Vitamin E – Chemistry, Functions, Food Sources, Deficiency
Evans and Bishop established that the fact that a fat soluble factor was necessary for reproduction in rats. They showed that the absence of this factor, or vitamin E, as it was designated, leads to infertility in rats.
Chemistry and Characteristics
Vitamin E consists of a group of chemical substances called ‘tocopherols’. Alpha tocopherol is the compound possessing the greatest Vitamin E activity. High temperature and acids do not affect the stability of this vitamin, but oxidation takes place in the presence of rancid fats or lead and iron salts. Decomposition occurs in ultraviolet light, alkalies and oxygen.
Functions
- The primary role of Vitamin E is to act as an antioxidant. By accepting the oxygen, it helps to prevent the oxidation of Vitamin A in the intestine, thereby sparing vitamin A.
- Vitamin E reduces the oxidation of polyunsaturated fatty acids, thereby helping to maintain the integrity of cell membranes.
- Vitamin E plays a role in the formation of RBC’s in the bone marrow.
- It helps in releasing the energy from carbohydrates and fats, through the synthesis of a coenzyme Q.
- In some animals Vitamin E is required to prevent the sterility.
Food Sources
Many vegetable oils such as wheat germ oil and cottonseed oils are good sources of vitamin E. Good concentration of Vitamin E is present in dark-green leafy vegetables, nuts, legumes, as well as whole grain cereals. Although foods of animal origin are low in vitamin E, liver, heart, kidney, milk and eggs are the animal sources of this vitamin. Human milk provides an adequate amount of Vitamin E to infants; cow’s milk is low in this vitamin.
Recommended Dietary Allowances
The vitamin E requirement is linked to that of polyunsaturated fatty acids (PUFA)content of the diet, as it protects the oxidation of PUFA. The requirement of Vitamin E suggested is 0.8mg/gof dietary essential fatty acids.
Deficiency
Vitamin E deficiency results in increased haemolysis (breakdown) of the red blood cells leading to anaemia. Premature infants also shows a low level of tocopherol. In some species of animals, vitamin E deficiency is also known to cause reproductive failure. In human beings vitamin E deficiency is not frequently reported.