A prebiotic has shown promise in helping the body's own natural killer cells fight bacterial infection and lower colon cancer risk, a study says. Prebiotics are dietary fibre supplements that serve as food for the trillions of tiny bugs living in the gut and stimulate the growth of the "good" bacteria. The evolution of prebiotic supplements (as well as probiotics, actual bacteria ingested into the system) provide new therapeutic targets for researchers and physicians, the Journal of Nutrition reports. Jenifer Fenton, a researcher at Michigan State University, US, reports that mice given the prebiotic galacto-oligosaccharide, or GOS, saw the severity of their colitis (an inflammatory bowel disease) significantly reduced. Inflammation is the immune system's response to illness, infection, according to a Michigan statement. Colon cancer symptoms can run the gamut from local, such as blood in the stool and constipation, to systemic, such as weight loss and fatigue. In fact, the mice fed GOS - a synthetic compound that is known to stimulate beneficial bacteria and is found in foods such as biscuits and infant formula - saw a 50 percent reduction in colitis. Research has shown certain types of foods and fibres can reduce colon cancer risk, said Fenton, researcher in food science. "There is something unique about certain types of fibres, such as GOS, and how they alter cells and influence the immune system to change disease risk, either for the good or bad," Fenton said. "Our overall goal is to identify either dietary patterns or diet components to reduce inflammation and cancer risk. In this case, we used prebiotics to stimulate changes in bacteria in the gut that may have a beneficial impact on the colon," the Michigan researcher added. "Our results suggest GOS may be effective in reducing colitis severity by priming the innate immune system," she said. The next step is to verify how that mechanism works; finding that link could help researchers apply the lessons learned to other intestinal ailments.