The role of probiotic cultures in the prevention of colon cancer.
Risk factors for colon cancer include both hereditary and environmental factors. Dietary patterns represent controllable risk factors for the development of colon cancer. Much attention has focused on decreasing colon cancer risk through increasing intake of dietary fiber; recently, this has included interest in the consumption of prebiotics and probiotics. Because factors involved in the initiation and promotion of colon cancer might be separated in time from actual tumor development, it is difficult to choose "outcomes" or "end points" that are definitive indicators of efficacy of probiotics or prebiotics. Studies that have explored the cause-effect relationship directly have used animal models. In this review, we have confined our discussion to animal studies from the last 10 years that have examined most directly the relationship between prebiotic and probiotic consumption and colon cancer development. To present the consensus of these studies first, it appears that probiotics with or without prebiotics have an inhibitory effect on the development of aberrant crypts (precancerous lesions) and tumors in animal models. The effect is not completely consistent and is small in some studies, but this may represent a dose or time effect.