Saccharomyces boulardii is a yeast that scientists discovered in the peels of certain tropical fruit Trusted Source. Its probiotic strain, S. boulardii CNCM I-745, was the first yeast that scientists studied as a probiotic for human medicine. Probiotics are supplements that contain live microbes that may have health benefits.
S. boulardii CNCM I-745 has some properties that make it potentially useful as a probiotic. It can survive the harsh conditions of the stomach. Acidic environments, high temperatures, bile, and digestive enzymes do not deactivate it, which means it can reach the intestines alive.