Nutritional Advice El Mondo- Selenium is a trace mineral.
- In foods, selenium is generally present as the amino acid derivatives selenomethionine and selenocysteine.
- Brewer's yeast, wheat germ, liver, butter, fish (mackerel, tuna, halibut, flounder, herring, smelts) and shellfish (oysters, scallops and lobster), garlic, whole grains, sunflower seeds and Brazil nuts are good sources of selenium.
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Selenium levels in food depend on how much selenium was in the soil where the food was grown.
Selenium is destroyed when foods are refined or processed. -
The biologically active form of selenium is selenocysteine. Selenocysteine is incorporated into selenoproteins, of which over thirty have been identified to date.
The selenoproteins include the glutathione peroxidases, which protect against oxidative damage, the iodothyronine deiodinases (involved in the production of the hormone triiodothyronine from thyroxine), selenoprotein P (which is involved in antioxidant and transport functions) and the thioredoxin reductases (maintenance of the intracellular redox state). - Selenium is most notable for its antioxidant properties.
- There are interactions between selenium and other nutrients, such as iodine and vitamin E.
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Selenium deficiency is rare.
Selenium deficiency can lead to heart disease, Keshan disease, hypothyroidism and a weakened immune system.
Selenium intakes of at least 20 mcg/day protect adults from Keshan disease. - A deficiency occurs at doses lower than 30 mcg per day.
- The RDA is 50-200 micrograms of selenium a day.
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The tolerable upper intake level (UL) for selenium is 400 mcg per day.
There is a relatively narrow range of selenium intake between toxicity (>400 mcg per day) and deficiency (30 mcg per day). Therefore, taking supplements is not without risk. - Too much selenium in the blood can cause a condition called selenosis. Selenosis can cause hair loss, nail problems, nausea, irritability, fatigue and mild nerve damage.
- Plasma or serum selenium concentrations of 8 micrograms (mcg)/dL or higher in healthy people typically meet needs for selenoprotein synthesis.
- The normal concentration in adult human blood serum is 70 to 150 ng/mL with a population mean value of 98 ng/mL.
- In the state of selenium deficiency associated with loss of glutathione peroxidase activity, the serum concentration is usually 40 ng/mL.
- The most abundant selenoproteins in blood are selenoprotein P, which accounts for approximately 50% of plasma selenium and GPx, which accounts for 10–30% of plasma selenium.
- The human body's content of selenium is believed to be in the 13-20 milligram range or sufficient for approximately 3 years.
- Skeletal muscle is the major site of selenium storage, accounting for approximately 28% to 46% of the total selenium pool.
Scientific studies on the relationship between selenium and disease prevention:
Review articles of randomized, placebo-controlled double-blind clinical trials (RCTs) will answer the following question:
"Is taking dietary supplements make sense?". Yes at a positive conclusion and no at a negative conclusion.
Review articles of cohort studies or case-control studies will answer the following question:
"Should I change my diet?".