The selenium content in whole plant foods depend on the level of the nutrient in the soil, and, unfortunately, many farming areas around the world are becoming increasingly selenium depleted. Most of the selenium is also lost when the food is processed or refined, so unless you consume lots of whole organic produce, you may be at risk of selenium deficiency.
It is because of these facts that supplements containing selenium have increased in popularity in the United States, to the extent that close to 25 percent of Americans over 40 take a selenium supplement or multivitamin that includes selenium. However, supplementing with sodium selenite and selenate may do more harm than good.
Beware of Inorganic Selenium
As explained in the featured article, sodium selenite and selenate are two potentially problematic ingredients found in many multivitamins.
According to PAN, a database for pesticide chemicals, both sodium selenite and sodium selenate are classified as “Highly Toxic,” based on oral administration trials using rabbits and rats. And according to the US Environmental Protection Agency (EPA), the highest allowable level of selenium in public drinking water is 50 parts per billion, which is equivalent to 50 micrograms, dry weight.
Studies have shown that:
- Long-term exposure to selenium, sodium selenite, sodium selenate, or selenium dioxide may cause paleness, coated tongue, stomach disorders, nervousness, metallic taste and a garlic odor of the breath. Damage to the liver and spleen in animals has also been observed, according to The National Institute for Occupational Safety and Health (NIOSH).
- According to the 1986 edition of the Handbook of the Toxicology of Metals, daily intake of about one milligram of selenium as selenite can be toxic.
- In one study, sodium selenite was found to induce substantial DNA damage in human fibroblasts.
- More recent research also indicates that too much selenium may contribute to the onset of diabetes.