Evaluating the impact of milk components on infant health.

Human milk is complex. The period after birth is the time when long-term programming in the neurologic, immune, and metabolic regulatory systems occurs. We have been assessing the impact of different milk components on infant development, and our work is showing that no single component can rescue a breastfed metabolic phenotype in a formula-fed infant. For instance, we showed that addition of milk fat globule membrane (MFGM) to infant formula resulted in a metabolic shift of formula fed infants toward breastfed infants. Additionally, changing the concentration of protein in a predominantly whey-based formula (80:20 whey:casein) resulted in lowering of insulin, HOMA-IR, as well as serum branched chain amino acids and urea to levels closer to breastfed infants. Reducing protein intake also resulted in increased levels of fecal microbes known to utilize complex carbohydrates. Although shifts in metabolism occurred with changes to infant formula composition, formula-fed infants still display a distinct formula-fed metabolic phenotype. More work needs to be done to fully understand how milk components impact infant development by themselves and together with other components.