Researchers testing the prevalence of allergies in babies from farming communities found evidence that mothers pass on protective effects against atopic diseases via their breast milk.

The study, published in Frontiers in Immunology, collected breast milk from 52 mothers with babies between two weeks and six months of age in the community of old order Mennonites of Penn Yan, New York, and from 29 mothers with a modern urban lifestyle in the nearby city of Rochester.

Old order Mennonites, anabaptist christians named after the Frisian reformer Minne Simens (1496-1561; commonly hollandized to Menno Siemens), are people of Swiss and South German heritage who live on traditional one-family farms with little modern technology. Their lifestyle is a reasonable proxy for that of rural communities in Western countries until the dawn of the 20th century.

For the study, researchers used questionnaires and follow-up phone calls to ask moms about their lifestyle and environment, and whether they or their babies had any symptoms of atopic diseases. They then measured the milk’s concentration and activity of IgA antibodies – important for protecting the respiratory system and gut against microbes – as well as the concentration of oligosaccharides, cytokines, and metabolites of fatty acids. They also using ribosomal RNA gene sequencing to determine which species of bacteria were carried from mother to baby in milk.

As expected, old order Mennonite mothers self-reported a greater exposure to farm animals, dogs, unpasteurized farm milk, and barns, a higher rate of giving birth at home, more frequent use to bleach to sterilize the home, and a lower exposure to antibiotics and pesticides. Crucially, they also reported a lower rate of atopic diseases for themselves and their babies.

The researchers show that breast milk from the old order Mennonite mothers contained more IgA1 and IgA2 antibodies against peanut, egg ovalbumin, dust mites, and the bacterium Streptococcus equii, a pathogen of horses. The milk from Mennonite mothers contained milk microbes, such as bacteria from the families Prevotellaceae, Veillonellaceae, and Micrococcaceae, and higher concentrations of certain oligosaccharides and fatty acids.

“Here we show that breast milk from moms in a community of old order Mennonites contains higher concentrations of IgA antibodies against food allergens, dust mites, and bacteria associated with farm animals, as well as higher levels of certain cytokines, signaling proteins important for regulating the immune system,” says Dr Juilee Thakar, an associate professor at the Department of Microbiology and Immunology and the Department of Biostatistics of the University of Rochester, and a coauthor of the study.

Coauthor Dr Antti E. Seppo, an associate professor at the Department of Pediatrics of the University of Rochester, concludes: “Our findings indicate that that breast milk from old order Mennonite mothers contains higher levels of beneficial antibodies, microbes and metabolites that help to ‘program’ the developing gut microbiota and immune system of their babies. These may protect infants against developing allergic diseases. This is important, because it can help explain why atopic diseases are currently exploding in Western populations, and perhaps one day these insights may help to prevent or mitigate these diseases.”