What is selenium?
Selenium is a pure chemical element with the symbol Se on the periodic table. Selenium has an atomic number of 34, meaning that each atom of selenium has 34 protons and 34 neutrons in its nucleus. Selenium is required in trace amounts for normal enzymatic function in humans; in large amounts, selenium is toxic.1
What does selenium do in the body?
Selenium plays an important role in selenoproteins, proteins that contain selenium and regulate thyroid and immune system function.1
Selenium is also an important component of enzymes that neutralize free radicals formed during normal oxygen metabolism. Selenium is important for the proper function of glutathione peroxidase, a major antioxidant enzyme that counteracts the degredation of hemoglobin, the molecule that transports oxygen in red blood cells.2
Selenium is also found in selenocysteine, an amino acid found in at least 25 human proteins.3
Where do I get selenium?
Selenium in the human diet comes mainly from plants, which can contain higher or lower amounts of selenium depending on soil concentrations where the plants are grown. Animals that eat selenium rich plants will also have higher concentrations of selenium than animals who eat plants grown in selenium poor soils.
Since the incorporation of selenium into the human food chain begins with plants, most foods contain at least some selenium. Excellent sources of selenium include brazil nuts, tuna, cod, turkey, chicken breast, and egg.1
How much selenium do I need?
Recommended Dietary Allowances (RDA) for Selenium for Children and Adults4
|Age (years)||Males and Females (mcg/day)||Pregnancy (mcg/day)||Lactation (mcg/day)|
Selenium is toxic in high concentrations.
Tolerable Upper Intake Levels for Selenium for Infants, Children and Adults4
|Age||Males and Females (mcg/day)|
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4 Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academy Press, Washington, DC, 2000.