REPORT

91HE MAJORITY of infants obtain total

.1. nutritionfrommilk duringthe earlyweeks or months of life. It seems logical,therefore, that knowledge of the usual composition as well as the variation in makeupof this biologic fluid should be of prime concern to those supervising the nutrition of infants. For this reason the memorandumwhich follows has been prepared by theCommittee on Nutrition of the American

Academy of Pediatrics.Milk is not constant in composition from

one human or animal to another, at all penods of lactation, or even hourly throughthe day. Unqualified statements about human or cow milk and comparison of themilks of different species may, therefore, besomewhat misleading when specific samplesof milk are considered. It is fortunate that asignificant and comprehensive literature isavailable concerning the variations to be expected.

SOURCESOF INFORMATION CONCERNING HUMAN AND COW MILK

A list of the major sources of such information is given here. These references areconcerned with human milk or with cowmilk as compared to human milk. Detaileddata on cow milk are available in the extensive literature of the dairy try2

A series of 21 papers on the secretion andcomposition of both human and cow milk, ineluding an extensive bibliography has beenpublished in the British Medical Bulletin.@

Macy, I. G. : Composition of human cobstrum and milk.4

Kon, S. K. and Mawson, E. H. : Human Milk.Wartime Studies of Certain Vitamins and otherConstituents.5 This report presents 12 studiesand a summarizing conclusion on the fat andvitamin content of milk.

Morrison, S. D. : Human Milk: Yield, Proximate Principles and Inorganic Constituents.6This publication is critical and selective.

Macy, I. G., Kelly, H. J., and Sloan, R. E.:The Composition of Milks.7 An exhaustive compilation, the booklet is presented in tabularform summarizing 268 publications.

Hytten, F. E., et al.: Clinical and chemicalstudies in human lactation.8@2 These reportsprovide useful data on the variations in amountof the major constituents of human milk.

COMPARISON OF HUMAN MILKAND COW MILK

The amount of human milk secreted varies widely, as shown in Figure 1. When theamount of “¿�immature―milk secreted duringearly lactation is small, the content of lac

FIG. 1. Variation in volume of human milk during

first 10 days post partum. Prepared by Morrison'from data of Roderuck et al.― (Reproduced withpermission of Commonwealth Agricultural Bureaux.)

ADDRESSFOR REPRINTS:American Academy of Pediatrics, 1801 Hinman Avenue, Evanston, Illinoil.P@wrnxcs, December 1960

1039

COMMITTEEON NUTRITIONComposition of Milks

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I

I:K@:;:,,/c\\@@ In

ComponentMean(gm/1O()ml)Standard

Deviation(±)(grn/100

ml)Range(grn/100ml)Totalsolids13.087O.39@21@.OO

—¿�13.88Protein3.4130.1503.05—¿�3.78Ash0.7350.0170.676—

0.781Calcium0

.1@40 .0030 .I15—0 .13@2Phosphorus0.1020.0040.09@2—

0.115

1040 COMPOSITION OF MILKS

TABLE I

YEAHLY MEAN COMPOSITION OF \%HOLE

Cow MILK―

:t@ IJAN FtB MARcH APRft MA' JUNI AlLY@ MIG @‘¿�@@ipi@_!@ö@v@ @c

FIG. 2. Seasonal variation in

composition of cow milk.―

tose is often relatively low and that of protein relatively high. 81VThe composition ofmilk is related not only to the amountsecreted and the stage of lactation, but alsoto the timing of its withdrawal (whetherearly or late in the feeding or pumping),and to the individual variations amonglactating mothers. These latter variationsmay be affected by such factors as maternal

age, health, social class and diet.Cow milk is at least as variable in com

position and probably more closely related@ to maternal diet and breeding than is hu

man milk. However, the general practice ofpooling milk from an entire herd or fromseveral herds of cows makes it unnecessaryto consider here the ranges of values formilk from individual cows, although considerable information on this topic is available.―2 The extent of seasonal variations incontent of pooled cow milk may be seen inFigure 2. Annual average composition maybe seen in contrast in Table I.

Colostrum and Transitional Milk

The composition of bovine cobostrum hasbeen presented in detail by Macy et al.@Cobostrum is described' as “¿�anextremelyrich solution of globulin in a fluid whichotherwise strongly resembles milk.―Unlikehuman colostrum, bovine colostrum contains a high content of protein and onlyslightly reduced amounts of fat, so that itsenergy value during the first 2 days is

greater than that of later colostrum or subsequent “¿�mature―cow milk.7 Human cobs

trum has a lower mean energy value dur

ing the first 5 days ( 58 cal/100 ml) thandoes mature milk (71 cal/100@

The total ash content of human cobostrumis relatively high. It may be noted in TableII that the concentrations of sodium, potassium and chloride are greater in human

colostrum than in mature human milk.Macy' has quoted a figure of 4.4 mg/100

ml for the concentration of amino acid nitrogen in two samples of human transitional

milk between the sixth and tenth days, ascompared with a mean value of 5 mg/100 mlfor mature human milk. There is some cvi

dence that there may be a higher concentration of nonprotein nitrogen in transitionalthan in mature human milk (48 vs. 32 mgI100 ml).4'7 Variations in the composition ofhuman cobostrum on any one day and fromone day to the next, are strikingly wide.

Mature Milk

Most authors consider that major changesfrom colostrum to mature milk are completed by the tenth day. The measurementsrecorded by Hytten@―Vwere made on milkpumped the seventh day after deliverywhile the mother was still in the hospital,when lactation was well established and 24-hour collections were sufficiently steady incomposition to be informative.

The recent work of Insull and Ahrens1@on fatty acids may cast doubt on the as

sumption that milk secreted on the seventhday is representative of established lacta

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Cobs TransiConcentrationintrumtionalMatureWhole

Milk(1—5days)(5—10days)MilkWater

(gin/100ml)87.286.487.6Energy

(cal/100ml)587471Totalsolids (gm/100ml)1@.813.61@2.4Ash0.330.Q4)0.@21Fat@2.93.63.8Lactose5.3

* 6.6@ 7.0@Total

protein@2 .71 .61.2Protein

Distribution(gm/100ml)Casein1.20.70.4Lactalbumin0

. 8 @0. 3@Lactoglobulin0

. 50.Ash,

MajorComponentsSodium

(meq/1)21137Chloride(ineq/1)261512Potassium(meq/1)191614Calcium

(mg/100ml)313433Sulfur(mg/100ml)222014Phosphorus

(mg/100ml)141715Magnesium

(mg/100ml)444Iron

(mg/100ml)0.090.040.15Iodine

(mg/100ml)0.0120.0020.007fCopper

(mg/100 ml)0.050.050.04

AMERICAN ACADEMY OF PEDIATRICS —¿�REPORT 1041

TABLE II

CoMPosITIoN OF HUMAN COLOSTRUM, TRANSITIONAL

AND MATURE MILK'

9@1oo',j.

FIG. 3. Total lipid content in mature human milk.'

(Reproduced with permission of CommonwealthAgricultural Bureaux.)

seventh day. Ninety per cent of the womenwhose milk contained at least 20 gm of faton the seventh day were still able to nurse3 months later, while only 20% of the womenwho secreted from 4.9 to 10 gm of fat onthe seventh day were still nursing 3 months

later.Hytten81' also showed that during a single

feeding or emptying by pump, the milk

from the two breasts might differ in fat con

tent by 1 to 2 gm/100 ml. The fat content

of the milk from each breast increasedrather regularly during its emptying, suggesting that fat was initially adsorbed to thesecretory and duct surfaces of the breast.

The lactose content of milk from eachbreast, and of milk at various stages of

emptying, varied inversely with its fat content. Figure 4 presents the frequency dis

tribution for the lactose content of a large

Fic. 4. The distribution of lactose in mature humanmilk.' (Reproduced with permission of Common

wealth Agricultural Bureaux.)

* Lack of agreement between sum ofconcentrations of

protein constituents and the concentration of total pro

tein arises from the different numbers of specimens onwhich the analyses were made. Similar considerationapplies to total arid individual solids.

t Skim niilk

tion. These authors reported that the total

fat content of milk produced by mothersfrom 9 to 21 days after delivery ranged

from 1.4 to 5.5 gm/100 ml. Five women who

had been lactating from 35 to 180 days produced milk with fat content ranging from0.63 to 2.14 gm/100 ml. Figure 3, however,based on the data of Morrison,6 indicatesthat greater concentrations of fat are oftenfound in mature human milk and suggeststhat the five women studied by Instill and

Ahrens may not have been representative of

the general population of nursing mothers.Hytten8―1' showed that the best predic

tion of later success@ in breast feeding isbased upon the total fat output on the

g./iOOaI.

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TOTAL NUN:@

@@rLi1,u,i}m

Is'

oo@, I a@s@

@/IoomLGà6@S@

number of samples of human milk. Changesin protein content were less marked. Morrison6 reported that variation in the proteincontent of human milk is very wide, andthat milk from American mothers hadslightly lower average content of proteinthan that from European mothers (Fig. 5).The protein content of various samplesranged from 0.6 to 2.9 gm/100 ml, and themaximum frequencies were 1.1 gm protein!

100 ml in American mothers and 1.4 gm!100ml in European mothers.

Another variation shown by Hytten811'was a diurnal rhythm in total yield and fat

content of the milk secreted. The amountof milk obtainable was greatest at 6 A.M.

Stand Coeffi

Meanard .Dev3a.cleat

of.

varzation(±)tion(%)Volume

(ml)41417241.5Fat(gm/lOOml)3.170.7824.6Lactose(gm/lOOml)6.290.4.57.2Total

nitrogen (mg/100ml)2963812.8Protein(gm/lOOml)'1.440.2215.3

1042 COMPOSITION OF MILKS

TABLE III

COMPOSITION OF 24-Houa SAMPLES OF

MATURE HUMAN MILK8V

* The mean concentration of protein is less in milk of

American mothers, as shown in Figure .5.

and beast at 10 P.M., while the highest fatcontent (approximately 4%) and the lowestfat content (between 2 and 3%) were observed at 10 A.M. and 6 A.M., respectively.

Although human milk becomes of moreconstant composition after the seventh day,it continues to vary in total amount and fatcontent. The figures in Table III indicatethe wide range of total 24-hour secretion ofmilk from 121 healthy primiparous inpatients, whose breasts were emptied bypumping five times at 4-hour intervals from6 A.M. through 10 P.M.

Hytten has also reported negative correlations between maternal age and seventhday post-partum milk yield, and betweenweight gain during pregnancy and milkyield. No correlation could be found between yield of milk and composition of thediet,8―1'and there is little accurate information concerning the degree to which maternal diet may affect composition of humanmilk. Morrison6 concluded that differencesin diet may affect the total volume of human milk secreted, but that moderatechanges in dietary intake of protein, fat andcalcium do not correlate well with changesin concentrations of these nutrients in human milk.

Kon and Mawson's investigations5 of human milk do not provide information whichwould permit direct comparison of the content of vitamins and other nutrients in milkas they are related to nutrient content ofmaternal diets. There was some suggestion

Fic. 5. Frequency distribution of concentrations ofprotein in the milk of American and European

women.' (Reproduced with permission of Commonwealth Agricultural Bureau.x.)

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AMERICAN ACADEMY OF PEDIATRICS —¿�REPORT 1043

that better diet and living conditions wereassociated with high concentrations of fatin milk. However, the samples studied wereexpressed manually from one breast, 4 to 6hours after its former emptying, and thedata may therefore be unsuitable for indicating relatively minor or subtle relationships. One clear relationship observed byKon and Mawson was an increase in vitamm A concentration in human milk whenmaternal intake of this vitamin was increased.

Excerpts from the valuable collection ofMacy et aL@concerning the composition ofhuman and cow milk are presented in TableIV. The single figure given for each constituent may suggest an impossible precision, but the reporting of mean valuesserves as a practical expedient although therange of values may be wide.

Fat

Not only is the fat content of milk important because fat provides a concentratedsource of calories, but the composition oflipids in serum and tissues of the body haslong been recognized to be dependent uponthe characteristics of the diet. Insull et al.17have shown that the fatty acid pattern ofhuman milk resembles that of the maternaldiet within as short a time as 2 days.

As may be seen from Table V, the contentof linoleic acid, the only fatty acid known tobe essential for the infant, is considerablygreater in human milk than in cow milk.The content of oleic acid is also greater inhuman milk than in cow milk, while thecontent of shorter chain fatty acids isgreater in cow milk.

Clinical data concerning adult subjectsand data from studies of laboratory animalsiiiiplicate saturated and certain unsaturated

fatty acids in development of atheromatosis.These data must be further clarified beforejudgment can be made concerning the mostdesirable composition of fat for infant feeding.

Protein

It was long believed that protein of human milk was nutritionally superior to that

of cow milk. Casein (the predominant pro

tein constituent of cow milk) was thoughtto have a lower biologic value than wheyprotein. In support of this view were theobservations of Edelstein and Langstein2°in children and the classic experiments ofOsborn and MendeP' who compared results of feeding casein and lactalbumin (themajor protein of whey) to growing rats. Inaddition, clinical observations indicatedthat infants fed raw or pasteurized cowmilk required more protein for normalgrowth than was provided by human milk.

Later work cast doubt on this widely accepted view. The clinical observations madebefore the days of milk processing do notprovide pertinent evidence, for much of thecasein escaped digestion and was found inthe stools in the form of bean-like curds.22The earlier study of Gordon et al.23 andmore recent clinical and metabolic studiesof infants fed human milk and cow-milk

425 have shown little difference

in nutritive values. In the experiments inwhich purified proteins were compared,the possibility of nutritional damage duringpurification was not eliminated. Mueller andCox26 suggested that comparisons of themilk proteins based on growth of rats mightnot be valid with respect to human nutrition, since fur-bearing animals have an increased demand for sulfur-containing aminoacids. The limiting amino acids of milk forinfant nutrition are not known with certainty, but if it be assumed that the totalsulfur-containing amino acids are limiting,the difference in nutritive value must besmall indeed, for protein from cow milkcontains fully four-fifths as much of theseamino acids as does human milk. The aminoacid pattern of the proteins of the twomilks is, in general, quite similar. Two recent studies of net protein utilization(N.P.U.)0 value of protein from human milkand cow milk have employed rate of growthof rats as a criterion. Miller27 has foundan N.P.U. value of 81.5 for a commercial

0 The N.P.U. value is the percentage of ingested

proteinretainedwhenproteinis fed at minimalorsubminimal intakes.

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(‘ontentin 100 mlofhumanCowWholeMilkMilkMilk

1044 COMPOSITION OF MILKS

TABLE IV—('ontinued

(‘ontentin l()O ml of human ComeJVhnleMilic ui/k ililk

TABLE IV

CoMeosuTuoN OF MATURE HUMAN

MILK AND Cow MILK*

Amniiio Acids ((‘ontinuel)Methionine

Plienylalanine

Threonine

Tryptophan

Valine

Fat, CharacteristicsFat melting point (°C)Iodine inimmiherReichert-Meisel numberSaponification miumher

Lipids (gui)

TotalLipoid phosphorus

Total cholesterolFree cholesterolLecithuui

VitaminsVitaminA (i@ig)

Carotinoids (pg)Thiamine (pg)Riboflavin (pg)Niacin (j.ig)

Pyridoxine (jig)Folic acid (/4g)B,2 (@mg)Vitamiii C (mug)Vitamin D (LU.)Vitamin K (;@g)

23 87

64 173

62 152

22 5090 228

31+ 35+

61.6 38.4

0.8 28.8

204.7 248.0

3.8 3.70.004 0.004

0.02() 0.014

0.012

0 . 078 0 . 057

Water(gm)87.687.3Energy(cal)7169Total

solids(gm)**12.412.7Ash0.210.72Fat3.83.7Lactose7.04.8Protein1.23.3

Proteins (g,n)**

CaseinLactaihumnin

Lactoglohulin

Ash, Major ComponentsChlorine (mneq/1)

Potassium (meq/1)

Sodium (meq/1)Calcium (mg/100 ml)Magnesium (mg/100 ml)

Phosphorus (mg/100 ml)Sulfur (mg/100 ml)Copper (mg/100 iiil)Iodine (mg/100 ml)Iron (mg/100 ml)Zinc (mg/100 ml)

Amino Acids (mg)AlanineAspartic AcidCystineGlutamie AcidGlycine

ProlineSerineTyrosineArginine

HistidineIsoleucineLeucineLysine

0.4 2.80.3 0.4

0.2 0.2

12 29

14 357 25

33 1254 1215 96

14 30

53

27

1643

172

11

0.180.18

4.300.4—10.0

1.5

34

38

42

15785

48

0.230.56

I.80

0.3—4.0

6.0

0.040 .0070.150.53

35

11629

2300

8069

6251

2386

161

79

0.030 .0210.100.38

75166

29

68011

250160190124

80212356

257

American skimmed cow milk as comparedwith 94.5 for a sample of dried humanmilk obtained from the Dutch Red Cross.Tomarelli and coworkers,28 comparing sampies of human and cow milk obtained inAmerica and equalizing the mineral intake,reported an N.P.U. value of 82.7 ± 2.6 forprotein of human milk and 85.1 ± 3.6 forprotein of cow milk. Snyderman and Holt9made comparisons of protein from humanmilk and cow milk in premature infants fedlow intakes of protein (2 gm/kg). Infantswere shifted from one feeding to the other

and no consistent changes in weight gain ornitrogen retention could be detected. It maybe concluded that if differences exist in thenutritional value for infants of the two milkproteins, they must be exceedingly small.

4 All data except those concerning vitamin content

are from the publication of Macy el al.7 This publicationalso includes data on composition of mature goat milk.I)ata on vitamin content are from Heinz handbook ofNutrition)'

*4 There is omily approximate agreement between

concentration of total solids amid sum of concentrations

of individual solids (ash, fat, lactose, and protein) amidbetween total protein amid sum of individual componemits of protein because the values represent values from

various studies in the literature, not all components being determined in each study.

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humanMilk6(‘owMilk66Fatly

Acid.standard

Mean . .Deviation

(±).HeaitStandard

.Deviation

(±)ESSENTIALtLinoleic10

.6 2 .9‘2 .I0.7NON-ESSENTIAL,UNSATURATEDOleic37.4

3.717.74.6Palmitok'ic3.4

1.03.20.7LinolenicIrace—¿�I . 70 .7NON-ESSENTIAL,SATURATEDPalmitic26.7

2.736.64.7Stearic8.3

1.78.13.2Myristic7.9

1.511.81.5Laurie4.7

2.23.61.1Capric@0.80.43.20.7Caprylic@0.1

0.21.20.2Caproic@0.1

0.12.00,2Butyric().26@]

—¿�‘2.70.5

IsOtOJ)Clie/f-life(‘oncentration

in@1Iilk(.ij@c*/l)Strontium'°28

yr3.7—74*6Strontium8'51

(lays15 —¿�78Cesium'3'27yr27 —¿�44Iodine'3'8days35—¿�275Barium'4013days@0 —¿�98

AMERICAN ACADEMY OF PEDIATRICS —¿�REPORT 1045

excretion is ordinarily considerably greater

than that provided by human milk. However, it would appear'' that the difference

between cow milk and human milk with respect to the load of solutes presented to thekidney is of little practical concern exceptwhen renal concentrating ability is grossly

impaired or when large extrarenal losses ofwater occur, as in febrile states and during

exposure to high environmental tempera

ture.

Radioactive Elements

Since the advent of atomic weapons testing programs, a group of new constituents

have appeared in milk. These are the van

ous radioactive fission products created byexplosion of atomic bombs. Upon reachingthe earth either as “¿�local―or “¿�distant―fallout these man-made elements can be in

conporated into food, including milk.

A few of the many fission products knownto be present in cow milk are listed in TableVI. All of these isotopes are retained to acertain degree by the body after ingestion.Their distribution varies greatly—strontiumand barium go to the bone, iodine to thethyroid, and cesium simulates the distnibution of potassium. The potential hazard of

each isotope depends on such factors as

amount ingested, physical half-life, type ofradiation emitted, and distribution withinthe body. Radioactive strontium (Sr9°)presents the greatest hazard of this group.

TABLE VI

FIsSIoN PRODUCTS PRESENT IN Cow MILK

(.JULY—SEPTEMBER, I 957)31

TABLE V

FATTY ACID CoMI'oNF@NTsOF MATUIIE hUMAN MILK―ANI) (‘ow MILK― AS i)ETEnMINED BY GAS

LIQLTI [) CIIROMATOGIIAI'1I Y

(J‘¿�amesexpressedas percentagesof totalfattyacids)

6 Data obtained by analysis of @280 samples of mature

human milk from 10 mothers iii various stages of suecessful lactation. Samples obtained through courtesy of

Mothers' Milk Bank, San Francisco.*6 Data obtained from analysis of 45 samples from 16

cows fed Oil typical California rations.

t Arachidonie acid, which may serve the same hpysiologic functions as linoleic acid, occurs in trace amountsin human milk and colnprises approximately 0.3% of

the fatty acids of cow milk.@ %Taluesfor human milk are limited to 64 saniples

from five mothers.

@1Butyric acid not recoveredin analytical procedureused by Stewart et al―Value given is that reported byInsull and Ahrens.―

Renal Solute Load

Because cow milk has higher concentrations of protein and electrolytes than doeshuman milk, metabolism of cow milk resuits in a greater load of solutes (electrolytes

and urea) for excretion in the urine. Evenwhen cow milk is diluted with water andcarbohydrate, as is common in infant feeding, the load of solutes presented for renal

6 10@2curies (a curie is ‘¿�2.2X10'2disintegrations/min

ute).

*6 6—30@ in 1958,32

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1046 COMPOSITION OF MILKS

The amount of Sr'°present in cow milkis subject to considerable variation: concentrations in 1957 were roughly four tofive times those present in 1954, and therewas a further increase of about 50% in1958;32 milk collected in the central area of

the United States contains more than thatfrom either coastal region. Seasonal fiuctuations are wide and, in general, the contentis higher in the Northern than in the Southem Hemisphere.

Only a few preliminary studies concerning content of Sr9°in human milk are avail

F33 Human milk contains about one

tenth as much Sr9°as cow milk, and it is

likely that woman exhibits a “¿�discrimination

factor― as does the cow in that the ratioof Sr―°:Cain the milk produced is less thanthat of the ingesta. A recent forecast of fu

tune concentrations of Sr'°in the diet (providing no further bombs are exploded) in

dicates that a maximal dietary content wasreached in 1959 and that the amount still in

the stratosphere is a fraction of that akeady

deposited.'@The content of stable strontium ( Sn'8), a

normal trace element, in cow milk in theUnited Kingdom was reported by Bryantet al.―as 200 to 300 micrograms per gramof calcium. A series of measurements madeon milk collected in various parts of theUnited States and on one sample from NewZealand was reported36 to contain a range

%Srof values for the ratio, X 10', of 0.14

%Cato 0.44. These values are in good agreementwith those reported from England. Thisratio is unlikely to vary significantly beyondthe range indicated while the ratio of theradioactive isotope (Sr'°) to calcium willcontinue to vary with time and region.Monthly variations in micromicrocunies ofSr9°per gram of calcium in cow milk punchased in New York City from January 1958

to February 1959 were large, the highest

value being 11.31 and the lowest@Table VII lists the contents of Sr°°and otherisotopes of shorter half-life per liter of milkobtained from ten areas in the United

States. This range of variation is of questionable significance with respect to biologiceffects.

The term “¿�maximumpermissible limits―can be viewed best by reference to thefollowing quotations :32

It is therefore assumed that long-continuedexposure to ionizing radiation . . . involvessome risk. However, man cannot entirely dispense with the use of ionizing radiations, andtherefore the problem in practice is to limit theradiation dose to that which involves a risk thatis not unacceptable to the individual and to thepopulation at large. This is called a permissibledose.

(It) is that dose . . . which in the light ofpresent knowledge carries a negligible probability of severe somatic or genetic injuries;furthermore, it is such a dose that any effectsthat ensue more frequently are limited to thoseof a minor nature that would not be consideredunacceptable by the exposed individual and bycompetent medical authorities.

It should be noted that the maximal permissible limits for various radiation sources,including ingested isotopes, are periodicallyrevised as new information becomes available.

The Sr'°content of milk produced by afew nursing mothers, and of the cow milkof their diets, have been@ Theresults suggest that human milk has significantly less Sr'° activity per gram of calciurn than has the cow milk of the maternaldiet.

Since the infant skeleton is a rapidly

growing tissue, infant bone contains abouteight times as much Sr'° per gram of cal

cium as adult bone. The skeletal burdenin infants is now at a maximum and willdecline to about one-half the present valueby 1970 provided no further bombs are ex

ploded.34It is not the prerogative of the Committee

on Nutrition to discuss the potential hazardsof ingested fission products. The presentbody burden of Cs137 delivers an amountof radiation equal to about 1% of that de

nived from natural sources; the dose to bone

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AreaCalcium(gm/I)Iodine― (@pc/I)Strontium―(@.q@c/I)Strontium'°(pvc/I)Barium'40 (@qsc/I)Cesium―7(@.q.tc/I)Atlanta,

Ga.1 . 24276213 .4884Austin,TexasI,2166275.7239Chicago,

Ill.1,131466.7064Cincinnati,Ohio1.14123311.7455Fargo,

N. D.Moorhead,Mmmi.1.15922712.3167NewYork,N.Y.1.0600106.9365Sacramento,

Calif.I . 1500154 .3035SaltLake City, Utah1 . 137264 .5534Spokane,

Wash.I . 2687209 .1373St.Louis,Mo.1.32977718.61464Permissible

limits*3,0007,00()80.0200,0(K)150,000

AMERICAN ACADEMY OF PEDIATRICS —¿�REPORT 1047

TABLE VII

SUMMARY OF SAMPLES COLLEC-FED IN JANUARY 1959 FROM MILKSHEDS SERVING

SPECIFIED ATEAS38

* These limits are the maximal permissible daily limits for lifetimne exposure of population groups to specific

radioisotopes in water and are derived from the current recommendations of the National Committee on RadiationProtection and Measurements.―The limits have been generally accepted as being applicable to milk.

from Sr9°is about 2% of that from naturalsources. These quantities are well belowthose currently accruing from diagnosticmedical roentgenography.

COMMENT

The profusion of available information onhuman and cow milk, and the lack of exactknowledge at certain points, both deserveemphasis. The physician who is seriouslyinterested in milk as a basic food for infantscan find a great deal of information on alarge number of the chemical constituentsand physical properties of milk from thereferences listed at the end of this report.However, information on the “¿�normal―variations in the composition of human andcow milk, and the effects which such variations may have upon the growth of theinfant, is not as complete as one might wish.The relations between maternal diet andthe composition and amount of milk Secreted remain insufficiently explored. Inview of the wide ranges observed in thecomposition of milk, and the numerous nondietary variables which may be involved,such investigations will require much painstaking effort,

CoMMrrraa@ ON NUTRITIONDavid H. Clement, M.D.Gilbert B. Forbes, M.D.Donald Fraser, M.D.Arild E. Hansen, M.D.Charles U. Lowe, M.D.Charles D. May, M.D.Clement A. Smith, M.D.Nathan J. Smith, M.D.Samuel J. Fomon, M.D., Chairman

October 12, 1960.

REFERENCES

1. Rogers, L. A., and Associates: Fundamentals of Dairy Science, 2nd Ed. NewYork, Reinhold, 1935.

2. Sommers, H. : Market Milk and RelatedProducts, 2nd Ed. Madison, Wisconsin,Hugo Sommers Publisher, 1946.

3. Lactation : Function and product (21papers by various authors). Brit. M.Bull., 5:120, 1947.

4. Macv, I. C. : Composition of human cobstrum and milk. Am. J. Dis. Child., 78:589, 1949.

5. Kon, S. K., and Mawson, E. H. : HumanMilk. Wartime Studies of Certain Vitamins and Other Constituents. MedicalResearch Council Special Report Series,No. 269, London, His Majesty's Stationery Office, 1950.

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1048 COMPOSITION OF MILKS

6. Morrison, S. D. : Human Milk: Yield, Proximate Principles and Inorganic Constituents. Commonwealth Agricultural Bureaux, Farnham Royal, Slough Bucks,England, 1952.

7. Macy, I. G., Kelly, H. J., and Sloan, R. E.:The Composition of Milks. A Compilation of the Comparative Compositionand Properties of Human, Cow and GoatMilk, Colostrurn, and Transitional Milk.Publication 254, National Academy ofScience-National Research Council,Washington, D.C., 1953.

8. Hytten, F. E.: Clinical and chemicalstudies in human lactation.

I. Collection of milk samples. Brit.M. J., 1:175, 1954;

II. \Tariation in major constituentsduring a feeding. Ibid., 176;

III. Diurnal variation in major constitiients of milk. Ibid., 179;

IV. Trends in milk composition duringcourse of lactation. ibid., 249;

V. Individual differences in composition of milk. Ibid., 253;

VI. The functional capacity of thel)reast. ibid., 917;

VII. The effect of differences in yieldand composition of milk on the infant's weight gain and the durationof breast-feeding. ibid., 1410;

VIII. Relationship of age, physique,and nutritional status of mother toyield and composition of milk.Brit.M. J.,2:844,1954;

Ix. Breast-feeding in hospital. ibid.,1447.

9. Hytten, F. E., and Thomson, A. M. : Clinical and chemical studies in human lactation. X. The maintenance of breast feeding. Brit. M. J., 2:232, 1955.

10. Hvtten, F. E. : Infant feeding, EtudesNeonatales, 4: 155, 1955.

1 1. Hvtten, F. E. : Differences in yield andcomposition of the milk from right andleft breasts (Abstract). Proc. NutritionSoc., 15:vi, 1956.

12. Hvtten, F. E., Yorston, J. C., and Thomson,A. XI. : Difficulties associated withbreast-feeding. Brit. M. J., 1:310, 1958.1958.

13. Roderuck, C., Williams, H. H., and Macy,I. C. : Metabolism of women during thereproductive cycle. VIII. The utilizationof thiarnin during lactation. j. Nutrition,32:249, 1946.

14. Personal communication. Ross Laboratories, Columbus, Ohio.

15. Insull, W., Jr., and Ahrens, E. H., Jr.:The fatty acids of human milk from

mothers on diets taken ad libitum. Biochem. J., 72:27, 1959.

16. Burton, B. T., ed.: The Heinz Handbookof Nutrition. A Comprehensive Treatiseon Nutrition in Health and Disease. NewYork, McGraw-Hill, 1959, p. 163.

17. Insull, W., Jr., Hirsch, J., James, T., andAhrens, E. H., Jr. : The fatty acids ofhuman milk. II. Alterations producedby manipulation of caloric balance andexchange of dietary fats. J. Clin. Invest.,38:443, 1959.

18. Stewart, R. A., Hughes, C., and Kelly,V. J. : Unpublished data.

19. Smith, L. M., and Ronning, M. : Unpublished data.

20. Edelstein, F., and Langstein, L. : DasEiweissproblem im Sauglingsalter: experimentelle Untersuchungen über dieWertigkeit der Milcheiweisskorper fürdas Wachstum. Ztschr. Kinderh., 20:112, 1919.

21. Osborn, T. B., and Mendel, L. B. : Thecomparative nutritive value of certainproteins for growth and the problem ofprotein minimum. J. Biol. Chem., 20:351, 1915.

22. Courtney, A. M. : Studies on infant nutnition. II. The hard or casein curds of infants' stools. Am. J. Dis. Child., 3:1,1912.

23. Gordon, H. H., et a!.: Respiratory metabolism in infancy and childhood. XX.Nitrogen metabolism in premature infants; comparative studies of human andcows' milk. Am. J. Dis. Child., 54:1030,1937.

24. Barness, L. A., et a!.: Nitrogen metabolismof infants fed human and cows' milk.J. Pediat., 51:29, 1957.

25. Fomon, S. J. : Comparative study of protein from human milk and cows' milk inpromoting nitrogen retention by normalfull-term infants. PEDIATIIICS, 26 :5 1,1960.

26. Mueller, A. J., and Cox, W. M., Jr. : Comparative nutritive value of casein andlactalbumin for man. J. Nutrition, 34:285, 1947.

27. Miller, D. S. : Cited by Platt, B. S., in Report to Protein Advisory Committee,World Health Organization. Unpublished.

28. Tomarelli, R. M., et a!.: Bioassay of thenutritional quality of the protein of human and cows' milk by rat growth procedures. j. Nutrition, 68:265, 1959.

29. Snyderman, S. E., and Holt, L. E., Jr.:Personal communication.

30. Committee on Nutrition, American Aca

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AMERICAN ACADEMY OF PEDIATRICS —¿�REPORT 1049

demy of Pediatrics: Water requirementin relation to osmolar load as it appliesto infant feeding. PEDIATRICS,19:339,1957.

3 1. Environmental Contamination from Weapons Tests (HASL-42) Health and SafetyLaboratory, U.S. Atomic Energy Commission, New York Operations Office.October, 1958.

32. Eisenbud, M. : Deposition of strontium 90through October 1958. Science, 130:76,1959.

33. Lough, S. A., Hamada, C. H., and Comar,C. L. : Secretion of dietary strontium 90

@ and calcium in human millcProc. Soc.Exper. Biol. & Med., 104:194, 1960.

34. KuIp, J. L., Schulert, A. R., and Hodges,E. J. : Strontium 90 in man. IV. Science,132: 448, 1960.

35. Bryant, F. J., Chamberlain, A. C., and

Spicer, G. S. : Strontium in diet. Brit.M. J., 1:1371, 1958.

36. Harley, J. H., Hardy, E. P., Jr., Whitney,I. B., and Eisenbud, M. : Summary ofaaaiyti.@a1 results from the HASL stron

tium program, July through December1956. U.S. Atomic Energy Commission,Health and Safety Laboratory. NewYork, March 15, 1957.

37. Hearings before Special Subcommittee onRadiation of Joint Committee on AtomicEnergy, Congress of U.S., May, 1957.

Government Printing Office, Washington25, D.C., May, 1959.

38. Health and Safety Laboratory, StrontiumProgram, Quarterly Summary Report(HASL-65). U.S. Atomic Energy Cornmission, New York Operations Office.May 29, 1959.

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1960;26;1039Pediatrics J. Fomon

SamuelHansen, Charles U. Lowe, Charles D. May, Clement A. Smith, Nathan J. Smith and Committee on Nutrition, David H. Clement, Gilbert B. Forbes, Donald Fraser, Arild E.

COMMITTEEON NUTRITION: Composition of Milks

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1960;26;1039Pediatrics J. Fomon

SamuelHansen, Charles U. Lowe, Charles D. May, Clement A. Smith, Nathan J. Smith and Committee on Nutrition, David H. Clement, Gilbert B. Forbes, Donald Fraser, Arild E.

COMMITTEEON NUTRITION: Composition of Milks

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