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Selenium is a trace mineral—a trace mineral is one that all humans need but in very small quantities. There is a type of protein known as a selenoprotein which requires selenium—there are about 25 selenoproteins that have been described

…but we know the functions of only about half of these. We do know that the function of these selenoproteins is quite important.  For example, there are 5 selenoproteins involved in the glutathione cycle—a cycle that is very important to control inflammation, an underlying cause of pain, discomfort and tissue/organ damage.

Glutathione is one of natures’ most powerful antioxidants…and it can recycle itself and other antioxidants over and over again! An antioxidant is a substance that is able to “mop up” the products of biochemical reactions in the body—the free radicals. These free radicals are highly reactive because they only have one unpaired electron and they really, and I mean REALLY want to gain another electron.  When that happens, it is very damaging to components of the cell—DNA, cells and tissues can all be damaged because the free radical doesn’t “care” where it gets the extra electron! The enzymes that help recycle glutathione are selenoproteins. Still another type of selenoprotein is involved in recycling vitamin C—and vitamin C is one of the best antioxidants around.

Selenium is also very important for thyroid health. The thyroid produces a hormone known as T4—but T4 is not the active thyroid hormone—a selenoprotein is needed to convert T4 to the active thyroid hormone, T3. In the heart, there is a selenoprotein (selenoprotein P) that is found on the inner walls of blood vessels. There, it functions as an antioxidant, directly protecting the vessel walls from damage from free radicals such as reactive nitrogen species (RNS). There are also selenoproteins in muscle (selenoprotein W) and in the testes (selenoprotein V). The selenoprotein V in the testes is thought to be essential for male fertility and protect against prostate cancer. 

Symptoms of Selenium Deficiency and Soil Deficient in Selenium

 

What are the symptoms of selenium deficiency?

There are areas around the world where the soil is deficient in selenium—in those areas, it was discovered that the lack of selenium was related to autoimmune diseases a form of heart disease called Keshan disease  and a joint disease called Kaschin-Beck disease.Selenium deficiency is also thought to be linked to worsening of some inflammatory conditions and diabetes. There is also some evidence that selenium may protect against certain cancers particularly in combination with vitamins C and E, zinc and beta-carotenes. The effect of selenium on the prostate and on prostate cancer is an area of active research.

How do I know if where I live, the soil is selenium deficient?


Wherever you live, check with your local university Geology or Agriculture department—they should be able to tell you if the soil in your area is selenium deficient. Local governments may have an agriculture department that can help you find out as well.  There is a narrow range for selenium supplementation—it can be toxic if too much is taken for too long, so make sure you talk to your doctor about selenium supplementation.  Selenium selenite appears to be the best form to supplement with. Check your multivitamin—you should be getting 70-100 mcg per day, particularly if you live in a selenium-deficient area. Be careful—make sure you talk to a knowledgeable health professional because too much selenium can be toxic! Also, be aware that some antioxidants, including selenium appears to work against certain drugs like the statins used to lower cholesterol.  Excess selenium results in hair loss, abnormal nails, emotional instability and a garlic odor to the breath. 

As already said the content of selenium in particular foods depends on the concentration of selenium in the soil where the crops were grown. However, generally foods such as nuts, and espcecially Brazil nuts and sunflower seeds are rich in selenium.

Vegans will also benefit from mushrooms, moslty button, crimini and shiitake. Grains, such as wheat germ, barley, brown rice and oats should be on the top of their list. Onions, often used in cooking are also rich is selenium.
 
Those who eat fish and shellfish will benefit from tuna, salmon and sardines, oysters, shrimps, scallops, and mussels. Eggs and meat, mostly beef, lamb, pork and poultry are rich in selenium.

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  • Photo courtesy of Fariac on Flickr: www.flickr.com/photos/fariac/4629969379