Probiotics are live, nonpathogenic microorganisms (usually bacteria or yeasts) marketed as dietary supplements. They have not been approved by the FDA for any indication. Since our last article on this subject,1 some new data have become available.
Several mechanisms have been proposed to explain how probiotics could have beneficial effects. Saccharomyces boulardii, a strain of the yeast S. cerevisiae, has been shown to inhibit the pathogenicity of bacterial toxins.2 Acetic, lactic and propionic acid produced by Lactobacillus spp could lower intestinal pH and inhibit growth of pathogenic bacteria such as Escherichia coli and Clostridium spp. The presence of Lactobacillus spp and other probiotics in the intestinal tract might physically or chemically prevent adhesion and colonization of pathogenic bacteria. They may also induce or enhance an immune response.
Probiotics Revisited. JAMA. 2014;312(17):1796. doi:10.1001/jama.2014.14389