Selenium is a trace mineral that the human body requires in small quantities. After digestion, the cells combine selenium and proteins together to form selenoproteins, a powerful antioxidant that prevents the kind of cellular damage acquired from the normal metabolic processes in the human body. Failure to obtain selenium from your diet can contribute to hypothyroidism, a condition characterized by weakness, fatigue, depression and weight gain.
Thyroid Gland and Selenium
The thyroid gland is a small organ in the front of the neck. It produces two different types of thyroid hormones that regulate energy production, cellular metabolism and normal growth and development. Iodine is the most important nutrient that the thyroid gland requires to produce these hormones. However, selenoproteins are also necessary for thyroid hormone synthesis, activation and metabolism. The thyroid gland has the highest concentration of selenium among all organs and will actively retain high levels even under conditions of inadequate selenium supply. Conversely, the repletion of selenium will result in the rapid accumulation in endocrine tissue, reproductive organs and the brain.
Hypothyroidism
Hypothyroidism occurs when the thyroid gland is no longer capable of producing enough hormones to meet the demands of the human body. A nutritional deficiency --- from the lack of iodine, selenium or other minerals --- is a common cause, though far less prevalent in the developed world. Treatment of a deficiency, then, will involve the increased consumption, either from food or dietary supplements, of the deficient nutrient. However, deficiencies of multiple nutrients will require the proper intake of all of them at once to fully ameliorate the condition. Consuming more selenium may not fully treat hypothyroidism if you need more zinc or magnesium too.
Selenium Deficiency
A selenium deficiency can affect the thyroid gland directly or worsen the effects of iodine deficiency to such a degree that it causes severe problems in mental and physical growth. Fortunately, the proper nutritional intake of selenium, besides reducing the risk of hypothyroidism, may also help protect against a goiter, which is the enlargement of the thyroid gland, and mask a few of the neurological effects associated with iodine deficiency.
Dietary Sources
Major dietary sources of selenium include Brazil nuts, beef, turkey, chicken, noodles, eggs, cottage cheese, oatmeal, rice and certain fish such as cod and tuna. In general, the concentration of selenium depends almost exclusively upon the selenium content of the soil in which the plants grow. From there the selenium enters the rest of the food chain. For adults above the age of 18, the recommended dietary allowance is only 55 mcg per day, though for pregnant and breastfeeding women it's 60 and 70 mcg, respectively.
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