Vitamin E refers to a group of compounds that include both tocopherols and tocotrienols. Of the many different forms of vitamin E, γ-tocopherol is the most common form found in the North American diet.γ-Tocopherol can be found in corn oil, soybean oil, margarine, and dressings. α-tocopherol, the most biologically active form of vitamin E, is the second-most common form of vitamin E in the diet. This variant can be found most abundantly in wheat germ oil, sunflower, and safflower oils.As a fat-soluble antioxidant, it interrupts the propagation of reactive oxygen species that spread through biological membranes or through a fat when its lipid content undergoes oxidation by reacting with more-reactive lipid radicals to form more stable products.
Regular consumption of more than 1,000 mg (1,500 IU) of tocopherols per day may be expected to cause hypervitaminosis E, with an associated risk of vitamin K deficiency and consequently of bleeding problems.
Vitamin E did not significantly affect the risk of stroke overall. The study did not evaluate which doses of vitamin E produced which outcomes. Instead, it looked at any association between vitamin E use and stroke. When looking at different types of stroke, researchers found that:
Taking vitamin E supplements increased the risk of hemorrhagic stroke by 22% but reduced the risk of ischemic stroke by 10%.
A total of 223 hemorrhagic strokes occurred among 50,334 who took vitamin E supplements, whereas 183 hemorrhagic strokes occurred among those taking a placebo.
A total of 884 ischemic strokes occurred among 45,670 people taking vitamin E supplements, whereas 983 ischemic strokes occurred among 45,733 people taking a placebo.
Vitamin E has many biological functions, the antioxidant function being the best known. Other functions include enzymatic activities, gene expression, and neurological function.