Benefits & Potential Harmful Effects of Selenium

Selenium is a mineral that the human body requires in small amounts. It helps prevent cell damage and offers other health benefits. Selenium is contained in a variety of commonly-consumed foods and in supplement form.

Definition

• Selenium is a trace mineral that is incorporated into proteins (called selenoproteins) to create antioxidant enzymes that prevent cell damage caused by free radicals. Certain types of selenoproteins also support thyroid function and the immune system.

Benefits

• In addition to its antioxidant and immunity-boosting properties, selenium seems to trigger the body's production of antibodies after vaccines are administered. It may also protect against toxicity caused by exposure to heavy metals and other dangerous substances. In addition, selenium may increase sperm production and sperm movement in men.

Side Effects

• Excess amounts of selenium can cause hair loss, nausea, irritability, fatigue, limited nerve damage and brittle nails. The National Academy of Science's Institute of Medicine recommends that adults take no more than 400 mcg per day.

  Although rare in the United States, selenium deficiency can cause a heart muscle abnormality called Keshan disease, joint and bone disease and mental retardation. Pregnant women may need higher amounts than other adults. People who are fed intravenously for long periods of time or have digestion problems may have trouble absorbing selenium.

Recommended Daily Dose

• Infants: 15-20 mcg*
  Children: 20-40 mcg
  Adolescents/Adults: 55 mcg

  *mcg = micrograms

Sources

• Selenium is found in many food staples, including corn, wheat and soybeans; Brazil nuts contain a particularly high amount (544 mcg per ounce). Tuna, beef and brewer's yeast are also good sources, and it is available in vitamin and individual supplement form.