 -2.350 0.96

General findngs ................................................................................ 1.269 0.645 1.966 3.53

Ever bean anmic ...........................................................................- 0.901 0.205 4.395 2.64

Any trouble eating ............................................................................ 0.464 0.161 3.011 1.58

10nly characfenaticawitha t-teststalistic> 1.96 (p < .05) are shown,

2See appandix I for dkussion of odds ralim.

Table 42. Logit analysis statistics showing the relationship between selected characteristics and transfernn saturation status for persons

ages 65-74 years: United States, 1971-74

CheractarMks

Logit analysis statistic

CoefY7cient Standard error t-test stafisiic 1 Odds ratioz

~nstant ............................................................................................. -0.637 0.993 . . . . . .

Race ................................................................................................... 0.364 0.311 1.160 1.44

sex. ..................................................................................................... 0.430 0.300 1.461 1.57

Education. o! head of household .................................................. -0.057 0.020 -2.894 0.94

General fltilngs ................................................................................ 1.406 0.065 1.625 3.84

Ever been anemic ............................................................................ 0.10.9 0.255 0.425 1.13

Any trouble eating ............................................................................ -0.083 0.194 -0.429 0.92

10nly characlaristics with a t-test statistic z 1.96 (p < .05) are shown.

2%ea appendixI fw dimmsion of 03ds ratiis.

73
Appendixes

Contents

1. Statistical notes .,... ........................................................................................................... ................................ .......... .......... ...

Survey design ............................................................................................................................................... .......... .......... ...

Nonresponse. ..................................................................... ......................................................................... ............. ..........

Missing data ................................................... ............................................................................................................ .........

Small numbers .....................................................................................................................................................................

Reliability of estimates of means and prevalence ..........................................................................................................

Analytic approach for relational analyses . .. ....................................................................................................................

Il. Definitions of terms ........................................ .........................................................................................................................

Demographic and socioeconomic terms ...........................................................................................................................

Age ...................................................................................................................................................................................

Race ................................................................................................................................................................................

Family income .................................................................................................................................................................

Poverty index ................................................................................................................................................................ ..

Other terms used in relational analyses ............................................................................................................................

75

75

76

76

77

77

79

81

81

81

81

81

81

82

List of appendix tables

1. Percent distribution of nonresponse adjustment factors: 1971-74 ..................................................................................... 77

11, Number and percent of examined persons in NHANES I with missing hematological, biochemical, and nutrient

intake measurements, by age ................................................................................................................................................. 77

Ill. Estimated design effects and correlations of selected health, demographic, and nutrient intake variables: NHANES I 78

IV. Number of persons classified as ‘(low” and “adequate” iron status in the original and logistic samples, by iron status

indicator and selected population group: NHANES 1,1971 -74.... ........................................................................................ 80

V. Weighted average thresholds at the low-income level in 1971, by farm-nonfarm residence, sex of family head, and

size of the family United States, ............................................................................................................................................. 82
Appendix L Statistical

notes

Survey design

Individuals examined during NHANES I were

selected in a three-stage, stratified probability sample

of loose clusters of persons by geographic location. The

sample was designed to be representative of the civilian

noninstitutionalized population ages 1-74 years living

within the coterminous United States; however, all

persons residing upon reservation lands set aside for

use of American Indians were excluded.

In the first stage of the design, the 1960 decennial

census lists of addresses and the nearly 1,900 primary

sampling units (PSU’S) into which the coterminous

United States is divided were examined. (Each PSU is

either a standard metropolitan statistical area, a single

county or two or three contiguous counties.) These

PSU’S were grouped into 40 strata on the basis of

geographic region and population density to select

target PSU’S for NHANES 1.

Of the 40 strata, 15 were composed of single large

metropolitan areas with more than 2 million persons.

These 15 metropolitan areas were chosen for the

sample with certainty. A modified Goodman-Kish

controlled selection technique was then used to choose

two PSU’S from each of the remaining 25 noncertainty

strata with probability proportionate to its 1960

population. In this manner, a total first-stage sample of

65 (15 + (2 X 25)) PSU”S or “stands” were selected

for study.

Within each PSU, a systematic sample of segments

(loose clusters of households) was chosen. Selection

was made using the most up-to-date information on

census enumeration districts (ED’s) at the time of the

visit—1960 census data for the first 44 stands and 1970

data for the remaining 21 stands. To make the sample

representative of the current U.S. population, lists

were supplemented by a sample of housing units that

had been constructed since the most recent decennial

census,

ED’s having addresses that could be used (the

majority of the areas visited) were divided into

segments containing an average of six households each

(in the first 44 stands) or eight households each (in the

remaining 21 stands). The change was made primarily

for operational advantages and was supported by

research by the U.S. Bureau of the Census, indicating

that the precision of estimates would not be tiected

appreciably. For ED’s without addresses that could be

used (generally located in rural areas), area sampling

was employed.

Enumeration districts were divided into two economic classes. The first class, identified as the “poverty

stratum,” was composed of “Current Poverty Areas”

that had been identified by the Census Bureau in the

1960 or 1970 census and other ED’s in the PSU with a

mean family income of less than $3,000 in 1959 (based

on the 1960 census). The second economic class, the

“nonpoverty stratum,” comprised all ED’s not designated as belonging to the poverty stratum.

Target segments were selected from each of the

two strata, All sample segments classified into the

poverty stratum were sampled with probability 1. For

the first 42 stands, sample segments in nonpoverty

stratum ED’s were divided into eight random subgroups, and one of the subgroups was chosen to

remain in the NHANES I sample. Ongoing research

then indicated that the efficiency of estimates could be

increased by changing the ratio of poverty to nonpoverty segments from 8:1 to 2:1. Therefore, in the

remaining 23 stands, the selected segments in the

nonpoverty ED’s were divided into two random

subgroups, and one of the subgroups was chosen to

remain in the sample.

After identifying the sample segments, a list of all

current addresses within the segment boundaries was

made, and a person in the household was interviewed

to determine the age and sex of each person as well as

demographic and socioeconomic information required

for the survey. If no one was at home after repeated

calls or if the household members refused to be

interviewed, the interviewer tried to determine the

household composition from neighbors.

To select the persons in sample segments to be

examined in NHANES I and at the same time to

75
oversimple certain groups at high risk of malnutrition,

all household members ages 1–74 in each segment first

were listed on a sample selection worksheet with each

household in the segment listed serially. The number

of household members in each of the six age-sex

groups shown below were then listed on the worksheet

under the appropriate age-sex group column. The

sample selection worksheets were put in segmentnumber order, and a systematic random sample of

persons in each age-sex group was selected to be

examined using the following sampling rates.

Age and Sex

1-5 years (males and females) ...................................

6-19 years (males and females) ................................

2044 years (males) ......................................................

2044 years (females) ...................................................

46-64 years (males and females) ..............................

65-74 years (males and females) ..............................

Rate

112

1/4

1/4

1/2

1/4

1

The persons selected in the 65-stand sample of

NHANES I constituted a representative sample of the

target population and included 28,043 persons ages

1–74 years, of whom 20,749 (74 percent) were examined. When adjustments were made for differential

sampling for high-risk groups, the response rate was 75

percent.

All data presented in this report are based on

“weighted” observations. That is, data recorded for

each person are inflated to characterize the subuniverse from which that person was drawn. The weight

for each examined person is a product of the reciprocal

of the probability of selecting the person, an adjustment for nonresponse cases (i.e., persons not examined), and a poststratified ratio adjustment that increases precision by bringing survey results into close

alignment with U.S. Bureau of the Census population

figures for 20 age, race, and sex groups in the United

States as of November 1, 1972, the approximate

midpoint of NHANES 1.

A more detailed description of the survey design

and selection technique has been published-z

Nonresponse

In any survey, after the sample is identified and the

persons are requested to participate, the survey meets

one of its more severe problems—nonresponse. The

problem is more severe in a health examination survey,

because often many persons will not participate in the

examination. A potential for bias results if the persons

in the sample who do not participate differ from the

persons in the sample examined with respect to the

characteristics under investigation. Intensive efforts

were made in NHANES I to develop and implement

procedures and inducements that would reduce the

NOTE: A list of references follows the text.

76

number of nonrespondents and thereby reduce the

potential bias due to nonresponse.z

Despite these intensive efforts, 25 percent of the

persons in the sample were not examined, compared

with previous surveys conducted by the Divisicln of

Health Examination Statistics that had response rates

of more than 86 percent. Consequently, the potential

for a sizable bias does exist in the estimates in this

publication. Because the response rate for the meldical

questionnaire was more than 95 percent of the persons

in the sample, however, it was possible to examine the

characteristics of the nonrespondents and the nature of

nonresponse.

An analysis of data on examined and nonexamlined

(but interviewed) persons was conducted using data

from the first 35 stands of NHANES 1.75The two

groups were quite similar with respect to the health

characteristics that were compared. For example, 11

percent of persons examined reported having an illhm.ss

or condition that interfered with their eating, compared with 9 percent of persons not examined but who

had a medical history.

As was mentioned earlier, the data in this report

were based on weighted observations, and one of the

components of the weight assigned to an examined

person was an adjustment for nonresponse. A procedure was adopted that mutiplied the reciprocal of the

probabilityy of selection of sample persons who ‘were

examined by a factor to bring estimates basecl on

examined persons up to a level that would have been

achieved if all sample persons had been examined. The

nonresponse adjustment factor was calculated by

dividing the sum of the reciprocals of the probability of

selection for all selected sample persons in each of five

income groups within each stand by the sum of the

reciprocals of the probability of selection for examined

sample persons in the same stand and income group.

The five income groups were (1) under $3,000, (2)

$3,000-6,999, (3) $7,000-9,999, (4) $10,OOCL14,999,

and (5) $15,000 and over. For sample weighting

purposes, income group was imputed for 5.6 percemtof

the sample persons using educational level of the head

of household. To the extent that the income-withinstand classes were homogeneous with respect to the

health characteristics under study, the adjustment

procedure was effective in reducing the bias due to

nonresponse. The percent distribution of the nonresponse adjustment factors computed for the 65-stand

sample of NHANES I is shown in table I.

Missing data

Examination surveys are subject to the loss of

information not only through the failure to examine all

persons in the sample, but also from the failure to.

obtain and record all items of information for examined persons. For several examinees, one or more of

the hematological and biochemical measurements
and/or one or more of the dietary interviews were not

available. The extent of these missing measurements is

indicated in table II.

The number of missing hemoglobin concentrations

was small for all age groups. Total iron-binding

capacity and percent transferringsaturation were available for most persons ages *74 years; the number of

missing measurements for these two variables for

children under 4 years of age, however, was large.

(Most missing biochemical determinations were a

result of refusal to give blood (especially young

children), loss of blood specimens in shipping to the

laboratory, and results that did not meet laboratory

quality control specifications.) Nutrient intake values

were missing for 479 persons due to unsatisfactory

dietary interview results.

For the descriptive information on persons ages

4-74 years, presented in tables 1–18 and figures 1–13,

imputed hematological, biochemical, and nutrient

intake measurements were used. These estimates were

made on the basis of multiple regression type decisions, substituting for the missing measurements those

of an individual who was of the same age, sex, race,

and geographic location. (For approximately onefourth of the missing records, a further adjustment of

Table 1. Percent distribution of nonresponse adjustment

factors 1971-74

Size of factor Percent distribution

Total ......................................................... 100.0

1.00-1 .24 ................................................. 32.6

1.25-1 .49 ................................................. 38.5

l.5&l.74 ................................................. 18.2

1.75-1 .99 ................................................. 7.4

2.0&2.49 ................................................. 2.8

2.5%2 .99 ................................................. 0.3

3.007......................................................... 0.3

1A size of 3.00was assignedfor all factorsgreaterthan 3.00.The final

poslstratitiedratioadjustmentcorrectsforthistruncation.

Table Il. Number and percent of examined persons in NHANES I

with missing hematological, biochemical, and nutrient intake

measurements, bv age

Measurement and age Number Percent

Hemoglobin

1-3 years ................................................ 18 1.0

4-74 years .............................................. 2,019 10.6

Total iron-binding capacity

1+ years ................................................ 704 45.5

4-74 years .............................................. 5,431 28.5

Percent transferring saturation

1-3 years ................................................ 704 45.5

4-74 yeam...l .......................................... 5,786 30.4

Nutrient intake

1-74 years .............................................. 479 2.3

the nutrient intake values was made on the basis of the

person’s body weight.) For children under 4 years of

age, the number of missing hematological values was

too great to use such an imputation procedure.

Therefore, data on persons ages 1–3 years with missing

hematological and biochemical measurements are

omitted from all detailed tables.

For the relational analyses presented in tables

1942, no imputed hematological values were used. In

this manner, no individual was assigned a particular

iron status without full and complete knowledge of

that individual’s measured status at the time of

examination. Imputed nutrient intake measurements

were retained for this sample.

Small numbers

In some tables, estimates are shown for cells for

which the sample size is so small that the estimates

shown, including those of variability, may not be

reliable. In such instances, the numbers, if shown, have

been included only to convey an impression of the

overall table.

Significance tests of mean differences were conducted only if there were at least 25 persons in each

group. Logit analyses were conducted only if there

were at least 50 individuals in each group.

Reliability of estimates of means and

prevalence

Because the statistics presented in this report are

based on a sample, they differ somewhat from the

figures that would have been obtained if the survey had

been conducted on the complete population using

precisely the same procedures. In other words, the

statisticsare subject to sampling variability.

The standard error is primarily a measure of

sampling variability, but also may include part of the

variation that arises in the measurement process. The

standard errors used to calculate the significance of

differences shown in tables 1–10 were calculated by a

technique referred to as “balanced repeated replication.” The need for this specialized technique for

estimating standard errors arose because of the complexity of the sample design of NHANES I. This

complexity made it inappropriate to calculate standard

errors by a technique that did not account for th’e

multistage cluster sample design. (Estimates of standard errors are subject to errors that may be large if

the number of cases upon which the estimates are

based is small, or the number of PSU’S used in the

variance calculations is small.)

However, to reduce the complexity of the effort

required to produce standard error estimates for all of

the means and proportions in this report, a “variance

smoothing” approach was used to calculate all other

standard errors.

77
Under this approach, a standard error estimate for

a sample mean (Xi) is produced in two steps. First, the

simple random sample (SRS) estimate of the standard

error (se.) is calculated with the usual formula,

s.e.~.~(~) = Sx,/(72i)z

where SX i is the sample standard deviation and ni is

the size of the sample. Second, the simple random

sample estimate of the standard error is multiplied by a

design effect (defined as the effect that the complex

sampling design has on the magnitude of the standard

errors) to produce the standard error estimate of X - i.

All standard errors of means presented in tables

11J12 were computed using this technique. The design

effects were estimated by the method of least squares.

The replicated half-sample variance estimates for a

subset of the variables presented in this report were

used as the dependent variables, and the corresponding

simple random sample variance estimates were used as

the independent variables in the model

se. (~) = (design effect) X s.e.~R~ (~) + e

to produce estimates of the design effects.

The estimated design effects and the correlations

between the half-sample variance estimates and the

“smoothed” or predicted variance estimates (giving a

measure of the strength of the relationship between the

two, that is, the effectiveness of the fitting process) are

given in table 111, For all eight variables examined, the

design effect never exceeded 1.50. In this report, the

generally conservative strategy of assuming a design

effect of 1.50 for all variables was used.

The usual test for the difference between two

means (denoted by 7A and xx ), in which the estimated standard errors are treated as constants and the

covariance is assumed to be zero, may then be used to

determine the significance of a difference as follows:

where se. (7A ) and se. ( ~X ) are the standard errors

for the two groups reported in the detailed table.

Table Ill. Estimated design effects and correlations of selected

health, demographic, and nutrient intake variables: NHANES I

Variable Desicrn effect Correlation

Have you ever had anemia? ........... .

Are you or have you ever been

pregnant? .............................................

Do you have trouble eating? .............

Have you used oral contraceptive

in past 6 months? .............................

Age at exam .........................................

Poverty income ratio............................

Iron intake ..............................................

Protein intake ........................................

1.09

1.10

0.98

1.49

0.88

1.14

1.25

1.32

0.01

o.a4

0.76

0.97

o.al

0.71

o.al

o.a5

For example, from table 19, the mean a,ge of

children ages 1–3 years with low hemoglobin is 2.19,

and the standard error is 0.09; the corresponding

statistics for the adequate hemoglobin group are 2.58

and 0.04, respectively. The significance test is, therefore:

z=

(2.19 - 2.58)

[(0.09)2 + (0.04)2]%

~Z.3,96~

This Z-statistic, if looked up in a table, is found tc~have

a probability of less than 0.001.

Standard error estimates for sample proportions

were similarly calculated in two steps. First, the simple

random sample estimate of the standard error was

calculated with the usual formula,

. ,, “-2-ZRS:, “ij~“ = Q’ij(l - Pij)/ni)z

where pij @ the estimated proportion, and ni is the size

of the sample. Second, the simple random sample

estimate of the standard error was multiplied by the

design effect to produce the standard error estimate of

Pij.

The following example may be illustrative. From

table 11, 14,9 percer~t o; males ages 65–74 years are

estimated to have low hemoglobin; for females, the

percentage is 4.3. The proportions denoted by Prn and

pf are, therefore, 0.149 and 0.043. The standard errors

under simple random sampling were estimated

through the following calculation:

s.e.~R~(pm) = (0.149 X 0.851/1581)% = .0089555

s.e.~~~(p~) = (0.043 X 0.957/1728)% = .0048799

The standard errors with design effects are, therefore:

s.e.(p~) = 1.5 X .0089555 = .0134332

s.e.@~) = 1.5 x .0048799 = .0073199

All standard errors of proportions presented in tables

11–1 3, 15, and 19-42 were computed using this

technique.

The usual test for the difference between two

proportions may then be used to determine significance:

Pm - Pf

z=

[(s.e.(pm ))2+(s.e.(pf))21 %

dThez.~tatistiapresentdin the detailed tables were calculat~ With

standard error values calculated to three or four decimal places. The

standard errors presented in the tables are rounded to two decimals.

Therefore, Z-statistics calculated using these values may differ slightly fmm

the values presented in the detailed tables.

NOTE A list of references follows the text.

78
For the example described in the previous paragraph,

z.

0.149-0.043

[(.0134332)2 + (.0073199)2]%

.106

z.

.0152981

Z = 6.93

This Z-statistic, if looked up in a table, is found to

have a probability of less than 0.001.

Analytic approach for relational

analyses

Logistic models were used to study the relationship between iron status (as measured by a dichotomous variable) and the dietary, health, socioeconomic

and demographic factors under study. These models

were developed to estimate the probability (or odds)

that an individual will have, for example, low transferringsaturation (TS), given a set of independent variables. Akin to multiple regression, logistic analysis

assumes that although only a discrete outcome can be

observed, an increase (or decrease) in each relevant

independent variable increases (or decreases) the likelihood that an individual has a low TS level. 76,77The

particular advantage of logistic models is that they

overcome the well-known problems of inefficiency and

possible misspecification associated with alternative

classification schemes, such as discriminant

analysis,7%E1

Under a logistic model, the natural logarithm of

the odds that an individual is iron deficient is expressed as a linear combination of independent variables. Mathematically, this relationship is expressed

as:

where: p = the probability of having a low

transfernn saturation level.

x, . . . x. = the independent variables under

study.

b,.. . b~ = the logistic coefficients associated

with these independent variables.

e = random error.

Estimated logistic coefficients (the b’s) represent the

change in the natural logarithm of the odds of a

person’s having a low TS that would be produced by a

NOTE A list of references follows the text.

unit change in the particular independent variable. As

the equation above cannot be solved explicitly, an

iterative procedure is used to solve for the b’s. In the

present study, a Fletcher minimization procedure was

used.’2

Although such an iterative solution is satisfactory

for estimating the logistic coefficients, the complexity

of the NHANES I sample design necessitated use of an

innovative approach to the estimation of the standard

errors of these coefficients. Jackknifing, an all-purpose

technique for determining the variance of any statistical parameter, is one approach. In essence, the

technique involves estimating the parameter of interest

(here, a logistic coefficient) on the full sample, then

systematically setting aside portions of the sample and

estimating the logistic coefficient on each of the sogenerated subsamples and finally, computing the

standard error of the logistic coefficient by studying

the variability of the deviations of the statistics in the

subsamples from the full sample estimate.ss,sqAlthough it would be possible to employ this technique

to estimate the requisite standard errors, such an

approach would be prohibitively expensive, as there

were over 5,000 subjects in some analytic groups.

Incorporating a second technique-sampling by

the dependent variable-into this strategy greatly

reduces the cost burden involved. This technique was

developed for estimating logit coefficients on large data

sets in which the prevalence of the particular health

condition under study is extremely 1ow.8S-B7The

rationale is based upon the fact that the relative

amount of information contained in two samples of

sizes nl and nz, where we wish to compare the means in

the two groups, is a function of the harmonic mean of

the sample sizes [2n1nz/(nl + n2)]. Thus if one group is

by nature very small (here, for example, the number of

persons classified as having low TS), very little is

gained by retaining all the individuals in the second

group to estimate their mean value (here, the adequate

TS group) because it does little to increase the

harmonic mean of the sample sizes. Hence a sample

can be drawn from the overall data set, taking all those

individuals with low TS and only a small fraction of

those who have adequate TS levels with small (if any)

loss of information. Logit coefficients estimated on a

subsample so drawn will be unbiased estimates of the

true logit coefficients.ss The jackknife technique may

then be used on this substantially reduced subsample

to produce an estimate of the standard error.

This strategy was used for all log-it analyses

presented in this report. SubSamples were selected

separately for persons with low and adequate iron

status. All persons with low values for the iron status

indicators were chosen with certainty. The sample of

persons with adequate levels was chosen so that the

rate of increase in the effective n, which determines the

power to detect effects, was small and constant across

groups (an additional adequate iron status individual

79
Table IV. Number of persons classified as “low” and “adequate” iron status in the original and logistic samples, by iron status indicator

and selected population group: NHANES 1, 1971-74

Iron status indicator and population group

Original sample Logit sample

Total Low Adequate Total Low Adequ~

Hemoglobin Number

Children, 1+3 years .......................................................................... 1,353 170 1,183 760 170 59CI

Adult women, 12–54 years ............................................................. 3,707 242 3,465 1,083 240 841

Elderly, 65-74 years ................. ...... ................ .......... ...... ....... .. 1,967 222 1,745 993 222 770

Transferring saturation

Adult women, 12–54 yearsl ............... ....... ..... ................ ....... 3,707 632 3,075 1,264 632 632!

Elderly, 65–74 years ........................................................................ 1,967 114 1,853 510 114 396

Hemoglobin and transferring saturation

Adult women, 12-54 years ............................................................. 3,707 134 3,573 600 134 466

I For adul[ women, the number with low TS levels was sufficlently large (632 persons) so that only an equal number of women with adequate TS were chosen.

in the sample would have increased the effective n by

only one-tenth). This has the effect of keeping the

prevalence constant across groups at 288 per 1,000

persons. Table IV presents the sizes of the sample so

drawn.

The odds ratios presented in the logit analysis

tables are “overall” odds ratios. For the dichotomous

characteristics (e.g., by sex, ever been anemic), the

odds ratio presented in the table represents the

increase or decrease in the likelihood that an individual has low iron status for the given indicator with a

unit change in the value of the characteristic under

study. A unit change for continuous variables may not

be the most appropriate comparison to make for any

analysis of the effects on iron status for that characteristic. The overall odds ratios are presented in the tables

for these variables, but must be interpreted appropriately.
Appendix Il. Definitions of

terms

Demographic and socioeconomic

terms

The demographic and socioeconomic characteristics of the population sampled are defined below:

Age

The age recorded for each examinee was the age at

last birthday on the date of examination. The age

criterion for inclusion in the sample used in this survey

was defined in terms of the examinee’s age at time of

census interview. Twenty of those who were 74 years

old at the time of interview became 75 years old by the

time of the examination. In the adjustment and

weighting procedures used to produce national estimates, these persons were included in the 74 year old

group.

For analyses on children ages 1–3 years, an

additional age variable was computed. This variable

represents the child’s age, in decimal form, computed

from her or his date of birth.

Race

For each individual, race was determined by

observation and recorded as “white,” “black,” or

“other races.” The last category included American

Indians, Chinese, Japanese, and all races other than

white or black. Mexican persons were incuded with

white unless definitely known to be knerican Indian

or of another race other than white.

Family income

The income recorded was the total income reported during the past 12 months by the head of the

household and all other household members related to

the head by blood, marriage, or adoption. This income

was the total cash income (excluding pay in kind, e.g.,

meals, living quarters, or supplies provided in place of

cash wages) except in the case of a family with its own

farm or business, in which case net income was

recorded. Also included in the family income figure

were allotments and other money received by the

family from a member of the Armed Forces whether

she or he was living at home or not.

Poverty index

Income status was determined by the poverty

income ratio (PIR). Poverty statistics published in the

Census Bureau reportsss were based on the poverty

index developed by the Social Security Administration

(SSA) in 1965. (For a detailed discussion of the SSA

poverty standards, see references 89 and 90.)

Modifications in the definition of poverty were adopted

in 1969.91 The standard data series on poverty for

statistical use by all executive departments and establishments was used to determine the poverty level.9z

The two components of the PIR are the total

income of the household (numerator) and a multiple of

the total income necessa~ to maintain a family with

given characteristics on a nutritionally adequate food

plan~ (denominator). The dollar value of the denominator of the PIR is constructed from a food plan

(economy plan) necessary to maintain minimum recommended daily nut ritional requirements. The economy plan is designated by the Department of Agriculture for “emergency or temporary use when funds are

low.”

As shown in table V, the annual income considered to be the poverty level increases as the family size

increases. A family with any combination of characteristics and with the same income as that shown in the

table has been designated as having a PIR (or poverty

level) of 1.0. The same family with twice the income

found in the table would have a PIR of 2.0. Ratios :If

less than 1.0 can be described as “below poven

NOTE: A list of references follows the text.

8i

.
Table V. Weighted average thresholds at the low-income level in 1971, by farm-nonfarm residence, sex of family head, and size off family

United Statas

Size of family

Nonfarm

Total

Farm

Total Male headl Female headl Total Male head~ Female headl

All unrelated indviduals, ...................................... $2,033 $2,040 S2,136 $1,978 $1,727 $1,703

Under 65 years ................................................. 2,093

$1,669

2,098 2,101 2,017 1,005 1,853

65 years and over...,, ....................................... 1,931

1,715

1,940 1,959 1,934 1,652 1,666 1,643

All families .............................................................. 3,700 3,724 3,764 3,428 3,235 3,242 3,079

2 persons ........................................................... 2,612 2,633 2,641 2,561 2,219 2,224

Head under 65 years .................................. 2,699

2,130

2,716 2,731 2,635 2,317 2,322

Head 65 years and over, ........................... 2,424

2,195

2,448 2,450 2,437 2,062 2,061

3 persons ........................................................... 3,207

2,069

3,229 3,246 3,127 2,745 2,749 2,627

4 parsons ........................................................... 4,113 4,137 4,139 4,116 3,527 3,528

5 parsons ........................................................... 4,645

3,513

4,660 4,884 4,637 4,159 4,159

6 persons ........................................................... 5,441

4,1,46

5,489 5,492 5,460 4,668 4,669

7 persons or more ........................................... 6,678

4,656

6,751 6,771 6,583 5,736 5,749 5,516

~Forunrelatedindividuals,sexofthe individual.

SOURCE U.S. BureauoftheCensus Chamtiefisticsofthelow-incomepopulation1971, CunentPopulationRepofis,SefiesP+O, No,86, p.l B.

ratios greater than 1.0 are described as “above poverty.”

Poverty thresholds are computed on a national

basis only. These thresholds have not been adjusted for

regional, state, or other local variation in the cost of

living (except for the farm and nonfarm difference).

None of the noncash public welfare benefits such as

food stamps or free food commodities are included in

the income of the low-income families reeeiving these

benefits.

The threshold income values in 1971 for the

combinations listed above are shown in table V.

Other terms used in relational

analyses

The following terms used in this report are abbreviations of the data items or questions listed under

description. These characteristics are listed on the

various NHANES I questionnaires or derived from

data collected on them.~

Term

Number of persons in

household

Marned

Education of examinae

Age of head of household

Education of head of

household

Total iron intake

Log total iron intake

Description

Total number of persons reported on

NHANES household questionnaire.

Are you married? (yes or no)

What is the highest grade or year of

ragular school the examinee has

ever attended?

How old was the head of the household on his or her last birthday?

What is the highest grada or year of

regular school the head of the

household has ever attended?

Milligrams of iron from all sources,

consumed during a 24-hour period.

Logarithm (base 10) of total iron intake,

NOTE: A list of references follows the text.

82

Term-Con. Description-Con.

Total animal tissue iron

intake

Total nonanimal tissue

iron intake

Total protein intake

Total animal tissue protein intake

Total nonanimal tissue

protein intake

Estimated available iron

Estimated available iron

with tea

Vitamin C

Pica

Regular vitamin use

Regular mineral use

Regular vitamin and

mineral use

Special diet

Ever breastfed

Age of mother at

child’s birth

Milligrams of animal tissue (i.e., from

meat, fish, and poultry) consumed

during a 24-hour period.

Milligrams of nonanimal tissue (i.e.,

from eggs, dairy products, and all

plant sources) consumed during a

24-hour period.

Grams of protein from all sources

consumed during a 24-hour period.

Grams of protein from meat, fish,

poultry consumed during a 24-hour

period.

Grams of protein from all plant

sources (grains, fruits, vegetables,

etc.); eggs and all dairy products

consumed during a 24-hour period.

Milligrams of iron from all sources,

modified by vitamin C and animal

tissue protein intake consumecl during a 24-hour period.

Milligrams of iron from all sources,

modified by vitamin C, animal tissue

protein and tea intake consumed

during a 24-hour period.

Milligrams of vitamin C consum,ed

during a 24-hour period.

Yes answers to “does person ever

eat dirt or clay, starch, paint c~r

plaster, or any material that might

be considered unusual?”

Has person taken vitamins within the

last 30 days and within the last

week?

Has person taken minerals within the

last 30 days and within the la~t

week?

Does person report that he or she

has taken vitamins and/or minerals

within the last 30 days and within

the last week?

Are you on a special diet?

Was child breastfed at any time?

How old was child’s mother whlen

(child) was born? years

.\
Term-Con.

1s child the first born?

Birth weight (pounds)

Premature bitth

Oral contraceptive usage in past 6 months

Age began menstruating

Ever been pregnant?

Ever been anemic?

Any trouble eating?

General findings

Present illness

Regular aspirin use

Abdominal operations

Desctiptiorr-Con.

How many children were born before

this child?

How much did child weigh when he

was born? pounds

ounces

Was child born prematurely? (That is,

early or not carried the full nine

months.)

Have you taken birth control pills during the past 6 months?

How old were you when your periods

or menstrual cycle started?

Are you or have you ever been pregnant?

Have you ever had anemia, sometimes called “low blood?”

Do you have any illness or condition

which interferes with your eating?

Any findings on the general medical

exam.

Is child presently ill?

Has person taken aspirin within last

30 days and within the last week?

Have you had an abdominal operation?

o U, S. 00VEKNMENT PIWT13JCOFFICE : 7983 361-161/107

83
Vital and Health Statistics series descriptions 

SERIES 1. Programs and Collection Procedures.-Reports describing 

the general programs of the National Center for Health 

Statistics and its offices and divisions and the data collection methods used. They also include definitions and 

other material necessary for understanding the data. 

long-term care, ambulatory care, hospital care, and family 

planning services. 

SERIES 2. Data Evaluation and Methods Research.-Studies of new 

statistical methodology including experimental tests of 

new survey methods, studies of vital statistics collection 

methods, new analytical techniques, objective evaluations 

of reliability of collected data, and contributions to statistical theory. 

SERIES 14. Data on Health Resources: Manpower and FecilitiasStatistics on the numbers, geographic distribution, and 

characteristics of health resources including physicians, 

dentists, nurses, other health occupations, hospitals, 

nursing homes, and outpatient facilities. 

SERIES 15. Data From Special Surveys.-Statistics on health and 

health-related topics collected in special surveys that are 

not a part of the continuing data systems of the National 

Center for Health Statistics. 

SERIES 3. Analytical and Epidemiological Studies.-Reports presenting analytical or interpretive studies based on vital 

and health statistics, carrying the analysis further than the 

expository types of reports in the other series. 

SERIES 4. Documents and Committee Reports.-Final reports of 

major committees concerned with vital and health statistics and documents such as recommended model vital 

registration laws and revised birth and death certificates. 

SERIES 20. Data on Mortality.-Various statistics on mortality other 

then as included in regular annual or monthly reports. 

Special analyses by cause of death, age, and other demographic variables; geographic and time series analyses; and 

statistics on characteristics of deaths not available from 

the vital records based on sample surveys of those records. 

SERIES 10. Data from the National Health Interview Survey.-Statistics on illness, accidental injuries, disability, use of hospital, medical, dental, and other services, and other 

health-related topics, all based on data collected in the 

continuing national household interview survey. 

SERIES 11. Data From the National Health Examination Survey and 

the National Health and Nutrition Examination Survey.- 

Data from direct examination, testing, and measurement 

of national samples of the civilian noninstitutionalized 

population provide the basis for (I) estimates of the 

medically defined prevalence of specific diseasas in the 

United States and the distributions of the population with 

respect to physical, physiological, and psychological 

characteristics and (2) analysis of relationships among the 

various measurements without reference to an explicit 

finite universe of persons. 

SERIES 12. Data From the Institutionalized Population Surveys.-Discontinued in 1975. Reports from these surveys are included in Series 13. 

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utilization of health manpower and facilities providing 

SERIES 21. Date on Netality, Marriage, and Divorce.-Various statistics on natality, marriage, and divorce other than as 

included in regular annual or monthly reports. Special 

analyses by demographic variables; geographic and time 

series analyses; studies of fertility; and statistics on 

characteristics of births not available from the vital 

records based on sample surveys of those records. 

SERIES 22. Date From the National Mortality end Netality Surveys.- 

Discontinued in 1975. Reports from these sample surveys 

based on vital records are included in Series 20 and 21, 

respectively. 

SERIES 23. Data From the National Survey of Family Growth.- 

Statistics on fertility, family formation and dissolution, 

family planning, and related maternal and infant health 

topics derived from a periodic survey of a nationwide 

probability sample of ever-married women 1544 years of 

age. 

For a list of titles of reports published in these series, write to: 

Scientific and Technical Information Branch 

National Center for Health Statistics 

Public Health Service 

Hyattsville, Md. 20782 
US DEPARTMENT OF HEALTH AND HUMAN SERVICES 

Public Health Serwce 

NatIonal Center for Health Statlsttcs 

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DHHS Pub. No. 83-1679, Series 11, No. 229 

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