Abstract:
Previously published data from our group and others demonstrate that human milk
oligosaccharide (HMOs), as well as milk and infant fecal microbial profiles, vary by geography.
However, little is known about the geographical variation of other milk-borne factors, such as lactose
and protein, as well as the associations among these factors and microbial community structures in milk
and infant feces. Here, we characterized and contrasted concentrations of milk-borne lactose, protein,
and HMOs, and examined their associations with milk and infant fecal microbiomes in samples
collected in 11 geographically diverse sites. Although geographical site was strongly associated with
milk and infant fecal microbiomes, both sample types assorted into a smaller number of community
state types based on shared microbial profiles. Similar to HMOs, concentrations of lactose and
protein also varied by geography. Concentrations of HMOs, lactose, and protein were associated
with differences in the microbial community structures of milk and infant feces and in the abundance
of specific taxa. Taken together, these data suggest that the composition of human milk, even
when produced by relatively healthy women, differs based on geographical boundaries and that
concentrations of HMOs, lactose, and protein in milk are related to variation in milk and infant fecal
microbial communities.
