Clinical Summary From MSK website:
(RB, see bold italics below)
Derived from plant oils and various foods. Patients use vitamin E to prevent and treat heart disease, cancer, diabetes, and Alzheimer's disease. Natural food sources include plant oils, wheat germ, eggs, green leafy vegetables, and whole grains (
3). Vitamin E acts as an antioxidant, preventing the propagation of free-radical reactions and protecting polyunsaturated fatty acids within membrane phospholipids. Although sold in a variety of formulations, only the d-isomer is considered active (
1). A recent analysis of seven brands of commercially available vitamin E revealed actual content to vary considerably from the labeled dosage (
5). Most research describes vitamin E in terms of milligrams, but most products are sold in international units (IU). The conversion is 1 IU natural vitamin E equals 0.67 mg d-alpha-tocopherol and 1 IU of synthetic vitamin E equals 0.45 mg d-alpha-tocopherol. Studies evaluating vitamin E supplementation suggest that it may reduce the risk of some cancers (
19) (
20), improve immune response in the elderly, and slow the progression of Alzheimer's disease (
9) (
15) (
16) (
18). However, 200mg of vitamin E per day has no effect on reducing the incidence of acute respiratory tract infection (
12). In addition, a meta-analysis of seven randomized trials showed that Vitamin E provided no benefit in mortality, nor reduced the risk of cardiovascular death or cerebrovascular accident when compared with control treatment (
26). Nor was it effective in arresting the development or progression of macular degeneration (
14) and Early Parkinson's Disease (
21). Vitamin E supplementation also has been shown to reduce the incidence of cisplatin induced neurotoxicity (
22). One clinical trial shows that vitamin E is more effective than a placebo in reducing hot flashes in breast cancer survivors (
27). There are no significant adverse effects associated with vitamin E, although toxicity may occur with chronic supplementation of doses greater than 800 IU. Daily supplementation over 400 IU may increase all-cause mortality (
29). A recent review of 14 clinical trials shows that supplementation with antioxidants beta-carotene, vitamins A, C, and E does not seem to prevent gastrointestinal cancer and may actually increase overall mortality (
28). Data from a large, multicenter Prostate, Lung, Colorectal, and Ovarian Cancer Screening trial also suggests that antioxidant supplementation may not lower the risk of prostate cancer (
31).
Vitamin E was recently found in a study to increase the risk of a second primary cancer in the first few years following supplementation. Researchers also suggest that it may interfere with radiation therapy (30). Vitamin E may also enhance the activity of warfarin, but data are inconsistent (
7) (
8). PT and INR should be monitored when vitamin E supplementation is initiated or discontinued in patients receiving warfarin. A clinical trial in women on HRT with coronary artery disease shows an increased risk of death and nonfatal myocardial infarction in patients who took Vitamin C and Vitamin E supplements (
13).
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Food Sources
Plant-derived oils (wheat germ, soybean, sunflower, almond, safflower, corn), wheat germ, liver, eggs, nuts and seeds, green leafy vegetables, whole grains (
1) (
2)
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Purported uses