A protein found in dairy is discovered to be a prebiotic that holds promise for treating gastrointestinal conditions and obesity, scientists report.

The protein glycomacropeptide (GMP) is derived from whey, the liquid by-product of the cheese-making process. GMP contains low amounts of the amino acid phenylalanine. Individuals who suffer from phenylketonuria -- a metabolic disorder that causes cognitive impairment when phenylalanine level is too high -- can use GMP as an alternative protein source. GMP supplementation has also been observed to improve gastrointestinal health by protecting the digestive system from pathogens and by having an anti-inflammatory effect.

A new study in American Journal of Physiology -- Gastrointestinal and Liver Physiology shows that the protein is a prebiotic: It causes changes to the gut microbiota that benefit the host. The researchers observed that mice that ate GMP as their protein source had fewer bacteria associated with inflammatory bowel disease, enhanced gastrointestinal function and reduced inflammation.

"There is considerable evidence that dietary prebiotics modulate the gastrointestinal microbiota with therapeutic applications to conditions, including irritable bowel syndrome, inflammatory bowel disease, obesity and bone health," according to the researchers. "Palatable functional and medical foods can be made with GMP, and such foods may be beneficial in the management of phenylketonuria, obesity and inflammatory bowel disease," the researchers wrote.