Probiotics and colon cancer

Although a myriad of health-promoting effects have been attributed to the probiotic lactic acid bacteria, perhaps the most interesting and controversial is that of anticancer activity, the vast majority of studies in this area dealing with protective effects against colon cancer. There is no direct experimental evidence for cancer suppression in humans as a result of the consumption of probiotic cultures in fermented or unfermented dairy products, but there is a wealth of indirect evidence, based largely on laboratory studies. Reports in the literature regarding the anticancer effects of lactic acid bacteria fall into the categories of in vitro studies, animal studies, epidemiological studies and human dietary intervention studies. Examples of these reports will be given in the current paper. The mechanisms by which probiotic bacteria may inhibit colon cancer are still poorly understood, but, several potential mechanisms are being discussed in the literature, and these will also be addressed in this review.