Selenium is found mainly in meat, fish, seafood, mushrooms, lentils, asparagus and Brazil nuts.

Selenium (symbol Se) is an essential trace element. It is a component of all body tissues and is only required in small amounts.

Selenium is present in selenium-dependent enzymes (selenoproteins), which are involved in the production and metabolism of thyroid hormones (see also iodine). Selenium is also an important antioxidant, protects against free radicals and is a building block of sperm.