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Selenium is a trace element that's important for the body's immune system and for reproduction.

Although selenium is available as a supplement, people who eat meat, fish, eggs or Brazil nuts should be able to get all the selenium they need from a balanced healthy diet.

Selenium uses

Selenium has attracted attention because of its antioxidant properties. Antioxidants protect cells from damage. There is some evidence that selenium in food may reduce the risk of prostate cancer, but more research is needed.

It remains unclear whether selenium can reduce the risk of other forms of cancer as research has provided conflicting results. Beware: taking selenium supplements appears to increase the risk of non- melanoma skin cancer.

Some health conditions - such as HIV, Crohn's disease and others - are associated with low selenium levels. People who are fed intravenously are also at risk of low selenium. Doctors sometimes suggest that people with these conditions use selenium supplements.

Selenium has also been studied for the treatment of dozens of conditions, ranging from asthma to arthritis to dandruff to infertility. However, the results have been inconclusive.

Selenium dose and instructions for use

Adults need the following amounts of selenium every day:

  • Men: 0.075mg
  • Women: 0.06mg

Taking too much selenium can be harmful. However, taking up to 0.35mg of selenium supplements a day is unlikely to cause any harm.

Selenium supplement information

Selenium supplements may be sold as tablets, capsules or topical treatments. Like any supplement, keep selenium supplements in a cool, dry place, away from humidity and direct sunlight.

Selenium warnings

  • Side effects. Taken at normal doses, selenium does not usually have side effects. An overdose of selenium may cause bad breath, fever, nausea, and liver, kidney and heart problems. At very high levels, selenium could cause death.
  • Interactions. Selenium may also interact with other medicines and supplements, such as antacids, chemotherapy drugs, corticosteroids, niacin, cholesterol-lowering statin drugs and oral contraceptives.
  • Skin cancer. Selenium supplements are associated with a risk of non-melanoma skin cancer so people at high risk of skin cancer should not take these supplements.


WebMD Medical Reference

Medically Reviewed by Dr Rob Hicks on July 29, 2015

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