"They also start to become colonized with bacteria, so it's very important that the gut learns what's good and what's bad. The baby's body needs to be able to recognize a bad bacteria or a bad virus and fight it, but it also needs to recognize that even though a food protein is foreign, that protein is okay and the body doesn't want to develop an immune response to it," she said.

If anything goes wrong at this stage, babies can develop food allergies, inflammatory bowel disease, and even asthma. "We're very interested in frequent sampling at this early period of development," she added.

Donovan also would like to learn how bacteria in the gut differ in formula- and breast-fed babies, and this technique should make that possible. "Now we'll be able to get a complete picture of what's happening in an infant-from the composition of the diet to the microbes in the gut and the genes that are activated along the way."

Of potential clinical importance: The gene expressed most often in breast-fed infants is involved in the cell's response to oxygen deprivation. Lack of oxygen is a factor in the development of necrotizing enterocolitis (NEC), a kind of gangrene of the intestine that can be fatal in premature babies. NEC is a leading cause of disease and death in neonatal intensive care units, with a reported 2,500 cases occurring annually in the United States and a mortality rate of 26 percent.

Source: University of Illinois College of Agricultural, Consumer and Environmental Sciences