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. Thiamine (Vitamin B-1) is an essential coenzyme in energy production. Thiamine is converted quickly into thiamine pyrophosphate, which is required for glycolytic and Krebs cycle reactions. Thiamine also appears to be related to nerve impulse transmission.