A recent article from the New York Times reported that indigestible components in breast milk affect the composition of the bacteria in babies’ intestines, helping to protect them as they develop. Three researchers at the University of California, Davis identified a strain of bacterium that is able to survive on the complex sugars derived from lactose that babies can’t digest. The bacterium, a subspecies of Bifidobacterium longum, coats the lining of the intestines in order to keep out other harmful strains. As Dr. German told the New York Times when commenting on this evolutionary genius, “mothers are recruiting another life-form to baby-sit their baby.”
Making up 21% of breast milk, the complex sugars encourage growth of the bifido strain, which in turn “serve[s]as decoys for noxious bacteria that might attack the infant’s intestines.” It would seem logical that babies would acquire this strain of bifido from their mothers, but in fact, it has yet to be found in adults. The researchers have plans to further investigate the potential benefits of complex sugars in premature babes and the elderly in order to apply some of the lessons of breast milk to benefit the larger population. Because each component of breast milk serves a function that aims towards healthy development, it can give us insights into how the immune system functions.