Selenium is a mineral that is important in the body for the production of selenoprotein, which are enzymes, as stated by Healthline. Because some of these enzymes are antioxidants, selenium has antioxidant properties that can help against the damaging effects of free radicals in the body. Selenium is also necessary for the proper functioning of the thyroid and immune system, notes the University of Maryland Medical Center.
Selenium may have various medical uses associated with it. For example, doctors may recommend its use when there is a selenium deficiency in patients with conditions that include HIV, Crohn's disease, or require intravenous feeding, reports WebMD. Although rare, other people without these health issues can be deficient in selenium if they do not get an adequate amount through diet.
Most people can get a sufficient amount of selenium by eating foods that are good sources of this essential mineral, including brewer's yeast, salmon, tuna, Brazil nuts and sunflower seeds. The recommended dietary allowance required for adults over the age of 19 is 55 micrograms per day. Although it is important to get this amount each day to stay healthy, high doses can be toxic. The safe upper limit for selenium is 400 micrograms per day, and any dose above this level can lead to an overdose.
Additionally, there are side effects and drug interactions possible with the use of selenium. When taken in high doses, it can cause side effects, such as the feeling tired, loss of weight and nausea. Similarly, selenium can have interaction with anticoagulants, barbiturates, certain chemotherapy drugs and corticosteroids, according to the University of Maryland Medical Center.