Selenium information, FAQ and product listing page. This page contains information and frequently asked questions about selenium as well as a complete list of products containing selenium.

What is selenium and what does it do?

Selenium is a trace mineral and is important to positive health – even in small amounts. In proteins, selenium is combined to form selenoproteins, antioxidant enzymes. As you may be aware, antioxidants help prevent your body and its cells from free radicals, foreign objects that can enter your body like toxins and cigarette smoke that can cause cancer and health disease.

Selenoproteins also help regular your thyroid function your immune system.

Selenium can be found mainly in plant foods throughout the world. The quantity of selenium found in the soil of a plant depends on where it is grown – same with animals. As an example, scientists and researches know that the ground near North/South Dakota and Nebraska has very high concentrations of selenium. Because of this, the people living in the regions near these areas have the highest intakes of selenium reported in the United States. On the contrary, some parts of Russia and China have very low amounts of selenium – and as expected, these areas have a high percentage of cases of a deficiency in selenium.

In addition, some seafood and various meats can contain selenium. Bread and nuts are also common sources of selenium in the United States.

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What are the benefits of taking selenium?

Selenium could possibly be a strong ally when it comes to fighting cancer. For over 20 years, researchers have believed through animal studies that even tiny amounts of selenium within your diet can help reduce the risk of cancer involving several organs. However, it is unknown if these health benefits translate into humans.

Over the past several years, clinical trials and laboratory experiments have determined that selenium has some type of role in helping the prevention of not only cancer, but cardiovascular diseases, inflammatory disease, neurological diseases, infections, and aging. Most of these benefits have to do with selenium’s antioxidant characteristics.

University of Arizona performed a study in the mid-90s that proved selenium’s positive traits. The study found that individuals that took 200 mcg of selenium a day for almost four years (54 months) reduced their risk of cancer by 32 percent. In addition, patients had their risk from a cancer-related death by 50 percent. Other research has shown that higher blood levels of selenium can lower mortality from cancer like colorectal, prostate, lung, and skin cancer.

Laboratory studies performed on selenium have indicated the possibility for selenium to play a beneficial role in the management of mammary cancer2. Selenium is an antioxidant and not only fights free radicals, but regenerates vitamins C and E which help do the same.

Research also shows that a lower antioxidant status has been linked to higher incidence of cardiovascular diseases due to increased levels of LDL oxidation3,4. Selenium is one of the antioxidants that may help to inhibit LDL oxidation.

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Who can benefit from taking selenium?

Those that have acute severe illnesses that develop inflammation and inflection usually have decreased levels of selenium in their blood system – these can benefit from supplementation. In addition, gastrointestinal disease in particular depletes selenium blood levels. In addition, those with an iodine deficiency can benefit from taking selenium. While iodine deficiency is rare in the United States, it’s still common in other more developing countries.

While specific medical conditions and problems like the ones listed above may provide a reason for using selenium, there is lacking evidence that would recommend selenium supplements for adults and children that are healthy.

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How much selenium should I take?

The required dosage is the Recommended Daily Allowance, or RDA, but you should be aware that this dosage is only the minimum amount that your body requires per day to ward off a serious bout of deficiency. This dosage is 70 mcg per day.

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Does selenium have any side effects?


As long as your thyroid is healthy, selenium is safe to take for at least up to 400 mcg per day. High dosages of selenium have hade side effects reported like nervous system problems, rashes, and fingernail loss.

If you have an iodine-deficiency goiter, selenium may make your thyroid function worse.

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Sources used:Rayman MP. The importance of selenium to human health. Lancet. 2000;356(9225):233-241. Gladyshev VN. Selenoproteins and selenoproteomes. In: Hatfield DL, Berry MJ, Gladyshev VN, eds. Selenium: Its molecular biology and role in human health. 2nd ed. New York: Springer; 2006:99-114.Ursini F, Heim S, Kiess M, et al. Dual function of the selenoprotein PHGPx during sperm maturation. Science. 1999;285(5432):1393-1396. Mustacich D, Powis G. Thioredoxin reductase. Biochem J. 2000;346 Pt 1:1-8. Bianco AC, Larsen PR. Selenium, deiodinases and endocrine function. In: Hatfield DL, Berry MJ, Gladyshev VN, eds. Selenium: Its Molecular Biology and Role in Human Health. 2nd ed. New York: Springer; 2006:207-219.Burk RF, Olson GE, Hill KE. Deletion of selenoprotein P gene in the mouse. In: Hatfield DL, Berry MJ, Gladyshev VN, eds. Selenium: Its Molecular Biology and Role in Human Health. 2nd ed. New York: Springer; 2006:111-122.Arteel GE, Briviba K, Sies H. Protection against peroxynitrite. FEBS Lett. 1999;445(2-3):226-230. Kioussi C, Whanger PD. Selenoprotein W in development and oxidative stress. In: Hatfield DL, Berry MJ, Gladyshev VN, eds. Selenium: Its Molecular Biology and Role in Human Health. 2nd ed. New York: Springer; 2006:135-140.Gu QP, Beilstein MA, Vendeland SC, Lugade A, Ream W, Whanger PD. Conserved features of selenocysteine insertion sequence (SECIS) elements in selenoprotein W cDNAs from five species. Gene. 1997;193(2):187-196.Sword JT, Pope AL, Hoekstra WG. Endotoxin and lipid peroxidation in vitro in selenium- and vitamin E-deficient and -adequate rat tissues. J Nutr. 1991;121(2):258-264.Burk RF, Levander OA. Selenium. In: Shils M, Olson JA, Shike M, Ross AC, eds. Modern Nutrition in Health and Disease. 9th ed. Baltimore: Williams & Wilkins; 1999:265-276.Foster LH, Sumar S. Selenium in health and disease: a review. Crit Rev Food Sci Nutr. 1997;37(3):211-228