Vitamin E supplements: no heart or cancer benefit, and a harm signal

Vitamin E supplements do not prevent heart disease or cancer, and at high doses they may do harm. The large randomised trials built to confirm the vitamin's promise came back null, and a meta-analysis tied doses of 400 IU a day or more to a small increase in all-cause mortality [s1][s2]. For most people the case for taking it is not thin or mixed — it is negative.

The antioxidant promise

Vitamin E is a fat-soluble antioxidant, and for years that biochemistry, plus observational studies of people who chose to take it, made it look like a plausible shield against the diseases driven by oxidative stress. Supplement use on that reasoning is widespread: the US Preventive Services Task Force notes that 52 percent of surveyed US adults reported taking at least one dietary supplement in the previous 30 days, and 31 percent a multivitamin, most often for general health and to fill perceived nutrient gaps [s4]. The way to test whether that reasoning holds is not another observational study of self-selected users but a randomised trial, and several large ones were done.

The trials that tested it

The HOPE-TOO trial gave 400 IU a day of natural-source vitamin E or placebo to patients at least 55 years old with vascular disease or diabetes, and followed them for a median of 7.0 years [s2]. It found no benefit on any primary outcome: cancer incidence carried a relative risk of 0.94 (95 percent confidence interval 0.84 to 1.06), cancer deaths 0.88 (0.71 to 1.09), and major cardiovascular events 1.04 (0.96 to 1.14) [s2]. What it did find was a signal in the wrong direction — a higher risk of heart failure (relative risk 1.13, 95 percent confidence interval 1.01 to 1.26) and of hospitalisation for heart failure (1.21, 1.00 to 1.47) in the vitamin E group [s2].

The Women's Health Study tested the question in healthier people: 39,876 apparently healthy US women aged at least 45, given 600 IU of natural-source vitamin E on alternate days or placebo, over an average of 10.1 years [s3]. Vitamin E did not lower major cardiovascular events (relative risk 0.93, 95 percent confidence interval 0.82 to 1.05), total cancer (1.01, 0.94 to 1.08) or total mortality (1.04, 0.93 to 1.16), and had no effect on heart attack or stroke individually [s3]. The one bright spot was a 24 percent reduction in cardiovascular death (relative risk 0.76, 0.59 to 0.98), an isolated secondary finding in an otherwise flat trial, and not enough for the authors to recommend the supplement [s3].

The mortality signal

The most-cited concern came from pooling the trials together. A meta-analysis of 135,967 participants across 19 randomised trials — with vitamin E doses ranging from 16.5 to 2,000 IU a day, median 400 — found that high-dosage trials (400 IU a day or more) tended to increase deaths [s1]. The pooled all-cause mortality risk difference in the high-dose trials was 39 extra deaths per 10,000 people (95 percent confidence interval 3 to 74; P = 0.035), while low-dose trials showed no such effect (−16 per 10,000; −41 to 10) [s1]. Nine of the 11 high-dose trials pointed the same way, and a dose-response analysis found a statistically significant rise in mortality above 150 IU a day [s1].

That result has real limits, which the authors stated plainly: the high-dose trials were often small and enrolled patients who already had chronic disease, so how well the finding generalises to healthy adults is uncertain, and the exact threshold at which risk begins is hard to pin down [s1]. It is a caution, not a proven poison. But it is the opposite of the benefit the supplement was sold on.

The prostate-cancer turn

The clearest harm came later, and from the largest trial. In the Selenium and Vitamin E Cancer Prevention Trial (SELECT), men taking 400 IU a day of vitamin E alone had a significantly raised risk of prostate cancer — a hazard ratio of 1.17 (99 percent confidence interval 1.004 to 1.36) — the reverse of what the antioxidant hypothesis predicted [s5]. We cover that trial, and the parallel selenium story, in selenium and cancer prevention.

What the guidelines say

The verdict has moved from research into formal advice. In 2022 the US Preventive Services Task Force recommended against the use of beta carotene or vitamin E supplements for the prevention of cardiovascular disease or cancer — a "D" recommendation, meaning it judges the harms to outweigh any benefit [s4]. That puts vitamin E in the same category as beta-carotene, and alongside the negative supplement stories for vitamin C and vitamin D in healthy adults.

How to read this

Frank vitamin E deficiency is rare and mostly affects people with fat-malabsorption disorders; for nearly everyone else the vitamin comes adequately from foods such as nuts, seeds and vegetable oils, and the gap that a pill is sold to fill is not there. This article is informational and is not medical or dietary advice; anyone managing a diagnosed deficiency should discuss it with a qualified clinician.