Vitamin E Usage

Observational studies raised hopes that vitamin E supplements could help prevent various forms of cancer as well as heart disease . ¹ However, observational studies are notoriously unreliable for determining the effectiveness of treatments. Only double-blind trials can do that (for information why, see Why Does This Database Rely on Double-blind Studies? ), and such studies have, on balance, found vitamin E ineffective for preventing heart disease or any common form of cancer other than, possibly, prostate cancer. ² . In fact, use of high-dose vitamin E for a long period might slightly increasedeath rate. ³ Other potential uses of vitamin E have limited supporting evidence.

Intriguing but far from definitive studies suggest that vitamin E might improve immune response to vaccinations, ⁴ decrease symptoms of menstrual pain , ⁵ reduce symptoms of premenstrual syndrome (PMS) , ⁶ control symptoms of restless legs syndrome , ⁷ and help prevent deep venous thrombosis (DVTs) . ⁸ While there is weak evidence that vitamin E supplements can reduce discomfort in rheumatoid arthritis, ⁹ there is strong evidence that it does not prevent it. ¹⁰ Although preliminary studies hinted that use of vitamin E might prevent or slow the progression of cataracts , ^{11 12 13} in a 10-year study of almost 40,000 female healthcare professionals, use of natural vitamin E at a dose of 600 mg every other day failed to have any effect on cataract development. ¹⁴ Evidence regarding whether vitamin E can slow the progression of Alzheimer's disease is inconsistent. ¹⁵ A very large study failed to find vitamin E helpful for preventing mental decline (resulting from any cause) in women over 65. ¹⁶ Studies of vitamin E in combination with vitamin C for prevention of preeclampsia have yielded inconsistent results. ¹⁷ Vitamin E has also shown equivocal promise in diabetes. One double-blind trial found benefits for cardiac autonomic neuropathy , ¹⁸ a complication of diabetes. Weaker evidence hints at possible benefits for diabetic peripheral neuropathy . ¹⁹ However, the best-designed study of all, a long-term trial involving 3,654 people with diabetes, found that use of vitamin E did not protect against diabetes-induced kidney or heart damage. ²⁰ Similarly, while a few studies performed by one research group suggested that vitamin E might be helpful for improving glucose control in people with diabetes, ^{21 22} subsequent evidence found that the benefits, if they exist at all, are limited to the short-term. ²³ In addition, in an extremely large double-blind study, use of vitamin E at a dose of 600 IU every other day failed to reduce risk of participants developing type 2 diabetes. 202 Finally, a study unexpectedly found that when people with diabetes took 500 mg of vitamin E daily (either as natural alpha tocopherol or a mixture of alpha and gamma tocopherol), their blood pressure increased. ²⁴ Similarly, studies on whether vitamin E is helpful for allergic rhinitis (hay fever) have produced conflicting results. ²⁵ A small double-blind study conducted in Iran reported that vitamin E (400 IU daily) was more effective than placebo for treating menopausal hot flashes . ²⁶ However, a larger US study failed to find vitamin E significantly helpful for hot flashes associated with breast cancer treatment. ²⁷ Vitamin E might help reduce the lung-related side effects caused by the drug amiodarone (used to prevent abnormal heart rhythms). ²⁸ A trial of 108 patients undergoing chemotherapy cisplatin found that vitamin E supplementation (extended 3 months past chemotherapy) reduced cisplatin-related neurotoxicity (damage to nerves not uncommonly occuring with cisplatin). ²⁹ Studies have yielded mixed results on whether vitamin E is helpful for controlling seizures in people with epilepsy , ^{30 31 32} reducing symptoms of tardive dyskinesia , ^{33 34 35 36} aiding recovery during heavy exercise , ³⁷ and treating male infertility . ³⁸ When combined with vitamin C , vitamin E may protect against sunburn to a small extent. ^{39 40 41 42} The same combination has also shown promise for acute anterior uveitis . ⁴³ A separate study failed to find vitamin E alone (at the high dose of 1,600 mg daily) helpful for macular edema (swelling of the center of the retina) associated with uveitis. ⁴⁴ Vitamin E has been tried for amyotrophic lateral sclerosis (Lou Gehrig's disease), but the results in the first reported double-blind study showed questionable benefits if any. ⁴⁵ Some vitamin E proponents felt that the dose of vitamin E used in this study might have been too low. Accordingly, they conducted another study using 10 timesthe dose, this one lasting 18 months and enrolling 160 people. ⁴⁶ Once again, vitamin E failed to prove significantly more effective than placebo.

In one observational study, high intake of vitamin E was linked to decreased risk of progression to AIDS in people with HIV infection. ⁴⁷ 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. ⁴⁸ It has been suggested that vitamin E may enhance the antiviral effects of AZT, but evidence for this is minimal. ⁴⁹ Vitamin E has been suggested for preventing the cardiac toxicity caused by the drug doxorubicin . However, while it has shown promise in animal studies, when studied in people vitamin E has persistently failed to prove effective for this purpose. ^{50 51 52} Vitamin E is sometimes recommended for osteoarthritis . However, a 2-year, double-blind, placebo-controlled study of 136 people with osteoarthritis of the knee failed to find any benefit in terms of symptom control or slowing disease progression. ⁵³ A previous 6-month, double-blind, placebo-controlled trial of 77 individuals with osteoarthritis also failed to find benefit. ⁵⁴ A 4-year, double-blind, placebo-controlled trial of 1,193 people with macular degeneration failed to find vitamin E alone helpful for preventing or treating macular degeneration. ⁵⁵ Vitamin E has also so far failed to prove helpful for preventing or treating alcoholic hepatitis , ⁵⁶ asthma , ⁵⁷ congestive heart failure , ⁵⁸ fibrocystic breast disease , ⁵⁹ or Parkinson's disease . ^{60 61} In a very large study involving over 29,000 male smokers, researchers failed to find benefit of alpha-tocopherol (50 IU/day), beta-carotene (20 mg/day), or the two taken together for the prevention of type 2 diabetes over 5-8 year period. ⁶²