This major review of 10 randomized controlled trials involving over 27,000 people found that selenium supplements did not reduce cancer risk. In fact, the data showed no meaningful difference between people taking selenium and those taking a placebo—the summary risk ratio was 1.01, meaning selenium supplements were essentially neutral for cancer prevention.

Researchers systematically reviewed randomized controlled trials and observational studies published through early 2017, pooling data from high-quality studies to determine if selenium supplements could prevent cancer in adults.

Funding not disclosed in abstract