Selenium and Cancer Prevention: A Critical Appraisal of the Evidence
Rayman MP
Published in British Journal of Nutrition
Abstract
Critical review of selenium and cancer prevention. SELECT trial showed no benefit in selenium-replete populations, but several trials in deficient populations showed reduced cancer incidence. Protective effects strongest when baseline selenium low. U-shaped dose-response - benefits at 100-200mcg, potential harm above 400mcg daily. Emphasizes importance of baseline status and avoiding excess.
Methodology
Critical appraisal of epidemiological studies and randomised trials of selenium status, supplementation and cancer incidence, including analysis of baseline status as an effect modifier.
Key Findings
Protective associations were concentrated in populations with low baseline selenium, while trials in selenium-replete populations showed no cancer benefit. The dose-response appears U-shaped, with plausible benefit in the region of 100-200 mcg daily and evidence of harm, including raised type 2 diabetes risk and selenosis, at higher intakes. Baseline status, not dose alone, determines whether supplementation is plausible.
Conclusions
Blanket selenium supplementation for cancer prevention is not supported; any potential benefit is confined to deficient populations, and intakes above roughly 400 mcg daily carry real risk.
Limitations
Appraisal of heterogeneous observational data and a limited number of trials with differing selenium forms, doses and baseline status; observational components subject to confounding, and later large trials such as SELECT reinforced the null result in replete populations.
Supplements Studied
Protective associations were concentrated in populations with low baseline selenium, while trials in selenium-replete populations showed no cancer benefit. The dose-response appears U-shaped, with plausible benefit in the region of 100-200 mcg daily and evidence of harm, including raised type 2 diabetes risk and selenosis, at higher intakes. Baseline status, not dose alone, determines whether supplementation is plausible.
Related Health Concerns
Study Details
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This information is for educational purposes only. Always consult a healthcare professional before starting any supplement regimen.