S. boulardii has proven particularly beneficial for balancing the intestinal microbiology. It functions in the modulation of both innate immunity by activating the complement system and adaptive immunity by boosting the intestinal secretion of IgA. Additionally S. boulardii sureties "soluble factors" demonstrated to reduce inflammation win a reduction of the production of NF-KappaB and mitogen-activated protein kinase and to block the expression of inflammatory cytokines, particularly IL-8 which is secreted during E. coli infection. It also enhances the secretion of mucosal immune factors which protect against enteric pathogens and in dendritic immune cells it increases IL-10, which limits unspecific immune response by down regulating Th-1 response.
Orally, Saccharomyces boulardii is used for treating and preventing diarrhea, including infectious types such as rotaviral diarrhea in children, diarrhea caused by bacterial overgrowth in adults, traveler's diarrhea, and diarrhea associated with enteral tube feedings. It is also used orally to prevent and treat antibiotic associateddiarrhea. Saccharomyces boulardii is also used orally for general digestion problems, irritable bowel syndrome (IBS), inflammatory bowel syndrome (IBD, Crohn's disease, ulcerative colitis), Lyme disease, relapsing Clostridium difficile colitis, and bacterial overgrowth in short bowel syndrome. It is also used orally for lactoseintolerance, urinary tract infections (UTIs), vaginal and Candida-related (yeast) infections, high cholesterol levels, hives, fever blisters, canker sores, and adolescent acne.