Breast milk composition and infant nutrient intakes during the first 12 months of life

Background/Objectives: The objective of this study was to quantify human milk supply and intake of breastfed infants up to age 12 months. In addition, human milk composition was quantified per energetic macronutrient and fatty-acid composition in a subsample of lactating mothers. Subjects/Methods: One hundred and seventy-four Italian breastfed children were followed using test-weighing and 3-day food protocols from birth to age 12 months. From a subsample of 30 mothers breast milk samples were collected at child ages one (T1), two (T2), three (T3) and six (T6) months, and were analyzed for the amount of protein, digestible carbohydrates, total lipids and fatty-acid composition. Results: One hundred and forty-two (82%) filled in at least one 3-day food protocol within the first 12 months of life and complied with test-weighing of all milk feeds. The number of valid food protocols declined from 126 infants at 1 month to 77 at 12 months of age. Only galactose, non-protein nitrogen and protein decreased significantly from age 1 to age 6 months of lactation. Maternal body mass index and age affected fatty-acid levels in human milk. Median human milk intake decreased from 625 ml at T1, over 724 ml at T3 to 477 ml/day at T6. Average energy and %energy from protein intake per day increased from 419 kcal (s.d. 99) and 8.4% (1.0) at T1, respectively, to 860 kcal (145) and 16.1% (2.6) at T12. Conclusions: These data provide a reference range of nutrient intakes in breastfed infants and may provide guidance for defining optimal nutrient intakes for infants that cannot be fully breastfed.