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    Ingredient guide · Ingredient reference

    Vitamin E and prostate cancer: what SELECT found and what it did not show

    In SELECT, the specified high-dose vitamin E regimen increased prostate-cancer diagnoses compared with placebo. The finding concerns that intervention, not all vitamin-E-containing foods.

    Read the evidence ↓

    Supplement Science Insights Editorial Team

    Published September 23, 2026

    A defined supplement-prevention question

    NCI’s SELECT summary describes a trial involving more than 35,000 men, funded primarily by NCI and conducted by SWOG. Eligibility began at age 50 for African-American men and 55 for other participants. The study tested supplements for prevention, not treatment of existing prostate cancer. [1]

    The vitamin E intervention was 400 IU daily of synthetic dl-alpha-tocopheryl acetate, alone or with selenium, compared with placebo groups. The population, form and amount should remain attached to any interpretation. [1]

    Relative risk is not the same as percentage-point change

    NCI reports that after an average of seven years, the vitamin-E-only group had a 17% relative increase in prostate-cancer diagnoses compared with placebo. Its illustration gives 76 cases per 1,000 men versus 65 per 1,000, a difference of 11 per 1,000 over that period. [1]

    The follow-up included approximately 5.5 years taking the supplements and 1.5 years after they had stopped. A 17% relative increase does not mean that 17 additional men in every 100 developed cancer. [1]

    Keep the denominator visible

    Imagine a reader sees only the phrase “17% increase.” Using NCI’s illustration, subtracting 65 from 76 gives 11 additional diagnoses per 1,000 men, or 1.1 percentage points over the stated period.

    That arithmetic explains the trial summary. It is not an individualized risk prediction for a person with a different age, exposure or follow-up.

    Hypothetical example — understanding the reported risk
    ObservationInterpretation
    Placebo illustration65 diagnoses per 1,000 men
    Vitamin E illustration76 diagnoses per 1,000 men
    Absolute difference11 per 1,000 over the stated follow-up

    Do not generalize the finding to every source of vitamin E

    NCI advises against taking vitamin E or selenium supplements for cancer prevention on the basis of the trial evidence. This does not establish that ordinary vitamin-E-containing foods cause the same effect as the tested regimen. [1]

    This page reports NCI’s explanation rather than an independent trial reappraisal. It does not verify all author disclosures or corrections, and it makes no claim that every vitamin E preparation has been studied equivalently. [1]

    Vitamin E and prostate cancer: what SELECT found and what it did not show — original article outline diagram
    Original editorial diagram of this article’s sections; no product photograph or clinical finding is depicted.

    Sources for this article

    1. NCI — SELECT: Questions and Answers
      Source consulted: 2026-09-17. This is a reference resource, not a claim that we conducted the studies or tested a product.