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 E as essential for fertilized eggs to result in live births (in rats), it was given the name "tocopherol" from Greek words meaning "birth" and "to bear" or "carry". Alpha-tocopherol, either naturally extracted from plant oils or synthetic, is sold as a popular dietary supplement, either by itself or incorporated into a multivitamin product, and in oils or lotions for use on skin. Vitamin E may have various roles as a vitamin. Many biological functions have been postulated, including a role as a fat-soluble antioxidant. In this role, vitamin E acts as a radical scavenger, delivering a hydrogen (H) atom to