Spatiotemporal Profile of the Human Milk Proteome across Populations and Lactation Stages: GEHM Study Insights

Abstract

Improved understanding of temporal and geographical differences in the human milk proteome may provide novel insights into changes in milk composition and function across the globe during breastfeeding. We have compared milk proteomes among three populations (Shanghai, China, Mexico City, Mexico and Cincinnati, United States; n = 9 for each population) at two different stages of lactation (4 and 26 weeks), with all samples collected as part of the Global Exploration of Human Milk (GEHM) study. At each of the two lactation stages, the profiles of milk proteins are largely similar among the three populations. Differences were found to be greater with respect to lactation stage as opposed to population. Interestingly, proteins with significant abundance changes over time show patterns of regulation that are broadly similar among populations. Nevertheless, at each of the two lactation stages, immunoglobulins IgA2, IgG1, IgG2 and IgM are present at higher levels in milk from China and Mexico compared to those from the U.S. with fold changes between China and U.S. samples of 2.0, 1.6, 2.3 and 2.1, respectively, and fold changes between Mexico and U.S. samples of1.8, 1.3, 1.1 and 2.0, respectively. Similar observations can be made for the antimicrobial protein lactoferrin. Our findings suggest broad congruency in milk protein composition among the three populations. This study also suggests that a number of host‐defense proteins may be more abundant in human milk from developing countries. This research was supported by Mead Johnson Pediatric Nutrition Institute.