Selenium (Se) is an important micronutrient, and when it is present in selenocysteine, it is referred to as the 21st amino acid. Selenocysteine is incorporated in selenoproteins that serve a wide range of biological functions (Fairweather-Tait et al. 2011). However, Se only has a narrow range of safe dietary intake levels for humans; too low dietary intake can lead to deficiency and too high intake leads to toxicity. Generally, Se concentrations in the environment are low, and it has been estimated that up to 1 billion people around the globe have low dietary Se intakes. One of the reasons for low dietary Se levels are low content in food crops, which is due to low concentrations and bioavailability of Se in soils.