Health effects of probiotics and prebiotics A literature review on human studies

Abstract

Human studies on health effects of probiotics and prebiotics were reviewed and evaluated. The main results can be summaries as follows: Certain probiotic lactobacilli may improve lactose digestion and reduce symptoms of lactose intolerance. The effect of probiotics on serum cholesterol is still inconclusive. Animal studies showing triacylglycerol-lowering effects of prebiotics need confirmation in humans. Data on effects of probiotics on constipation are not convincing, whereas inulin has dose-related laxating effect. Effects of a probiotic drink have been reported on symptoms in irritable bowel syndrome, but more studies are needed for firm conclusions. A significant shortening of acute watery rotavirus-included diarrhoea has been demonstrated for two lactobacilli, whereas possible effects on the risk of getting traveller's diarrhoea need further studies. There are promising indications that probiotics could be useful against antibiotic-associated diarrhoea, and a yeast preparation has been shown to reduce the risk of relapsing Clostridium difficile diarrhoea. Promising results from studies on the effect of probiotic products in the treatment of gastritis and inflammatory bowel disease should encourage further studies with pro-, pre- and synbiotic foods. Certain prebiotic oligosaccharides may increase calcium absorption. Probiotics can be regarded as safe although occasional infections have been reported in immunosuppressed patients. Prebiotics such as fructans may cause dose dependent gastrointestinal side-effects. The documentation of health-promoting effects of probiotic and prebiotic products is rapidly increasing. The food industry that develops pro- and prebiotic products should increase their efforts to develop high quality research and well-designed clinical trials on ordinary food products. This area is of great importance for improving human health.