Selenium for preventing cancer

Study answer

What this study found

Overall, selenium supplements did not provide convincing cancer prevention benefit, and regular supplementation cannot be recommended on current evidence. In SELECT, selenium alone did not reduce prostate cancer risk versus placebo (HR 1.04, 95% CI 0.90 to 1.18) or total cancer incidence (HR 1.01, 95% CI 0.89 to 1.15), and selenium plus vitamin E was similarly null for prostate cancer (HR 1.05, 95% CI 0.91 to 1.20). The NPCT main trial reported lower total cancer incidence (adjusted HR 0.75, 95% CI 0.58 to 0.97) and cancer mortality (adjusted HR 0.59, 95% CI 0.39 to 0.87), but also increased…

Study & population

Systematic review of prospective observational studies and six randomized controlled trials assessing selenium exposure or selenium supplementation for cancer prevention in adults.

Intervention

The randomized evidence evaluated oral selenium supplementation in several forms and doses, including selenium yeast 200 µg/day in the main NPCT trial, 400 µg/day in a NPCT sub-study, sodium selenite 0.5 mg/day for 3 years, selenium yeast 200 µg/day for 2 to 4 years, and L-selenomethionine 200 µg/day in SELECT for a…

Key limitation

The evidence was heterogeneous in populations, baseline selenium status, selenium species, dose, and follow-up duration, which limits comparability across trials.

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Original abstract