Composition of human milk
1979
Hambræus, Leif
Human milk is specifically adapted to meet the nutrient needs of the newborn infant. Breast milk is relatively high in lactose, and low in protein and minerals; it contains a heterogeneous mix of proteins and a high content of non-protein nitrogen; casein contributes 20-40% of total milk protein. Human milk's amino acid composition fits the infant's metabolic capacities. Alpha-lactalbumin, lactoferrin, and IgA are the predominant whey proteins present. Iron-binding lactoferrin defends against gastrointestinal infection and facilitates iron absorption by the infant intestine. Nitrogen and protein composition of human milk vary with stage of lactation but the qualitative composition of breast milk, except for fat, does not appear to be greatly influenced by maternal nutritional status or diet. Fat content, however, varies during a single feed and throughout the day, possibly to regulate the infant's appetite. The low mineral content of human milk results in lower renal solute loads for the infant kidney. Human milk is a rich source of calcium and phosphorus and provides adequate amounts of most vitamins. These characteristics of breast milk, as compared with milks of other mammalian species, have nutritional and metabolic significance for the human infant. (nm)
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