Nancy Toedter Williams


Am J Health Syst Pharm. 2010;67(6):449-458. 

In This Article


Probiotics are regulated as dietary supplements and not subjected to the same rigorous standards as medications. A challenge with these products involves the complexity of quality control with live microorganisms. As a result, individuals may obtain a product that is ineffective or that contains varying quantities of bacteria or yeast. Published studies involving probiotics have often utilized small sample sizes and lacked appropriate randomization, blinding, or control groups. Therefore, the results from many probiotic studies should be interpreted cautiously due to methodological limitations. There is also heterogeneity among studies, since different probiotic doses, strains, treatment durations, and patient populations may have been used. Since probiotic effects are specific to a particular strain, this may have important implications when interpreting meta-analyses, particularly if strain designations were not provided. Future research needs to encompass more well-designed clinical trials in larger populations and for longer durations to better evaluate the efficacy of probiotics.


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