Disclaimer: This is for educational purposes only and should not be used for diagnostic purposes.
Selenium is a trace mineral. This means the body requires it in small amounts. This nutrient is present in enzymes known as selenoproteins that participate in DNA synthesis, help protect cells from oxidative damage (they act as antioxidants to neutralize harmful reactive oxygen species such as peroxides) and regulate thyroid function. The thyroid is an endocrine gland located at the base of the neck that secretes certain hormones that participate's in the regulation of nutrient metabolism (essentially, how you body uses energy). The thyroid gland controls metabolic rate and affects virtually every cell in the body as they all need energy to support the overall functioning of the host. If the thyroid is dysfunctional this will have negative repercussions for the body's metabolism.
Majority of the body's selenium is stored in skeletal muscle. There are two forms of selenium that can both serve as a dietary source of the nutrient. There is the inorganic form and the organic from. Plants get the inorganic form of selenium from the soil and convert it to the organic form. Animals who then feed on these plants acquire the organic form of selenium. Therefore we can get selenium from both plant and animal sources. Selenium content will vary in these sources based on the geographical location as selenium content in soil across regions may vary.
Sources
Dietary sources include seafood, eggs, organ meats like kidney and liver, and Brazil nuts which has the highest amount of selenium content. You may also find it in cereals that have been fortified with the nutrient.
Recommended Dietary Allowance
The RDA for selenium for adults (male and female) is 55micrograms(ug) per day. For pregnant or lactating women the RDA is 60ug and 70ug per day respectively.
Intake, Status and Deficiency
A deficiency of selenium in the American diet is rare and might be more common in areas where the selenium content in the soil is low. Americans typically get selenium from sources such as grains, breads, eggs and red meat etc. Two major diseases linked to a selenium deficiency include Keshan disease (a from of cardiomyopathy) and a form of osteoarthritis known as Kashin-Beck Disease. Symptoms of a selenium deficiency include: headaches, lethargy, nausea etc. Individuals at risk of a selenium deficiency include people living with kidney failure and undergoing dialysis treatment, vegans or vegetarians who live in a region that has low selenium content in the soil. Selenium status is typically measured from plasma or serum in the blood.
A Few Interesting Facts about Selenium
Selenium works with iodine to regulate thyroid function. Iodine is a component of thyroid hormone which is converted to its active form by selenoproteins.
Selenium deficiency can increase or worsen iodine deficiency.
Selenium concentration in the blood decreases with age and has been implicated as a potential reason for age related neurological decline due to the potential loss of the antioxidant activity that they provide.
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