Vitamin E is a nutrient that's important to vision, reproduction, and the health of your blood, brain and skin.

Vitamin E also has antioxidant properties. Antioxidants are substances that might protect your cells against the effects of free radicals — molecules produced when your body breaks down food or is exposed to tobacco smoke and radiation. Free radicals might play a role in heart disease, cancer and other diseases. If you take vitamin E for its antioxidant properties, keep in mind that the supplement might not offer the same benefits as naturally occurring antioxidants in food.

Foods rich in vitamin E include canola oil, olive oil, margarine, almonds and peanuts. You can also get vitamin E from meats, dairy, leafy greens and fortified cereals. Vitamin E is also available as an oral supplement in capsules or drops.

Vitamin E deficiency can cause nerve pain (neuropathy).

The recommended daily amount of vitamin E for adults is 15 milligrams a day.

Research on vitamin E use for specific conditions shows:

• Alzheimer's disease. Some research has shown that high-dose vitamin E might delay the progression of Alzheimer's disease in people who have been diagnosed with mild to moderate Alzheimer's disease. Other studies haven't shown this benefit. Vitamin E supplements appear to have no effect on whether people with mild cognitive impairment progress to Alzheimer's disease.
• Liver disease. Studies show that vitamin E might improve symptoms of nonalcoholic fatty liver disease. However, some evidence suggests that taking oral vitamin E for this purpose for two years is linked to insulin resistance.
• Preeclampsia. Increasing your intake of vitamin E hasn't been shown to prevent this pregnancy condition that affects blood pressure.
• Prostate cancer. Research shows that vitamin E and selenium supplements don't prevent prostate cancer. There is also concern that use of vitamin E supplements might increase the risk of prostate cancer.

When taken at appropriate doses, oral use of vitamin E is generally considered safe. Rarely, oral use of vitamin E can cause:

• Nausea
• Diarrhea
• Intestinal cramps
• Fatigue
• Weakness
• Headache
• Blurred vision
• Rash
• Gonadal dysfunction
• Increased concentration of creatine in the urine (creatinuria)

Taking higher doses of vitamin E might increase the risk of side effects. Also, there is concern that people in poor health who take high doses of vitamin E are at increased risk of death.

Use of vitamin E can interact with many conditions. For example, research suggests that oral use of vitamin E might increase the risk of prostate cancer. Other research suggests that vitamin E use might increase the risk of death in people with a severe history of heart disease, such as heart attack or stroke. Talk with your doctor before taking vitamin E if you have:

• A vitamin K deficiency
• An eye condition in which the retina is damaged (retinitis pigmentosa)
• Bleeding disorders
• Diabetes
• A history of a previous heart attack or stroke
• Head and neck cancer
• Liver disease

The supplement might increase your risk of bleeding. If you're planning to have surgery, stop taking vitamin E two weeks beforehand. Also, talk to your doctor about vitamin E use if you're about to have or you just had a procedure to open blocked arteries and restore normal blood flow to your heart muscle (angioplasty).

Use of some drugs can affect your vitamin E levels. Possible interactions include:

• Alkylating agents and anti-tumor antibiotics. There's concern that high doses of vitamin E might affect the use of these chemotherapy drugs.
• Anticoagulants and anti-platelet drugs, herbs and supplements. Use of vitamin E with these drugs, herbs and supplements to reduce blood clotting might increase the risk of bleeding.
• Cytochrome P450 3A4 (CYP3A4) substrates. Use caution when taking vitamin E and other drugs affected by these enzymes, such as omeprazole (Prilosec, Zegerid).
• Statins and niacin. Taking vitamin E with statins or niacin, which might benefit people with high cholesterol, could reduce niacin's effect.
• Vitamin K. Taking vitamin E with vitamin K might decrease the effects of vitamin K.