Vitamins are essential organic (carbon-containing) nutrients that are found in food, and they contribute to good health by regulating metabolism and assisting in the biochemical processes that release energy from digested food. They are classified as either fat- or water-soluble. The fat-soluble vitamins include A, D, E and K. The water-soluble vitamins include thiamin (B1), riboflavin (B2), niacin (B3), B6, folate, B12, biotin, pantothenic acid (B5), and vitamin C (ascorbic acid). With the exception of B12, water-soluble vitamins are stored in the body in limited amounts and are excreted within one to four days; therefore, they must be replenished on a daily basis. Fat-soluble vitamins, however, are stored in the body’s adipose tissues and liver. These storage sites for fat-soluble vitamins may reduce the chance for a deficiency, but they still must be consumed on a daily basis for good health.