As co-enzymes, the B vitamins are essential components in most major metabolic reactions. They play an important role in energy production, including the metabolism of lipids, carbohydrates, and proteins. B vitamins are also important for blood cells, hormones, and nervous system function. As water-soluble substances, B vitamins are not generally stored in the body in any appreciable amounts (with the exception of vitamin B-12). Therefore, the body needs an adequate supply of B vitamins on a daily basis. Riboflavin is an essential coenzyme in energy production. It is a component of the coenzymes FAD and FMN, which are intermediates in many redox reactions, including energy production and cellular respiration reaction.