Shipud writes: It is pretty much common knowledge that mother’s milk is the healthiest food for infants, and that it bestows health benefits upon the baby that formula feeding cannot match. But a recent study of the baby gut metagenome has revealed an unknown benefit: mom's milk enriches a small population of disease causing bacteria in the infant's gut. Just enough to train the infant's immune system, but not enough to cause actual disease. The interesting thing is that the same pathways that enrich the baby's immune system, also help in the development of the gut tissue. An all-around win situation as explained by one of the coauthors.