Vitamin amino acids. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, vitamin E consists of four tocopherols and four tocotrienols. The thirteen vitamins required by human metabolism are: vitamin A (retinols and carotenoids), vitamin B (thiamine), vitamin B (riboflavin), vitamin B (niacin), vitamin B (pantothenic acid), vitamin B (pyridoxine), vitamin B (biotin), vitamin B (folic acid or folate), vitamin B (cobalamins), vitamin C (ascorbic acid), vitamin D (calciferols), vitamin E (tocopherols and tocotrienols), and vitamin K (quinones). Vitamins have diverse biochemical functions. Some forms of vitamin A function as regulators of cell and tissue
Vitamin K2 Vitamin K2 Vitamin K or menaquinone () has nine related compounds, generally subdivided into the short-chain menaquinones (with MK-4 as the most important member) and the long-chain menaquinones, of which MK-7, MK-8 and MK-9 are nutritionally the most recognized. Vitamin K, the main storage form in animals, has several subtypes, which differ in isoprenoid chain length. These vitamin K homologues are called menaquinones, and are characterized by the number of isoprenoid residues in their side chains. Menaquinones are abbreviated MK-"n, where M stands for menaquinone, the K stands for vitamin K, and the n" represents the number of isoprenoid side