Results of at least five large observational studies suggest that increased vitamin E consumption is associated with decreased risk of heart attack (‘myocardial infarction’) or death from heart disease in both men and women (91). Each prospective study measured vitamin E consumption in presumably healthy people and followed them for a number of years to determine how many were diagnosed with or died as a result of heart disease. In two of the studies, individuals who consumed more than 7 mg/day alpha-tocopherol in food were only approximately half as likely to die from heart disease as those who consumed less than 3 –5 mg/day alpha-tocopherol (11),(12). Two other large studies found a significant reduction in risk of heart disease only in women and men who consumed at least 100 IU supplemental RRR-alpha-tocopherol (67 mg RRR-alpha-tocopherol) daily (13),(14).
A randomized, placebo-controlled trial in 39,876 women participating in the Women's Health Study found that supplementation with 600 IU RRR-alpha-tocopherol (400 mg RRR-alpha-tocopherol) every other day for ten years had no effect on the incidence of various cardiovascular events (myocardial infarction and stroke), but the vitamin E intervention decreased cardiovascular-related deaths by 24% (15).
Analysis of data from the Women's Health Study also showed that women receiving the vitamin E intervention experienced a 21% reduction in risk of blockage of blood flow in veins by a blood clot (‘thromboembolism’) (16).
However, other randomized clinical trials cast doubt on the efficacy of vitamin E supplements to prevent cardiovascular disease. For example, the Heart Outcomes Prevention Evaluation (HOPE) study and its follow-up HOPE-TOO found that participants taking 400 IU/day natural vitamin E were not protected from cardiovascular problems such as heart attacks, strokes, or heart failure (17),(18).
The benefits of vitamin E supplementation in chronic disease prevention are discussed in a more recent review (19).
Several observational studies have examined the association between antioxidant vitamin E consumption and the incidence and severity of cataracts, which appear to be formed by protein oxidation in the lens of the eye.
Results of these studies are mixed: some report that increased vitamin E intake protects against cataract development, while others report no association (95, 96).
Two placebo-controlled trials in men and women found that daily antioxidant supplements containing vitamin C, synthetic vitamin E, and beta-carotene did not affect development and progression of age-related cataracts over a 5- to 7-year period (21),(22). A 4-year randomized, placebo-controlled trial reported that supplements containing 500 IU/day natural vitamin E (335 mg RRR-alpha-tocopherol) did not reduce the incidence or progression of cataracts in older adults (23).
Vitamin E (alpha-tocopherol) has been shown to enhance specific aspects of the immune response that appear to decline as people age.
For example, elderly adults given 200 mg/day synthetic alpha-tocopherol (equivalent to 100 mg of RRR-alpha-tocopherol) for several months showed increased formation of antibodies supporting immune function in response to hepatitis B vaccine and tetanus vaccine (24).
A randomized, placebo-controlled trial in elderly nursing home residents reported that daily supplementation with 200 IU synthetic alpha-tocopherol (equivalent to 90 mg RRR-alpha-tocopherol) for one year significantly lowered the risk of contracting upper respiratory tract infections, especially the common cold, but had no effect on lower respiratory tract (lung) infections (25).
More research is needed to determine whether supplemental vitamin E may protect the elderly against the common cold or other infections (e.g., flu).
The ability of vitamin E (alpha-tocopherol) to neutralize the damaging oxidizing effects of free radicals has made it the subject of a number of cancer prevention studies, as many types of cancer are thought to result from oxidative damage to DNA.
Several large prospective studies failed to find significant associations between alpha-tocopherol intake and the incidence of lung or breast cancer (4).
One study in a group of 77,126 men and women reported that current smokers using vitamin E supplements over a 10-year period had an increased risk of lung cancer (26).
A randomized, placebo-controlled trial in 39,876 women participating in the Women's Health Study found that supplementation with 600 IU RRR-alpha-tocopherol (400 mg RRR-alpha-tocopherol) every other day for ten years had no effect on overall cancer incidence or cancer-related deaths (15). This vitamin E intervention also did not affect the incidence of tissue-specific cancers, including breast, lung, and colon cancers.
Moreover, a meta-analysis of 12 randomized controlled trials concluded that vitamin E supplementation was not associated with overall cancer incidence, cancer mortality, or total mortality (27).
To date, most clinical trials have found that vitamin E supplementation has no effect on the risk of various cancers.
A placebo-controlled intervention study that was designed to look at the effect of alpha-tocopherol supplementation on lung cancer development noted a 34% reduction in the incidence of prostate cancer in smokers given daily supplements of 50 mg synthetic alpha-tocopherol (equivalent to 25 mg of RRR-alpha-tocopherol) (28). A meta-analysis that combined the results of this study with three other randomized controlled trials associated vitamin E supplement use with a 15% lower risk of prostate cancer (27).
However, a large randomized, placebo-controlled intervention study using alpha-tocopherol and selenium supplementation (the SELECT trial), alone or in combination, was recently halted because there was no evidence of benefit in preventing prostate cancer (29). After an average of 5.5 years of follow-up in the SELECT trial, participants taking vitamin E (400 IU/day all-rac-alpha-tocopherol) alone had a higher risk of prostate cancer, but the increase was not statistically significant (30).
Research suggests that vitamin E might help to prevent Alzheimer’s disease. Since oxidative stress is thought to contribute to the development of Alzheimer’s disease, fat-soluble antioxidants like vitamin E could theoretically exert their antioxidative properties in the brain and prevent oxidative stress.
Clinical studies have suggested that vitamin E supplementation together with vitamin C may prevent the development of Alzheimer’s disease (31).
Authored by Dr Peter Engel in 2010, reviewed and updated by Dr Szabolcs Peter on 18.06.2017