Brewer's yeast is a type of fungus, specifically a single-celled organism known as Saccharomyces cerevisiae. It is commonly used in the brewing of beer and the baking of bread, where it ferments sugars to produce carbon dioxide and alcohol. This fermentation process is essential for creating the bubbles in beer and the rise in bread. In addition to its culinary uses, brewer's yeast is also a nutritional supplement. It is rich in vitamins, particularly B vitamins, and minerals like chromium. Many people take it for its potential health benefits, including supporting digestion and boosting energy levels.