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Other name(s):

selenious acid, selenium methylselenocysteine, selenomethionine, sodium selenite

General description

Selenium is an essential trace element and antioxidant. It’s a cofactor in enzyme regulation. It also plays a role in maintaining the health of tissue and muscle. Selenium may help treat and prevent prostate cancer. It may be especially helpful in prostate cancer.

Selenium has antioxidant properties. It may serve some of the same antioxidant functions as vitamin E.

Medically valid uses

Selenium is needed to maintain the circulatory system. It also keeps the heart muscle and skin tissue healthy. It may also help treat and prevent cancer.

Selenium compounds, such as selenium sulfide, are used topically in some shampoos. It’s used in this form to treat seborrhea and dandruff.

Unsubstantiated claims

Please note that this section reports on claims that have not yet been substantiated through studies.

Selenium may prevent aging of the skin. It also slows the aging process. It’s also said to enhance immune system function. It may also protect against heart disease. It may also bind to heavy metals and reduce the toxicity of mercury.

Recommended intake

Selenium is measured in micrograms (mcg). It’s available as 50–200 mcg tablets. The RDA is the Recommended Dietary Allowance.



Infants (0 to 6 months)

15 mcg*

Infants (7 months to 1 year)

20 mcg*

Children (1–3 years)

20 mcg

Children (4–8 years)

30 mcg

Children (9–13 years)

40 mcg

Children (14–18 years)

55 mcg

Adults (19 years and older)

55 mcg

Pregnant women

60 mcg

Breastfeeding women

70 mcg

*Adequate Intake (AI)

Food source

Nutrient content per 100 grams

Wheat germ

106.6 mcg

Brazil nuts

96 mcg

Whole wheat bread

63 mcg


53.3 mcg

Brown rice

36.6 mcg

Orange juice

18.3 mcg

*mcg = microgram

The amount of selenium in vegetables and grains depends on the soil in which they are grown.

Selenium is suggested in doses of no more than 200 mcg per day. The treatment range for selenium is narrow. You shouldn’t take too much selenium. The recommended dose for therapeutic reasons is 100–200 mcg per day.

Selenium deficiency can cause symptoms. These can include lightening of fingernail beds, muscle weakness, and muscle discomfort. In parts of the world where selenium isn’t found in the soil and water, people may develop Keshan disease. This is a form of cardiomyopathy. This condition is weakness of the heart muscle. Selenium deficiency has also been linked with Kwashiorkor. This is a protein malnutrition.

Side effects, toxicity, and interactions

Consuming selenium from normal dietary sources doesn’t seem to cause side effects. Consuming more than 200 mcg of selenium per day for a long period of time may cause side effects. These can include itchy skin, diarrhea, and weakening and loss of fingernails, hair, and teeth. Other symptoms can include nausea, vomiting, peripheral neuropathy, and fatigue. Selenium can also cause your breath to have a garlic-like odor.

Adults who work in industrialized areas with high selenium content have a higher chance of liver and heart disease.

Even though optimal amounts of selenium may reduce the risk of cancer, consuming too much can be harmful. It may increase the risk for cancer.

Women who are pregnant or breastfeeding should talk to their healthcare providers before taking any supplements. Too much selenium can lead to bone and cartilage problems in unborn babies.

Kidney problems can cause high selenium levels in the body.

There are no known food interactions with selenium. It can interact with some antibiotics. It can also interact with some medicines used to treat osteoporosis.

Talk to your healthcare provider about selenium before taking it.



Online Medical Reviewer: Poulson, Brittany, RD, CDE
Online Medical Reviewer: Wilkins, Joanna, R.D., C.D.
Date Last Reviewed: 8/1/2016