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 has attracted attention because of its antioxidant properties. Antioxidants protect cells from damage. Most recent scientific research has found that selenium does not reduce the risk of prostate cancer.
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.
- 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 medications 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.