Selenium is a nutritionally essential element. People need selenium for healthy joints, heart, and eyes. It plays a critical role in DNA synthesis, the immune system, and the reproductive system. It also helps fight cancer and other diseases. Selenium is important to several enzymes, including antioxidant enzymes glutathione peroxidase and thioredoxin reductase and the deiodinase enzymes that convert thyroid hormones into other forms. Selenium salts are used to help control dandruff. Selenium is protective against mercury poisoning. Some plants require high levels of selenium to survive, so the presence of those plants means the soil is rich in the element. Disruption of the intracellular balance between free radicals and the antioxidant system is a prominent and early feature in the neuropathology of Alzheimer's disease (AD). Selenium, a vital trace element with known antioxidant potential, has been reported to provide neuroprotection through resisting oxidative damage bu