We have recently shown that the Old Order Mennonites (OOM) residing in Western NY, with farm lifestyle and exposure to unpasteurized milk, have a low prevalence of atopic diseases compared to U.S. population (NHANES). Higher levels of breast milk IgA have been associated with environmental factors related to microbial load and low incidence of atopic diseases. Presence of stable bacterial communities have recently been confirmed in breast milk, related to maternal and infant gut microbiome. We hypothesized that diversity of breast milk microbiome and specific IgA responses would be higher in breast milk from OOM than in Rochester mothers.
In this pilot study, breast milk samples were collected from 40 OOM and 21 Rochester city/suburban mothers using a manual breast pump, when infants were 1-2 months old. Specific IgA to 8 fixed whole bacterial species was measured using ELISA. Bacterial DNA was extracted for microbiome analysis by 16S rRNA gene sequencing in 17 samples.
Comparison of Phylogenetic Diversity Whole Tree indices, a measure of alpha diversity, showed a significantly higher microbiome diversity in the milk of OOM than Rochester mothers (p=0.008). Levels of IgA to Enterococcus faecalis (p=0.0001), Lactobacillus reuteri (p=0.0002), and Salmonella typhimurium (p=0.058) were higher in OOM than in Rochester mothers.
Our data support the view that breast milk reflects maternal microbial pressure, and that greater microbial diversity is associated with a more robust mucosal immune response in a population with low prevalence of allergy. These breast milk factors may convey protection against atopic diseases amongst OOM children.