Saccharomyces boulardii is a unique, non-pathogenic and tropical yeast (fungus) – a hardy, acid-resistant, temperature-tolerant micro-organism. It differs greatly from other better-known species, such as acidophilus and bifidobacterium bacteria strains for example. Although it is in the same genus as Saccharomyces cerevisiae (baker’s, brewer’s or dietary yeast), Saccharomyces boulardii is not linked to the Candida species (Candida albicans, tropicalas, etc.). Saccharomyces boulardii yeast was first isolated from lychee and mangosteen fruit in the 1920s by a French scientist called Henri Boulard.