Biotin, also known as vitamin H or B7, is a water-soluble vitamin that helps the body metabolize fats, carbohydrates, and protein. Water-soluble vitamins are not stored in the body so daily intake is necessary. 

Biotin is necessary for cell growth, the production of fatty acids, and the metabolism of fats and  amino acids. It plays a role in the citric acid cycle, which is the process by which biochemical energy is  generated during aerobic respiration. Biotin not only assists in various metabolic reactions but also helps  to transfer carbon dioxide. Biotin may also be helpful in maintaining a steady blood sugar level. Biotin is often recommended for strengthening hair and nails. As a consequence, it is found in many  cosmetics and health products for the hair and skin, though it cannot be absorbed through the hair or skin  itself.