The Cochrane group looked at 55 studies that included over a million people.
Despite anecdotal reports of selenium's cancer powers, the investigators found no proof of a protective effect against skin cancer or prostate cancer. And taking selenium over a long period of time could have toxic effects, they found.
Lead author Dr Gabriele Dennert, of the Institute for Transdisciplinary Health Research in Germany, said: "We could find no evidence to recommend regular intake of selenium supplements for cancer prevention in people whether or not they already have enough selenium."
Small amounts of selenium are essential for health and help build a strong immune system to fight off infections and diseases. Many foods, including brazil nuts, tuna and pasta, contain selenium.