If you look at the list of vitamins and minerals on your multivitamin, you might find selenium there. Selenium is a “trace mineral” — one that your body needs, but only in very small amounts.
What does selenium do for the body? This mineral is used by proteins in the body to make antioxidants called selenoproteins. Antioxidants are good things — they help prevent cell damage from free radicals. Selenoproteins also help the immune system function and assist in regulating thyroid function.
Many people get their necessary selenium from foods — plant foods in particular. The selenium content of grains and plants depends on the selenium content of the soil where the plants are grown. In the United States, soil with the highest selenium content can be found in the high plains of northern Nebraska and North and South Dakota. Selenium can also be found in meats (including seafood) and nuts.
Foods that contain selenium can include: Brazil nuts and walnuts, tuna and cod, oatmeal and rice, bread and pasta, beef and turkey. Levels of selenium can vary widely, depending on where the food was grown or what the animals were fed.
The recommended daily allowance for selenium is 55 micrograms per day for ages fourteen and up. Children between the ages of nine and thirteen should have 40 micrograms per day, and children under the age of nine should get 30 micrograms or less.
A national study of diets in the 1980s and 1990s indicated that the majority of Americans get the selenium they need from diet alone, and don’t need a supplement. However, people with severe or chronic digestive disorders (such as Crohn’s disease) may need a selenium supplement. Gastrointestinal problems can impair selenium absorption. People with widespread inflammation and/or infection may also have decreased levels of selenium in the blood. Selenium deficiency can also worsen the effects of iodine deficiency, so doctors may suggest a selenium supplement.
Selenium supplements may contain organic selenium (from grains) or inorganic selenium. A 1995 study found that taking supplements with organic selenium increased amounts of selenium in the blood better than supplements with inorganic selenium.