Vitamin E - tocopherol

Vitamin E refers to a group of eight fat-soluble compounds that include both tocopherols and tocotrienols. Both of these exist in four forms (alpha, beta, vitamin E has a marked antioxidant effect gamma, delta). Alpha-tocopherol is the most biologically active form.

The important function of vitamin E is the antioxidant function protecting lipids and preventing the oxidation of polyunsaturated fatty acids (PUFAs).

Vitamin E is incorporated into cell membranes protecting them from oxidative damage. Other functions include enzymatic activities and gene expression.

Vitamin E also plays a role in neurological functions and inhibition of platelet aggregation.

Sources

The best sources of alpha-tocopherol are nuts, seeds, and vegetable oils (wheat germ oil, sunflower oil, and safflower oil). Significant amounts are also available in green leafy vegetables and fortified cereals.

Most vitamin E in American diets is in the form of gamma-tocopherol from soybean, canola, corn, and other vegetable oils and food products such as commercial breakfast cereal and tomato sauce.

Although originally extracted from wheat germ oil, most natural vitamin E supplements are now derived from vegetable oils, usually soybean oil. Here is a list of foods having the highest content of vitamin E.

Daily intake

The recommended daily intake for adults is 15 mg (22.5 IU). The upper tolerable intake level (UL) for vitamin E is 1000 mg (1500 IU) per day.

Deficiency

Signs of vitamin E deficiency include neuromuscular problems such as spinocerebellar ataxia, myopathies, dysarthria, absence of deep tendon reflexes, loss of vibratory sensation and proprioception, and positive Babinski sign (abnormal plantar reflex).

Deficiency can also cause anemia due to oxidative damage to red blood cells, retinopathy, impairment of the immune response and male infertility.

Excess

When obtained from food sources alone, vitamin E has no documented toxicity.

Please note that for persons with vitamin K deficiency, a high intake of vitamin E can prolong bleeding time and interfere with clotting of the blood.

Vitamin E supplements, when taken in very high doses of 2000 mg (3000 IU) or more, have toxic effects including intestinal cramps and diarrhea, fatigue, double vision, and muscle weakness.

References: 1 , 2 , 3 , 4