Probiotics are living microorganisms that can be ingested to exert health benefits beyond basic nutrition. Interest in developing probiotics for a wide range of gastrointestinal disorders and other diseases has increased. Christian Mottet, MD, and Pierre Michetti, MD, provided commentary in the January 2005 issue of Digestive and Liver Disease, describing some promising results and highlighting the need for more substantive clinical trials to support probiotic use. In studies of inflammatory bowel disease, positive results have been observed with a probiotic mixture for preventing the onset or relapse of pouchitis and preventing the relapse of ulcerative colitis. Mixed results have been obtained in studies of Crohn's disease.
Probiotics may function by competing with, and modulating, the gut microflora. New data, however, suggest that the mode of action in at least some instances may be related to effects on the mucosal immune system or that certain DNA structural motifs rather than microbial metabolites can elicit beneficial effects. Although the potential exists for significant therapeutic benefits from probiotics, the challenge is to understand their mechanisms of action and to identify appropriate strains and mixtures to achieve those benefits.