Saccharomyces boulardii is a non-pathogenic probiotic yeast that survives stomach acid to nourish the intestines, support the immune system and provide a favorable growth environment for the beneficial bacteria that support health and digestive comfort. Medical studies have shown the efficacy and safety of S. boulardii for a number of health challenges in both adults and children. These applications include protection against antibiotic-related diarrhea, recurrent C. difficile-related diarrhea and colitis, traveler's diarrhea, acute bacterial and viral diarrhea, inflammatory bowels and irritable bowels.

S. boulardii acts as a temporary flora that quickly achieves high concentrations in the GI tract. It is one of the few yeasts that survives best at human body temperatures and is able to colonize and persist in the gut.