Vitamin E was discovered in early 1920’s by Maltill, Evans and sure. During their investigations on the influence of diet on the reproductive cycle of rats, they observed that rats become sterile when fed on a purified diet having all the known nutrients even though they were healthy. When fed with fresh green leaves or dried alfalfa the reproductively was restored in the female but not in males. The unknown factor which prevented sterility was first called substances X and was later named Vitamin E.
Vitamin E consists of a group of chemical substances called ‘tocopherols’. There are six different tocopherols which are collectively called Vitamin E. It occurs as yellow viscous oil, insoluble in water, but soluble in fat solvents. High temperature and acids do not affect the stability of this vitamin. In the presence of rancid fats or salt of lead or iron, however, oxidation takes place. Decomposition occurs in ultraviolet light, alkalies and oxygen.
The primary role of Vitamin E appears to be as an antioxidant .it is believed that it also functions as an activator in certain enzymatic reactions. Vitamin E plays an important role in the protection of Vitamin A, carotene and ascorbic acid from oxidation in the digestive tract and in the body cells. By accepting oxygen itself, it helps prevents the oxidation of Vitamin A. In the body tissue Vitamin E plays another important role by reducing the oxidation of the polyunsaturated fatty acids, thereby helping to maintain the integrity of the cell membranes. Thus the protective of Vitamin E enhances the efficient use of vitamin A and ascorbic acid.
In many species of animals deficiency of vitamin E is known to cause reproductive failure in the form of permanent and temporary sterility. No such effect has so far been proved in respect of human being.
Many vegetables oils such as wheat-germ oil are good sources of tocopherols although they are high in poly unsaturated fatty acids. Good concentration of vitamin E is present in the dark green leafy vegetables, nuts and legumes as well as whole grain cereals. Although food of animal origin is low in vitamin E, liver heart kidney milk and eggs are the animal sources of this vitamin. While human milk provides an adequate amount of vitamin E to the infant, Cow’s milk contains very little of this vitamin.
There is a satisfactory level of vitamin E in the diet through the intake of vegetable oil and margarine. Since this vitamin is also widely distributed in many other food items, a deficiency does not normally develop in human beings. The need for vitamin E is higher when there is an increased intake of polysaturated fatty acid.
Vitamin E deficiency results in increased haemolysis (breakdown) of the red blood cells leading to anaemia. Premature Infant also shows a low level of tocopherol. In some species of animals Vitamin E deficiency is known to cause reproductive failure. In human being vitamin E deficiency is not frequently reported.