Vitamin E is a general term for a group of compounds, each with varying degrees of vitamin E activity. The most abundant and active form of vitamin E is alpha-tocopherol, but significant amounts of beta-tocopherols, gamma-tocopherols are also found in diet. The main function of vitamin E is as a membrane antioxidant.
Foods with Vitamin E
Salad oils (safflower, corn, and sunflower oils), wheat germ, margarine, grain products, seeds and nuts, green leafy vegetables (spinach, asparagus, broccoli, and turnip greens), avocado, dried prunes, and mango.
Absorption, metabolism, and excretion of Vitamin E
The primary site of absorption is jejunum and of excretion is via bile in the feces. Most vitamin E is stored in adipose tissue. Maximum transfer of vitamin E is across the placenta occurs just before term delivery.
Functions of vitamin E
The major function of vitamin e is an antioxidant. The process by which a substance combines with oxygen is called oxidation. Several substances can be destroyed by oxidation, including vitamin E, vitamin A, and vitamin C. some molecules become very unstable when they are oxidized. Their accelerated movements can damage nearby molecules. Vitamin E accepts oxygen instead of allowing other molecules to become unstable. In this role, vitamin E protects vitamin A and unsaturated fatty acids from oxidation. Vitamin E in lung cell membranes provides an important barrier against air pollution. It also protects the stability of the polyunsaturated fatty acids in the red blood cell membranes from oxidation in the lungs.
Antithrombotic action – vitamin E slows down the action of thrombin ( a blood clotting protein) and reduces platelet aggregation by inhibiting thromboxane. Although vitamin E is a natural “blood thinner” it does not increase risk of bleeding in healthy people.
Increased risk of deficiency vitamin E
Many people do not obtain adequate dietary vitamin E. in most foods vitamin E is removed by processing. For example, refined flour and white rice lose nearly all of the vitamin originally present in the whole grain.
Vitamin E requirements are sharply increased by urban environments, air and water pollution, certain food pesticides and additives, and radiation.
Other conditions are
- Alzheimer’s disease
- Biliary cirrhosis
- Bronchopulmonary dysplasia
- Cardiovascular disease
- Cystic fibrosis
- Drug use (oral contraceptives, clofibrate)
- Malabsorption syndrome
- Musculoskeletal disorders
- Pancreatic disease
- Pulmonary disease
Signs and symptoms of Vitamin E deficiency
Rupture of red blood cells, nerve damage, impaired bone mineralization, impaired vitamin A storage, and prolonged blood coagulation. Vitamin E is one of the least toxic vitamins, but at high doses, it can antagonize the utilization of other fat soluble vitamins.
Signs of excess
Excessive intake does not seem to cause hypervitaminosis but has caused isolated cases of dermatitis, fatigue, pruritis ani, acne, vasodilatation, hypoglycemia, gastro intestinal symptoms, increased requirement for vitamin K, and impaired coagulation, and muscle damage.
Use in prevention and therapy
Cardiovascular disease, including coronary heart disease and peripheral vascular disease
Vitamin E is beneficial in angina pectoris, peripheral claudication, and venous thrombosis. It reduces oxidation of cholesterol in low-density lipoprotein and very low density lipoprotein particles in the blood and thereby can reduce the risk of coronary heart disease.
Vitamin E functions as an antioxidant and stabilizes red blood cell membranes, enhancing function and durability of red cells.
Disorders of premature infants
Risk of hemolytic anemia and bronchopulmonary dysplasia is increased in newborns with vitamin E deficiency.
Ample vitamin E intake may decrease oxidative damage to the lenses and reduce the risk of developing cataract
Vitamin E reduces joint inflammation and stiffness beneficial for treatment of osteoarthritis and rheumatoid arthritis.
Vitamin E, applied topically to abrasions or burns, may reduce scar formation and contraction, and improve healing
Protection from environmental toxins
Vitamin E helps protect the lungs against the toxic effects of air pollutants, such as ozone and nitrous oxide.
Protection from cancer
Higher intakes of vitamin may help reduce the risk of cancer of the skin, lung, esophagus, and stomach.
Vitamin E may reduce breast tenderness, fatigue, appetite cravings, depression, and insomnia associated with menstrual cycle.
The loss of brain function in Alzheimer’s disease may be caused by oxidant damage to neurons. Vitamin E can slow progression of Alzheimer’s disease and help maintain function.
Vitamin E may protect against the oxidative damage that underlies many of the complications of diabetes. It can enhance the action of insulin and thereby reduce insulin requirements for blood sugar control
Exercise and training
Vitamin E helps protect against the damaging oxidative by-products of strenuous exercise.
Vitamin E may increase resistance to viral and bacterial infections. It enhances antibody production by white blood cells and increases their ability to engulf and destroy bacteria.