Principles of Biochemistry (2+1)

10.2.3 Vitamin E

10.2.3 Vitamin E-alpha Tocopherols

Vitamin E refers to a group of compounds known as There are four tocopherols (alpha, beta, gama and delta). All are isoprenoid-substituted 6-hydroxychromanes (tocols). D-a-Tocopherol has the widest natural distribution and the greatest biologic activity. Vitamin E is a most important natural antioxidant. Vitamin E is destroyed by commercial cooking and food possessing, including deep-freezing.

Functions: Vitamin E appears to be first line of defense against per-oxidation of polyunsaturated fatty acids contained in cellular and sub-cellular membrane phospholipids. Vitamin E and selenium act synergistically. Glutathione peroxidase, of which selenium is an integral component, provides a second line of defense against hydroperoxides before they can damage members and other components. Thus, tocopherol and selenium reinforce each other each other in their actions against lipid peroxides. In addition selenium is required or normal pancreatic function, which is necessary for the digestion and absorption of lipids, including vitamin E. Conversely, vitamin E reduces selenium requirements by preventing loss of selenium from the body or maintaining it in an active form.

Deficiency: There is a possible need for supplementation of tocopherol in the diets of pregnant and lactating women and for newborn infants where anemia can arise as a result of insufficiency of vitamin E. Anemia may be due to decreased production of hemoglobin and a shortened erythrocyte life and a shortened erythrocyte life span.

RDA The requirement for vitamin E is increased with greater intake of polyunsaturated fat (0.4mg/g of PUFA).

Children : 5 IU

Adults  : 10-15 IU ( IU=0.8mg )

Sources

Good Sources: Meat, eggs, liver, fish, chicken, oatmeal, corn oil, dairy products, vegetable fats, oils, cereals, nuts, leafy green vegetables and yellow vegetables.