What Is Vitamin E ?
Vitamin E is the collective name of a group of closely related lipids called tocopherols. It is fat soluble vitamin.Primary function of vitamin E is an antioxidant in prevention of the nonenzymic oxidation of cell components.
Sources :Vegetable oils like, cotton seed oil, corn oil,sunflower oil ,wheat germ oil margarine are the richest source of vitamin E. It is found in fair quantities in dry soyabeans ,yeast cabbage and peanuts.
Chemistry:VitaminE, the collective name for a group of closely related lipids called tocopherols , all of which containa substituted aromatic ring and a long isoprenoid side chain.
Vitamin E being hydrophobic,tocopherols associates with cell membranes, lipid deposits and lipoproteins in the blood . Tocopherols are biological antioxidants , the aromatic ring reacts with and destroys the most reactive form of oxygen radicals and other free radicals, protecting unsaturated fatty acids from oxidation and preventing oxidative damage to membrane lipids , which can cause cell fragility . The presence of the phenolic –OH group on 6th carbon of structure is the most important groupfor its an toxidant activity.
Absorption , Distribution and Excretion:Free tocopherols and their esters are readily absorbed in sall intestine with the help of bile acids .Absorbed vitamin E is transported to liver where it gets incorporated into lipoproteins and carried by blood to muscle tissues and to adipose tissue for storage . The normal value of blood level is around 1mg\d1 and it is transported chiefly in the a- lipoprotein fraction .Under normal dietary conditions, there is no significant excretion of tocopherols in urine or faces as rapidlyand extensively undergoes destruction in the tract and in tissues.Placental transfer of vitamin E is limited , mammary transfer is much more extensive . Thus the serum a-tocopherol level of breast fed infants increases more rapidly than that of bottle fed infants.
Antioxidant property: This is the most important functional aspect of vitamin E .
Removal of free radicals:Vitamin E is involved in removal of free radicals and prevents their peroxidative effects on unsaturated lipids of membrane and thus helps to maintain the integrity of cell membrane vitamin E prevents per oxidation. Chromanol ring of tocopherols donates its phenolic hydrogen to reduce the free radical and is itself oxidized to the quinone form.
- Antioxidant activity of vitamin E combine with the other factors mainly prevents the peroxidative effects of O3 , H2O2 and NO2 on respiratory membrane and thus prevent their damage.
- Vitamin E prevents the peroxidative changes in membranes of mitochondria and helps in maintaining the smooth translocation of phosphate ions into mitochondria . Thus the oxidative phosphorylation is enhanced.In addition the oxidationof sulfhydryl enzymes is also prevented by tocopherols.
- Tocopherols prevents oxidation of vitamin A and carotenes and reduce their wastage.
Vitamin E deficiency: In man , deficiency symptoms are not well established , primarily because known cases of deficiency are rare it is agreed that man requires vitamin E .
Red blood cell are subject to hemolysis by hydrogen peroxide or dialuric acid to a greater degree in vitamin E deficiency.
In some new born infants , the red blood cell are readily hemolyzed by hydrogen peroxide.
Administration of vitamin E by mouth prevents this hemolysis Rapid Tone.