Clark and Selenium, 1996

In 1996, Clark et al1 published the results from a double-blind placebo-controlled trial investigating the role of selenium supplements in cancer. In the study, 1312 subjects with a history of non-melanoma skin cancer were randomised to receive either 200 µg per day selenium yeast or a placebo. When the authors analysed the results they found that selenium had no significant effect on non-melanoma skin cancer rates. However, the group being administered the 200 µg per day selenium a had 50 % lower total mortality from cancer, a 37 % lower total cancer incidence, 63 % fewer cases of prostate cancer, 58 % fewer cases of colon cancer and 46 % fewer cases of lung cancer. Those subjects who experienced the greatest benefit from the selenium supplements were the ones in the lowest tertile for plasma selenium (<106 µg/L). Supplementation of this lowest tertile resulted in a 48 % reduction in the risk of cancer.


1Clark, L. C., Combs, G. F., Turnbull, B. W., Slate, E. H., Chalker, D. K., Chow, J., Davis, L. S., Glover, R. A., Graham, G. F., Gross, E. G., Krongrad, A., Lesher, J. L., Park, K., Sanders, B. B., Smith, C. L., Taylor, R. 1996. Effects of selenium supplementation for cancer prevention in patients with carcinoma of the skin. Journal of the American Medical Association. 276: 19571985