Herbs & Supplements:
Vitamin E

Supplement Forms / Alternate Names
  • Alpha Tocopherol, D-Tocopherol, DL-Tocopherol, DL-Alpha-Tocopherol, Tocopheryl Succinate, Tocopheryl Acetate, D-Alpha-Tocopherol, D-Delta-Tocopherol, D-Beta-Tocopherol, D-Gamma-Tocopherol, Mixed Tocopherols
Principal Proposed Uses
  • Cancer Prevention
Other Proposed Uses
  • Heart Disease Prevention, Preeclampsia Prevention, Impaired Immunity, Alzheimer's Disease, Tardive Dyskinesia, Menstrual Pain, Low Sperm Count/Infertility, Complications of Diabetes, Sunburn Prevention, Acute Anterior Uveitis , Rheumatoid Arthritis, Diabetic Neuropathy , Cataracts, Macular Degeneration, Osteoarthritis, Restless Legs Syndrome, Vascular Dementia, PMS, Sports Performance, HIV Support, Amyotrophic Lateral Sclerosis, Fibrocystic Breast Disease , Parkinson's Disease, Asthma, Acne, Dupuytren's Contracture, Gout, Fibromyalgia, Psoriasis, Menopause, Intermittent Claudication, Nutritional Support for Smokers

Vitamin E is an antioxidant that fights damaging natural substances known as free radicals. It works in lipids (fats and oils), which makes it complementary to vitamin C, which fights free radicals dissolved in water.

There is some evidence that vitamin E can help prevent certain forms of cancer. Vitamin E has also shown considerable promise for preventing preeclampsia (a complication of pregnancy), treating tardive dyskinesia (a side effect of antipsychotic drugs), improving immunity, slowing the progression of Alzheimer's disease, and improving male fertility. However, contrary to earlier indications, vitamin E does not appear to prevent heart disease, at least in those at high risk for it.

Requirements/Sources

Vitamin E dosage recommendations are a bit complex, because the vitamin exists in many forms.

New vitamin E recommendations are in milligrams (mg) of alpha-tocopherol. Alpha-tocopherol can come from either natural vitamin E (called, somewhat incorrectly, d-alpha-tocopherol) or synthetic vitamin E (called, also somewhat incorrectly, dl-alpha-tocopherol). However much of the alpha-tocopherol in synthetic vitamin E is inactive. For this reason, you have to take about twice as much of it to get the same effect.^1,2,3

There are other forms of vitamin E as well, such as beta-, delta-, and gamma-tocopherols, all of which occur in food. These other forms may be important; for example, preliminary evidence suggests that gamma-tocopherol may be the most important form of vitamin E for preventing prostate cancer.⁴ On this basis, it has been suggested that the best vitamin E supplement would be a mixture of all these.^5,6,7

To make matters even more confusing, vitamin E dosages are commonly listed on labels as international units (IU). Here's how you make the conversion. One IU natural vitamin E equals 0.67 mg alpha-tocopherol; one IU synthetic vitamin E equals 0.45 mg alpha-tocopherol. Therefore, to meet the new dietary recommendations for vitamin E (15 mg per day), you need to get either 22 IU natural vitamin E (22 IU x 0.67 = 15 mg) or 33 IU synthetic vitamin E (33 IU x 0.45 = 15 mg). The official U.S. and Canadian recommendations for daily intake of vitamin E are as follows:

• Infants 0–6 months, 4 mg
  7–12 months, 5 mg
• Children 1–3 years, 6 mg
  4–8 years, 7 mg
  9–13 years, 11 mg
• Males and females 14 years and older, 15 mg
• Pregnant women, 15 mg
• Nursing women, 19 mg

In developed countries, dietary deficiency of vitamin E is relatively common.^8,9,10 In addition, bile acid sequestrants might inhibit absorption of vitamin E.¹¹

The best food sources of vitamin E are polyunsaturated vegetable oils, seeds, nuts, and whole grains. To get a therapeutic dosage, though, you need to take a supplement.

Therapeutic Dosages

The optimal therapeutic dosage of vitamin E has not been established. Most studies have used between 50 and 800 IU daily, and some have used even higher doses. This would correspond to about 50 to 800 mg of synthetic vitamin E (dl-alpha-tocopherol), or 25 to 400 mg of natural vitamin E (d-alpha- or mixed tocopherols).

Note: In general, IUs rather than mg are used in the following discussion, as that was the most commonly used measurement at the time the studies were performed.

If you wish to purchase natural vitamin E, look for a label that says "mixed tocopherols." However, some manufacturers use this term to mean the synthetic dl-alpha-tocopherol, so you need to read the contents closely. Natural tocopherols come as d-alpha-, d-gamma-, d-delta-, and d-beta-tocopherol.

Therapeutic Uses

Although observational studies suggest that higher intake of vitamin E is associated with reduced risk of various forms of cancer as well as cardiovascular disease,^{82-84,86,104-107,144,145} large double-blind trials have failed to find evidence of benefit for any of these conditions other than prostate cancer.^{75-78,81,96-102,146}

Tardive dyskinesia consists of involuntary movements of the face, arms, and head, usually caused by the long-term use of antipsychotic drugs. Vitamin E appears to reduce symptoms of this disorder.^29–33 However, not all studies agree.

When combined with vitamin C, vitamin E appears to help prevent sunburn.^34–38 There is also evidence that vitamin E in combination with vitamin C (and the standard drug treatment) may be helpful for acute anterior uveitis. This condition involves painful inflammation of the iris of the eye, with acute sensitivity to light, increased ocular pressure, and a loss of visual clarity; it most often occurs in conjunction with autoimmune diseases. While acute anterior uveitis usually responds to conventional treatment after 10 to 14 days, vision problems may persist. In one study, the use of vitamin E (alpha-tocopherol) at 100 mg twice daily and vitamin C at a dose of 500 mg twice daily improved vision after 8 weeks as compared to placebo.³⁹Note: Acute anterior uveitis is a potentially dangerous condition. Physician supervision is mandatory.

Vitamin E may be helpful for cardiac autonomic neuropathy, a complication of diabetes.⁴⁰

Intriguing evidence suggests that vitamin E may also prevent preeclampsia,⁴¹ improve immunity,⁴² slow the progression of Alzheimer's disease,⁴³ decrease symptoms of menstrual pain,¹³⁹ reduce pain in rheumatoid arthritis and possibly help prevent it,^{44,45,147-149} improve symptoms of diabetic neuropathy,^46,47 and help protect people with diabetes from developing damage to their eyes and kidneys.⁴⁸ Vitamin E may also be helpful in treating male infertility,⁴⁹ although a double-blind study of 31 individuals found no benefit.⁵⁰ Weaker evidence suggests that vitamin E can prevent cataracts,^51–54 improve blood sugar control in people with type 2 diabetes,^55,56,57 help prevent or treat macular degeneration, control symptoms of restless legs syndrome,⁵⁹ help prevent vascular dementia,⁶⁰ and reduce symptoms of PMS.^61,62

There is also some evidence that vitamin E may be useful during weight training.^63,64 Heavy exercise produces free radicals that can disrupt the muscles and cause pain. Vitamin E appears to exert a protective effect in this regard. However, while vitamin E has been suggested as a treatment to prevent symptoms that can occur after endurance running, such as gastrointestinal bleeding, stomach cramps, nausea, or muscle injury, one double-blind trial found no significant benefit for any of these symptoms.⁶⁵

Additionally, vitamin E might help reduce the lung-related side effects caused by the drug amiodarone (used to prevent abnormal heart rhythms).⁶⁶

In one observational study, high intake of vitamin E was linked to decreased risk of progression to AIDS in HIV infected people.⁶⁷ However, a double-blind study of 49 people with HIV who took combined vitamins C and E or placebo for 3 months did not show any significant effects on the amount of HIV virus detected or the number of opportunistic infections.⁶⁸ It has been suggested that vitamin E may enhance the antiviral effects of AZT, but evidence for this is minimal.⁶⁹

Vitamin E has been tried for amyotrophic lateral sclerosis (Lou Gehrig's disease), but the results showed questionable benefits if any.¹³⁷

Vitamin E does not appear to be helpful for fibrocystic breast disease.⁷⁰ In addition, despite some claims to the contrary, supplemental vitamin E does not seem to be helpful for treating Parkinson's disease.^71,72,73 Vitamin E and other antioxidants are frequently recommended for asthma, on the grounds that they may protect inflamed lung tissue, but there is no scientific evidence that they work. Similarly, although vitamin E has been suggested as a treatment for acne, Dupuytren's contracture, gout, fibromyalgia, and psoriasis, there is no real supporting evidence for any of these uses.

Although vitamin E is often recommended for menopausal hot flashes, there is no real evidence that it is effective. One 9-week, double-blind, placebo-controlled trial followed 104 women with hot flashes associated with breast cancer treatment, but it found marginal benefits at best.⁷⁴

Vitamin E is sometimes recommended for osteoarthritis.  However, a 6-month, double-blind, placebo-controlled trial of 77 individuals with osteoarthritis found that treatment with vitamin E at dose of 500 IU daily failed to provide any benefit as compared to placebo.¹³⁸

Vitamin E has been proposed as a treatment for congestive heart failure, but a small, double-blind study did not find it effective.⁸⁰

What Is the Scientific Evidence for Vitamin E?

Cancer Prevention

The results of observational trials have been mixed, but on balance, they suggest that high intake of vitamin E is associated with reduced risk of many forms of cancer, including stomach, mouth, throat, laryngeal, lung, liver and prostate cancer.^{83–84,86,144,145} The evidence regarding colon cancer is mixed.^87–95

However, the results of observational studies are unreliable as guidelines to treatment. The results of intervention trials are far more persuasive in drawing conclusions about cause and effect.

One intervention trial provides evidence that taking vitamin E supplements can help prevent prostate cancer. In this double-blind trial of 29,133 smokers, 50 mg of synthetic vitamin E (dl-alpha-tocopherol) daily for 5 to 8 years caused a 32% reduction in the incidence of prostate cancer and a 41% drop in prostate cancer deaths.⁸¹

Surprisingly, results were seen soon after the beginning of supplementation. This was unexpected because prostate cancer grows very slowly. A cancer that shows up today actually started to develop many years ago. The fact that vitamin E almost immediately lowered the incidence of prostate cancer suggests that it somehow blocks the step at which a hidden prostate cancer makes the leap to being detectable.

An observational study suggests that gamma-tocopherol may be even more helpful for preventing prostate cancer.⁸² Intervention trials are under way to determine whether supplementation with this form of vitamin E may be helpful.

Intervention trials of vitamin E supplements have not found benefit for preventing lung cancer.^76,77,78

Cardiovascular Disease

Most but not all observational studies have found associations between high intake of vitamin E and reduced risk of cardiovascular disease.^{104–107,150,151} However, as noted in the previous section, observational studies by themselves cannot be relied upon to identify useful treatments. Intervention trials, which provide much more convincing evidence of effectiveness, have generally failed to find vitamin E supplements effective.

The Heart Outcomes Prevention Evaluation (HOPE) trial found that natural vitamin E (d-alpha-tocopherol) at a dose of 400 IU daily did not reduce the number of heart attacks, strokes, or deaths from heart disease any more than placebo.⁹⁶ The details of this well-designed, double-blind trial were published in the January 20, 2000, issue of The New England Journal of Medicine. The trial followed over 9,000 men and women who had existing heart disease or were at high risk for it.

In addition, a large open trial compared the effectiveness of aspirin and vitamin E for the prevention of heart attacks, strokes, and other diseases related to atherosclerosis.⁹⁸ While aspirin treatment proved dramatically helpful, vitamin E had little-to-no benefit.

Negative results were seen in other large trials, as well.^{99–102,129,152,153}

The Cambridge Heart Antioxidant Study (CHAOS) trial,¹⁰³ published in 1996, is what really raised researchers' hopes. In that trial, people with existing heart disease who took natural vitamin E (400 IU or 800 IU daily) had substantially fewer nonfatal heart attacks compared to the placebo group after about 1.5 years. Even so, heart-related deaths were not reduced in the vitamin E group. Furthermore, it has been suggested that possible flaws in the design of this trial might make its findings questionable.

It has been suggested that another form of vitamin E (gamma-tocopherol) might be more helpful than the vitamin E used in these trials (alpha-tocopherol).^140-142,154 Gamma-tocopherol is present in the diet much more abundantly than alpha-tocopherol, and it could be that the studies showing benefits with dietary vitamin E actually tracked the influence of gamma-tocopherol. However, an observational study specifically looking to see if gamma-tocopherol levels were associated with risk of heart attack found no relationship between the two.¹⁴³ Nonetheless, intervention trials of gamma-tocopherol are currently underway.

Preeclampsia Prevention

Preeclampsia is a dangerous complication of pregnancy that involves high blood pressure, swelling of the whole body, and improper kidney function. A double-blind, placebo-controlled study of 283 women at increased risk for preeclampsia found that supplementation with vitamin E (400 IU daily of natural vitamin E) and vitamin C (1,000 mg daily) significantly reduced the chances for developing this disease.¹¹²

While this research is promising, larger studies are necessary to confirm whether vitamins E and C will actually work. The authors of this study point out that studies of similar size found benefits with other treatments, such as aspirin, that later proved to be ineffective when large-scale studies were performed. Furthermore, keep in mind that we don't know whether such high dosages of these vitamins are absolutely safe for pregnant women.

Tardive Dyskinesia

Between 1987 and 1998, at least five double-blind studies were published which indicated that vitamin E was beneficial in treating TD.^113,114 Although most of these studies were small and lasted only 4 to 12 weeks, one 36-week study enrolled 40 individuals.¹¹⁵ Three small double-blind studies reported that vitamin E was not helpful.^116,117 Nonetheless, a statistical analysis of the double-blind studies done before 1999 found good evidence that vitamin E was more effective than placebo.¹¹⁸ Most studies found that vitamin E worked best for TD of more recent onset.¹¹⁹

However, in 1999, the picture on vitamin E changed with the publication of one more study—the largest and longest to date.¹²⁰ This double-blind study included 107 participants from nine different research sites who took 1,600 IU of vitamin E or placebo daily for at least 1 year. In contrast to most of the previous studies, this trial did not find vitamin E effective in decreasing TD symptoms.

Why the discrepancy between this study and the earlier ones? The researchers, some of whom had worked on the earlier, positive studies of vitamin E, were at pains to develop an answer.^121,122 They proposed a number of possible explanations. One was that the earlier studies were too small or too short to be accurate, and that vitamin E really didn't help at all. Another was the most complicated: that vitamin E might help only a subgroup of people who had TD—those with milder TD symptoms of more recent onset—and that fewer of these people had participated in the latest study. They also pointed to changes in schizophrenia treatment since the last study was done, including the growing use of antipsychotic medications that do not cause TD.

The bottom line: The effectiveness of vitamin E for a given individual is simply not known. Given the lack of other good treatments for TD, and the general safety of the vitamin, it may be worth discussing with your physician.

Immunity

One double-blind study suggests that vitamin E may be able to strengthen immunity. In this trial, 88 people over the age of 65 were given either placebo or vitamin E at 60 IU, 200 IU, or 800 IU dl-alpha-tocopherol daily.¹²³ The researchers then gave all participants immunizations against hepatitis B, tetanus, diphtheria, and pneumonia, and looked at subjects' immune response to these vaccinations. The researchers also used a skin test that evaluates the overall strength of the immune response.

The results were promising. Vitamin E at 200 mg per day and, to a lesser extent, at 800 mg per day significantly increased the strength of the immune response.

Alzheimer's Disease

Preliminary evidence suggests that high-dose vitamin E may slow the progression of Alzheimer's disease.¹²⁴ In a double-blind placebo-controlled study, 341 subjects received either 2,000 IU daily of vitamin E (dl-alpha-tocopherol), the antioxidant drug selegiline, or placebo. Those given vitamin E took nearly 200 days longer to reach a severe state of the disease than the placebo group. (Selegiline was even more effective.)

Warning: Such high dosages of vitamin E should not be taken except under a doctor's supervision (see Safety Issues).

Dysmennorhea (Menstrual Pain)

In a double-blind, placebo-controlled trial, 100 young women complaining of significant menstrual pain were given either 500 IU of vitamin E or placebo for five days.¹³⁹ Treatment began two days before and continued for three days after the expected onset of menstruation. While both groups showed significant improvement in pain over the two months of the study (presumably due to the power of placebo), pain reduction was greater in the treatment group as compared to the placebo group.

Low Sperm Count/Infertility

In a double-blind placebo-controlled study of 110 men whose sperm showed subnormal activity, treatment with 100 IU of vitamin E daily resulted in improved sperm activity and higher actual fertility (measured in pregnancies).¹²⁵ However, a smaller double-blind trial found no benefit.¹²⁶ 

Complications of Diabetes

Individuals with diabetes sometimes develop irregularities of their heart-beat called cardiac autonomic neuropathy. A 4-month double-blind placebo-controlled trial found that vitamin E at a dose of 600 mg daily might improve these symptoms.¹²⁷

Safety Issues

The adult safe upper intake level (UL) for vitamin E is set at 1,000 mg daily.¹²⁸ The equivalent amounts are 1,500 IU of natural vitamin E and 1,100 IU of synthetic vitamin E. (For technical reasons, the conversion factor is a bit different than in the daily intake recommendations above.) For pregnant women under 19 years of age, the upper limit is 800 mg.

Vitamin E has a "blood-thinning" effect that could lead to problems in certain situations. In one study of 28,519 men, vitamin E supplementation at the low dose of about 50 IU synthetic vitamin E per day caused an increase in fatal hemorrhagic strokes, the kind of stroke caused by bleeding.¹²⁹ (However, it reduced the risk of a more common type of stroke,¹³⁰ and the two effects essentially canceled out.) Based on its blood-thinning effects, there are concerns that vitamin E could cause problems if it is combined with medications that also thin the blood, such as Coumadin (warfarin), heparin, Plavix (clopidogrel), Ticlid (ticlopidine), Trental (pentoxifylline), and aspirin. Theoretically, the net result could be to thin the blood too much, causing bleeding problems. A study that evaluated vitamin E plus aspirin did in fact find an additive effect.¹³¹ In contrast, the results of a study on vitamin E and Coumadin found no evidence of interaction, but it would still not be advisable to combine these treatments except under a physician's supervision.¹³²

There is also at least a remote possibility that vitamin E could also interact with supplements that possess a mild blood-thinning effect, such as garlic, policosanol, and ginkgo. Individuals with bleeding disorders such as hemophilia, and those about to undergo surgery or labor and delivery should also approach vitamin E with caution.

In addition, vitamin E might enhance the body's sensitivity to its own insulin in individuals with adult-onset diabetes.^133,134 This could lead to risk of blood sugar levels falling too low. If you are taking oral hypoglycemic medications, do not take high-dose vitamin E without first consulting your physician.

Finally, considerable controversy exists regarding whether it is safe or appropriate to combine vitamin E with standard chemotherapy drugs.¹³⁵ The reasoning behind this concern is that many chemotherapy drugs work in part by creating free radicals that destroy cancer cells. Antioxidants like vitamin E might interfere with this beneficial effect. However, there is also some evidence that vitamin E might help protect against the side effects of certain chemotherapy drugs without interfering with their action.¹³⁶ Nonetheless, in view of the high stakes involved, we strongly recommend that you do not take any supplements while undergoing cancer chemotherapy, except on the advice of a physician.

Interactions You Should Know About

If you are taking

• Blood-thinning drugs, such as Coumadin (warfarin),heparin, Plavix (clopidogrel), Ticlid (ticlopidine), Trental (pentoxifylline), or aspirin: Seek medical advice before taking vitamin E.
• Amiodarone: Vitamin E may help protect you from lung-related side effects.
• Phenothiazine drugs:Vitamin E may help reduce side effects.
• Chemotherapy drugs: Seek medical advice before taking vitamin E.
• Oral hypoglycemic medications: High-dose vitamin E might cause your blood sugar levels to fall too low, requiring an adjustment in medication dosage.

Last reviewed August 2002 by Medical Review Board

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