Abstract

Iron deficiency severe enough to cause anemia may affect children’s ability to grow and learn and, consequently,

their lifelong productivity and earnings. This study examined the iron status of infants and toddlers ages 6-24

months with a prevalence of anemia of at least 10 percent participating in the Special Supplemental Nutrition

Program for Women, Infants, and Children (WIC) in West Virginia counties. Blood screening performed especially

for this study found that 12 of the 57 infants and toddlers (21 percent) were iron deficient, considerably more than

the 4 of 49 (8 percent) with anemia. Because the screening methods routinely performed outside of the study are

unable to detect iron deficiency before it progresses to anemia, primary prevention of iron deficiency is the only

option that may be universally applied. Expert feeding recommendations—such as introducing iron-rich complementary foods after 6 months of age and limiting consumption of milk among children ages 12-24 months to no more

than 24 ounces—are useful for promoting adequate intake of readily-available iron and may help prevent iron

deficiency.

Factors Associated With Iron Status

Among WIC Infants and Toddlers in

Rural West Virginia

Contractor and Cooperator Report No. 35

December 2007

By Cindy Fitch, West Virginia University

This study was conducted by West Virginia University under a cooperative

research contract with USDA’s Economic Research Service (ERS) Food

and Nutrition Assistance Research Program (FANRP): contract number

43-3AEM-0-80073 (ERS project representative: Elizabeth Frazao). The views

expressed are those of the authors and not necessarily those of ERS or

USDA.
Contents 

Executive Summary..................................................................................................................... iii 

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

Background ....................................................................................................................................3 

 Iron Status ..................................................................................................................................3 

 Consequences of Iron Deficiency ..............................................................................................5

 Factors that Influence Iron Status ..............................................................................................6 

 Primary Prevention of Iron Deficiency......................................................................................8 

Methods...........................................................................................................................................9 

 Iron Status ................................................................................................................................11 

 Dietary Intake...........................................................................................................................12 

 Statistical Analyses ..................................................................................................................16 

Results...........................................................................................................................................17 

 Iron Status ................................................................................................................................19 

Discussion......................................................................................................................................28 

 Blood Lead Levels ...................................................................................................................35 

Conclusions...................................................................................................................................36 

References.....................................................................................................................................39 

 

ii
Executive Summary

Issue 

Adequate iron status is essential for health and development, and consequently for 

lifelong productivity and earnings. The WIC Program strives to eliminate iron-deficiency 

anemia in low income children by providing iron-fortified foods such as infant formula, 

infant cereals, and adult cereals. Yet several counties in West Virginia have a prevalence 

of anemia among WIC infants and toddlers (ages 6-24 months) greater than 10% -- 

higher than the State average, and higher than the 5% that would be expected in a 

population without iron deficiency. This project examined the iron status in a sample of 

WIC infants and toddlers in West Virginia. 

Background 

Iron deficiency develops when iron stores are depleted. Although the terms “iron 

deficiency” and “anemia” are often used interchangeably, they are not the same. Anemia 

is a late sign of iron deficiency, but iron deficiency is not the only cause of anemia. 

Other causes of anemia include infection and inflammation that are unrelated to 

nutritional status, severe deficiency in intake of certain other nutrients (such as vitamins 

B6 and B-12, folate, copper, zinc, and protein), and mild hereditary traits such as 

thalassemia. Iron deficiency severe enough to cause anemia may affect children’s ability 

to learn and grow, permanently alter behavioral, mental and psychomotor development, 

decrease resistance to infections, and increase the risk of lead poisoning. 

iii
Clinical manifestations of iron deficiency include weakness, muscle fatigue, and 

decreased cognitive ability -- conditions not specific to iron deficiency. Thus, many 

children with iron deficiency may not be diagnosed because they are not anemic. 

In order to determine the iron status of infants and toddlers and examine the factors 

associated with iron status, the project recruited parents of infants and toddlers aged 6-24 

months in WIC clinics in 10 counties in West Virginia where the prevalence of anemia 

was greater than 10%. Children were weighed and measured, and parents were 

interviewed to get a brief medical and feeding history for the child—including whether 

the child was ever breastfed and for how long, use of vitamin or mineral supplements, 

dietary intake (collected over 2 days), and information on infections over the past 6 

months. Parents were then given a requisition for blood work for the child, to be done in 

a local hospital or physician’s office. After the clinic visit, a check for $40 was sent to the 

parent as a thank you gift and compensation for the time they spent participating in the 

study. Recruitment was very low, however, even after the incentive was increased to 

$80. 

Infants and toddlers were defined as iron deficient if both serum ferritin and transferrin 

saturation values were below the criteria established by the Centers for Disease Control 

and Prevention (CDC); anemia was defined as hemoglobin below 11 grams/liter. 

Children with anemia in the presence of iron deficiency were defined as having irondeficiency anemia; those with low hemoglobin and normal iron status were considered 

anemic without iron deficiency. 

iv
Findings

Iron deficiency was observed among 12 of the 57 (21%) children in the sample for whom 

laboratory values were available. All cases of iron deficiency were observed among 1-

year olds, resulting in a prevalence of 31% among 1-year olds (12 out of 39 toddlers). 

This is considerably more than the goal established for Healthy People 2010 for toddlers 

aged 1-2 years, 5%. It is also nearly 3 times the prevalence of anemia in the sample (4 of 

49 children, or 8%)1. The much higher prevalence of iron deficiency relative to anemia 

may be indicative of improvements in iron status in US children: as iron status improves, 

cases of iron deficiency become milder. In such cases, screening for anemia becomes 

less effective as a marker for iron deficiency. 

High intakes of cow’s milk and calcium were associated with poor iron status and low 

serum ferritin (an indicator of iron stores). While milk and dairy products are excellent 

sources of nutrients during the second year of life, it is important that they not replace 

other healthy foods in the diet, especially iron-rich foods. The American Academy of 

Pediatrics (AAP) recommends that toddlers ages 12-24 months limit milk consumption to 

no more than 24 ounces per day. Nine of the 39 toddlers (23%) ages 12-24 months drank 

more than 24 ounces of cow’s milk per day, and 5 of the 9 (55%) drank 40-60 ounces per 

day. 

Low meat intake was associated with poor iron status when protein intake was controlled. 

Meats are good sources of iron, and can be introduced into the diet after 6 months of age. 

 

1

 The finding of an 8% prevalence of anemia in counties with a prevalence of 10% or more may be partly 

due to the small sample and the project’s use of venous blood to measure hemoglobin. 

v
However, commercially-prepared jars of baby food “combination dinners” may not be 

the best way to introduce meats into the diet, since they provide about half the iron and 

protein per serving than commercially-prepared jars of baby food plain meats. 

Vitamin C and iron intakes were not associated with iron status, although iron intake did 

account for some of the variance in serum ferritin. 

There were no discernable relationships between iron status, blood lead levels, and 

number of infections in the past 6 months. Blood lead levels were related positively to 

intake of protein and negatively to intakes of phosphorus and vitamin E; iron and calcium 

intakes were not related to blood lead levels. 

Conclusion 

Because of very low participation rate in the study, sample size was small and may not be 

representative of the population. However, the study’s finding of a large prevalence of 

iron deficiency without anemia is consistent with improvements in iron status in US 

children. 

Iron deficiency was seen exclusively in toddlers aged 12 to 24 months, although infants –

particularly those with suboptimal dietary intake—may still be at risk for iron deficiency. 

The transition to table foods is a vulnerable time for the development of iron deficiency. 

Current screening methods are unable to detect iron deficiency before it progresses to 

anemia, so iron deficiency may be a hidden problem among children, especially those 

vi
vii

ages 12-24 months. Feeding recommendations from the CDC and the AAP—such as 

introducing iron-rich complementary foods after 6 months of age and limiting 

consumption of milk among 12-24 months old to no more than 24 ounces—are useful for 

promoting adequate intake of readily-available iron and can help prevent iron deficiency. 
Factors Associated With Iron Status Among 

WIC Infants and Toddlers in Rural West Virginia 

This grant was funded by the USDA ERS as a Developmental Grant for the budget 

period from 9/27/00 to 9/30/02 and extended to 8/31/03. Data collection began July 5, 

2001. 

Introduction

Adequate iron status is a necessary feature of a healthy, well-nourished population. One 

of the goals of Healthy People 2010 is to reduce the prevalence of iron deficiency to 5% 

among children aged one to two years (US Department of Health and Human Services, 

2000). Data collected for the 1999-2000 National Health and Nutrition Examination 

survey (NHANES) indicate that the prevalence of iron deficiency and iron-deficiency 

anemia in children aged one to two years was 7% and 2% respectively (Centers for 

Disease Control and Prevention, 2002). 

The Centers for Disease Control and Prevention (CDC) monitor the prevalence of anemia 

in low-income infants (six to 11.9 months of age) and young children using the Pediatric 

Nutrition Surveillance System (PedNSS). Most PedNSS data come from children 

participating in the Special Supplemental Nutrition Program for Women, Infants, and 

Children (WIC) and reflect hemoglobin values measured in capillary blood using a handheld instrument (Hemocue Inc., Mission Viejo, CA). The first hemoglobin measurement 

is done at around six months of age. Anemia is defined as hemoglobin less than the 5th

percentile value for healthy persons with no evidence of iron deficiency. In infants and 

toddlers aged six to 24 months, that value is 11.0 g/L (Centers for Disease Control and 

Prevention, 1998). 

1
Based on data from PedNSS, in 1999 the prevalence of anemia among West Virginia 

infants younger than 12 months of age was 7.8%, up from 6.8% in 1998. The prevalence 

of anemia for toddlers aged 12 to 24 months was 8.4 percent. In both age groups, this 

number is lower than the national average (18.1% for infants younger than 12 months of 

age and 18.3% for those aged 1 to 3 years) but exceeds the expected prevalence of 

anemia (5%) for a population of U.S. children without iron deficiency. 

A number of counties in West Virginia have a prevalence of anemia that was greater than 

10% among WIC children aged six to 24 months. Since iron is generally well absorbed 

from human breast milk, infant formula, and infant cereal, and WIC provides ironfortified formula and infant cereal to infants, as well as iron-fortified cereals for children 

older than 12 months, it is not clear why some infants and young children in the WIC 

program continue to be anemic. It is possible that some infants and young children are 

anemic due to factors such as infection or inflammation that are unrelated to nutritional 

status. Dietary factors that could lead to anemia include inadequate intake of iron or other 

nutrients required for erythropoiesis, excess intake of dietary inhibitors, a delay in 

introducing meat into the diet (Roquejo et al., 1999), or excessive intake of unmodified 

cow's milk. 

The objectives of this project were as follows: 

1. Determine the prevalence of iron deficiency, iron deficiency anemia (low 

hemoglobin in the presence of iron deficiency), and normal iron status in a group of 

2
infants and toddlers aged six to 24 months who were served by the WIC program in 

West Virginia counties where the prevalence of anemia was greater than 10%; 

2. Describe dietary patterns and the intake of specific nutrients (iron, calcium, and 

vitamin C) that influence iron status and serum ferritin in a group of infants and 

toddlers participating in the WIC program in those counties; and 

3. Quantify the relationships among iron status, blood lead levels, number of reported 

infections during the last six months, and nutrient intake. 

Background 

Iron Status 

Iron is present in all body cells and fulfills several vital functions, including oxygen 

transport and diffusion and electron transport for the production of energy. Optimal iron 

status can be defined as sufficient body iron to prevent any limitation in tissue iron 

supply (Cook, 1999). In the early stages of iron depletion, iron stores are decreased. As 

long as the production of essential iron-containing compounds is not diminished, there is 

no apparent physiological dysfunction, but the individual is vulnerable to iron deficiency 

(Herbert, 1992). Iron deficiency refers to inadequate production of essential ironcontaining compounds such as cytochromes and iron-sulfur compounds in the 

mitochondria of all cells and implies that the vital functions of these compounds are 

impaired (Dallman and Yip, 1989). 

Iron deficiency and anemia are terms that are often used interchangeably, but they are 

different. Anemia is a late sign of iron deficiency, but iron deficiency is not the only 

3
cause of anemia. Normal synthesis and maturation of red blood cells require a 

constellation of nutrients that include vitamins B-12, B-6, and folate, copper, zinc, and 

protein. A severe deficiency of any one of them can cause anemia. More commonly, if 

not caused by iron deficiency, anemia may be caused by infection, inflammation, or mild 

hereditary traits such as thalassemia (Yip, 1989). 

In determining how to assess iron status, it is important to note that iron is found in two 

main compartments in the body, storage iron and functional iron. Iron is stored in the 

liver, bone marrow, and spleen as ferritin. Serum ferritin is in equilibrium with tissue 

ferritin and represents body iron stores. Infection and inflammation can elevate serum 

ferritin even in the presence of iron deficiency. Despite this drawback, serum ferritin is 

often used in epidemiological studies as an indicator for stored iron and a low serum 

ferritin indicates depletion of iron stores. Individuals with depleted iron stores would be 

at risk for iron deficiency if their physiological need for iron was greater than their iron 

intake, but the amount of functional iron may not be impaired. In iron deficiency, stored 

iron is depleted and transport iron (as measured by transferrin saturation) is reduced 

(Centers for Disease Control and Prevention, 1998). At this stage, the lack of iron limits 

the production of red blood cells (as measured by erythrocyte protoporphyrin). Because 

no single laboratory test is truly reflective of iron status, the CDC used a multipleindicator model to assess iron status for the 1999-2000 NHANES (Centers for Disease 

Control and Prevention, 2002). They defined iron deficiency as an abnormal value for at 

least two of the following three indicators: serum ferritin, transferrin saturation, and free 

4
erythrocyte protoporphyrin. Iron deficiency anemia was defined as low hemoglobin in the 

presence of iron deficiency. 

Consequences of Iron Deficiency 

When iron status is compromised, iron stores will be depleted first, then non-storage iron 

in other tissues will be used before any measurable decrease in hemoglobin. The decrease 

in iron-containing proteins in the cells is responsible for the clinical manifestations of 

iron deficiency. These include weakness, muscle fatigue, and decreased cognitive ability 

(Committee on Nutrition, 1999). These signs are not specific to iron deficiency. 

Consequently, many children with iron deficiency will not be diagnosed because they are 

not anemic. Iron deficiency that is severe enough to cause anemia has adverse 

consequences that may not be reversible. Iron-deficiency anemia (IDA) has been 

associated with an increased risk of lead poisoning (Hammad et al., 1996), decreased 

resistance to infections (Chandra and Saraya, 1975) and permanent alterations in 

behavioral, mental, and psychomotor development (Moffat et al., 1994; Lozoff et al., 

1987). 

The interactions between iron status and infection are complex. Infection and 

inflammation can cause anemia that is unrelated to nutritional status (Yip, 1989). Excess 

iron stores and iron deficiency are both associated with impaired immune function 

(Mencacci et al., 1997, Berger et al., 2000). Iron deficiency alters cellular immunity 

including T lymphocyte proliferation to mitogens and the function of natural killer cells 

(Walter et al., 1997, Scrimshaw and SanGiovanni, 1997). Cellular immunity is 

5
particularly important for infants because humoral immunity, the other type of immunity, 

is slower to develop. 

The age of six to 24 months is a period of rapid brain growth and cognitive and motor 

development. A number of studies have documented lower test scores on Bayley Scales 

of Infant Development in infants with iron-deficiency anemia, and in most of these 

studies, correction of the anemia did not lead to improvement in test scores (Reviewed by 

Grantham-McGregor and Ani, 2001). 

Factors that Influence Iron Status 

Infants and toddlers aged six to 24 months are particularly vulnerable to developing iron 

deficiency. They have a rapid rate of growth and blood volume expansion and the need 

for exogenous iron is high in proportion to body weight. After two years of age, the rate 

of growth begins to slow and iron stores begin to build up so that the risk of iron 

deficiency is decreased. Full term infants are born with an iron endowment that is 

adequate to prevent iron deficiency for about the first four to six months of life. How 

quickly and to what extent those iron stores are used up depends on the amount of iron 

stored before birth and the postnatal diet. 

Two major factors influence iron absorption - iron stores and the synthesis of red blood 

cells (erythropoiesis) (Bothwell, 1995). Declining iron stores and stimulation of 

erythropoiesis both cause iron absorption to increase. Dietary factors play a lesser, but 

still important role in enhancing or inhibiting iron absorption. 

6
Although the concentration of iron in human milk is low, absorption of that iron is high. 

The exact mechanism is not known, but is believed to be a low molecular weight 

component in the whey portion of human milk (Etcheverry et al., 2004). While 

unfortified infant formula and whole cow's milk have about the same iron content as 

human milk does, only about 10% of that iron is absorbed compared to about 50% of the 

iron in human milk. Iron-fortified infant formula is a good source of iron for infants who 

are not breastfed. 

One dietary practice that is known to impair iron status is the introduction of unmodified 

cow's milk into an infant's diet. Not only is the absorption of the iron in cow’s milk very 

low, but cow’s milk may replace foods with higher iron content in the diet, and it may 

cause losses of small quantities of blood from the gastrointestinal tract (Woodruff et al., 

1972). In addition, calcium has been reported to inhibit heme and non-heme iron 

absorption in animal and human studies (Hallberg et al., 1991; Barton et al., 1983). 

Epidemiological studies have reported an inverse relationship between milk or calcium 

intake and serum ferritin (van de Vijver et al., 1999). Pediatric clinical dietitians often 

see toddlers who consume large volumes of milk to the exclusion of other foods. These 

toddlers are at risk for iron deficiency. 

Other dietary factors that influence iron status include the form of iron (heme or nonheme iron) and the presence of promoters or inhibitors of absorption. Heme iron is 

supplied in the diet by meats, poultry and fish, and is two to three times more absorbable 

7
than is non-heme iron. Non-heme iron is affected by dietary factors that promote or 

inhibit absorption. The major promoters are meat proteins and ascorbic acid (vitamin C). 

Factors that have been shown in some studies to inhibit non-heme iron absorption include 

polyphenols in tea and some vegetables and phytates in cereals and legumes. Most of the 

studies on iron inhibitors were done with single foods, and the inhibitory effects in a 

mixed meal that also contain factors that enhance iron absorption may be much less 

important than once believed. 

Primary Prevention of Iron Deficiency 

The CDC and the American Academy of Pediatrics have published recommendations for 

the primary prevention of iron deficiency in infants and toddlers (Centers for Disease 

Control and Prevention, 1998) (American Academy of Pediatrics, 2004). These 

recommendations are based on the best scientific knowledge about factors that enhance 

and impair iron absorption. Although each organization issued its recommendations 

separately, the recommendations are similar enough that they can be combined. The 

recommendations are as follows: 

• All infants younger than 12 months should receive only breast milk or iron-fortified 

infant formula for any milk-based part of the diet. 

• Encourage exclusive breastfeeding of infants for the first four to six months of life in 

infants who are breastfed. 

• After four to six months, when the infant is developmentally ready, encourage a 

supplemental source of iron preferably from complementary foods. Iron-fortified 

8
infant cereal and/or meats are a good source of iron for initial introduction of an ironcontaining food. 

• A breastfed infant who is not able to consume sufficient iron from dietary sources 

after six months of age should be given iron drops. 

• By age six months, encourage one feeding per day of foods rich in vitamin C, 

preferably with meals, to improve iron absorption. 

• Children aged one to five years should consume no more than 24 ounces of cow's 

milk, goat's milk, or soymilk per day because of the concern that milk will replace 

iron-rich foods in the diet. Twenty-four ounces of milk per day will meet the dietary 

intake recommendations for calcium for children from one to eight years of age. 

Methods 

Infants and toddlers aged 6 to 24 months and their parents were recruited in WIC clinics 

in 10 counties in West Virginia where the prevalence of anemia was greater than 10%. 

The WIC clerk or nutritionist informed parents about the study when they came in for 

nutrition education or their regular visits and gave a stamped, addressed postcard to the 

parents who were interested. The parents filled out contact information on the postcard 

and sent it to the investigators. The investigators then contacted the parent and arranged a 

time to see that child in the WIC clinic. The Institutional Review Board at West Virginia 

University approved the study and all parents gave informed consent. 

At the WIC clinics, the investigators interviewed the parent to get a brief medical and 

feeding history for the child. Data collected included length of gestation, presence of 

9
chronic or infectious disease, whether the child was ever breastfed and for how long, and 

use of vitamin or mineral supplements. Dietary intake was assessed using a multiple-pass, 

24-hour intake with a standardized script and household measuring utensils. A second 24-

hour intake was obtained by phone 3 to 5 days later. 

Children were weighed and measured without clothes or a diaper. Weight was recorded 

in pounds and ounces and length was recorded to the nearest eighth of an inch. Heightfor-age, weight-for-age, and weight-for-height z scores were calculated using EpiInfo 

2000. For infants who were born prematurely, adjusted age was used to calculate z scores 

instead of chronological age. 

The mother was given a requisition for blood work and instructions as to where the blood 

would be drawn -- a local hospital or physician's office. While we would have preferred 

having a trained phlebotomist on site in the WIC clinics, we were not able to identify 

qualified and willing people to do that in the rural counties in which this study was 

conducted. All laboratories to which the infants were referred were affiliated with the 

Laboratory Corporation of America (LabCorp). LabCorp is an independent, national 

company that provides laboratory analysis for diagnostic, clinical, and research purposes. 

Approximately 6 ml blood was drawn, divided between an EDTA tube and a serum 

separator tube and sent to the regional laboratory operated by LabCorp. Blood samples 

were analyzed for lead by atomic absorption spectrometry, hemoglobin by automatic cell 

counter, and ferritin by immunochemiluminometric assay. Transferrin saturation was 

10
calculated from measurements of serum iron (colorimetric assay) and transferrin 

(immunologic assay). 

In the interest of minimizing the volume of blood drawn and laboratory expense, we did 

not measure erythrocyte protoporphyrin. The specificity of erythrocyte protoporphyrin 

for detecting iron depletion is estimated at 61% compared to 100% for serum ferritin and 

93% for transferrin saturation (Centers for Disease Control and Prevention, 1998). 

Decreases in transferrin saturation precede changes in erythrocyte protoporphyrin (Cook, 

1999). 

After the clinic visit, a check for $40 was sent to each parent as a thank you gift and 

compensation for the time that they spent participating in the study. During the last 5 

months of the study, this incentive was raised to $80 in an attempt to increase 

recruitment. At the same time, the method of delivery was changed to provide $10 in 

cash at the time of the visit with the remainder to be sent as a check. The cash was 

provided to enable them to get to the laboratory facility. 

Iron Status 

Normal iron status was defined as normal values on either serum ferritin (equal to or 

greater than 15 micrograms/liter (μg/L)) or transferrin saturation (greater than15%). The 

values considered “normal” were based on CDC criteria (Centers for Disease Control and 

Prevention, 1998). If values for both ferritin and transferrin saturation were below the 

criteria, the child was considered iron deficient. Anemia was defined as hemoglobin less 

11
than the 5th percentile value for healthy persons with no evidence of iron deficiency. In 

infants and toddlers aged six to 24 months, that value is 11.0 grams/liter (g/L) (Centers 

for Disease Control and Prevention, 1998). Children with anemia in the presence of iron 

deficiency were considered to have iron-deficiency anemia. Those with low hemoglobin 

and normal iron status were considered anemic without iron deficiency. 

Dietary Intake 

Average intakes from the 24-hour recalls were calculated using Food Processor, Version 

7.1 for Windows. There were a small number of children for whom only one day of 

intake information was available. This day was treated the same as the two-day average 

for analysis. There was no attempt to account for any variation between weekend and 

weekday intake. 

For infants who were breastfed at the time of the study, it was assumed that the intake of 

breast milk was 600 ml per day and the mean nutrient content was comparable to that of 

pooled human milk (National Research Council, 1989). If a breastfed infant was also 

taking infant formula, the volume of formula consumed was subtracted from 600 ml and 

the remainder was calculated as breast milk. 

Dietary iron, vitamin C, and calcium are nutrients that reportedly affect iron status. The 

reported 2-day average intake of these nutrients was compared to appropriate Dietary 

Reference Intakes to determine the proportion of infants who were likely getting adequate 

intake on the study days. When an Estimated Average Requirement (EAR) was 

12
available, the EAR cut point method was used (Institute of Medicine, 2000). For calcium, 

and for all nutrients except iron in infants younger than 12 months, there is no EAR 

established, therefore the Adequate Intake (AI) was used for reference. The AI represents 

a value that meets the needs of almost all healthy individuals in that group. Although the 

AI cannot be used to calculate the prevalence of inadequate nutrient intake for groups, if 

mean intake levels are equal to or exceed the AI it can generally be assumed that the 

prevalence of inadequacy is low (Institute of Medicine, 2000). 

Five dietary factors, based on recommendations from the CDC and the American 

Academy of Pediatrics (AAP), were examined as independent variables for their 

influence on iron status: 

• consumption of age-appropriate servings of iron-fortified infant or adult cereal 

• consumption of age-appropriate servings of meat, fish, or poultry 

• consumption of fruit, vegetable, or juice with a meal 

• use of a multivitamin/mineral supplement 

• age-appropriate use of milk 

For infants younger than 12 months of age, “age-appropriate use of milk” was 

represented by no use of unmodified cow’s milk, since this is a known risk factor for 

iron-deficiency anemia (Woodruff et al., 1972). For toddlers aged 12 to 24 months, 

appropriate use of milk was defined as “not more than 24 ounces of milk per day”. 

13
In addition, all intake records were examined for the consumption of tea because the 

tannins in tea are known to inhibit iron absorption (Charlton and Bothwell, 1983). 

There are no specific guidelines for serving sizes for children younger than 24 months of 

age. A general guideline used by pediatricians and pediatric dietitians is one tablespoon 

of each food for every year of age (American Academy of Pediatrics, 2004). In addition, 

USDA’s Food and Nutrition Service has issued meal guidelines for the Child and Adult 

Care Food Program (CACFP) that provides serving sizes for reimbursable meals. We 

used the more specific serving sizes from the CACFP to establish acceptable serving 

sizes for use in determining whether the intake recommendations were met or not. The 

specific serving sizes and types of foods that were considered to have met the guidelines 

are as follows: 

• Iron-fortified cereal - 1 tablespoon of an iron-fortified infant cereal for infants 

younger than 12 months, 1/4 cup of an iron-fortified hot or cold cereal for those from 

12 to 24 months. Cereals listed in the WIC food list were accepted as iron-fortified. 

Those not on the WIC food list were accepted as iron-fortified if they provided at 

least 4 milligrams of iron per serving based on information in our nutrient database. 

• Meat, fish, or poultry - 1 tablespoon for infants younger than 12 months and 1 ounce 

for those aged 12 to 24 months. Pepperoni on pizza, meat from canned soups, and 

commercially-prepared baby food combination dinners were not considered meat 

servings because they provide minimal amounts of meat. The exact proportion of 

ingredients in commercially-prepared baby food combination dinners is proprietary 

14
information, but, per serving, they generally provide about 50% of the iron and 

protein provided by plain meats. 

• Fruits and vegetables - 1 tablespoon for infants younger than 12 months and 1/4 cup 

for those from 12 to 24 months. Baby food desserts and fruit pies, cobblers, and 

fruited gelatins were excluded. 

• Juice - 2 ounces for infants younger than 12 months and 4 ounces for those aged 12 

to 24 months. Only 100% juice beverages were included. 

Each dietary factor was coded as "yes” (met recommendations) or "no” (did not meet 

recommendations) and used as a dichotomous independent variable. If the 

recommendation was met on only one of two days, it was still considered as met. 

Independent continuous variables were the growth parameters, number of infections in 

the past six months, ounces of unmodified cow's milk (averaged over two days), number 

of servings of meat, fish or poultry; ounces of tea; grams of fiber and protein; and 

milligrams of iron, calcium, and vitamin C (averaged over two days). 

Breastfeeding was coded as a categorical variable, i.e. breastfed for less than six months, 

breastfed for six months or longer, or not breastfed at all. Iron status was used as an 

independent variable to test for differences in growth parameters or numbers of infections 

between children with normal iron status and those who were iron deficient. 

15
The dependent variables were growth, number of infections during the past six months, 

iron status (normal or deficient), serum ferritin, hemoglobin, and blood lead levels. 

Serum ferritin was used as a dependent variable because it represents the storage form of 

iron and is the first laboratory test to change when iron is depleted. Blood lead levels 

were of interest in this group because we did not know whether or not these children were 

being exposed to lead. If they were, those with iron deficiency or with low iron or 

calcium intake would be at risk for higher blood lead levels. 

Statistical Analyses 

Student's T-test was used to make comparisons between the group with normal iron status 

and those that were iron deficient. Backward logistic regression was used to evaluate the 

dietary variables (dichotomous and continuous) that influenced iron status. All 

independent variables were initially included in the model. We then dropped the ones that 

had no significant influence on iron status. This method was used because combinations 

of variables that are significantly associated with the outcome sometimes show up in a 

backward regression when they were not apparent in a stepwise logistic regression 

model. The relationship between serum ferritin and continuous variables (ounces of milk, 

servings of meat, fish or poultry, number of infections, and dietary intake of specific 

nutrients was tested using multiple linear regression. The relationship between nutrient 

intake and blood lead levels was tested using multiple linear regression. Data were 

analyzed using SAS, Version 8.0 (SAS Institute, Cary, NC). 

16
Results 

Ten counties in West Virginia were identified in which the prevalence of anemia among 

WIC children was greater than 10% based on data from the 1999 PedNSS. The counties, 

clustered in four different areas of the state -- west, central, and southeastern parts of the 

state, and the eastern panhandle—had a total WIC population of 1440 infants and 

toddlers aged 6 to 24 months. We were able to recruit 87 children from 8 of the 10 

counties identified for the study and have at least partial laboratory values for 57. The 

most common reason that parents gave for not consenting to participate was that they did 

not want their child to have blood drawn. A venous blood draw is more invasive than a 

finger stick and is perceived by many people to be more painful. The most common 

reason that parents gave for participating is that they wanted to know the results of the 

laboratory tests, particularly the blood lead level. 

The complete sample included 32 infants and 55 toddlers, all of them white (Table 1). 

Mean height-for-age, weight-for-age, and weight-for-height z scores are within normal 

limits. None of the children were stunted (height-for-age z score less than -2.0) or wasted 

(weight-for-height z score less than -2.0). Eighteen participants had been born 

prematurely. 

17
Table 1. Characteristics of Participants 

Total N = 87 

6 to 11.9 months/12 to 24 months 32/55 

Male/female 45/42 

Race White (100%) 

Mean ± SD 

Age in months 14.8 ± 6.3 

Height in inches 30.2 ± 3.3 

Weight in pounds 23.1 ± 4.6 

Mean height-for-age z-score -0.03 ± 1.08 

Mean weight-for-age z-score 0.25 ± 1.12 

Mean weight-for-height z-score 0.39 ± 1.25 

The 2-day average intakes for various vitamins and minerals were compared to the 

appropriate Dietary Reference Intakes (DRIs) to determine the adequacy of intake (Table 

2)2. For nutrients with only an Adequate Intake (AI) reference value (as is the case for 

most nutrients for infants), mean intake exceeded the AI value (listed in the table). It is 

likely that the prevalence of inadequacy for these nutrients is low (Institute of Medicine, 

2000). For nutrients with an Estimated Average Requirement (EAR), the proportion of 

children with inadequate intake (intake less than the EAR) is also low for most nutrients. 

The nutrient most likely to be inadequate is vitamin E in the diets of children aged 12 to 

24 months. There was a wide variability in intake of vitamin E in this group. Other 

studies have also found high prevalence of inadequate intakes of vitamin E among 

various population groups. Devaney et al (2007) caution that difficulties with nutrient 

composition databases and dietary assessment methods may underestimate vitamin E 

intake, and overestimate the prevalence with inadequate intakes. 

18
Table 2. Dietary intakes appear adequate except for Vitamin E 

Nutrient Age 6 to 11.9 Months 

N=32 

Age 12 to 24 Months 

N=55 

Mean 

Intake 

(SD) 

Adequate 

Intake 

(AI) 

# (%) 

Below 

EAR 

Mean 

Intake 

(SD) 

Adequa

te 

Intake 

(AI) 

# (%) 

Below 

EAR 

Vitamin A (μg) 1178 

(485) 

500 849 (397) 0 (0) 

Thiamin (mg) 0.9 (0.4) 0.3 1.1 (0.5) 1 (2) 

 Riboflavin (mg) 1.3 (0.6) 0.4 1.9 (0.7) 0 (0) 

Niacin (mg) 12 (5.3) 4 19 (7.6) 0 (0) 

Vitamin B6 (mg) 0.9 (0.5) 0.3 1.2 (0.5) 0 (0) 

Vitamin B12 (μg) 2.1 (1.0) 0.5 3.7 (2.6) 2 (4) 

Vitamin C (mg) 129 (63) 50 101 (92) 4 (7) 

Vitamin D (μg) 6 (5) 5 9 (5) 5 

Vitamin E (mg) 15 (7) 5 6 (5) 33 (60) 

Folate (μg) 126 (54) 80 201 (114) 10 (18) 

Calcium (mg) 591 (239) 270 1052 (484) 500 

Copper (μg) 666 (207) 220 484 (247) 0 (0) 

Iron (mg) 14 (7) 2 (6) 11 (5) 1 (2) 

Magnesium (mg) 99 (39) 75 157 (56) 1 (2) 

Phosphorous (mg) 463 (201) 275 942 (353) 0 (0) 

Selenium 24 (10) 20 44 (21) 1 (2) 

Zinc 6.5 (3.0) 2 (6) 6.5 (3.5) 2 (4) 

Energy (kcal/day) 914 (277) 4(12.5) 1312 (393) 3 (5) 

Protein (g/kg) 3.3 (1.8) 2 (6) 4.1 (2.0) 1 (2) 

Iron Status 

Partial or complete laboratory values were available for 18 infants and 39 toddlers. Since 

our outcomes of interest were based on laboratory values, further analyses were done on 

data from these participants. This group of infants and toddlers is similar to the entire 

sample in growth parameters and dietary intake. Table 3 shows characteristics and 

dietary intake for infants and toddlers. 

 

2

 Use of the 2-day average instead of “usual” intake may result in a wider distribution of intakes, and 

19
Table 3. Characteristics and Dietary Intake of Infants and Children with Lab 

Values 

Infants (6 to 11.9 months) 

N=18 

Mean ± SE 

Toddlers (12 to 24 

months) 

N=39 

Mean ± SE 

Age (months) 8.4± 0.45 19.3±0.55 

Weight (pounds) 19.8±0.6 25.8±0.6 

Length (inches) 27.9±0.3 32.6±0.3 

Weight for age Z score 0.39±0.3 0.27±0.2 

Height for age Z score 0.09±0.2 0.09±0.2 

Weight for height Z score 0.41±0.3 0.34±0.2 

Ferritin (μg/L) 44.2±5.4 19.2±2.3*** 

Hemoglobin (g/dL) 11.6±1.0 11.8±1.0 

Meat (# of servings) 0.09±0.05 1.1±0.1 

Unmodified cow's milk 

(ounces per day) 

0.5±0.5 22.5±2.5 

Protein (g/kg) 2.4±0.2 4.5±0.3 

Energy (kcal/kg) 870±205 1339±396 

Iron (mg/day) 14.5±1.4 10.6±0.8 

Calcium (mg/day) 554±41 956±59 

Vitamin C (mg/day) 130±14 108±15 

***P<0.0001 compared to younger infants 

Table 4 shows the mean values for the laboratory tests and the number (percent) of 

infants and toddlers that were below the criterion value. In the case of blood lead level, 

being below the criterion value is preferable. 

 

 

overestimate the proportion of children with inadequate or low intakes. 

20
Table 4. Mean Laboratory Values 

Lab value N Criterion Value Mean (SD) Number (% ) 

Below Criterion 

Serum ferritin 57 15.0 μg/L 27.1 (20.1) 26 (46) 

% Transferrin 

saturation 

57 16 % 18.1 (8.4) 22 (39) 

Hemoglobin 49 11.0 g/dL 11.8 (0.72) 4 (8) 

Blood lead level 55 <10 μg/dL 2.95 (1.6) 55 (100) 

Hemoglobin was not available for 8 subjects because of insufficient quantities of blood to 

run all the tests. Of the 49 subjects with complete laboratory values, four (8%) were 

anemic. This is somewhat lower than the reported prevalence for the selected counties 

(all greater than 10%). The lower prevalence of anemia could be due to the low number 

of participants in our study, or to these children self-selecting into the study, but it may 

also reflect differences in hemoglobin measured in venous blood versus capillary blood. 

Capillary blood sampling are more prone to false low hemoglobin readings because they 

sample mostly the blood that has accumulated near the end of the finger or heel, rather 

than providing a good sample of venous blood (Thomas and Collins, 1982). The Centers 

for Disease Control and Prevention (CDC) monitor the prevalence of anemia in lowincome infants (six to 11.9 months of age) and children using the Pediatric Nutrition 

Surveillance System (PedNSS). Most PedNSS data come from the WIC program and 

reflect hemoglobin values measured in capillary blood using a hand-held instrument 

(Hemocue Inc., Mission Viejo, CA). In contrast, the hemoglobin for this project was 

based on venous blood samples. 

21
Iron deficiency was defined as having both serum ferritin less than 15 mg/L and 

transferrin saturation less than 16%. Twelve toddlers, all 12 months of age or older, were 

iron deficient based on this standard (Table 5). That represents 21% of the entire sample 

of 57 children ages 6-24 months, but 31% of the 12 to 24 months age group. 

Of the four children who were anemic, two were iron deficient (both older than 12 

months) and two had normal iron status (one older than 12 months and one younger). 

Therefore, the prevalence of iron-deficiency anemia was 4.1% (2 of 49) for the entire 

group and 5.1% (2 of 39) for toddlers 12 to 24 months of age. The one infant who was 

anemic had low transferrin saturation but normal ferritin3

. There was no report of a recent 

infection that may have accounted for an elevated ferritin level, but it is possible that he 

was truly iron deficient and our tests did not pick it up. There was no difference between 

male and female children in numbers who were iron deficient. 

Table 5. Iron Status of Participants 

Normal Iron Status 

Number (%) 

Iron Deficient 

Number (%) 

Total 

Number (%) 

45 (79) 12 (21) 57 (100) 

Anemia (n=49) 2 (4) 2 (4) 

Iron status (normal or deficient) was the dependent variable of greatest interest. There 

were too few children with iron-deficiency anemia in this sample to use that as a 

dependent variable. 

 

3

 Among toddlers ages 12-24 months, all those with low ferritin and low hemoglobin levels also had low 

transferrin saturation.

22
Infant growth is very sensitive to nutritional factors. It is possible that severe iron 

deficiency can impair growth or that children who are growing poorly due to inadequate 

intake may be iron deficient for the same reasons. Student's T test was used to compare 

the group of children with normal iron status to those who were iron deficient. Mean 

height-for-age, weight-for-age, or weight-for-height z scores were all within normal 

limits (-2.0 to +2.0). Overall, the iron deficient group was not significantly different from 

the group with normal iron status in terms of length-for-age, weight-for-age, or weightfor-length z scores. However, when we separated out the toddlers aged 12 to 24 months, 

there was a significant difference in weight-for-age, but not weight-for-length or lengthfor-age. Mean weight-for-age z scores were 0.11 in the iron deficient group and 0.42 in 

the group with normal iron status (p=0.04). The mean weight-for-age z scores for both 

groups were within normal limits. 

Immune function is also sensitive to nutritional factors. Severe iron deficiency can impair 

immune function and lead to increased risk of infections. Likewise, frequent infections 

can decrease dietary intake and impact iron status. Infection can also affect the 

identification of iron deficiency by increasing serum ferritin concentrations. There was no 

difference between the group with normal iron status and those that were iron deficient in 

number of infections based on parents' report. For both groups the mean was about 1.7 

infections per child (range 0 to 4) in the last six months. 

Children who were iron deficient took in significantly more calcium (1077±87 mg v. 

759±54 mg, p=0.007), phosphorous (1027±76 mg v. 717±60 mg, p=0.004), and protein 

23
(4.9±0.4 g/kg v. 3.5±0.3 g/kg, p=0.005) compared to those with normal iron status. There 

were no other significant differences in nutrient intake between groups. 

We examined dietary factors (dichotomous and continuous variables) that influenced iron 

status using stepwise logistic regression analysis (see the listing of variables in the 

Methods section). The results are shown in Table 6. The models were not adjusted for 

demographic variables such as age or sex. Whether or not the child met the 

recommendations from the AAP (dichotomous variables) did not influence iron status, 

but total amount of milk or meat intake did. For example, in models 1 and 2, ounces of 

cow's milk and grams of calcium each had a negative impact on iron status. For each one 

ounce increase in cow’s milk intake, the chance of normal iron status decreased by 0.9%. 

For each one milligram increase in calcium intake, the chance of normal iron status 

decreased by 0.02%. 

In Model 3, meat intake positively influenced iron status while protein intake was a 

negative influence. If meat intake is held at a fixed value, which implies that the protein 

is coming from non-meat sources, increasing protein intake by one gram per day 

decreased the odds of normal iron status by about 0.9%. Likewise, if protein intake is 

held at a fixed value, each additional serving of meat increased the odds of normal iron 

status by about 30%. In this model, intake of milk or calcium did not influence iron 

status. 

24
In Model 4, not breastfeeding at all was associated with better iron status than was 

breastfeeding for longer than 6 months when controlling for meat and protein intake. It 

should be noted that each additional serving of meat increased the odds of normal iron 

status in breastfed infants by about 50%. No other dietary variables significantly 

influenced iron status. 

Table 6. Dietary Variables Associated with Iron Status 

Dietary Variable Odds Ratio 95% Confidence 

Interval 

Model 1 

Cow's milk (ounces/day) 0.94 0.899 to 0.989 

Model 2 

Calcium (g/day) 0.017 <0.001 to 0.412 

Model 3 

Meat (servings/day) 29.26 2.88 to 296.9 

Protein (total g/day) 0.857 0.779 to 0.943 

Model 4 

Breastfeeding (not at all v. 

longer than 6 months) 

30.3 2.1 to 437.9 

Breastfeeding (less than 6 

months v. longer than 6 

months) 

2.75 0.29 to 25.97 

Meat (servings/day) 49.6 2.98 to 824.4 

Protein (g/day) 0.829 0.733 to 0.938 

We examined the dietary records for intake of tea, another food that interferes with iron 

absorption. Tea consumption did not influence iron status in our stepwise regression 

models. Only three children, all older than 12 months of age, consumed any tea on the 

25
recall days and the volumes consumed were small (two to six ounces). However, one of 

the three children was iron deficient. 

Serum ferritin represents the storage form of iron. As such, it is also a dependent variable 

of interest. It is less important than iron status, because depletion of storage iron does not 

imply iron deficiency but it does mean that the individual is at risk for developing iron 

deficiency. The relationship between dietary intake and serum ferritin was tested using 

multiple linear regression analysis. Intake of protein (r2=0.15, p=0.003), calcium 

(r2=0.15, p=0.004), and cow's milk (r2=0.26, p<0.001) were negatively associated with 

serum ferritin and iron intake (r2=0.12, p=0.01) was positively associated with serum 

ferritin. There were no other associations between any dietary or nutrient variables and 

serum ferritin. 

There were no significant associations between nutrient or food intake and hemoglobin. 

This was an expected finding. Hemoglobin is affected by many factors other than 

nutrition. It is not particularly sensitive to nutritional status, as it requires a fairly long 

period of inadequate intake before detectable changes in hemoglobin. 

We had a trained psychology graduate student working with us during the first summer to 

assess the participants' development using the Bayley Scales of Infant Development. 

After that time, she was no longer available, nor was anyone else who could administer 

the test. Twenty children were tested, all within normal limits for all parts of the scale 

(cognitive, psychomotor, and behavioral). Based on a review of literature, we would only 

26
expect to see developmental delays in children with iron deficiency anemia, not iron 

deficiency without anemia. Our very limited results were consistent with what others 

have reported. 

Fifty-four children had data on both blood lead level and iron status. The mean blood lead 

level was 2.95 ± 1.6 μg/dL with a range from 0 to 7. No child had a blood lead level 

greater than 10 μg/dl, the cut-off value used by the CDC to recommend treatment. Eight 

children had blood lead level greater than 5 μg/dL. This level has been associated with 

cognitive impairment and has been proposed as the new standard for treatment (Lanphear 

et al., 2000). Mean blood lead level was 2.8 ± 1.7 μg/dL in the group with normal iron 

status and 3.3 ± 1.7 μg/dL in the iron deficient group. The difference was not statistically 

significant. 

Multiple regression analysis of all nutrients revealed that protein was positively 

associated, and phosphorous and vitamin E were negatively associated, with blood lead 

levels (Table 7). These 3 factors accounted for about 23% of the variance in blood lead 

levels. Other nutrients, including dietary iron and calcium, had no impact on blood lead 

levels. 

Table 7. Nutrients Associated with Blood Lead Levels 

Nutrient Parameter 

Estimate 

Standard Error P value 

Protein 0.058 0.02 0.004 

Phosphorous -0.004 0.001 0.001 

Vitamin E -0.101 0.03 0.005 

27
Children who were breastfed for 6 months or longer (n=8) had higher blood lead levels 

than did those who were breastfed for less than 6 months (n=17) or not at all (n=32) (4.5 

μg/dL v. 2.9 μg/dL v. 2.5 μg/dL, respectively, p=0.02). One possible explanation is that

the mother's lead burden may be a greater factor in the child’s blood lead level than is 

current lead exposure. Women who were exposed to environmental lead as children tend 

to deposit that lead in their bones, and that lead is released during periods of bone 

remodeling such as pregnancy and lactation (Gulson et al., 1998). Alternatively, there 

may be other differences in environmental risk factors between these two groups.

Discussion 

All infants and toddlers in this study were participating in the WIC Program. WIC 

promotes breastfeeding and provides nutrition education and supplemental foods that are 

good sources of iron, vitamin C, vitamin A, protein, and calcium – nutrients that tend to 

be low in the diets of low-income households. The prevalence of anemia has declined 

country-wide since WIC was implemented in 1974. Improved iron intake during infancy 

and early childhood, delayed introduction of unmodified cow's milk until one year of age, 

and increased emphasis on breastfeeding are all factors that are thought to have 

contributed to the decline in anemia among infants and young children (Fomon, 1987; 

Yip, 1989). 

It is important to note the limitations of this study and how they may have influenced the 

results. The participation rate was very low at about 4% of the eligible infants and 

toddlers in the identified counties. This does not allow us to generalize to the population 

28
as a whole. Those that participated may have been different in some very important ways. 

Their parents may have been more interested in their child's iron status or blood lead 

levels, or may have been more knowledgeable about nutrition. Dietary intake data that 

were collected may not reflect usual intake. Using regression analysis in a crosssectional, observational study is useful for descriptive purposes and for suggesting 

hypotheses, but does not allow a determination of cause and effect. 

In this sample, group, 12 of the 39 toddlers aged 12-24 months were iron deficient, for a 

prevalence of 31%, almost four times the national average. Two of the 39 toddlers aged 

12-14 months were iron deficient and anemic, for a 5% prevalence of iron-deficiency 

anemia, more than twice the national average for children aged 1 to 2 years in 1999-2000 

(Centers for Disease Control and Prevention, 2002). One toddler (of 39) had anemia 

without iron deficiency, raising the total prevalence of anemia to 8%, although anemia 

without iron deficiency is likely due to other factors, such as current or recent infection, 

or statistical anemia (approximately 5%).

Our finding of a high prevalence of iron deficiency without anemia is consistent with the 

changing picture of childhood iron status. As iron status improves in the population, the 

cases of iron deficiency become milder, and screening for anemia becomes less effective 

as a marker for iron deficiency (Schneider et al., 2005). 

Iron deficiency was seen exclusively in the children who were aged 12 to 24 months and 

no longer taking breast milk or iron-fortified infant formula. Iron status is a continuum. 

29
Full term infants have an iron endowment that is generally adequate to prevent iron 

deficiency for about the first four to six months of life. How quickly and to what extent 

those stores are used up depends on the amount of iron stored before birth and the 

postnatal diet. If the intake of available iron is marginally adequate during the first year 

of life, iron deficiency may not become apparent for several months. 

We found no association between current iron intake and iron status, and a weak 

association with iron stores (serum ferritin). Our findings are similar to those of other 

investigators using cross-sectional (Soh et al., 2002) and longitudinal (Lind et al., 2003) 

methods. Soh et al. (2002) reported a positive association between iron intake (estimated 

by 3-day, weighed food records) and serum ferritin among non-breastfeeding infants and 

children aged six to 24 months. Lind et al. (2003), in a longitudinal, intervention study, 

reported a positive association between iron intake (estimated from 5-day food records 

recorded each month) from 12 to 17 months and serum ferritin at 18 months of age. 

There was no association between iron intake from six to eleven months and serum 

ferritin at nine or twelve months. 

The transition from primarily a milk-based diet at age six months to a more adult-like 

dietary pattern after 12 months of age is a time of many changes in sources of nutrients 

and in concentrations of nutrients in the diet. It is reasonable to note that current iron 

intake in the children in our study may not accurately reflect prior intake, but our results 

are similar to those of Lind et al. (2003) that were based on longitudinal data. 

30
Three infants and eight toddlers in our study were taking supplemental iron, either as a 

part of a multivitamin with iron or alone. The use of these supplements was also not 

associated with iron status or serum ferritin. This is not surprising, given the absence of 

an association between current iron intake and iron status. It may be that many of those 

taking supplements were already taking in adequate amounts of iron from other sources. 

Cowin et al. (2001) and Thane et al. (2000) reported that fruit and/or vitamin C 

consumption was positively associated with serum ferritin, an association that we did not 

see in our sample. Neither investigator measured iron status. However, Cowin et al. 

(2001) reported average vitamin C intakes of 41 mg per day (boys) or 37 mg per day 

(girls) in 18-month-old infants while the average intake in the children in our sample was 

108 mg per day and all but two met the EAR for vitamin C. The lack of association 

between vitamin C and iron status and serum ferritin in our study may be because all 

participants were taking in more than enough vitamin C to enhance iron absorption. Our 

subjects were all participating in the WIC program, which provides participants with a 

supplemental food package that targets particular nutrients including vitamin C and iron. 

This may account for the better intake in our group compared to that reported by others. 

Both volume of unmodified cow's milk consumed and intake of calcium were negatively 

associated with iron status (normal or deficient) and with iron stores (serum ferritin). 

Intake of unmodified cow's milk does not appear to be a major problem among the 

infants younger than 12 months of age. Although three (16%) had some cow's milk on 

the days when the diet history was taken, only one of the three had a full serving. 

31
Although mean intake of cow's milk in the toddlers aged 12 to 24 months was not 

excessive (22.5 ounces per day), 9 of the 39 toddlers (23%) were taking more than 24 

ounces per day. In addition, many had other sources of calcium, such as yogurt, cheese, 

and pudding. 

Our finding that calcium intake has a negative impact on iron status and iron stores is 

consistent with reports by others (Cowin et al., 2001, Thane et al., 2000). This 

relationship may be due to a variety of factors. Unmodified cow's milk can cause occult 

blood loss from the gastrointestinal tract of young infants (Fomon et al., 1981), but this 

effect generally diminishes or disappears in older infants and young children (Jiang et al., 

2000). Some investigators have found that calcium interferes with iron absorption in 

single meals (Monsen and Cook, 1976; Hallberg et al., 1991), but others have found no 

interference when calcium is part of a mixed diet (Grinder-Pedersen et al., 2004). None 

of these studies were conducted in children as young as those in our study. 

We did find a positive association between meat intake and iron status. This study was 

cross-sectional in design so we do not have information on history of meat intake or 

when meats were first introduced. Requejo et al. (1999) reported that preschoolers who 

were first introduced to meat in their diets after eight months of age were more likely to 

be iron deficient than were those who were introduced to meat at or younger than eight 

months. In an intervention study, Engelmann and colleagues (1998) randomly assigned 

partially breast-fed 8-month-old infants to low meat (10 g/day) or high meat (27 g/day) 

intake. After two months, mean hemoglobin and ferritin concentrations were significantly 

32
higher in the high meat group, although there was no significant difference in total iron 

intake. Meat intake seems to play a more important role in maintaining iron status than 

total iron intake does. This may be related to the proportion of heme iron in meats or to 

the factor in meat, fish and poultry that enhances absorption of non-heme iron from other 

foods (or both). 

The finding that not breastfeeding was positively associated with iron status, compared to 

breastfeeding for longer than six months, should not be used to discourage breastfeeding. 

The rate of breastfeeding was low in our sample. Of the 18 infants younger than 12 

months, six (33%) were breastfed initially and two (11%) were still being breastfed at the 

time of the study (i.e. for six months or longer). Among the 39 toddlers ages 12-24 

months, 20 (51%) were never breastfed, 13 (33%) were breastfed initially but for less 

than six months and six (15%) were breastfed for six months or longer. The American 

Academy of Pediatrics recommends that breastfed infants be given an exogenous source 

of iron, either iron-fortified infant cereal or strained meat, at four to six months of age or 

when they are developmentally ready. They note that recommendations for solid foods 

are more crucial for breastfed infants than for formula-fed infants to ensure adequate 

nutrition (American Academy of Pediatrics, 2004). Our finding that breastfeeding for 

longer than six months was associated with iron deficiency when controlling for current

meat intake supports that recommendation. 

Traditionally, cereal is the first food that is introduced into an infant's diet, then fruits and 

vegetables, and only later, at around 8 months, is meat introduced. Some have 

33
recommended that meats be introduced at six months of age before fruits and vegetables 

are introduced (Krebs, 2000). This is an interesting recommendation that warrants further 

deliberation. Although none of the infants younger than 12 months of age were iron 

deficient at the time of the study, suboptimal dietary intake during the second six months 

of life could contribute to iron deficiency after 12 months of age. Only two infants 

younger than 12 months had any meat, poultry, or fish that was not a part of a 

commercially-prepared baby food combination dinner on the days for which we had 

intake data. Similar findings have been reported in 12-month-old middle class infants in 

Tennessee (Skinner et al., 1997) and in the Feeding Infants and Toddlers Study (FITS) 

(Briefel et al., 2004). In FITS, 3% to 4% of infants aged seven to 11 months consumed 

plain, baby food meats, but 34% to 40% consumed jarred baby food combination dinners, 

which have less protein and iron per serving than do plain meats, presumably because 

they contain less meat. Although the infants in our study were not iron-deficient at the 

time of the study, their dietary patterns may increase their risk for iron deficiency as they 

get older, particularly if they are breastfed. 

While we did not find an association between iron stores and the intake of iron-fortified 

infant or adult cereal, others have reported a positive relationship (Cowin et al., 2001). 

Slightly more than half (30/57) of the children in our sample consumed iron-fortified 

cereals on either day of the dietary recall. This low number was surprising since the WIC 

program provides such cereals. These cereals are good sources of readily available iron 

and may help to prevent depletion of iron stores. 

34
Blood lead levels 

It is unclear how protein and vitamin E intake may mediate blood lead levels. A search of 

several databases did not return citations regarding associations between vitamin E and 

blood lead levels. In rats, low protein diets were associated with higher blood lead levels 

(Baltrop and Khoo, 1975), but the infants and children in our study had a high protein 

intake (average 2.3 g/kg for infants younger than 12 months and 4.5 g/kg for those aged 

12 to 24 months). These relationships require confirmation in other studies. 

The significant inverse relationship between dietary phosphorous and blood lead levels is 

consistent with other reports (Blake and Mann, 1983). Some investigators have reported 

associations between blood lead levels and dietary iron or calcium (Mahaffey, 1995). We 

did not find that association. Our results may be due to differences in lead exposure or 

dietary intake. Calcium intake in our sample was good with all but three infants meeting 

the AI for calcium. Our findings are consistent with those of other studies in which the 

intake of calcium was adequate (Gallichio et al., 2002). 

In animal studies, data suggest that low iron diets lead to increased lead absorption 

(Crowe and Morgan, 1996), probably due to a shared transporter for iron and lead 

(Bannon et al., 2002). The children in our study likely had adequate iron intake. Only two 

were taking in less iron than the EAR. Data in humans have demonstrated a significant 

association between iron deficiency and elevated blood lead levels (Wright et al., 2003). 

That was not seen in our study. Blood lead levels were generally low in our sample 

indicating that their exposure to environmental lead was probably low as well (Gallichio 

35
et al., 2002). It is possible that the level of lead exposure in these rural infants may not 

have been high enough to show significant nutritional effects on lead absorption. 

Conclusions

The first objective of this study was to determine the prevalence of iron deficiency, irondeficiency anemia, and normal iron status in a group of infants and toddlers aged six to 

24 months. Although our small sample size (57 infants and toddlers) precludes 

generalization to the population, the results in this group of children indicate that iron 

deficiency (21%) is nearly three times more prevalent than anemia is (8%). The 

prevalence of iron deficiency exceeds the goal for Healthy People 2010 (5% of children 

aged one to two years). 

The greater prevalence of iron deficiency without anemia is consistent with 

improvements in iron status in US children (Yip, 1989). As iron status improves, the 

cases of iron deficiency become milder, and screening for anemia becomes less effective 

as a marker for iron deficiency. Because current screening programs only detect anemia 

and not less severe cases of iron deficiency, iron deficiency is a hidden problem in this 

group of toddlers aged 12 to 24 months who participated in the WIC program. 

The dietary factors and nutrients that influenced both iron status and serum ferritin were 

intake of cow's milk and calcium. In our sample, the intake of cow's milk and calcium 

were negatively associated with iron status and serum ferritin. Although the majority of 

older infants were not drinking excessive amounts of cow's milk, 9 of the 39 toddlers 

36
(23%) took in more than 24 ounces per day and 5 of them (55%) drank from 40 to 60 

ounces per day. While milk and dairy products are excellent sources of nutrients during 

the second year of life, it is important that they not be allowed to replace other healthy 

foods in the diet, especially iron-rich foods. That may mean limiting milk and dairy 

products to three to four servings per day (an amount that meets the AI for calcium in 

children aged one to eight years) as recommended by the American Academy of 

Pediatrics. 

 

Meat intake was positively associated with iron status when protein intake was 

controlled. Children who were breastfed for longer than six months were more likely to 

be iron deficient when controlling for meat and protein intake. During transition to table 

foods, infants need a reliable source of dietary iron. Meats are good sources of iron and 

can be introduced into the diet after six months of age. This is particularly important for 

infants who are breastfed. However, commercially-prepared jars of baby food 

combination dinners may not be the best way to introduce meats into the diet since the 

amount of meat they contain is unknown, but is less than the amount in jars of baby food 

meats. 

The only nutrients that influenced iron status and serum ferritin were calcium and protein, 

and protein only influenced iron status when meat intake was held constant. Vitamin C 

and iron intakes were not associated with iron status, although iron intake did account for 

some of the variance in serum ferritin. 

37
There were no discernable relationships among iron status, blood lead levels, and number 

of infections. Blood lead levels were related positively to intake of protein and negatively 

to intakes of phosphorous and vitamin E. Iron and calcium intakes were not related to 

blood lead levels. 

The transition from breast milk or infant formula to unmodified cow's milk and table 

foods is a vulnerable time for the development of iron deficiency. Most cases of iron 

deficiency will not be detected with current screening methods. It is important to develop 

and validate specific, sensitive screening tools for iron deficiency before it progresses to 

anemia. Until that time, primary prevention of iron deficiency is the only option that can 

be universally applied. The recommendations from the CDC and the AAP are useful to 

promote adequate intake of readily available iron and can help to prevent iron deficiency. 

38
References Cited 

American Academy of Pediatrics. Pediatric Nutrition Handbook, Fifth Edition. Kleinman 

RK, Editor. American Academy of Pediatrics, 2004. Pages 299-312. 

Baltrop D, Khoo HE. “The influence of nutritional factors on lead absorption.” 

Postgraduate Medical Journal, 1975; 51: 795-800. 

Bannon DI, Portnoy ME, Olivi L, Lees PSJ, Culotta VC, Bressler JP. “Uptake of lead 

and iron by divalent metal transporter 1 in yeast and mammalian cells.” Biochemical and 

Biophysical Research Communications 2002; 295: 978-984. 

Barton JC, Conrad ME, Parmley RT. “Calcium inhibition of inorganic iron absorption in 

rats.” Gastroenteroleogy 1983; 84: 90-101 

Berger J, Dyck JL, Galan P, Aplogan A, Schneider D, Traissac P, Hercberg S. “Effect of 

daily iron supplementation on iron status, cell-mediated immunity, and incidence of 

infections in 6-36 month Togolese children.” European Journal of Clinical Nutrition

2000; 54: 29-35. 

Blake KCH, Mann M. “Effect of calcium and phosphorous on the gastrointestinal 

absorption of 203Pb in man.” Environmental Research 1983; 30: 188-194. 

Bothwell TH. “Overview and mechanisms of iron regulation.” Nutrition Reviews 1995; 

53: 237-245. 

Briefel, RR, Reidy K, Vatsala K, Devaney B.”Feeding Infants and Toddlers Study: 

Improvements needed in meeting infant feeding recommendations.” Journal of the 

American Dietetic Association 2004; 104: S31-S37. 

Centers for Disease Control and Prevention. “Iron Deficiency - United States, 1999-

2000.” Morbidity and Mortality Weekly Report 2002; 51: 897-899. 

Centers for Disease Control and Prevention. “Recommendations to prevent and control 

iron deficiency in the United States.” Morbidity and Mortality Weekly Report 1998; 47: 

1-29. 

Chandra RK, Saraya AK. “Impaired immunocompetence associated with iron 

deficiency.” Journal of Pediatrics 1975; 86: 899-902. 

Charlton RW, Bothwell TH. “Iron absorption.” Annual Review of Medicine 1983; 34: 55-

68. 

Committee on Nutrition, American Academy of Pediatrics. “Iron fortification of infant 

formulas.” Pediatrics 1999; 104: 119-123. 

39
Cook JD. “Defining optimal body iron.” The Proceedings of the Nutrition Society 1999; 

58: 489-495. 

Cowin I, Edmond A, Emmett P, and the ALSPAC Study Team. “Association between 

composition of the diet and haemoglobin and ferritin levels in 18-month-old children.” 

European Journal of Clinical Nutrition 2001; 55: 278-286. 

Crowe A and Morgan EH. “Interactions between tissue uptake of lead and iron in normal 

and iron-deficient rats during development.” Biological Trace Element Research 1996; 

52: 249-261. 

Dallman PR and Yip R. “Changing characteristics of childhood anemia.” Journal of 

Pediatrics 1989; 114: 161-164. 

Devaney, B, M.K. Crepinsek, K. Fortson, and L. Quay. Review of Dietary Reference 

Intakes for Selected Nutrients: Challenges and Implications for Federal Food and 

Nutrition Policy. Economic Research Service Contractor and Cooperator Report No. 

(CCR-28) 96 pp, February 2007. 

Engelmann MD, Sandstrom B, Michaelsen KF. “Meat intake and iron status in late 

infancy: an intervention study.” Journal of Pediatric Gastroenterology and Nutrition

1998; 26: 26-33. 

Etcheverry P, Miller DD, Glahn RP. “A low-molecular-weight factor in human milk 

whey promotes iron uptake by Caco-2 cells.” Journal of Nutrition 2004; 134: 93-98. 

Fomon SJ. “Reflections on infant feeding in the 1970s and 1980s.” American Journal of 

Clinical Nutrition 1987; 46: 171-182. 

Fomon SJ, Ziegler EE, Nelson SE, Edwards BB. “Cow milk feeding in infancy: 

gastrointestinal blood loss and iron nutritional status.” Journal of Pediatrics 1981; 98: 

540-545. 

Gallichio L, Scherer RW, Sexton M. “Influence of nutrient intake on blood lead levels 

of young children at risk for lead poisoning.” Environmental Health Perspectives 2002; 

110: A767-A772. 

Grinder-Pedersen L, Bukhave K, Jensen M, Hojgaard L, Hansen M. “Calcium from milk 

or calcium-fortified foods does not inhibit nonheme-iron absorption from a whole diet 

consumed over a 4-day period.” American Journal of Clinical Nutrition 2004; 80: 404-

409. 

Gulson BL, Jameson CW, Mahaffey KR, Mizon KJ, Patison N, Law AJ, Korsch MJ, 

Salter MA. “Relationships of lead in breast milk to lead in blood, urine, and diet of the 

infant and mother.” Environmental Health Perspectives 1998; 106: 667-674. 

40
Hallberg L, Brune M, Erlandsson M, Sandberg AS, Rossander-Hulten L. “Calcium: 

effect of different amounts on nonheme- and heme-iron absorption in humans.” American 

Journal of Clinical Nutrition 1991; 112-119. 

Hammad TA, Sexton M, Langenberg P. “Relationship between blood lead and dietary 

iron intake in preschool children. A cross-sectional study.” Annals of Epidemiology 1996; 

6: 30-33. 

Herbert V. “Everyone should be tested for iron disorders.” Journal of the American 

Dietetic Association 1992; 92: 1502-1509. 

Institute of Medicine, Subcommittee on Interpretation and Uses of Dietary Reference 

Intakes. Dietary Reference Intakes, Applications in Dietary Assessment. National 

Academy Press, Washington, DC. 2000. 

Jiang T, Jeter JM, Nelson SE, Ziegler EE. ”Intestinal blood loss during cow milk feeding 

in older infants, quantitative measurements.” Archives of Pediatric & Adolescent 

Medicine 2000; 154: 673-678. 

Krebs NF. “Dietary zinc and iron sources, physical growth and cognitive development of 

breastfed infants.” Journal of Nutrition 2000; 130: 358S-360S. 

Lanphear BP, Dietrich K, Auinger P, Cox C. “Cognitive deficits associated with blood 

lead concentrations < 10 μg/dL in US children and adolescents.” Public Health Reports

2000; 115: 521-529. 

Lind T, Hernell O, Lonnerdal B, Stenllund H, Domellof M, Persson L-A. “Dietary iron 

intake is positively associated with hemoglobin concentration during infancy but not 

during the second year of life.” Journal of Nutrition 2004; 134: 1064-1070. 

Lozoff B, Brittenham G, Wolf A, McClish D, Kuhnert P, Jimenez E, Jimenez R, Mora L, 

Gomez I, Krauskoph D. “Iron deficiency anemia and iron therapy effects on infant 

developmental test performance.” Pediatrics 1987; 79: 981-995. 

 Mahaffey KR. “Nutrition and Lead: Strategies for public health.” Environmental Health 

Perspectives 1995; 103 (Suppl 6); 1991-1996. 

Mencacci A, Cenci E, Boelaert JR, Bucci P, Mosci P, Fe d'Ostiani C, Bistoni F, Romani 

L. “Iron overload alters innate and T helper cell responses to Candida albicans in mice.” 

Journal of Infectious Diseases 1997; 175: 1467-1476. 

Moffat M, Longstaff S, Besant J, Dureski C. “Prevention of iron deficiency and 

psychomotor decline in high-risk infants through use of iron-fortified infant formula: A 

randomized clinical trial.” Journal of Pediatrics 1994; 125: 527-534. 

41
Monsen ER, Cook JD. “Food iron absorption in human subjects. IV. The effects of 

calcium and phosphate salts on the absorption of nonheme iron.” American Journal of 

Clinical Nutrition 1976: 29: 1142-1148. 

National Research Council. Recommended Dietary Allowances: 10th Edition. National 

Academy Press, Washington DC. 1989. 

Roquejo AM, Navia B, Ortega RM, Lopez-Subaler AM, Quintas E, Gaspar MJ, Osorio 

O. “The age at which meat is first included in the diet affects the incidence of iron 

deficiency and ferropenic anaemia in a group of pre-school children from Madrid.” 

International Journal for Vitamin and Nutrition Research. 1999; 69: 127-131. 

Schneider JM, Fujii ML, Lamp CL, Lonnerdal B, Dewey KB, Zidenberg-Cherr S. 

“Anemia, iron deficiency, and iron deficiency anemia in 12-36-mo-old children from 

low-income families.” American Journal of Clinical Nutrition 2005; 82: 1269-1275. 

Scrimshaw NS, SanGiovanni JP. “Synergism of nutrition, infection, and immunity: an 

overview.” American Journal of Clinical Nutrition 1997; 464S-477S. 

Skinner JD, Carruth BR, Houck KS, Coletta F, Cotter R, Ott D, McLeod M. 

“Longitudinal study of nutrient and food intakes of infants aged 2 to 24 months. Journal 

of the American Dietetic Association 1997; 97: 496-504. 

Soh P, Ferguson EL, McKenzie JE, Skeaff S, Parnell W, Gibson RS. “Dietary intakes of 

6-24-months’ old urban South Island New Zealand children in relation to biochemical 

iron status.” Public Health Nutrition 2002; 5: 339-346. 

Thane CW, Walmsley CM, Bates CJ, Prentice A, Cole TJ. “Risk factors for poor iron 

status in British toddlers: further analysis of data from the National Diet and Nutrition 

Survey of children aged 1.5-4.5 years.” Public Health Nutrition 2000; 3: 433-440. 

Thomas WJ, Collins TM. “Comparison of venipuncture blood counts with microcapillary 

measurements in screening for anemia in one-year-old infants.” Journal of Pediatrics

1982;101: 32-35. 

US Department of Health and Human Services. Healthy People 2010 (Conference 

Edition, in Two Volumes) Washington, DC: January 2000. 

Van de Vijver LP, Kardinaal AF, Charzewska J, Rotily M, Charles P, Maggiolini M, 

Ando S, Vaananen K, Wajszczyk B, Heikkinen J, Deloraine A, Schaafsma G. “Calcium 

intake is weakly but consistently negatively associated with iron status in girls and 

women in six European countries.” Journal of Nutrition 1999; 129: 963-968. 

Walter T, de Andraca I, Chadud P, Perales C. “Iron deficiency anemia: Adverse effects 

on infant psychomotor development.” Pediatrics 1989; 84: 7-17. 

42
43

Walter T, Olivares M, Pizarro F, Munoz C. “Iron, anemia, and infection.” Nutrition 

Reviews 1997; 55: 111-124. 

Woodruff CW, Wright SW, Wright RP. “The role of fresh cow's milk in iron deficiency. 

II. Comparison of fresh cow's milk with a prepared formula.”.American Journal of 

Diseases of Children 1972; 124: 26-30. 

Wright RO, Hu H, Maher TJ, Amarasiriwardena C, Chaiyakul P, Woolf AD Shannon 

MW. “Effect of iron deficiency anemia on lead distribution after intravenous dosing in 

rats.” Toxicology and Industrial Health 1998; 14: 547-551. 

Wright RO, Shannon MW, Wright RJ, Hu H. “Association between iron deficiency and 

low-level lead poisoning in an urban primary care clinic.” American Journal of Public 

Health 1999; 89: 1049-1053. 

Wright RO, Tsaih S, Schwartz J, Wright RJ, Hu H. “Association between iron deficiency 

and blood lead levels in a longitudinal analysis of children followed in an urban primary 

care unit.” The Journal of Pediatrics 2003; 142: 9-14. 

Yip R. “The changing characteristics of childhood iron nutritional status in the United 

States.” In: Filer LJ, Jr. Ed. Dietary Iron: Birth to Two Years. New York, NY: Raven 

Press, 1989: pages 37-61.