Vitamins are organic compounds essential for normal metabolism that the body cannot synthesize in sufficient amounts. They are broadly classified based on their solubility: fat-soluble vitamins (A, D, E, K) and water-soluble vitamins (B complex and C). Fat-soluble vitamins are stored in the body's fatty tissues and liver. Water-soluble vitamins are not significantly stored in the body and are excreted in urine; therefore, regular intake is necessary. Vitamin A, D, and E are fat-soluble. Vitamin B complex is a group of several vitamins (B1, B2, B3, B5, B6, B7, B9, B12) that are all water-soluble.