Biotin, also known as Vitamin B7 and Vitamin H is important in many functions of the body. The main function of biotin is to help improve energy and function as a coenzyme in CO2 (carbon dioxide) transfer. But, did you know that without vitamin B7, your bone marrow, sweat glands and even nerves won't function optimally? Biotin is required for the proper breakdown of carbohydrates, fat and protein. Biotin is probably best known as the supplement that helps nails and hair grow. Biotin is often included in hair and nail supplements as well as various shampoos and conditioners. The most common sign of a biotin deficiency is often brittle nails and/or hair loss.