The essential trace mineral, selenium, is of crucial importance to human health. It is a necessary component of several major metabolic pathways including thyroid hormone metabolism, antioxidant defense and immune regulation.
While the body requires selenium, it does not produce this mineral, therefore selenium must be obtained through the diet or supplementation.
The role of selenium in thyroid function
Selenium concentration is highest in the thyroid than in any other organ of the body, and, like iodine, selenium has an important role in thyroid hormone synthesis and metabolism.
Selenium is required for convertible T4 to the active form of thyroid hormone T3, and has a particular affect on iodothyronine deiodinases (DIOs), the protein responsible for this conversion. In conjunction to this, selenium is required for the recycling of iodine, the main building block of thyroid hormone.
Because of the potent antioxidant quality of selenium, this nutrient contributes to antioxidant defense within the thyroid, by removing oxygen free radicals generated during the production of thyroid hormones.
Selenium & autoimmune thyroid
Patients with autoimmune thyroid disease can reduce their level of thyroid antibodies by increasing their intake of selenium.
Studies have shown that patients with autoimmune thyroiditis who undertook supplementation with 200mcg/day of selenium had a 40% decrease in thyroid antibodies antithyroidperoxidase (TPOAb) and antithyroglobulin (TgAb).
Selenium also has the potential to reduce the risk of developing autoimmune thyroid disease. This is due to selenium's ability to neutralise hydrogen peroxide produced by the conversion of iodide to iodine for thyroid hormone production.
Because of seleniums role in converting T4 to T3, deficiency can cause symptoms of hypothyroidism such as:
Unexplainable weight gain
anxiety and/or depression
Other signs you may be experiencing selenium deficiency include:
Discolouration of the nails
Frequent cold and flu's
Excessive hair loss (see my post on 6 causes of hair loss in thyroid disorders)
Selenium and gut health
Selenium affects the microflora found in the digestive tract and helps to modify the inflammatory response in the gut. Deficiency is associated with increases inflammation and oxidative stress, resulting in damage to the intestinal lining causing increased intestinal permeability.
For this reason selenium deficiency is associated with gastrointestinal conditions such as irritable bowel syndrome, irritable bowel disease, crohn's disease, ulcerative colitis and celiac disease. Although it is uncertain as to whether these conditions cause deficiency or whether selenium deficiency contributes to these conditions.
Selenium in the diet
Just like any nutrient, the right amount is required for optimal health. The recommended daily allowance (RDI) of selenium for the average healthy adult is 55mcg, with higher demand required in pregnancy and lactation.
Selenium may be obtained in the diet through consumption of brazil nuts, sardines, eggs, spinach, and animal meat. Just two brazil nuts a day will give you your RDI of selenium. although because of the high selenium content of brazil nuts you shouldn't over do it. Try limit yourself to 2-4 nuts to prevent selenium overdose.
Because the exact amount of selenium found in foods such as brazil nuts can not be measured, supplementation may be a better choice for people with autoimmune thyroid conditions such as Hashimoto's and Graves, allowing their intake to be monitored.
While increasing your dietary selenium alone will not cure thyroid disease, it is one factor to consider in the management of these conditions.
If you would like to discuss your thyroid health in more detail, please feel free to get in contact via the contact us page or book an appointment for your personalised treatment plan.