Group of fungi that ferment sugars. Yeast is a source of beta-glucan, which is a good antioxidant. Yeasts are basically fungi that grow as single cells, producing new cells either by budding or fission (splitting). Because it reproduces well, Saccharomyces cerevisiae is the organism that is most widely used in biotechnology. Nevertheless, some forms of yeast are human pathogens, such as Cryptococcus and Candida albicans.

In relation to skin, there is limited information about how Saccharomyces cerevisiae may provide a benefit. Live yeast-cell derivatives have been shown to stimulate wound healing (Source: Archives of Surgery, May 1990, pages 641–646), but research about this is scant. Much of what is known about yeast’s effects for skin is theoretical, and concerns yeast’s tissue-repair and protective properties (Source: Global Cosmetic Industry, November 2001, pages 12–13) or yeast’s antioxidant properties (Source: Nature Genetics, December 2001, pages 426–434). As a skin-care ingredient yeast has potential, but what its function may be or how it would affect skin is not fully understood.