Selenium
Why do I need selenium?
Selenium is required for the activation of an enzyme called glutathione peroxidase. This enzyme is an antioxidant that quenches hydroperoxides, "high energy" oxygen-containing molecules that are produced during the metabolism of fat and that are highly toxic to cells. Recent research showed that selenium could reduce the severity of some cancers. This is thought to be due to selenium inducing "apoptosis" (programmed cell death) in cancer cells.
Selenium is also involved in a healthy immune system and proper thyroid function.
Where is selenium found?
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Brazil nuts
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Yeast
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Whole grains
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Seafood
Do I need selenium?
Deficiency is rare in Western countries. Soils in some areas are selenium deficient, and people who eat foods grown primarily in those soils are at risk for deficiency. However, in today's supermarket, foods come from far and wide, thus compensating for poor local soil conditions.
Chronic alcohol use depletes selenium stores in the body.
Caution
Taking more than 10 times the recommended daily allowance of selenium can result in toxic effects such as brittle hair and fingernails, skin rash, changes in the nervous system, nausea, diarrhea and fatigue.
Concomitant use of ascorbic acid (vitamin C) may inactivate sodium selenite supplements.
What to look for in a selenium supplement
Selenomethionine is the principal form of selenium found in foods. Selenomethionine is virtually 100% absorbed and well retained as compared to inorganic selenium, which is rapidly excreted.
Yeast preparations can be produced to contain substantial amounts of selenomethionine suitable for selenium supplements.
Some manufacturers mechanically mix sodium selenite or selenium dioxide, with ordinary yeasts. These yeast products contain virtually no selenomethionine. The selenium in these yeasts is significantly less bioavailable than selenomethionine. Studies have shown that such yeast products produce only small increases in blood selenium concentrations.
Other artificially selenized yeasts contain sodium selenate, which is not normally present in foods. A study found that selenate was less effective than selenomethionine to correct a deficiency.
Read labels to determine which form of selenium is in the supplement.
Best choice: selenomethionine.