Multivitamins are supplements that contain an assortment of nutrients required by the human body. The specific nutrients and the amounts of each provided per serving vary from product to product. Most contain doses of all or most of the 13 essential vitamins: A, C, D, E, K, thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyroxidine (B6), biotin (B7), folate (B9) and cobalamin (B12). In addition, most formulas also include minerals, such as potassium, calcium and iron.