What are the adverse effects of vitamin E toxicity?

Updated: Dec 26, 2017
  • Author: Mark Rosenbloom, MD, MBA; Chief Editor: Michael A Miller, MD  more...
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Answer

Note that these published studies have used only the alpha-tocopherol form of vitamin E and not a balanced mixture of the 8 different forms of vitamin E that naturally occur and have important physiologic functions. Supplementing with only one form of vitamin E has been shown to suppress the other 7 forms, resulting in physiological dysfunction, which may account for some of the negative studies presented here. [23]

Most studies using up to 3200 IU/d of vitamin E did not observe significant acute clinical or biochemical adverse effects. [24] Vitamin E supplementation does not seem to significantly increase or decrease cardiovascular events, [25, 26, 27, 28] although it may increase the risk of mortality. [12, 11]

Vitamin E supplementation was shown to increase the risk of prostate cancer in healthy men, in the Selenium and Vitamin E Cancer Prevention Trial (SELECT). [29]

In the Heart Outcomes Prevention Evaluation (HOPE-TOO) study, a randomized trial examining the effects of 400 IU of vitamin E versus those of a placebo in patients with diabetes or vascular disease, vitamin E did not decrease the incidence of cancer deaths or vascular events during follow-up (mean 7.2 y). Evidence indicated, however, that it did increase the incidence of heart failure. [30, 31, 32, 33, 34, 27, 35, 36]

An increased risk of bleeding has been observed with coadministration of vitamin E and warfarin, with an increased PT due to the depletion of vitamin K–dependent clotting factors. This does not occur in healthy individuals with normal vitamin K levels. Increased gingival bleeding also was observed in patients taking vitamin E and aspirin. [37]

The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study showed that, compared with placebo, alpha-tocopherol at dosages of 50 mg/day increased the risk of fatal subarachnoid hemorrhage by 181% in men aged 50-69 years who smoked cigarettes. The risk of cerebral infarction was decreased by 14% in the vitamin E group, with no significant net effect of vitamin E on mortality from total strokes. These results had not been found in previous studies. [38, 39]


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