Selenium is a mineral essential to human health. It is involved in thyroid and immune function. Due to low requirements, intake is typically within the recommended range.
Selenium supplements have shown associations with multiple health outcomes, though the results are inconclusive. Results include: increased diabetes risk, increased skin cancer risk, reduced prostate cancer risk, improved male fertility. Excessive intake may lead to symptoms including hair and nail loss, skin lesions, digestive issues, and liver, kidney, and heart problems.
Supplementing with selenium when consuming a diet rich in fish and animal products can increase risk of excessive intake. Similarly, caution should be taken when consuming Brazil nuts: one ounce may contain over 700% of the recommended intake.
Fish, shellfish, beef, poultry, brazil nuts, walnuts, grains
University of Maryland Medical Center
Food and Chemical Toxicology
The Lancet
De Gruyter
The Lancet 2
Self Nutrition Data
Live Science