What are they: Vitamins are organic compounds necessary for the body to have biological functions, but they are not produced endogenously. That means we need to make them go on a diet. There are 13 vitamins-in fact, most of them are vitamin families with different chemical structures but similar biological activities-play a variety of roles, most commonly as precursors or cofactors for enzymatic reactions, which means they have Helps develop along the direction of chemical reactions. Make up for our metabolism. Despite the existence of multiple vitamins, humans still obtain most of the essential vitamins from whole foods or fortified processed foods through diet. Common vitamins: The vitamin family includes A, B1, B2, B3, B5, B6, B7, B9, B12, C, D, E and K. For example, the vitamin B3 family includes niacin, nicotinamide and nicotinamide ribose, which are precursors of the coenzyme NAD + with different efficacy, and are also involved in other processes such as lipid metabolism.