Vitamin E
Vitamin E
This information describes the common uses of Vitamin E, how it works, and its possible side effects.

Common Name

Tocopherol, Alpha-tocopherol, dl-tocopherol, Tocotrienol, RRR-alpha-tocopherol

How It Works

A diet containing adequate amounts of vitamin E is important in maintaining general health, and may prevent against some forms of cancer. The ability of vitamin E to prevent or treat Alzheimer’s disease, rheumatoid arthritis, or heart disease requires further study.

Vitamin E, also known as alpha-tocopherol, is a natural antioxidant that is found in foods such as plant oils, eggs, nuts, green leafy vegetables, and whole grains. The major function of vitamin E is to act as a free-radical scavenger, meaning that it neutralizes free radicals and protects cells from their damaging effects. Therefore, vitamin E is being investigated in conditions such as Alzheimer’s disease and cancer, in which free radical damage is known to play a part. (See the Research Evidence section for more information about this.)

Vitamin E also lessens the blood’s ability to clot by suppressing the number of adhesion molecules on the lining of the blood vessel walls. With fewer adhesion molecules, cells in the blood are less likely to “dock” on the blood vessel wall and start forming a clot. In addition, vitamin E causes the release of prostacyclin, which itself dilates the blood vessels and inhibits blood clotting. This may be helpful in patients with coronary artery disease, in which blood clots can form around atherosclerotic plaques in coronary arteries.

Scientists think that vitamin E also inhibits a molecule called protein kinase C, which is involved in cell proliferation and differentiation in smooth muscle, platelets, and monocytes (a type of immune cell). Although in theory this would be helpful against cancer cells, this effect has not been strongly shown in humans. An animal study shows NAC can speed up the growth of lung cancer cells due to its antioxidant activity.

Purported Uses

  • To prevent the progression of Alzheimer’s disease
    One clinical trial showed that vitamin E helped prevent progression of Alzheimer’s disease. A few population-based studies have suggested that high intake of vitamin E in the diet is associated with a lower risk of developing Alzheimer’s disease.
  • To treat arthritis
    One clinical trial suggested that vitamin E can relieve pain in patients with rheumatoid arthritis, but has no anti-inflammatory effect. No other clinical trials have tested this use.
  • To prevent cancer
    Large population-based studies in Finland found that taking vitamin E supplements reduced the risk of prostate and colorectal cancers in male smokers. However, initial data from the large-scale SELECT (Selenium and Vitamin E Cancer Prevention) Trial shows vitamin E taken alone or with selenium for five years, did not reduce the risk of prostate cancer. Vitamin E supplementation had no effect on lung, urinary tract, pancreas, mouth or stomach cancer risks. Another trial in patients with head and neck cancers found that patients who received vitamin E had a higher rate of second primary cancers compared with those on placebo, and that vitamin E may interfere with radiation therapy.
  • To manage heart disease
    Data from clinical trials show that vitamin E does not help prevent heart disease.
  • To prevent cataracts
    Two clinical trials do not support this use
  • To prevent the cardiovascular complications of diabetes
    Several clinical trials have shown that vitamin E supplements may be helpful in preventing LDL oxidation in patients with diabetes, which may help prevent progression to atherosclerosis.
  • To treat liver diseases
  • Vitamin E can be used to treat fatty liver disease not caused by alcohol in adults
  • To stimulate the immune system
    No scientific evidence supports this use.
  • To prevent the progression of Parkinson’s disease
    Clinical trials do not support this use.
  • To improve wound healing
    No scientific evidence supports this use.
  • To reduce hot flashes
    A clinical trial showed that vitamin E reduces hot flashes in breast cancer survivors somewhat, but most patients did not prefer vitamin E over placebo at the end of the study and.

Patient Warnings

  • A recent analysis of seven brands of commercially available vitamin E found their actual content to vary considerably from the labeled dosage, from 41% less than the labeled amount, to 57% more.
  • This product is regulated by the FDA as a dietary supplement. Unlike approved drugs, supplements are not required to be manufactured under specific standardized conditions. This product may not contain the labeled amount or may be contaminated. In addition, it may not have been tested for safety or effectiveness.

Do Not Take If

  • You are taking warfarin or other blood thinners: Doses of vitamin E greater than 400 IU per day may increase the risk of bleeding. PT and INR should be monitored if vitamin E is started or discontinued.

Side Effects

  • Symptoms of vitamin E toxicity from long-term consumption of >400-800 IU per day include: fatigue, dizziness, weakness, headache, blurred vision, rash, and thrombophlebitis (inflammation of a vein due to a blood clot).
  • Vitamin E may increase the risk of stroke.

Special Point

  • Natural vitamin E supplements that are derived from plant oils contain d-alpha-tocopherol, which is believed to be the active form, while synthetic vitamin E supplements are a mixture of d-alpha-tocopherol and l-alpha-tocopherol (inactive forms).
  • It is controversial whether antioxidants like vitamin E can lessen or negate the effects of chemotherapy and radiation therapy. Because these therapies work by creating free radicals that kill cancer cells, some physicians have suggested that high levels of antioxidants can neutralize these free radicals and thereby protect cancer cells from these therapies. So what protects healthy cells may protect cancer cells as well. This question is still not fully understood and patients who are interested in taking more than the RDA of any antioxidant should consult with their doctor.