While you don't need much selenium, just 55 micrograms per day, if you don't get enough of this mineral it could cause major health problems. It isn't hard to get plenty of selenium in your diet since seafood, meat, eggs, grains, dairy products, Brazil nuts and sunflower seeds are all good sources of selenium. However, if you are a very picky eater, have certain health problems or live in an area where there isn't much selenium in the soil, you may need to take supplements to avoid a deficiency.
Decreased Immune Function
Your immune system won't work as well if you don't have enough selenium in your body. Selenium may help you make more of the white blood cells you need for fighting infections and illnesses. A study published in "The American Journal of Clinical Nutrition" in July 2004 found that when people with low levels of selenium took selenium supplements their immune function improved.
Impaired Thyroid Function
Selenium helps regulate thyroid hormones, so your thyroid function may become impaired if you don't get enough selenium in your diet. Selenium deficiency may also cause thyroid damage that could increase your risk for autoimmune thyroid disorder, according to a study published in "Minerva Medica" in December 2008.
Keshan Disease and Kashin-Beck Disease
Keshan disease and Kashin-Beck disease are two health conditions associated with low levels of selenium. Keshan disease causes heart damage that can be prevented, but not cured, by improving your selenium levels, and Keshin-Beck disease is a type of degenerative arthritis that affects children in areas where selenium levels are low but which may be caused by other factors, according to the Linus Pauling Institute.
Some medications can interfere with selenium absorption and make you more likely to become deficient. These include corticosteroids, some types of chemotherapy medications, valproic acid, clozapine and gold salts. Smoking cigarettes, drinking alcohol or taking birth control pills could make you more likely to have low levels of selenium, as can ulcerative colitis and Crohn's disease.