A meta-analysis of 12 studies with a total of 13,254 participants and 5,007 cases of prostate cancer (PCa) showed that prostate cancer (PCa) risk decreased with increasing plasma/serum selenium up to 170 ng/mL.

Three high-quality studies of toenail selenium and cancer risk indicated a reduction in prostate cancer risk (estimated relative risk: 0.29) with a toenail selenium concentration between 0.85 and 0.94 µg/g, investigators reported in The American Journal of Clinical Nutrition (2012;96:111-122).