Selenium is an essential trace mineral found in Brazil nuts ( 544 mcg per ounce !) sunflower seeds, fish and poultry products , onions and grains. Plants do not require selenium and therefore the content of plant sources varies with the soil content. Brazil nuts are grown in selenium rich soil in Brazil. Selenium content of the body is estimated to be 3-6mg in individuals living in low selenium areas and 13 mg in those living in high selenium areas. It is found mainly in the liver and kidneys.

What does selenium do? 

The major importance of selenium lies in its place in 25 selenium dependent enzymes called selenoproteins. 5 important selenoproteins are

1)  Cellular glutathione peroxidase

2)  Extracellular glutathione peroxidase

3)  Phospholipid hydroperoxide glutathione peroxidase

4)  Gastrointestinal glutathione peroxidase

5)  Olfactory glutathione peroxidase