One more reason to breast feed

Turns out that up to a fifth of breast milk is indigestible for an infant. So what are those complex sugars doing? Some serve as food for a strain of bacteria that coats the newborn's gut. Others mimic the surface structure of the intestines, tricking undesirable bacteria into attaching to them and thereby sweeping them out of the digestive system. Together these effects help protect the baby at a time when his or her immune system is still very undeveloped.

Amazing.