Vitamin E is an essential nutrient found in spinach, watercress, mustard greens, and many green leafy vegetables. Good sources of Vitamin E are oily plant seeds such as peanuts and sunflower kernels. Vitamin E acts like an antioxidant, and a deficiency of this vitamin causes degeneration of nerve cells and fragility of red blood cells that is generally diagnosed as hemolytic anemia. The Recommended Dietary Allowance (RDA) for d-alpha-tocopherol, which is the biologically active form of Vitamin E, is 15 mg (22.5 IU) for adolescents and adults.
Many people take Vitamin E supplements because consumption of antioxidant vitamins may reduce the risk of certain cancers. The supplement are usually sold in capsules of doses of 200, 400 and 1000 IU, but more is not better. A recent study of 118,765 subjects split relatively evenly between the placebo and vitamin E groups found that overall, supplemental vitamin E had no effect on the risk for total stroke; however, when examining the stroke subtypes, there was a 22 percent increase in risk for hemorrhagic stroke (intracranial bleeding), and a 10 percent decrease in ischemic stroke (blockage of the blood supply by a clot).
It is not necessary to take Vitamin E supplements if you eat a nutritious diet with plenty of leafy greens and some nuts.
 Markus Schürks, et al., Effects of vitamin E on stroke subtypes: meta-analysis of randomised controlled trials, BMJ 2010; 341:c5702