Nutrition During Lactation (1991) / Chapter Skim
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6 Milk Composition
6 Milk Composition
Pages 113-152
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From page 113... ...
Rather, this chapter provides a framework for understanding how maternal nutrition can have an impact on the composition of human milk, as well as when and in what context nutritional factors are likely to be operational. Furthermore, it provides the information needed to estimate maternal nutrient requirements the subject of Chapter 9 and provides a basis for considering some of the effects of maternal nutrition on the nursing infant's health (Chapter 7)
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From page 114... ...
114 NUTRITION DURING LACTATION Classes of Constituents in Human Milk Protein and Nonprotein Nitrogen Compounds Carbohydrates Proteins Lactose Caseins ~x-Lactalbumin Lactoferrin Secretory IgA and other immunoglobulins Lipids ~ -Lactoglobulin Lysozyme Enzymes Hormones Growth factors Nonprotein Nitrogen Compounds Urea Creatine Creatinine Uric acid Glucosamine cx-Amino nitrogen Nucleic acids Nucleotides Polyamines Water-Soluble Vitamins Thiamin Riboflavin Niacin Pantothenic acid Biotin Folate vitamin B6 vitamin Bi2 Vitamin C Inositol Choline Cells Leukocytes Epithelial cells Oligosaccharides Bifidus factors Glycopeptides Triglycerides Fatty acids Phospholipids Sterols and hydrocarbons Fat-soluble vitamins A and carotene D E K Minerals Macronutrient Elements Calcium Phosphorus Magnesium Potassium Sodium Chlorine Sulfur Trace Elements Iodine Iron Copper rat ~ Zinc Manganese Selenium Chromium Cobalt and properties can be found in several recent review articles and books (e.g., Blanc, 1981; Carlson, 1985; Gaull et al., 1982; Goldman et al., 1987; Goldman and Goldblum, 1990; Hamosh and Goldman, 1986; Jensen, 1989; Jensen and Neville, 1985; Koldovsky, 1989; Lonnerdal, 1985a, 1986a; Picciano, 1984a, 1985; Ruegg and Blanc, 19821.
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From page 115... ...
Variation in the First Weeks Post Partum Changes in milk composition over the course of lactation are most marked during the first weeks of lactation (see examples in Figure 6-1~. Colostrum is the fluid secreted by the mammary gland immediately following parturition.
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From page 116... ...
has higher protein, sodium, and chloride concentrations and lower lactose concentrations than mild secreted by mothers of full-term infants. While some investigators report higher fat concentrations in preterm mild (Anderson et al., 1981; Guerrini et al., 1981)
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From page 117... ...
MILK COMPOSITION a) In _ O ~ 4 Ct ~_ _ 0.3 ~u J 1 8 _ 1 ye 1 __ 0.5~ I 1 0.1 _ it: 3 1 ~ O 1 ~ ~ 1 ~ ~ ~ ~ T ~ _ J O_ 1 6 · 1 '1: 0.8 OL , 120 _ ' 60 117 -a = _~ ~~N ~ ~ _~ A_ 0 204060 3 5 7 9 2 3 4 5 40 20 Days Hours Days Months Pre Partum Post Partum FIGURE 6-1 Changes in the concentrations of lactose and whey proteins in human mink during the progression of lactation in four women during late pregnancy and the first 5 months of lactation.
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From page 118... ...
. These large variations complicate the measurement of total fat secreted by lactating women and, in turn, affect calculations of the energy value of milk, which are determined mainly by milk fat content.
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Thus, the data on the nutrient content of human milk must be interpreted with caution. Large variations reported for many milk constituents may reflect improper sampling or analytic inaccuracies or both rather than true biologic variance.
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From page 120... ...
The origins of the fatty acids can be distinguished: fatty acids synthesized within the mammary gland have chain lengths of 16 carbons or less; those derived
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From page 121... ...
Both of these channel fat to the lactating mammary gland, where it is incorporated in the milk. MATERNAL NUTRITION AND THE COMPOSITION OF HUMAN MILK Three aspects of maternal nutrition could have an impact on human milk composition: current dietary intake, nutrient stores, and alterations in nutrient utilization as influenced by the hormonal milieu characteristic of lactation.
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From page 122... ...
increased total nitrogen, protein, and nonprotein nitrogen contents of mature human milk and 24-hour miLk protein output. There have been reports of low concentrations of protein and altered free and total amino acid nitrogen profiles in milk of women from countries with limited food supplies: India (Deb and Cama, 1962)
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From page 123... ...
(1985a) reported that the bans fatty acid content of human milk was directly related to maternal intake of partially hydrogenated fats and oils; in women experiencing postpartum weight loss, fat mobilized from adipose tissue also contributed bans fatty acids to human milk fat independently of current dietary intake.
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reportthathigh- (>10) parity Gambian women had a decreased capacity for total miLk fat synthesis and, thus, lower miLk fat concentrations.
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From page 125... ...
3-Carotene is stored in the mammary gland during pregnancy and is rapidly secreted into miLk during the first few days of lactation (Patton et al., 19901. Several reports indicate that the amount of vitamin A in human miLk decreases with maternal deficiency of the vitamin and increases with excessive intake (Ajans et al., 1965; Butte and Calloway, 1981; Hrubetz et al., 1945~.
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From page 126... ...
Bates and colleagues (1983) report that the vitamin C content of mature human milk levels off at 50 to 60 mg/liter if daily maternal intakes are equal to or exceed 100 mg (approximately the mother's Recommended Dietary Allowance tRDA]
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From page 127... ...
However, milk folate levels were found to increase from 5 to 60 ,(lg/liter after 4 days of oral folate supplementation of two lactating women with megaloblastic anemia resulting from dietary folate insufficiency (Metz et al., 19681. Folate levels in human milk typically increase with the progression of lactation, even as levels in maternal serum and red blood cells decrease (Smith et al., 19831.
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From page 128... ...
with maternal dietary intake (Song et al., 1984~. These investigators found that four women receiving pantothenic acid in supplements (>1.0 mg/day)
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From page 129... ...
Iron, Copper, and Zinc The concentrations of iron, copper, and zinc in human mild are highest immediately following parturition (Cavell and Widdowson, 19641. Reported mean values for the concentration of iron in mature human milk range from 0.2 to 0.9 mg/liter (Picciano and Guthrie, 1976; Siimes et al., 1979, respectively)
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A study of rural African women living in an area where the selenium content of the diet varies with food availability indicates that milk selenium concentrations are low when maternal intake is low and also decrease
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From page 131... ...
do not increase unless water fluoride content exceeds 1.4 ppm. iodine Iodine is unique among the trace elements because the mammary gland avidly accumulates it.
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From page 132... ...
The many complex functions of mild constituents can be illustrated by describing the role of the mild protein oe-lactalbumin, which constitutes approximately 25 to 30% of the total protein in human mild and thus is a major supplier of amino acids to the developing infant. It also is one of the two protein components of the system that synthesizes lactose within the mammary gland.
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From page 133... ...
Antiinfectious Agents In human milk, there is a complex system of antimicrobial factors (Goldman and Goldblum, 1989b, 1990) (Table 6-4)
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From page 134... ...
· Certain forms of lactofemn that do not bind to iron may inhibit the replication of some viruses (Furmanski et al., 1989~. Antibodies are abundant in human mild throughout lactation; they are TABLE 6-5 Concentrations of Immunologic Factors in Human Milk During Several Phases of Lactationa Mean Concentration, mg/ml + SD,b by Stage of Lactation Factors 2-3 days 1 month 6 months1 year 2 years Lactoferrin 5.3 + 12.9 1.9 + 0.3 1.4 + 0.41.0 + 0.2 1.2 + 0.1 Secretory IgAC 2 + 2.5 1 + 0.3 0.5 + 0.11 + 0.3 1.1 + 0.2 Lysozyme 0.09 + 0.03 0.02 + 0.03 0.25 + 0.120.2 + 0.1 0.19 + 0.03 aFrom Goldman and Goldblum (1989b)
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From page 135... ...
Because these B cells originate at maternal sites where exposure to environmental pathogens is high, the IgA is protective against pathogens to which the infant might be exposed. Secretory IgA has at least three other important features: it is particularly suited to act at mucosal surfaces, since it is relatively resistant to proteolysis (Lindh, 19754; it protects by noninflammatory mechanisms (Goldman et al., 1986, 1990~; and it acts in synergy with several other host resistance agents in human milk to achieve antimicrobial effects.
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From page 136... ...
A study that more completely defined maternal nutritional status was conducted with 23 Columbian women during the first 2 months of lactation (Miranda et al., 1983~. Malnutrition was characterized by lower weight-toheight ratios and by lower creatinine-height indices and serum concentrations of total proteins, albumin, IgG, and IgA.
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From page 137... ...
Cell counts obtained thereafter for as long as 180 days of lactation were similar in the well nourished and poorly nourished populations. Since appropriate cytochemical studies were not performed, it was difficult to determine whether any major alterations in cell populations in mink occurred as a result of changes in maternal nutritional status.
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From page 138... ...
However, it is known that the regulation of enzyme activity in the lactating mammary gland differs from that of identical enzymes in other organs. Thus, in the lactating mammary gland the activity of lipoprotein lipase, which is markedly reduced in adipose tissue by fasting, is unaffected by fasting (Hamosh and Hamosh, 1983~.
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From page 139... ...
139 C;= .> Ct .~ cn o A_ A o ;^ .-o V)
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From page 140... ...
Those maintained at the expense of maternal stores or tissues include the macronutrients, most minerals, and folate. · The kinds of fatty acids present in human miLk are strongly influenced by maternal diet: the type and amount of fat in the diet and the adequacy of energy intake.
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From page 141... ...
1980. Neonatal hypernatremia associated with elevated sodium concentration of breast milk.
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1985a. Trans fatty acids in human milk lipids: influence of maternal diet and weight loss.
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1985. Breast milk composition: fat content and fatty acid composition in vegetarians and nonvegetarians.
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1976. Breast milk composition in Ethiopian and Swedish mothers.
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1989. Human lactation II: endogenous fatty acid synthesis by the mammary gland.
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1977. Breast milk composition in Ethiopian and Swedish mothers.
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1985. The effects of dietary zinc supplement during lactation on longitudinal changes in maternal zinc status and milk zinc concentrations.
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1983. Dietary zinc intake and zinc concentrations of plasma, erythrocytes, and breast milk in antepartum and postpartum lactating and nonlactating women: a longitudinal study.
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1976. Copper, iron, and zinc contents of mature human milk.
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FLYBY. ureas~-m~K fatty acids of rural Gambian mothers: effects of diet and maternal parity.
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1982. Toxic breast milk: neonatal hypernatremia associated with elevated sodium in breast milk.
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1979. Free amino acid, protein, and fat contents of breast milk from Guatemalan mothers consuming a corn-based diet.
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