Condition
    Strong Evidence
    Effectiveness 1/5

    Selenium for Prostate Cancer

    Selenium showed no preventive benefit for prostate cancer in SELECT, and higher baseline selenium was linked to worse outcomes in some analyses.

    Overview

    Selenium showed no preventive benefit for prostate cancer in SELECT, and higher baseline selenium was linked to worse outcomes in some analyses.

    Verdict

    Not supported

    A well-tested hypothesis that failed clearly.

    How It Works

    Selenoproteins including glutathione peroxidase reduce oxidative damage, which was the rationale; supplementation in already-replete populations provides no additional substrate.

    Dosing & Protocol

    Typical dose

    Recommended dose
    Not recommended for prevention
    Expected timeframe
    Not applicable.

    Protocol

    form
    n/a
    notes
    Narrow safety margin — avoid stacking multiple selenium-containing products
    duration
    n/a
    starting dose
    Not recommended for prevention

    Evidence

    What the studies say

    SELECT found no reduction in prostate cancer incidence with 200μg of selenomethionine daily across more than 35,000 men. Secondary analyses suggested that men with already-high baseline selenium status who supplemented had an increased risk of high-grade disease. Earlier positive signals came from the NPC trial, where prostate cancer was a secondary endpoint in a selenium-replete-deficient population, and did not replicate. Selenium supplementation is also associated with increased type 2 diabetes risk in some analyses.

    Selenium supplementation, baseline plasma selenium status and incidence of prostate cancer: an analysis of the complete treatment period of the Nutritional Prevention of Cancer Trial

    Score: 7/10
    2003
    rct
    n=1312

    Duffield-Lillico AJ, Dalkin BL, Reid ME +5 more

    Selenium reduced prostate cancer incidence only in men in the lowest tertile of baseline plasma selenium.

    View source

    Effect of Selenium and Vitamin E on Risk of Prostate Cancer and Other Cancers: The Selenium and Vitamin E Cancer Prevention Trial (SELECT)

    Score: 10/10
    2009
    rct
    n=35533

    Lippman SM, Klein EA, Goodman PJ +30 more

    Selenium 200 mcg/day did not prevent prostate cancer, and a non-significant increase in type 2 diabetes risk was observed in the selenium arm.

    View source

    Vitamin E and the risk of prostate cancer: the Selenium and Vitamin E Cancer Prevention Trial (SELECT)

    Score: 9/10
    2011
    rct
    n=35533

    Klein EA, et al

    Selenium supplementation showed no benefit on prostate cancer risk compared with placebo.

    View source

    Selenium for preventing cancer

    Score: 10/10
    2018
    systematic_review
    0

    Vinceti M, Filippini T, Del Giovane C +7 more

    Randomised evidence shows no reduction in cancer incidence or mortality with selenium supplementation, alongside increased risk of type 2 diabetes.

    View source

    Selenium and Vitamin E Cancer Prevention Trial (SELECT): null and adverse findings

    Score: 10/10
    2011
    rct
    n=35533

    Klein EA, Thompson IM, Tangen CM +18 more

    Selenium provided no protective benefit against prostate cancer

    View source

    Vitamin E and the Risk of Prostate Cancer: The Selenium and Vitamin E Cancer Prevention Trial (SELECT) updated follow-up

    Score: 10/10
    2011
    rct
    n=35533

    Klein EA, Thompson IM, Tangen CM +18 more

    Extended follow-up showed vitamin E increased prostate cancer risk by 17 percent, while selenium alone conferred no protection.

    View source

    Safety

    Caveats

    Selenium has a narrow therapeutic window; chronic intake above 400μg daily causes selenosis with hair and nail loss and neuropathy. Associated with increased diabetes risk.

    Less likely to help if

    Men in selenium-replete populations, which includes most high-income countries.

    Medical Disclaimer

    The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.

    Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.