Selenium (Se) is one of the essential trace elements in human body, with a very narrow concentration range from sufficient to deficient or toxic (Olmedo et al. 2013, Sun et al. 2013). Selenium deficiency can lead to anemia, coronary heart disease, Kashin-beck disease, diabetes, and more than 40 other diseases (Rayman 2000). High levels of Se can, however, also cause chronic toxic symptoms, such as cirrhosis, liver cancer, tooth, hair and nail loss, eye irritation, and paralysis (Bem 1981, Najafi et al. 2012).