Function

Selenium is a trace mineral. The body only needs it in small amounts.

Selenium helps the body with:

• Making special proteins, called antioxidant enzymes, which play a role in preventing cell damage
• Helping your body protect you after a vaccination

Some medical studies suggest that selenium may help with the following conditions, but more studies are needed:

• Prevent certain cancers
• Prevent cardiovascular disease
• Help protect the body from the poisonous effects of heavy metals and other harmful substances
• Boost fertility, especially among men. The mineral has been shown to improve the production of sperm and sperm movement.

Food Sources

Plant foods, such as vegetables, are the most common dietary sources of selenium. How much selenium is in the vegetables you eat depends on how much of the mineral was in the soil where the plants grew.

Fish, shellfish, red meat, grains, eggs, chicken, liver, and garlic are all good sources of selenium. Meats produced from animals that ate grains or plants found in selenium-rich soil have higher levels of selenium.

Brewer's yeast, wheat germ, and enriched breads are also good sources of selenium.

Side Effects

Selenium deficiency is rare in people in the United States. However, selenium deficiency may occur when a person is fed through a vein (IV line) for long periods of time.

Keshan disease is caused by a lack of selenium. This leads to an abnormality of the heart muscle. Keshan disease caused many childhood deaths in China until the link to selenium was discovered and selenium supplements were provided.

Two other diseases have been linked to selenium deficiency:

• Kashin-Beck disease, which results in joint and bone disease
• Myxedematous endemic cretinism, which results in mental retardation

Severe gastrointestinal disorders may also affect the body's ability to absorb selenium.

Too much selenium in the blood can cause a condition called selenosis. Selenosis can cause hair loss, nail problems, nausea, irritability, fatigue, and mild nerve damage. However, selenium toxicity is rare in the United States.

Recommendations

The Recommended Dietary Allowance (RDA) for vitamins reflects how much of each vitamin most people should get each day. The RDA for vitamins may be used as goals for each person.

How much of each vitamin you need depends on your age and gender. Other factors, such as pregnancy and illnesses, are also important. Women who are pregnant or breast-feeding need higher amounts. Ask your health care provider which amount is best for you.

Dietary Reference Intakes for selenium:

Infants

• 0 - 6 months: 15 micrograms per day (mcg/day)
• 7 - 12 months: 20 mcg/day

Children

• 1 - 3 years: 20 mcg/day
• 4 - 8 years: 30 mcg/day
• 9 - 13 years: 40 mcg/day

Adolescents and Adults

• Males age 14 and older: 55 mcg/day
• Females age 14 and older: 55 mcg/day

The best way to get the daily requirement of essential vitamins is to eat a balanced diet that contains a variety of foods.

References

Escott-Stump S, ed. Nutrition and Diagnosis-Related Care. 6th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2008.

Sarubin Fragaakis A, Thomson C. The Health Professional's Guide to Popular Dietary Supplements. 3rd ed. Chicago, Il: American Dietetic Association; 2007.

Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academy Press, Washington, DC, 2000.

Update Date: 2/14/2012

Reviewed by: Alison Evert, MS, RD, CDE, Nutritionist, University of Washington Medical Center Diabetes Care Center, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.