As we have explained before in this blog, breast milk is one major way in which an infant’s gut microbiota starts developing. We now know that an antibody contained in breast milk provides lifelong protection from illnesses such as the inflammatory bowel disease (IBD), by setting up defences in the gut flora of breastfed babies. These are the main findings of an experiment with mice (that clarifies related evidence found in humans) published recently in the Proceedings of the National Academy of Sciences (PNAS) by a team based at the University of Kentucky.
These results add to increasing evidence that maternal milk generates health benefits that persist into adulthood. A lot of these advantages are conveyed through the microbial populations contained in the intestine, the gut microbiota.
Babies are born sterile, but their body is colonized by external bacteria from the very beginning of their life. Most of these microbes go into their digestive tract, forming their gut flora. Far from being dangerous, the vast majority of these bacteria are essential for health. They allow babies and humans to digest certain types of food, train the immune system, and prevent infectious organisms to colonize the intestine.
In the latest study, scientists have focused their attention on a specific ingredient of maternal milk, which is an antibody called SIgA. While adult mice (and humans) produce it naturally, babies don’t: mother’s milk is the only source of it for them.
The authors engineered mutant rodent mothers that didn’t have SIgA in their milk. Then, they looked at the guts of their pups, and found they hosted very different bacterial communities, compared to the standard ones. In particular, they displayed certain groups that are often found in IBD patients.
The researchers then exposed the mice to food that generates intestinal inflammation. The mice’s organisms reacted by activating a set of genes that have been linked, once again, to IBD in humans.
These results match evidence showing that breastfed babies may be less likely to develop IBD later in life. At present, the team is exploring whether supplementing formulas with SIgA, or providing the antibody to adults with intestinal problems, may improve their health.