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Selenium is a chemical element of atomic number 34, which is a gray crystalline nonmetal and is commonly found in the soil. This supplement has attracted attention because of its antioxidant properties and the nutritionally essential role in reproduction, thyroid hormone metabolism, DNA synthesis, and protection from oxidative damage and infection. Selenium is available in multivitamin/multi-mineral supplements and as a stand-alone supplement. (via National Institutes of Health)


The recommended dietary allowance (RDA) of selenium for adult females and males who are 19-50 years old, and 50 plus years old, is 55 micrograms. For pregnant women, 60 micrograms is the RDA, and 70 micrograms are allowed during lactation.

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Selenium is commonly found in foods in the American diet, but the content is largely dependent on location and soil condition. Whole foods have the best sources of selenium since they are not processed. Here are a list of common items that it is found in:

  • Nuts
  • Seafood and organ meats
  • Beef and poultry
  • Grains

If you’re interested in learning more about the amount of selenium in each food item, the National Institutes of Health Office of Dietary Supplements has a chart on their website of common foods with its selenium content. Click here to check it out!

According to the NIH, “selenium deficiency produces biochemical changes that might predispose people who experience additional stresses to develop certain illnesses”, and might be associated with the development of Keshan disease and male infertility. (via NIH) When taken at a normal dose, selenium does not usually have any side effects, but at an overdose, it may cause minor side effects such as bad breath, fever, nausea, and possibly liver and heart problems.

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Taking selenium supplements might interfere with other medicines and supplements such as antacids, chemotherapy drugs, corticosteroids, niacin, cholesterol-lowering statin drugs, and birth control pills. Those who have a high risk of developing skin cancer, prostate cancer and diabetes should not take selenium supplements. (via WebMD)

In the United States and Canada, selenium deficiency is very rare. Even in regions with low-selenium levels, people are still able to get adequate amounts of this element with no critical complications. Those who are the most likely to have inadequate levels of selenium are people going undergoing kidney dialysis, people living with HIV, and people who are living in selenium-deficient areas (on top of other factors).

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