The Use of Whole Cow's Milk in Infancy

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AMERICAN

ACADEMY

OF PEDIATRICS

The

Use

of Whole

Cow’s

Milk

in Infancy

Committee on Nutrition

The Committee on Nutrition continues to monitor

and review nutritional issues concerning the use of

whole cow’s milk (WCM) in the diets of infants. The

goal of those concerned with infant nutrition is the

provision of an optimal diet. The recommendations

in this statement replace those provided in the 1983

statement, “The Use of Whole Cow’s Milk in

In-fancy.” The 1983 statement focused primarily on the

issue of iron nutriture in infancy. In a broader context, the statement addressed a substantial number of often controversial nutrition issues, defined as “research

needs,” surrounding the appropriateness of using

whole cow’s milk for infants during the first 12

months. The purpose of this statement is to provide

new recommendations on the optimal feeding of

in-fants. The use of skim milk and reduced-fat milk (eg,

2% milk) remains inappropriate during the first year

of life and will not be reviewed in this statement.

REVIEW OF PREVIOUS STATEMENTS

During the last 20 years, the use of whole cow’s

milk in infancy has been discussed by the Committee

on Nutrition principally, but not exclusively, in the

context of meeting infants’ iron needs. In 1969, an

extensive commentary2 reviewed iron requirements

in infancy, and in 1971, a policy statement3

recom-mended that iron-fortified formulas be used for the

first 1 2 months of life. Those recommendations were

prompted by a significant prevalence of iron

defi-ciency in older infants associated with the extensive use of whole cow’s milk in later infancy. “Fluid whole milk (available in bottle or carton) or evaporated milk,

both of which contain only trace amounts of iron, are

substituted at the time of greatest iron need and

highest prevalence of iron deficiency anemia.”3 Several clinical studies demonstrated that feeding

iron-fortified formulas to infants for the first 12

months resulted in excellent iron status.47 The Com-mittee believed that adding iron to the infant’s major source of calories (milk-based formula) was a practical and effective method to alleviate the high prevalence of iron deficiency anemia.

In 1976, the Committee on Nutrition issued a

statement8 recommending the use of either iron-for-tified formula or infant cereal during older infancy.

The Committee noted the following; “Infant formula

and other heat-treated milk products are preferable

The recommendations in this statement do not indicate an exclusive course of treatment or procedure to be followed, Variations, taking into account individual circumstances, may be appropriate.

to fresh [pasteurized] cow’s milk as substitutes for

breast milk feeding during the first 6 to 1 2 months of

life because excessive ingestion of fresh cow’s milk

may contribute to iron deficiency by increasing

gas-trointestinal blood lOS5.8

In 1983, the Committee on Nutrition developed a

new position,’ based largely on a study by Fomon et

al9 of gastrointestinal blood loss in infants aged 4 to

6 months fed WCM, heat-treated WCM, or infant

formula. All infants received supplemental ferrous

sulfate and ascorbic acid. Enteric blood loss was

great-est in WCM-fed infants younger than 4#{189}months of

age. In infants between 4’/2 and 6 months of age,

there was no difference among the three groups

(WCM, heat-treated WCM, or infant formula) in the number of guaiac-positive stools, mean hemoglobin

levels, serum iron levels, iron binding capacity, or

transferrin saturation. Consequently, the 1983

statement’ suggested that whole cow’s milk could

replace iron-fortified formulas when infants older

than 6 months of age were consuming at least one

third of their calories from supplemental foods. The

question of whether feeding iron-fortified formula to

infants for the first 6 months of life would be

suffi-aent to prevent iron deficiency during the next 6

months when they are started on whole cow’s milk

could not be answered from the existing data.

REVIEW OF RESEARCH QUESTIONS POSED IN THE

1983 STATEMENT2 ON THE “USE OF WHOLE COW’S

MILK IN INFANCY.”

Since the 1983 recommendations, several new

studies have been published that address the five

questions posed in this statement. Results of these

studies require further refinement regarding the feed-ing recommendations for later infancy.

1. “What is the rate and variability of maturation of infant gastrointestinal mucosal barrier function?”

The gastrointestinal tract is immature early in life. Consequently, there is an increased transfer of intact

dietary protein from the intestinal lumen into the

circulation in the immediate neonatal period,

partic-ularly in preterm infants and infants who have gut

injury.dlu Although controversial, it is believed that

increased intestinal permeability may contribute to

the high incidence of cow’s milk protein allergy, a

condition that affects 0.4% to 7.5% of the infant

population.” There is no information to suggest that

WCM is more allergenic than infant formulas that

contain intact cow’s milk proteins. Infants with cow’s

milk protein allergy should not be fed either WCM or

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1106 USE OF WHOLE COW’S MILK

formulas containing intact WCM proteins. In

nonal-lergic infants, the introduction of whole cow’s milk

should be based on digestive and nutritional

consid-erations, not on the development of the mucosal

barrier.

2. “What is the relative importance of the amount and bioavailability of iron in the total diet when whole cow’s milk is substituted for iron-enriched formula at 6 months of age? Does iron-fortified cereal meet the infant’s need for iron?”

Six studies’2’7 based on four independent surveys (Second National Health and Nutrition Examination

Survey Department of Agriculture Food

Consump-tion, Ross Mothers Study, and Gerber Nutritional

Survey) have been published to date and reviewed.

Five of the six studies suggest that infants fed whole cow’s milk in later infancy have median iron intakes

below the recommended daily allowance. These

re-sults clearly indicate that an insufficient quantity of iron-fortified infant cereal is currently incorporated

into the diet of most infants to meet iron needs.

However, infant cereal is the single largest source of iron from infant solid foods available in the United

States. Parents who feed their infants whole cow’s

milk must also judiciously select solid foods that

contain iron.

The bioavailability of electrolytic iron, the form of

iron that is added to infant foods, remains

incom-pletely defined and controversial. Furthermore, quan-titative studies of electrolytic iron absorption have been conducted only with adult subjects. Electrolytic iron is produced by electrolytic deposition of iron that

is mechanically commuted to powder (grade A-131).

Fomon’8 notes that cereals marketed in the United

States and Canada containing electrolytic iron are

fortified with 45 mg of iron/100 g of dry weight, or

approximately 7 mg of iron/100 g of cereal as fed (ie, after dilution with milk or formula). Forbes et al,’9 using a farina-based meal, demonstrated absorption

of iron of a similar particle size to be 75% that of

ferrous sulfate. Elwood2#{176} demonstrated that absorp-tion of commercially used iron powder in baked bread is about 5% that of ferrous sulfate. Fomon,’8’2’ using

Elwood’s data, calculated that absorbed iron from

infant cereal could only account for 0.12 mg of the

0.6 to 0.7 mg of absorbed iron that infants require

each day. Both Fomon and Elwood concluded that

without evidence of adequate bioavailability, the

elec-trolytic iron used in infant cereals is not sufficient to

meet the iron needs of infants fed whole cow’s milk.

The composition of whole cow’s milk (ie, high

calcium, high phosphorus, and low vitamin C) may

decrease the bioavailability of iron from other dietary sources such as infant cereals.22 Three studies2325

compared the iron status of infants receiving

iron-fortified formulas for the first 6 months of life and

then fed WCM or iron-fortified formulas in

accord-ance with the 1983 American Academy of Pediatrics

recommendations for the next 6-month period. In all

three studies, iron status was significantly poorer in infants fed WCM.

Fortification of other infant foods, including wet-pack cereal-fruit products, grape juice, or milk

forti-fied with a highly bioavailable form of iron (ferrous sulfate with vitamin C), but less modified than regular infant formula, appear promising,26 but largely unex-plored in the United States. Haschke et al27 demon-strated indices of iron adequacy similar to infants fed only iron-fortified formula using meat-containing in-fant foods fortified with ferrous sulfate and ascorbic

acid that are commercially available in Austria and

the Federal Republic of Germany, but not in the

United States. Stekel et al28 in Chile studied the

bioavailability of ferrous sulfate-fortified (elemental

iron, 10 to 19 mg/L) low-fat and whole milks (less

modified than regular commercial formula) fed to

infants, many of whom were iron-deficient. Iron

ab-sorption from milk containing ascorbic acid (100 mgI L) ranged from 5.9% to 1 1 .3% and was not influenced by the amount of milk fat, the addition of carbohy-drate, or acidification. Results of longitudinal field trials of infants from age 3 to 1 5 months with a full-fat iron-fortified acidified milk showed effective elim-ination of iron deficiency.29

Evidence now suggests that the current feeding

practice in the United States of using iron-fortified

cereal does not meet the requirement for iron when

WCM is used during the second 6 months of life. This

may be due to poor compliance or insufficient

bio-availability of electrolytic iron. However, providing

iron-fortified formula and cereal for the first 12

months, as utilized in the Women, Infants, and

Chil-then Program, has been successful in reducing iron

331

3. “Can the change to cow’s milk when the infant is 6 months old produce anemia from occult blood loss when the milk is fed in excessive amounts and there is no iron supplementation?”

This question has been the subject of additional

study and commentary. Both Woodruff32 and

Wilson33 concluded that blood loss did occur in

in-fants fed WCM after 6 months of age. Following the

gastrointestinal blood loss study by Fomon et al,9

Ziegler et al34 used a more sensitive assay for stool

hemoglobin in a second study of blood loss in

6-month-old infants fed either infant formula or WCM

without iron supplementation. Intestinal blood loss

increased in 30% of infants fed WCM but did not

increase in the formula-fed group, even though all

were previously fed iron-fortified formula or were

breast-fed in the first 6 months of life.34 One infant

in the WCM group was removed from the study

because of iron deficiency. The investigators

con-cluded that infants fed WCM had a nutritionally

significant loss of iron in the stools. These studies clearly show that blood loss will occur in a substantial

percentage of infants who receive WCM for the first

time after 6 months of age. On the basis of these

recent results,34 Fomon and Ziegler reversed their

earlier positions,9 stating that they no longer

recom-mended WCM in the second 6 months, but preferred

breast milk or iron-fortified formula for the first 12 months of life.35’36 The reasons for these

recommen-dations include the substantial enteric blood loss in

infants fed WCM, the probable low bioavailability of

iron absorbed from infant cereals, and the probable

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inhibition of iron availability in WCM due to high

concentrations of calcium and phosphorous and low

concentration of ascorbic acid.

4. “What is the relative importance of the high solute load of whole cow’s milk in the total feeding regimen of a 6- to 12-month-old infant? For example, how much of the high-solute load of whole cow’s milk is diluted by other foods in the diet?”

Data from several studies show that infants fed

WCM instead of infant formula have a markedly

increased intake of sodium, potassium, chloride, and

protein.’2’6 The sodium intake (1000 mg/d) of

WCM-fed infants substantially exceeds the estimated

mini-mum requirements (120 mg/d for infants from birth

to 5 months old and 200 mg/day for infants 6 to 11

months old). By comparison, the median sodium

in-take for formula-fed infants (7 to 1 2 months old) is

580 mg/d.’2 Consequently, the renal solute load of

WCM-fed infants exceeds that of formula-fed infants

by two- to threefold (from approximately 1 25 to 300

mOsm).’6 Ziegler36 calculated the potential renal

sol-ute load of two hypothetical infants, 6- and

10-months-old, fed infant solids and formula versus

infant solids and WCM. When WCM replaced

for-mula, the potential renal solute load increased

two-fold in the 6-month-old infant (42 vs 21 mOsm/100

kcal) and nearly twofold in the 10-month-old infant

(39 vs 26 mOsm/100 kcal). He concluded that both

infants exceeded their recommended maximum (33

mOsm/100 kcal) potential renal solute load when fed

WCM and that WCM feeding would narrow the

margin of safety in situations that may lead to

dehy-dration. Thus, the high renal solute load of WCM was

not diluted by other foods in the diet.

5. “What is the relative importance of the nutrients not present in whole cow’s milk but present in infant formula and breast milk, ie, essential fatty acids, tocopherol, ascorbic acid? How much of these nutrients are obtained from the other foods commonly used in the 6- to 12-month age group?”

Substitution of WCM for formula reduced the

in-take of ascorbic acid, but not below the recommended

daily allowance’2”3 However, the median intake of

linoleic acid was reduced dramatically to 1 .8% of total

energy intake, well below the recommended level of

3% 1’,16

In one study37 of 97 older infants, intake of

a-tocopherol was significantly lower in WCM-fed

in-fants than in formula-fed infants (3.7 ± 2.6 mg/d vs

10.9 ± 3.1 mg/d). Moreover, a-tocopherol status, as

assessed by plasma concentrations, was significantly

greater in the formula-fed infants (1 .14 ± 0.42 vs

0.86 ± 0.28).

The studies of the past 7 years demonstrate the

difficulty of providing a balanced diet for older

in-fants when WCM replaces breast milk or

iron-forti-fied formula. Nutrients from commonly consumed

solid foods do not complement nutrients from WCM;

rather, they exaggerate the deficiencies (iron, linoleic acid, and vitamin E) and excesses (sodium, potassium, chloride, and protein) in the infant’s diet.

NEW STUDIES ON IRON DEFICIENCY AND

BEHAVIOR

Earlier studies by Oski and co-workers38 show that

iron deficiency in infants and children is associated with subtle behavioral differences. Additional recent

studies3942 suggest that iron deficiency in early

child-hood may lead to long-term changes in behavior that

may not be reversed even with iron supplementation

sufficient to correct the anemia. Newly published

studies on iron deficiency and behavior show the

importance of iron deficiency in WCM-fed infants.

The biochemical mechanism linking iron deficiency

and behavior may be identified from studies from

Youdim’s group in experimental animals.4345 These

researchers have shown that the number of dopamine

D-2 receptors in the rat brain is reduced when the

experimental animals undergo a transient period of

iron deficiency during infancy and are not

subse-quently restored with iron supplementation.

Al-though they require confirmation and further

ampli-fication, these studies provide a possible model of a

mechanism in which a transient nutritional event may

produce long-term changes in the neurologic status

of the brain of the animal studied. Additional research

is necessary to understand the implications of iron

deficiency to possible brain dysfunction in humans.

SUMMARY

The pediatrician is faced with a difficult challenge

in providing recommendations for optimal nutrition

in older infants. Because the milk (or formula) portion

of the diet represents 35% to 100% of total daily

calories and because WCM and breast milk or infant

formula differ markedly in composition, the selection of a milk or formula has a great impact on nutrient intake.

Infants fed WCM have low intakes of iron, linoleic

acid, and vitamin E, and excessive intakes of sodium,

potassium, and protein, illustrating the poor

nutri-tional compatibility of solid foods and WCM. These

nutrient intakes are not optimal and may result in

altered nutritional status, with the most dramatic

effect on iron status. Infants fed iron-fortified formula or breast milk for the first 1 2 months of life generally

maintain normal iron status. No studies have

con-cluded that the introduction of WCM into the diet at

6 months of age produces adequate iron status in later infancy; however, recent studies have demonstrated

that iron status is significantly impaired when WCM

is introduced into the diet of 6-month-old infants.

Data from studies abroad of highly iron-deficient infant populations suggest that infants fed partially

modified milk formulas with supplemental iron in a

highly bioavailable form (ferrous sulfate) may

main-tam adequate iron status. However, these studies do

not address the overall nutritional adequacy of the

infant’s diet. Such formulas have not been studied in

the United States.

Optimal nutrition of the infant involves selecting the appropriate milk source and eventually introduc-ing infant solid foods. To achieve this goal, the

Amer-ican Academy of Pediatrics recommends that infants

be fed breast milk for the first 6 to 1 2 months. The

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1108 USE OF WHOLE COW’S MILK

only acceptable alternative to breast milk is

iron-fortified infant formula. Appropriate solid foods

should be added between the ages of 4 and 6 months. Consumption of breast milk or iron-fortified formula,

along with age-appropriate solid foods and juices,

during the first 1 2 months of life allows for more

balanced nutrition. The American Academy of

Pedi-atrics recommends that whole cow’s milk and

low-iron formulas not be used during the first year of life.

COMMFI-rEE ON NUTRITION, 1991 TO

1992

Ronald E. Kleinman, MD, Chairman Susan S. Baker, MD

Edward F. Bell, MD Terry F. Hatch, MD William J. Klish, MD Rudolph L. Leibel, MD John N. Udall, MD Liaison Representatives

Margaret Cheney, PhD, Bureau of Nutritional Sciences, Canada

Joginder Chopra, MD, Food and Drug Administration

Cynthia Ford, RD, MS. US Department of Agriculture Van S. Hubbard, MD, National

Institute of Diabetes & Digestive & Kidney Diseases

Ephraim Levin, MD, National Institute of Child Health & Human

Development

Ann Prendergast, RD, MPH, Bureau of Health Care Delivery & Assistance

Micheline Ste-Marie, MD, Canadian Paediatric Society

Alice Smith, RD, American Dietetic Association

Ray Yip, MD, MPH, Centers for Disease Control

AAP Section Liaison

Ronald M. Lauer, MD, Section of

Cardiology

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39. WaIter R, De Andraca I, Chadud P. et al. Adverse effect of iron deficiency anemia on infant psychomotor development. Pediatr Res. 1988;23:650

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Pediatrics