Selenium for Preventing Cancer

The review updated previous findings on selenium's role in cancer prevention, analyzing 55 observational studies with over 1,100,000 participants and 8 RCTs with 44,743 participants. Observational studies suggested a lower cancer incidence and mortality with higher selenium exposure, particularly for stomach, bladder, and prostate cancers, but these results were limited by study design and quality. RCTs showed no clear evidence that selenium supplementation reduced cancer risk or mortality, with some trials indicating potential harmful effects, such as increased risk of type 2 diabetes, alopecia, and dermatitis. Overall, no convincing evidence supported selenium supplements as a preventive measure against cancer in humans.