What is selenium?

Selenium is an essential micronutrient that both humans and animals depend on in order to stay healthy. It is a so-called trace element, which means that we only need it in microscopic (or trace) quantities to support our health by controlling various biological functions.

In the human body there are 25-30 different selenium-dependent enzymes called selenoproteins. They are assigned to undertake specific functions. Selenoproteins cannot function properly without selenium. Selenoproteins are needed to:

  • support normal function of the immune system
  • support normal thyroid function
  • support normal hair and nails
  • support the production of normal sperm cells
  • support the protection of cells from oxidative stress


Where is selenium found?
Selenium is found in such things as fish, shellfish, nuts (especially Brazil nuts), and whole-grain. People who do not consume these food items on a regular basis may benefit from taking a supplement as a way of ensuring a sufficient selenium intake. The recommended daily allowance (RDA) for selenium is around 50-70 micrograms (guidelines can vary from one country to another). Men generally need a slightly higher selenium intake than women.

Different forms of selenium
Selenium occurs in two forms: Inorganic (selenate and selenite) and organic (selenomethionine and selenocysteine). Selenium in the soil is inorganic, but as soon as plants absorb the selenium, they convert it into organic selenium, which is more readily available to humans. In human (and animal) tissues, most selenium is in the form of selenomethionine that can be embedded in different protein compounds in the body.

Organic selenium compounds are generally absorbed and utilised better in the body. Organic selenium compounds are not reduced when ingested together with vitamin C, which is otherwise the case with inorganic selenium compounds.