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Selenium by Mary Calvagna, MS

Image for selenium 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.

What Does Selenium Do?

Selenium's functions include:

Acting as a co-factor for the antioxidant enzyme glutathione peroxidase
Stimulating immune function
Ensuring proper function of the thyroid gland
Aiding cell growth

How Much Should I Take?

Age Group	Recommended Dietary Allowance micrograms/day (mcg/day)
Age Group	Male	Female
0-6 months	No RDA; Adequate Intake (AI) = 15	No RDA; AI = 15
7-12 months	No RDA; AI = 20	No RDA; AI = 20
1-3 years	20	20
4-8 years	30	30
9-13 years	40	40
14 years and older	55	55
Pregnancy	n/a	60
Lactation	n/a	70

What If I Do Not Get Enough Selenium?

Symptoms of selenium deficiency may include:

Enlarged heart
Heart disease
Bones and joints disease
Altered thyroid function
Intellectual disability
Weak immune system

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:

Garlicky breath
Hair loss
General weakness
Stomach upset
Irritability
White, blotchy nails
Mild nerve damage

Where Can I Find Selenium?

Major food sources of selenium include:

Brazil nuts (from selenium-rich soil)
Shrimp
Crab meat
Salmon
Halibut
Noodles, enriched
Rice, brown
Chicken, pork, and beef
Whole wheat bread

How Can Selenium Affect My Health?

Cancer

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 cancer or to die from cancer if they already have it. However, other studies have not found selenium to be protective for cancers. If selenium affects 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.

Heart Disease

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.

Rheumatoid Arthritis

Free radicals can promote inflammation and destroy cartilage and collagen in joints, contributing to the pain of rheumatoid arthritis . As an antioxidant, selenium can help limit free radical production and therefore ease the pain of arthritis.

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.

RESOURCES:

Academy of Nutrition and Dietetics http://www.eatright.org
United States Department of Agriculture http://www.usda.gov/

CANADIAN RESOURCES:

Canadian Cancer Society http://www.cancer.ca/
Dietitians of Canada http://www.dietitians.ca/

References:

Dietary supplement fact sheet: selenium. Office of Dietary Supplements. National Institutes of Health. National Institutes of Health website. Available at: http://ods.od.nih.gov/factsheets/selenium.asp . Accessed September 19, 2012.
Duyff RL. 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.
Selenium. EBSCO Natural and Alternative Treatments website. Available at: http://www.ebscohost.com/biomedical-libraries/natural-alternative-treatments. Updated July 2012. Accessed September 19, 2012.
Selenium. Oregon State University Linus Pauling Institute website. Available at: http://lpi.oregonstate.edu/infocenter/minerals/selenium/index.html#function. Updated January 22, 2009. Accessed September 19, 2102.
Wardlaw GM, Insel PM. Perspectives in Nutrition . 2nd ed. Mosby: Philadelphia, PA; 1993.
1/13/2009 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). JAMA. 2009;301:39-51. Epub 2008 Dec 9.

Last reviewed September 2012 by Brian Randall, MD

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