While research shows that a newborn’s gut microbiome colonizes heavily from bacteria ingested during vaginal birth,1 a new study from researchers at the University of California-Berkeley focuses on the potential impact of breastfeeding on preserving the integrity of an infant’s fledgling microbiome.

In a study using mice, Meghan Koch et al. examined whether a mother’s maternal antibodies could help newborns tolerate beneficial bacteria in the gut by preventing an inflammatory response from the infant’s immune system. Conventional wisdom already indicated that Immunoglobulin A (IgA), an antibody type contained in breast milk, would help suppress such a response. However, Koch and her colleagues found that another type of antibody, Immunoglobulin G (IgG), actually had more effect on the body’s response to the harmless bacteria. They also discovered that IgG passed through breast milk was the most important mechanism for establishing gut bacteria tolerance.2

From a human standpoint, gut bacteria not only aid in digestion, but provide a barrier to harmful bacterial overgrowth, and are beneficial to proper immune function. Having an improperly trained immune system could lead to gut inflammatory diseases, such as Crohn’s disease and ulcerative colitis, yet further study is needed. In humans, for instance, less IgG is taken up through breast milk, when compared to mice subjects.3 That said, Koch et al. provide a new understanding of the role of IgG in gut microbiome tolerance in mammals. The more we learn about how the relationship between our human immune system and gut microbiome is formed during infancy, the more opportunity we have of being able to address gut microbiome issues early in life.

First published in the Inside Tract® newsletter issue 197 – 2016
Image Credit: © bigstockphoto.com/petunyia
1. Neu J et al. Cesarean versus vaginal delivery: Long term infant outcomes and the hygiene hypothesis. Clinics in Perinatology. 2011;38(2):321-331.
2. Koch MA et al. Maternal IgG and IgA antibodies dampen mucosal T helper cell responses in early life. Cell. 2016;165(4):827-841.
3. Breast milk primes the gut for microbes. The Scientist. Available at: http://www.the-scientist.com/?articles.view/articleNo/46027/title/Breast-Milk-Primes-Gut-for-Microbes/. Accessed 2016-05-09.