Saccharomyces Boulardii is a kind of unicellular fungi, it belongs to Saccharomyces, a strain of saccharomyces cerevisiae subspecies. As probiotics, Saccharomyces Boulardii can promote the proliferation and maturity of intestinal epithelial cells, make the villi longer and intestinal crypt deeper, thus to improve the ability of digestion and absorption of nutrients. Saccharomyces Boulardii can also promote the intestinal mucosa to generate immune globulin (IgA), to build the first line of defense against pathogens.