Jarrow Saccharomyces Boulardii plus MOS is a dietary supplement made with a probiotic yeast that promotes healthy microbial balance in the intestinal tract for better digestive health. This type of yeast is hardy enough to survive through stomach acid so it can colonize in the intestines. Once it is in the intestines, it protects beneficial microbiota and supports immune function. MOS further improves digestive health by preventing bacteria from sticking to the epithelial cells and reducing their growth.