Human studies on probiotics: Aspects of scientific documentation

Abstract

The assessment of probiotic health effects has to be based on human studies. Knowledge of the mechanisms is an important factor, complemented with target functions and biomarkers that are accepted as relevant to the state of health and well-being or reduction in risk of disease. Human studies should preferably be conducted by at least two independent research groups in different locations. In conclusion, well-designed human studies with requirements similar to those for pharmaceutical studies are required to demonstrate health benefits. Additionally, epidemiological studies or post-marketing surveillance can be recommended to assess both safety and efficacy of probiotics. Using these criteria, only a few health-promoting effects can be considered scientifically proven for specific strains. These include effects upon rotavirus diarrhoea, antibiotitic-associated diarrhoea and alleviation of lactose intolerance symptoms. The reported effects are strain-specific and product-specific. As more information is accumulating the evidence may be soon obtained for other health effects.