Supplement analysis backed by scientific evidence · PT

← All supplements
Limited evidenceLongevity & antioxidants

Vitamin E

Vitamin E deficiency is essentially nonexistent in people who eat food, and as a supplement it has failed nearly every large prevention trial ever run on it — including one that found more prostate cancer. The only defensible uses are niche: biopsy-proven NASH, and weakly, slowing functional decline in Alzheimer's.

What the science says

  • Does not prevent cancer — and increased prostate cancer risk Limited evidence

    SELECT randomised 35,533 healthy men to 400 IU/day of synthetic alpha-tocopherol; with extended follow-up the vitamin E group had significantly MORE prostate cancer (HR 1.17, 99% CI 1.004-1.36, P=0.008), an absolute excess of about 1.6 cases per 1,000 person-years. No large trial has shown a cardiovascular or cancer benefit from vitamin E supplements.

  • High doses (400+ IU/day) may modestly increase all-cause mortality Limited evidence

    A dose-response meta-analysis of 19 trials (135,967 participants) found a pooled all-cause mortality risk difference of +39 per 10,000 people in trials using 400 IU/day or more (95% CI 3 to 74, P=0.035), with no excess at lower doses. The signal is contested and the trials were mostly in chronically ill populations — but with no demonstrated upside, there is nothing to offset it.

  • Improves liver histology in non-diabetic NASH Moderate evidence

    In the PIVENS trial (247 non-diabetic adults, 96 weeks), 800 IU/day of natural alpha-tocopherol improved NASH histology in 43% of patients versus 19% on placebo (P=0.001), with reductions in steatosis (P=0.005) and lobular inflammation (P=0.02) but no improvement in fibrosis. This is one good trial in one specific population, and it is why guidelines mention vitamin E at all.

  • May slightly slow functional decline in mild-to-moderate Alzheimer's Limited evidence

    TEAM-AD randomised 613 patients for a mean 2.3 years; 2,000 IU/day alpha-tocopherol slowed ADCS-ADL decline by 3.15 units versus placebo (95% CI 0.92-5.39), roughly 19% less functional loss. Memantine and the combination showed no benefit. A single trial, at a dose double the tolerable upper limit.

Dosage & safety

Studied doseRDA is 15 mg/day alpha-tocopherol — about 22 IU of natural d-alpha-tocopherol or 33 IU of synthetic dl-alpha-tocopherol. Trial doses far exceed this: 800 IU/day for NASH, 2,000 IU/day in the Alzheimer's trial, 400 IU/day in the failed prevention trials. Tolerable upper limit is 1,000 mg/day (about 1,500 IU natural). Natural d-alpha-tocopherol has roughly twice the bioavailability of the synthetic form; mixed tocopherol and tocotrienol products have essentially no clinical outcome data.
SafetyDoses of 400 IU/day and above are not benign: increased prostate cancer in SELECT, increased haemorrhagic stroke in ATBC and Physicians' Health Study II, and antiplatelet effects that raise bleeding risk. Clinically significant interactions with warfarin, DOACs, aspirin and clopidogrel; very high doses can also antagonise vitamin K-dependent clotting. Stop at least 2 weeks before surgery. Avoid in people with bleeding disorders or on anticoagulants without medical supervision. True deficiency is confined to fat-malabsorption syndromes, abetalipoproteinemia and rare genetic transport defects — not to ordinary diets.

Scientific references

Where to buy

Swanson Vitamins, Vitamin E Mixed Tocopherols, 134 mg (200 IU), 100 Softgels

View on iHerb

Referral link — this site may earn a commission on purchases.

Related in Longevity & antioxidants