Selenium is a trace element found in soil. In humans it is present in nearly every cell, especially in kidneys, liver and pancreas. Humans need small amounts of selenium through their diet to maintain good health. In human body selenium acts as an antioxidant against free radicals. Selenium also protects us from toxic minerals, fights against viral infections and protects from heart disease. Selenium can also increase male potency and it has a role in the maintenance of hair, skin and eyes. Efficiency of selenium can be further improved by taking it together with vitamin E.
The antioxidant properties of selenium make it a powerful remedy against common cold. Selenium can assist the body in defending itself against bacteria and viruses, including viruses causing common cold and influenza. Study made in University of North Carolina has shown that dietary deficiency of selenium may cause a harmless strain of flu virus to mutate into a more virulent pathogen.
RDA for selenium is (depending of country you live in) roughly 55 micrograms per day for adults, 35 micrograms per day for children and 20 micrograms per day for infants. A daily dosage of 150-300 mcg is still considered to be safe for the average adult. More than 400mcg per day can in the long run lead to toxicity (selenosis).
The best and safest way to obtain selenium is to eat selenium rich foods. Selenium content in foods depends highly on selenium content of the soil where the food was grown. For example in the United States, selenium levels in the soil are relatively high. But in other areas like Russia, Europe, China, Australia and New Zealand, levels of selenium in soil tend to be much lower. Good sources for selenium include Brazil nuts, button mushrooms, shitake mushrooms, eggs, sunflower seeds and mustard seeds. For example just by eating two Brazil nuts you will get on average 100mcg of selenium.
Since selenium can easily be obtained through diet, supplementation is seldom needed. Cases of selenium deficiency are usually associated only with severe gastrointestinal problems, such as Chron’s disease. Also people with acute severe illness who develop inflammation and widespread infection often have decreased levels of selenium in their blood. In these cases physicians will evaluate need for supplementation. If selenium supplement is used then the suggested form is selenomethionine which is generally considered to be the best absorbed and utilized form of selenium. Many supplements and multivitamins contain selenium in the form of sodium selenite or selenate. These two forms of selenium are potentially problematic and should be avoided. Both sodium selenite and selenate are classified as “Highly Toxic” in PAN pesticides database.