Selenium is extremely toxic, similar to arsenic. Both are necessary micronutrients in mammalian biology but this requirement is easily satisfied by traces in wa

Selenium is extremely toxic, similar to arsenic. Both are necessary micronutrients in mammalian biology but this requirement is easily satisfied by traces in water and soil entering the food supply. Deficiency typically only occurs at the intersection of significant medical issues limiting the ability to absorb them and consuming food limited to the rare locales where soil and water is unusually depleted in these elements and therefore absent from the food supply. Supplementing selenium carries risk with very little reward. It is unlikely that you need more selenium than you are already getting with a normal, modern diet.