Selenium: The Missing Link for Thyroid Health?

Did you know your thyroid has the highest concentration of selenium? Selenium concentrates in the thyroid as it’s an essential nutrient for thyroid function.

In fact, studies show selenium not only helps prevent thyroid disease, it also helps this fragile gland run smoothly.

Top 4 Reasons Selenium Supports Thyroid Health

ONE: Selenium Teams Up With Zinc For Effective Conversion of T4 to T3.

The enzyme that converts thyroxine (T4) to active triiodothyronine (T3) is a zinc and selenium-dependent enzyme. If zinc and selenium levels are low T4 remains stuck in the inactive state. As you can imagine, this is a critical pathway to have working properly, especially when you’re taking T4-only medication.  Under conversion of T4 to T3 is common, and it results in low T3 which is associated with a range of low thyroid symptoms.

TWO: Selenium Safeguards The Thyroid From Environmental Damage

These days it’s almost impossible to completely avoid exposure to hazardous environmental chemicals. They are in the air, water and the food we eat.

Selenium concentrates in the thyroid as it has antioxidant activity to help defend the thyroid from environmental stress.

THREE: Selenium Safeguards The Thyroid From High Iodine Intake

Research has shown that when selenium is low supplementing taking mega doses of iodine increases your risk of experiencing an autoimmune flare. For this reason, it’s important that those with a diagnosed autoimmune thyroid disorder avoid taking iodine well above what is generally recommended. It’s a trace nutrient, and for this reason only small quantities are normally required.

The Australian National Health and Medical Research Council (NHMRC) and the US National Institutes of Health have both set the recommended safe upper level of intake at 1,100 micrograms per day.

It’s important to know this is the equivalent of 1.1 milligrams when assessing iodine supplements, or thyroid health formulas. For example, you will see some iodine supplements advertised that contain 12.5 milligrams per tablet which is an extremely high dose.

FOUR: Selenium Can Help Reduce Raised Thyroid Antibodies

Selenium supplement has been shown in clinical trials to reduce thyroid antibodies by up to 50%.

In these studies, women with a diagnosed autoimmune thyroid disorder were given 200 to 250 micrograms of selenium per day. Over time they saw a marked reduction in their thyroid peroxidase (TPO) antibody levels.

As you may already know, the TPO antibody test is the most sensitive test for detecting autoimmune thyroid disease. Due to these findings there are healthcare practitioners now prescribing 200-250 micrograms of selenium daily to assist with autoimmune hypothyroid disorders.

How Much Selenium Is Safe To Take?

Firstly, it’s good to know that this nutrient is generally considered safe when taken as recommended.

For adults, the safe upper level of intake is set at 400 micrograms daily. This maximum level is based on current research, and reflects the current data on selenium toxicity. It’s therefore wise not to take more than is recommended as selenium does have the potential to build up in the body.

In some circumstances healthcare practitioners may prescribe 200 – 250 micrograms of selenium per day. This is normally done after considering your individual health circumstances.

In Summary

Selenium plays multiple roles to support ongoing thyroid health. The nutrient is involved in thyroid hormone synthesis, it may help protect the thyroid from the detrimental effects of environmental chemicals, it may assisting in reducing raised TPO levels, and it may safeguard the thyroid from excessive iodine intake.


Australian National Health and Medical Research Council (NHMRC) and the New Zealand Ministry of Health (MoH). Nutrient Reference Values for Australia and New Zealand. Selenium. Page 221-227. 2006. Link

Braun L, Cohen M. Herbs and natural supplements: an evidence-based guide, 3rd ed. Churchill Livingstone. 2007.

Drutal, A. S. Selenium and the thyroid gland: more good news for clinicians. Clin Endocrinol. 2013 Feb;78(2):155-64. PubMed

Duntas LH. Selenium and the thyroid: a close-knit connection. 2010 Dec;95(12):5180-8. PubMed

Gartner R1, Gasnier BC, Dietrich JW, et al. Selenium supplementation in patients with autoimmune thyroiditis decreases thyroid peroxidase antibodies concentrations. J Clin Endocrinol Metab. 2002 Apr;87(4):1687-91. PubMed

Hu S, Rayman MP. Thyroid. Multiple Nutritional Factors and the Risk of Hashimoto’s Thyroiditis. 2017 May;27(5):597-610. PubMed

Lacka K, Szeliga A. Significance of selenium in thyroid physiology and pathology. Pol Merkur Lekarski. 2015 Jun;38(228):348-53. PubMed

Saranac L, Zivanovic S, Bjelakovic B, et al. Why is the thyroid so prone to autoimmune disease? Horm Res Paediatr. 2011;75(3):157-65. PubMed

Toulis KA, Anastasilakis AD, Tzellos TG, et al. Selenium supplementation in the treatment of Hashimoto’s thyroiditis: a systematic review and a meta-analysis. Thyroid.2010 Oct;20(10):1163-73. PubMed

Turker O, Kumanlioglu K, Karapolat I, et al. Selenium treatment in autoimmune thyroiditis: 9-month follow-up with variable doses. J Endocrinol 2006 Jul;190(1):151-6. PubMed

Wichman J, Winther KH, Bonnema SJ, Hegedüs L. Selenium Supplementation Significantly Reduces Thyroid Autoantibody Levels in Patients with Chronic Autoimmune Thyroiditis: A Systematic Review and Meta-Analysis. Thyroid. 2016 Dec;26(12):1681-1692. PubMed

Yaofu Fan, Shuhang Xu, Huifeng Zhang, et al. Selenium Supplementation for Autoimmune Thyroiditis: A Systematic Review and Meta-Analysis. Int J Endocrinol. 2014; 2014: 904573. Link

Zaletel K, Gaberšček S. Hashimoto’s Thyroiditis: From Genes to the Disease. Current Genomics. 2011;12(8):576-588. Link


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