(P23-28-26) Human Milk Macronutrient Composition and Intakes in U.S. Infants

Objectives: To determine human milk intake and macronutrient composition in an US infant cohort and compare with the multi-country Mothers, Infants and Lactation Quality (MILQ) Study.

Methods: 191 healthy, 5-month-old full-term infants were recruited from the Denver, CO area to participate in a longitudinal randomized controlled complementary feeding trial, the MINT Study (Front Pediatr. 2022 Jan 13:793215). Fasting milk samples from a full-breast expression and milk intakes using test weighing were obtained between 3.5-7 months of age (baseline of the MINT Study). Milk macronutrients were measured using the MIRIS Human Milk Analyzer (Uppsala, Sweden). Milk macronutrient intake was calculated using the average weight of milk consumed per day over three consecutive days. Cross-sectional data for milk macronutrient composition was divided into month increments (4-5, 5-6 and 6-7 months) and the intake data was examined from 3.5-5.9 months. A two-sided one sample T-test was utilized to compare to MILQ Study values. Since the data were not normally distributed, the medians were compared.

Results: The median milk intakes for the MINT Study from 3.5 through 7 months ranged from 412 to 499 kcal/d, 23-28 g/d of fat, 45-53 g/d of carbohydrates and 4.4-5.3 g/d of protein. For the same time period, the energy composition of the milk was 736-754 kcal/L; the fat content 40-45 g/L; the carbohydrate content 77-78 g/L; and the protein content 7.4-8.1 g/L. When comparing the intakes from 3.5 to 5.9 months of age between the two studies, total energy (kcal/d) and fat intakes (g/d) were similar, whereas carbohydrate and protein intakes (g/d) were lower than the MILQ study (p < 0.001). The protein content of the milk did not differ between the two studies during the three months studied (4-5, 5-6, 6-7). On the other hand, the energy, carbohydrate and fat content were lower in the MILQ study for all three months evaluated (p < 0.05).

Conclusions: The differences observed between MINT and MILQ studies may reflect geographical, demographic or methodology differences. Future studies need to consider these factors when evaluating human milk values.

Funding Sources: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Mead Johnson Nutrition, National Dairy Council