Predictors of breast milk macronutrient composition in Filipino mothers

There is increasing evidence that breastfeeding has long-term effects on offspring biology and health, which has heightened interest in understanding the extent of variation in breast milk composition and its underlying determinants. Here, we report variation in milk macronutrient composition in a well-characterized cohort of young Filipino mothers and test underlying maternal predictors of this variation.

Morning breast milk samples, anthropometrics, dietary recalls, and other interview data were collected in 102 Filipino young breastfeeding mothers (age range 24.6-25.4 years) living in Cebu City, Philippines. Milk samples were analyzed for protein, fat, sugar, and milk energy density. Regression models were used to test associations between milk macronutrient composition and maternal diet, body composition, breastfeeding duration, and feeding frequency.

Consistent with past studies, milk fat and energy increased with duration of breastfeeding; there were no associations between maternal diet or percent body fat and milk composition with the exception of a modest, inverse association between maternal adiposity and milk sugar content.

The relative lack of associations between maternal diet or body composition and milk composition at Cebu is consistent with past studies and suggests that milk composition may be buffered against fluctuations in maternal dietary intake or nutritional status. We speculate that the tendency for milk composition to vary between populations faced with different nutritional ecologies, but to show minimal responsiveness to intake during lactation, may enhance the reliability of milk composition as a stable intergenerational cue of typical local environmental quality.