Live Well Vitamins & Lifestyle Guide

Selenium

Selenium is a mineral found in the soil.  Selenium naturally appears in water and some foods.  While people only need a very small amount, selenium plays a key role in the metabolism.

Selenium Uses

Selenium has attracted attention because of its antioxidant properties. Antioxidants protect cells from damage.  There is some evidence that selenium supplements may reduce the odds of prostate cancer. Selenium does not seem to affect the risk of colorectal or lung cancer. But beware: selenium also seems to increase the risk of non-melanoma skin cancer.

Among healthy people in the U.S., selenium deficiencies are uncommon. But 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 for 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. They range from asthma to arthritis to dandruff to infertility.  However, the results have been inconclusive.

Selenium Dose and Instructions for Use

The recommended dietary allowance (RDA) includes the total amount of selenium you should get from foods and from any supplements you take. Most people can get their RDA of selenium from food.

In studies supporting the use of selenium for prostate cancer prevention, men took 200 micrograms daily.

The safe upper limit for selenium is 400 micrograms a day in adults.  Anything above that is considered an overdose.

Selenium Food Sources

Good natural food sources of selenium include:

• Nuts, like Brazil nuts and walnuts
• Many fresh and salt-water fish, like tuna, cod, red snapper, and herring
• Beef and poultry
• Grains

Whole foods are the best sources of selenium.  The mineral may be destroyed during processing.

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 high enough 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 birth control pills.
  
  
• Skin cancer.  Selenium supplements are associated with a risk of skin cancer (squamous cell carcinoma), so people at high risk of skin cancer should not take these supplements.
  
  
• Diabetes.  One study found that people who took 200 micrograms a day of selenium were 50% more likely to develop type 2 diabetes.  So far, it's unknown if the selenium actually caused the disease.  Discuss the risk with your doctor.