Selenium is an essential trace mineral that acts as an
antioxidant—a substance that protects the body's cells against the effects of free radicals. Free radicals are normal by-products of metabolism, but they can cause cell damage. Selenium can function alone or as part of enzyme systems.
What Does Selenium Do?
Selenium's functions include:
Acting as a co-factor for the antioxidant enzyme glutathione peroxidase
Aiding the metabolism of sulfur-containing amino acids
Binding heavy metals and possibly reducing toxicity from mercury contamination
Allowing for normal fetal development during pregnancy
Groups of people who may be at risk for selenium deficiency include:
People living in areas where the soil is very low in selenium, such as parts of China and Russia
People with gastrointestinal disorders, such as
Crohn's disease, that may decrease absorption of selenium
People receiving total parenteral nutrition (TPN); however these people now routinely receive selenium supplementation
Can Too Much Selenium Be Toxic?
The government has set the tolerable upper intake level (UL) for selenium at 400 mcg for people ≥ 14 years of age. Selenium toxicity is rare in the United States. However, when it occurs, symptoms may include:
White, blotchy nails
Mild nerve damage
Where Can I Find Selenium?
The major food sources of selenium are seafood, eggs, and meats, especially organ meats. Seeds and grain products are also good sources. The amount of selenium these plant foods provide depends on the level of selenium in the soil they were grown in. This level varies by region. Fruits and vegetables generally don't have much selenium.
*DV = Daily Value. DVs are reference numbers developed by the Food and Drug Administration (FDA) to help consumers determine if a food contains a lot or a little of a specific nutrient. The DV for selenium is 70 micrograms (ug). Most food labels do not list a food's selenium content. The percent DV (%DV) listed on the table indicates the percentage of the DV provided in one serving. A food providing 5% of the DV or less is a low source while a food that provides 10-19% of the DV is a good source. A food that provides 20% or more of the DV is high in that nutrient. It is important to remember that foods that provide lower percentages of the DV also contribute to a healthful diet. For foods not listed in this table, please refer to the U.S. Department of Agriculture's Nutrient Database Web site: http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl.
Source: Dietary Supplement Fact Sheet: Selenium. Office of Dietary Supplements. National Institutes of Health.
How Can Selenium Affect My Health?
Some studies that have examined selenium intakes and blood selenium levels effect on cancer. Some of these studies have suggested that people with greater intakes of selenium are less likely to develop
or to die from cancer if they already have it. However, other studies have not found selenium to be protective for cancers.
If selenium effects cancer, it is thought to be due to its action as an antioxidant. Also, it may be that selenium helps stimulate the immune system, making it better able to fight cancer.
In population studies, people with low intakes of selenium have been found to have a greater incidence of heart disease, while those with higher selenium intakes have lower risks for heart disease.
Again, selenium's action as an antioxidant is likely the means by which it protects the heart. Selenium and other antioxidants help limit the oxidation of LDL ("bad") cholesterol. This oxidation leads to plaque build-up on artery walls, and subsequently, heart disease.
Free radicals can promote inflammation and destroy cartilage and collagen in joints, contributing to the pain of
As an antioxidant, selenium can help limit free radical production and therefore ease the pain of arthritis. Selenium is also believed to affect other biochemical pathways that lead to arthritis. Studies of people with rheumatic diseases, including arthritis, have found these people to have low tissue levels of selenium.
Tips for Increasing Your Selenium Intake
For a simple lunch, open a can of tuna or salmon and make a sandwich on whole wheat bread.
Choose fish or seafood for dinner 2-3 times per week.
Choose lean meats for entrees.
Select a breakfast cereal that is rich in nutrients. Check the nutrition facts label on the side.
Choose brown rice over white, and whole wheat or rye bread over white.
Dietary supplement fact sheet: selenium. Office of Dietary Supplements. National Iinstitutes of Health. National Institutes of Health website. Available at:
http://ods.od.nih.gov/factsheets/selenium.asp. Accessed July 2, 2010.
The American Dietetic Association's Complete Food & Nutrition Guide
. 3rd ed. John Wiley and Sons, Inc.: Hoboken, NJ; 2006.
Garrison Jr R, Somer E.
The Nutrition Desk Reference
. 3rd ed. Keats Publishing: New Canaan, CT; 1995.
Wardlaw GM, Insel PM.
Perspectives in Nutrition
. 2nd ed. Mosby: Philadelphia, PA; 1993.
¹1/13/2009 DynaMed's Systematic Literature Surveillance
DynaMed's Systematic Literature Surveillance
: Lippman SM, Klein EA, Goodman PJ, et al. Effect of selenium and vitamin E on risk of prostate cancer and other cancers: the Selenium and Vitamin E Cancer Prevention Trial (SELECT).
2009;301:39-51. Epub 2008 Dec 9.
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a