Vitamin E : Uses and Health Benefits

by MedlinePlus

Vitamin E is a fat-soluble vitamin with antioxidant properties.

Forms of vitamin E: Vitamin E exists in eight different forms ("isomers"): alpha, beta, gamma and delta tocopherol; and alpha, beta, gamma and delta tocotrienol. Alpha-tocopherol is the most active form in humans. Dosing and daily allowance recommendations for vitamin E are often provided in Alpha-Tocopherol Equivalents (ATE) to account for the different biological activities of the various forms of vitamin E, or in International Units (IU) which food and supplement labels may use. For conversion, 1mg ATE = 1.5 IU. Vitamin E supplements are available in natural or synthetic forms. The natural forms are usually labeled with the letter "d" (for example, d-gamma-tocopherol), whereas synthetic forms are labeled "dl" (for example, dl-alpha-tocopherol).

Proposed uses: Vitamin E has been proposed for the prevention or treatment of numerous health conditions, often based on its antioxidant properties. However, aside from the treatment of vitamin E deficiency (which is rare), there are no clearly proven medicinal uses of vitamin E supplementation beyond the recommended daily allowance. There is ongoing research in numerous diseases, particularly in cancer and heart disease.

Safety concerns: Recent concerns have been raised about the safety of vitamin E supplementation, particularly in high doses (400 IU/day or greater). An increased risk of bleeding has been proposed, particularly in patients taking blood-thinning agents such as warfarin, heparin, or aspirin; or in patients with vitamin K deficiency. Recent evidence suggests that regular use of high-dose vitamin E supplements may increase the risk of death (from "all causes") by a small amount, although a different study found no effects on mortality in women who took 600 IU units daily. Caution is warranted.

Evidence

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Uses based on scientific evidence

Vitamin E deficiency

Vitamin E deficiency is rare, and may occur in people with diminished fat absorption through the gut (due to surgery, Crohn's disease, or cystic fibrosis), malnutrition, very low-fat diets, several specific genetic conditions (abetalipoproteinemia, "Ataxia and Vitamin E deficiency" [AVED]), very low birthweight premature infants, or infants taking unfortified formulas. Supplementation may be necessary in these conditions. Prolonged vitamin E deficiency may cause severe neurologic complications including ataxia (unsteady walking and malcoordination of voluntary muscles), muscle weakness, diminished reflexes, or peripheral neuropathy (nerve degeneration in the hands and feet). Prolonged severe deficiency may ultimately result in blindness, abnormal heart rhythms, and dementia. Mild vitamin E deficiency has been suggested as possibly related to numerous disorders including cancer or heart disease, although the evidence in these areas is less clear. Vitamin E supplementation is accepted as an effective therapy for vitamin E deficiency to halt progression of complications. Diagnosis of this condition and management should be under the care of a physician and nutritionist.

Anemia

Studies of vitamin E supplementation for anemia have yielded mixed results. Further research is needed before a firm recommendation can be made.

Angina

Vitamin E has been suggested and evaluated in patients with angina, although possible benefits remain unclear. Further evidence is necessary before a clear conclusion can be drawn. Patients with known or suspected angina should be evaluated by a physician.

Antioxidant

Vitamin E possesses antioxidant activity, but it is not clear if there is any benefit of this property in humans. The American Heart Association has recommended obtaining antioxidants such as vitamin E by eating a well-balanced diet high in fruits, vegetables, and whole grains, rather than from supplements, until further scientific evidence is available.

Atherosclerosis

Vitamin E has been proposed to have a role in preventing or reversing atherosclerosis by inhibiting oxidation of low-density lipoprotein ("bad cholesterol"). Several population studies have suggested that a high dietary intake of vitamin E and high blood concentrations of alpha-tocopherol are associated with lower rates of heart disease. However, while the Cambridge Heart Antioxidant Study supported this hypothesis, the more recent prospective Heart Outcomes Prevention Evaluation (HOPE) study did not. This area remains controversial.

Bladder cancer

There is preliminary evidence of possible benefits of long-term vitamin E supplementation to reduce the risk of mortality in bladder cancer patients, although additional research is necessary before a clear conclusion can be reached.

Breast cancer

Vitamin E has been suggested as a possible therapy for the prevention or treatment of breast cancer. Published studies have included measurement of vitamin E levels, laboratory experiments, and population studies. Evidence remains inconclusive, and no clear conclusion can be drawn at this time.

Breast cancer-related hot flashes

A study of oral vitamin E 800 IU/day reports a very small reduction in hot flash frequency (approximately one less hot flash per day), but no preference among patients for vitamin E over placebo.

Cancer treatment

There is no reliable scientific evidence that vitamin E is effective as a treatment for any specific type of cancer. Caution is merited in people undergoing treatment with chemotherapy or radiation, because it has been proposed that the use of high-dose antioxidants may actually reduce the anti-cancer effects of these therapies. This remains an area of controversy and studies have produced variable results. Patients interested in using high-dose antioxidants such as vitamin E during chemotherapy or radiation should discuss this decision with their medical oncologist or radiation oncologist.

Cardiovascular disease in dialysis patients

It has been suggested that hemodialysis patients may be under increased oxidative stress, and therefore may benefit from the chronic use of antioxidants (particularly for the reduction of risk of heart disease). There is some research of the use of high-dose chronic vitamin E use in dialysis patients for heart disease prevention (up to 800 IU/day), although benefits or risks remain unclear in this population. Recent concern has been raised that regular use of high-dose vitamin E supplements may actually increase the risk of death (from "all causes") by a small amount, although this remains an area of controversy and active investigation. Additional research is necessary in this area before a firm conclusion can be reached.

Cataract prevention

There is conflicting evidence regarding the use of vitamin E to prevent cataracts. Although some studies across populations have suggested some protective effects (which may take up to 10 years to yield benefits), other studies in humans report a lack of benefits when used either alone or in combination with other antioxidants. Additional research is necessary before a clear conclusion can be reached.

Chemotherapy nerve damage (neurotoxicity)

Like other antioxidants, vitamin E has been suggested as a therapy to prevent complications due to chemotherapy, such as nerve damage (neuropathy). There is some evidence of benefits, for example when used with cisplatin. However, caution is merited, because it is not known if the use of high-dose antioxidants during chemotherapy may actually reduce the anti-cancer effects of some chemotherapy agents or radiation therapy. This remains an area of controversy and patients interested in using antioxidants during chemotherapy should discuss this decision with their oncologist.

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