Inside: Selenium and its role in thyroid health, especially its importance in autoimmune thyroid conditions. Does taking selenium supplement to improve thyroid health ? What is the best form of selenium and whats the correct dosage!
Selenium is an important micronutrient, that has multiple functions in our body. Over the last several years its role has been studied in human physiology, and scientific reports have revealed its crucial role in the maintenance of immune-endocrine function, metabolism, and cellular homeostasis.
In adult body, Thyroid gland is the organ with the highest amount of selenium per gram of tissue.
Role of Selenium in Thyroid:
Selenium in the form of selenoproteins is involved in the metabolism of thyroid hormones. These selenoproteins are part of two thyroid enzymes named deiodinaes and glutathione peroxidase [1,2,3] .
These deiodinas enzymes is responsible for conversion of T 4 hormone to T3 hormone. Thyroid hormone is produced in T4 form but the active form is the T3 form which your body can actually utilize for optimal functioning.
So inadequate levels of selenium in your body can lead to impaired production of the deiodinase enzyme which in turn interferes with conversion of T4 to T3 and thus body feels it has low thyroid hormones.
The other enzyme glutathione peroxidase is involved in antioxidant activities in thyroid. During production and conversion of thyroid hormones, there are free radicals which are formed. These free radicals if left alone can damage your body, so the body has created defense mechanisms to get rid of these free radicals through the enzyme called glutathione peroxidase.
You can simply compare this to a factory which is manufacturing a finished product. During the process of making the product there is waste material generated. Proper methods need to be implemented to get rid of the waste material otherwise it will accumulate and will become harmful for the factory and the workers in the factory. So similarly during the process of producing thyroid hormones free radicals are generated and if they are not removed through detoxification then they accumulate and in turn destroy our own thyroid gland.
Why Selenium Deficiency
Selenium levels in the body are dependent on the population’s characteristics and its diet and also on the soil composition .
With the modern agriculture practices, we are noticing that even though people might be eating healthy, but still they have nutrient deficiency especially selenium because the soil has been depleted of this mineral.
So that’s the reason several people are deficient in selenium even though they have been trying to eat foods that are high in it.
Another reason is that the majority of the absorption ( around 50-80%) of selenium from food happens in the small intestine , so people having gut dysfunction will have impaired absorption. You might have heard of the term leaky gut and SIBO ( Small intestinal bacterial overgrowth ) which are common conditions and can interfere with its absorption as these conditions affect small intestine.
Link of Selenium with Thyroid Dysfunction
Since the role of selenium in thyroid has been known, special attention has been given to see if selenium can impact autoimmune thyroid conditions like Hashimoto’s and Graves disease.
Now as you might know that the major reason for hypothyroid or low thyroid is Hashimoto’s disease. Most of my thyroid patients were never aware of it and they never knew they had Hashimoto’s disease. So if you have low thyroid problem most likely it is because of Hashimoto’s and that’s where the importance of selenium comes into place.
Huge population based studies have supported a relationship between selenium levels and thyroid gland function.
A study on 1,900 participants indicated an inverse relationship between serum selenium concentrations and thyroid volume, risk of goiter, and risk of thyroid tissue damage in people with mild iodine deficiency [6,7].
Another study was conducted to see the role of selenium supplementation in people who have low thyroid, and are already on levothyroxine . The results showed that group with selenium supplementation had reduction in thyroid antibodies, and also saw improvement in their symptoms. While the group with just the levothyroxine didn’t show these benefits.
Similar studies have been done which have shown beneficial effects of selenium in reducing the thyroid antibodies and also in some cases improving thyroid levels also .
There was another study done to see the effect of selenium supplementation on thyroid antibodies and also to see if discontinuation of selenium causes recurrence of these antibodies. The results showed that after taking selenium 200 ug/day for 6 months, there was a reduction in the level of thyroid antibodies, but people who discontinued selenium had increase of antibodies again.
Food Sources of Selenium
Selenium exists in two forms: inorganic (selenate and selenite) and organic (selenomethionine and selenocysteine).
Soil contains inorganic selenites and selenates, that plants accumulate and convert to organic forms, mostly selenocysteine and selenomethionine and their methylated derivatives.
The main sources of selenium are meat products (31%), followed by fish (19%), pasta or rice (12%), and bread or cereals (11%). .
Other food sources are brazil nuts, crimini mushrooms, cod, shrimp, tuna, halibut, salmon, scallops, chicken, eggs, shiitake mushrooms, lamb, and turkey.
I like brazil nuts especially because they have a high content of selenium and just with 2 brazil nuts a day you can get adequate selenium. But as I mentioned most of our soil is deficient in selenium and these food sources can’t be relied completely.
Especially if your have Thyroid problems you need to take supplements to get adequate levels of Selenium.
What’s the Best Dosage of Selenium and are There Different Forms of Selenium
A study was conducted to find the right dosage of selenium. People were given either 100 ug/ day or 200 ug/day of selenium for 9 months and their levels of thyroid antibodies were monitored. The results showed that the group who were given 200 ug / day of selenium showed significant reduction in thyroid antibodies while the other group who was getting 100 ug/day of selenium did not. So they concluded selenium dosage should be at least 200 ug/day .
Different forms of selenium exists as we discussed above in both organic and inorganic form. So supplements are available with both different forms like sodium selenate or selenomethionine.Is one better than the other ?
The organic form selenomethionine has better absorption than selenite form .
In one study, people were randomly assigned to receive a placebo or either 200 or 600 mcg/day selenium as selenomethionine, sodium selenite, or high-selenium yeast (in which an estimated 75% of selenium was in the form of selenomethionine) for 16 weeks. Selenium bioavailability,was greatest for selenomethionine and lowest for selenite.
So my preferred go to Selenium supplement is selenomethionine and in dosage of 200 ug/day.
Caution with Selenium
High doses of selenium can cause side effects and very high dosage can cause toxicity.
So its important to stick with the recommended dosage and also your individual factors might also play a role in how much your body requires so working with practitioner is recommended.
Symptoms associated with high selenium can be : GI disturbances, hair loss, changes in hair and nails, fatigue, peripheral neuropathy, irritability, garlic-smelling breath, fever, nausea and a jaundice-like yellow tint to the skin.
Also important to remember that if you have low iodine and you take selenium than you might feel worse.
So in short selenium is an important mineral that plays a vital role in thyroid functioning. Research has shown that selenium supplementation at doses 200 ug/day reduced thyroid antibodies and also improved thyroid-related symptoms. Food sources are limited and brazil nuts can be a good source. Supplementation is common and should be considered especially people with thyroid disease, The form of supplement to use is Selenomethionine in dosage 200 ug / day.
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References for Selenium: The Essential Mineral for Thyroid Health:
Schomburg L. Selenium, selenoproteins and the thyroid gland: interactions in health and disease. Nature Reviews Endocrinology. 2012;8(3):160–171. doi: 10.1038/nrendo.2011.174.
Saranac L., Zivanovic S., Bjelakovic B., Stamenkovic H., Novak M., Kamenov B. Why is the thyroid so prone to autoimmune disease? Hormone Research in Pædiatrics. 2011;75(3):157–165. doi: 10.1159/000324442.
Selenium and the thyroid gland: more good news for clinicians.Drutel A, Archambeaud F, Caron P. Clin Endocrinol (Oxf). 2013 Feb; 78(2):155-64.
Selenium and human health.Rayman MP. Lancet. 2012 Mar 31; 379(9822):1256-68.
Selenium: an element for life.Duntas LH, Benvenga S. Endocrine. 2015 Apr; 48(3):756-75.
Derumeaux H, Valeix P, Castetbon K, Bensimon M, Boutron-Ruault MC, Arnaud J, Hercberg S. Association of selenium with thyroid volume and echostructure in 35- to 60-year-old French adults. Eur J Endocrinol 2003;148(3):309-15.
Rasmussen LB, Schomburg L, Kohrle J, Pedersen IB, Hollenbach B, Hog A, et al. Selenium status, thyroid volume, and multiple nodule formation in an area with mild iodine deficiency. Eur J Endocrinol 2011;164:585-90. [PubMed abstract]
Selenium supplementation in patients with autoimmune thyroiditis decreases thyroid peroxidase antibodies concentrations. Gärtner R, Gasnier BC, Dietrich JW, Krebs B, Angstwurm MWJ Clin Endocrinol Metab. 2002 Apr; 87(4):1687-91.
Effects of a six month treatment with selenomethionine in patients with autoimmune thyroiditis.Duntas LH, Mantzou E, Koutras DA. Eur J Endocrinol. 2003 Apr; 148(4):389-93.
Selenium in the treatment of autoimmune thyroiditis.Gärtner R, Gasnier BC. Biofactors. 2003; 19(3-4):165-70.
Predicted dietary intake of selenium by the general adult population in Belgium.Waegeneers N, Thiry C, De Temmerman L, Ruttens A. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2013; 30(2):278-85.
Selenium treatment in autoimmune thyroiditis: 9-month follow-up with variable doses..Turker O, Kumanlioglu K, Karapolat I, Dogan I. J Endocrinol. 2006 Jul; 190(1):151-6.
Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academy Press, Washington, DC, 2000.
Burk RF, Norsworthy BK, Hill KE, Motley AK, Byrne DW. Effects of chemical form of selenium on plasma biomarkers in a high-dose human supplementation trial. Cancer Epidemiol Biomarkers Prev 2006;15:804-10