Biotin, also known as vitamin H or B7, has the chemical formula C10H16N2O3S (Biotin; Coenzyme R, Biopeiderm), is a water-soluble B-complex vitamin which is composed of an ureido (tetrahydroimidizalone) ring fused with a tetrahydrothiophene ring. A valeric acid substituent is attached to one of the carbon atoms of the tetrahydrothiophene ring. Biotin is a cofactor in the metabolism of fatty acids and leucine, and in gluconeogenesis. Biotin is widely distributed in a variety of foods, but most often at low concentrations. Estimates are that the typical U.S. diet provides roughly 40 ug/day. There are only a couple of foods which contain biotin in large amounts, including royal jelly and brewer's yeast The best natural sources of biotin in human nutrition are liver, legume, soybeans,swiss chard, tomatoes, romaine lettuce, and carrots. This includes almonds, eggs, onions, cabbage, cucumber, cauliflower, goat's milk, cow's milk, raspberries, strawberries, halibut, oats, and walnuts. The most important natural sources in feeding nonruminant animals are oilseed meals, alfalfa, and dried yeasts. It is important to note that the biotin content of food varies and can be influenced by factors such as plant variety, season, and yield (endosperm-to-pericarp ratio).[2]