Category: Thyroid Function

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Selenium and Thyroid Health Reviewed

What is the role of selenium for thyroid health?
Thyroid gland
The thyroid gland is the small gland in the front of the neck that makes thyroid hormones. The hormones regulate how the body uses energy. Optimal selenium status is important for good thyroid health.

Sufficient selenium is essential for normal thyroid hormone synthesis and activation. Furthermore, selenium is important for protection of the thyroid gland against oxidative stress. Note that both deficiency and excessive intake can impair thyroid health [Gorini 2021].

Several selenium-dependent enzymes catalyze thyroid hormone synthesis and activation. Similarly, selenoenzymes provide antioxidant protection against oxidative damage [Gorini 2021].

Importantly, selenium is incorporated into deiodinases. These enzymes convert the T4 hormone into the biologically active hormone T3. In addition, antioxidant selenoenzymes such as the glutathione peroxidases and the thioredoxin reductases neutralize hydrogen peroxide radicals that are generated during thyroid hormone production [Gorini 2021]. read more

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Selenium and Thyroid Function

Data from a 2025 KiSel-10 sub-study analysis suggest that serum CD5L levels may be an additional biomarker for improved thyroid function. Serum CD5L levels may also be a suitable biomarker for adequate selenium status and for reduced mortality risk.

Illustration of thyroid gland
Adequate selenium intake is necessary for good thyroid function. Selenium is a component of the deiodinase enzymes that help convert inactive T4 thyroid hormone to active T3 thyroid hormone. Some selenoproteins act as antioxidants to protect the thyroid against oxidative damage. Selenium may help reduce the risk of autoimmune thyroid disorders.

Combined supplementation of elderly citizens with selenium and Coenzyme Q10 for 48 months significantly increased the level of circulating CD5L. The supplementation was associated with improved health-related quality of life and improved survival odds. Meanwhile, in the study’s placebo group, significantly higher cardiovascular mortality within 10 years was associated with low levels of circulating CD5L. The combined selenium and Coenzyme Q10 supplementation reduced the mortality risk. The active treatment in the KiSel-10 clinical trial was 200 mcg of selenium from selenium-enriched yeast and two times 100 mg of ubiquinone Coenzyme Q10 daily [Alehagen 2025]. read more

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Selenium and Graves’ Disease

Graves’ disease is an autoimmune disease. It is the most common cause of hyperthyroidism, i.e., overactive thyroid disorder. Ultimately, it is the overproduction of thyrotropin receptor (TRAb) antibodies that results in hyperthyroidism. Over time, Graves’ disease causes extensive damage to thyroid gland cells and tissues [Song 2023].

Thyroid system
In Graves’ disease, the thyroid gland produces too much thyroid hormone, a condition called hyperthyroidism. Attribution: Wikimedia Commons.

Oxidative stress appears to play an important role in Graves’ hyperthyroidism. Oxidative stress is the medical term for a disruption of the balance between harmful free radical oxidants and protective antioxidants. The increased production of reactive oxygen
radicals and inflammatory cytokines drives the development and progression of Graves’ disease [Song 2023]. read more

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Selenium and Vitamin D for Thyroid Health

Supplementation with selenium and vitamin D can improve the prognosis of type 2 diabetes mellitus and Hashimoto’s thyroiditis. Adding a daily dose of selenium and vitamin D to conventional diabetes medication can give significant health benefits [Yu 2024].

Selenium and Vitamin D for Type 2 Diabetes and Thyroid Disorder
A Chinese study suggests that combining conventional diabetes medicine with selenium and vitamin D supplements  reduces the levels of TSH and TPOAb and blood glucose and blood lipids in patients with concomitant type 2 diabetes and Hashimoto’s thyroiditis.

Researchers at Hunan University of Chinese Medicine, Hunan Province, China, recommend 100-200 mcg/day of selenium and 100 mcg/day of vitamin D for three to six months for patients with Hashimoto’s thyroiditis and especially for Hashimoto’s thyroiditis patients with concomitant type 2 diabetes [Yu 2024].

A 2024 study by Feng et al has shown that adding 200 mcg of selenium daily and 100 mcg of vitamin D to standard anti-diabetic drugs significantly improved thyroid function, thyroid antibodies, blood glucose, and blood lipids in type 2 diabetes patients who were also diagnosed with Hashimoto’s thyroiditis. read more

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Selenium: Why We Need It

In an online article in the Cleveland Clinic’s Health Essentials series, the registered dietician Kayla Kopp explains that selenium is an essential trace element that helps thyroid gland function and reproductive function, among other health benefits [Cleveland Clinic 2023].

Hospital care
The Cleveland Clinic article about the essential trace element selenium highlights the effect of selenium on thyroid health, reproductive health, asthma management, and cancer.

What does it mean that selenium is an essential trace element? Answer: our bodies need adequate selenium to function well. However, our bodies cannot synthesize selenium. We have to get our selenium from our food.

What are the health benefits of adequate selenium intake and adequate selenium status? Answer: Kopp says that selenium is important for the following reasons [Cleveland Clinic 2023]:

  • helps to protect our cells from damage
  • promotes good thyroid function
  • promotes good reproductive function
  • plays a role in DNA synthesis

Selenium Supports Thyroid Health

The thyroid gland is responsible for producing and releasing the hormones that control our metabolism. The metabolism rate is what determines how rapidly or slowly our bodies convert food into energy. The selenium we absorb from our food or from supplements gets converted into selenoproteins. These selenoproteins then help to regulate our thyroid hormones [Cleveland Clinic 2023]. read more

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Correcting Selenium Deficiency in Thyroid Disorders

Selenium supplementation. There seem to be two different approaches. One approach regards selenium supplementation as a direct pharmaceutical treatment. For example, it is considered a form of medication administered to thyroid disorder patients. Alone or together with thyroid disorder medication, the selenium supplementation is intended to 1) alleviate symptoms, 2) slow the progression of the disorder, and 3) perhaps provide a cure [Schomburg 2019].

Selenium researcher Urban Alehagen
Data from the Swedish KiSel-10 study show that combined daily selenium and Coenzyme Q10 supplementation has a beneficial effect on thyroid hormones and quality of life. outcomes.

A second approach to selenium supplementation does not regard the administration of selenium as a pharmaceutical intervention. Rather, the second approach considers selenium supplementation to be a nutritional intervention designed to address and correct a deficiency condition. This approach recognizes that both sub-optimal selenium status and selenium deficiency limit the body’s expression of vital selenoproteins. These selenoproteins are needed to minimize health risks and to alleviate disease symptoms. Supplemental selenium can be necessary to enable the full endogenous expression of selenoproteins [Schomburg 2019]. read more

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Selenium and Hashimoto’s Thyroiditis

Hashimoto’s disease is an autoimmune disease. It is a disease that causes underactive thyroid (hypothyroidism). The body’s own immune-system cells attack the cells of the thyroid gland and gradually break them down and destroy them. This, of course, has a detrimental effect on thyroid gland function and on important metabolic processes in the body.

Selenium and thyroid gland function
The thyroid gland regulates energy metabolism, heart rate, breathing, digestion, body temperature, mental activity, and other body processes. Adequate selenium intake is necessary for thyroid hormone production.

Hashimoto’s is a bit tricky. In its early development and progression, there may not be any obvious symptoms. Eventually, such symptoms as fatigue and lethargy and weight gain will make themselves manifest. Hashimoto’s thyroiditis is a debilitating disease. It lessens a person’s quality of life. It tends to affect women more than men.

Of all the organs in the body, the thyroid gland has the highest concentration of selenium. It is a greedy organ with respect to selenium. An adequate intake of selenium can lessen the severity of hypothyroidism symptoms and is associated with lowered levels of autoimmune thyroid peroxidase antibodies. read more

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Selenium and Thyroid Health

Good thyroid health depends, in part, upon the bio-synthesis of selenium-dependent seleno-enzymes called deiodinases. These seleno-enzymes are key factors in thyroid hormone metabolism and regulation. Thyroid hormones regulate the body’s metabolism (think: energy expenditure, body weight, body temperature, digestion, heart rate, etc.).

Dr. Jan Alexander - selenium researcher
Guest author Dr. Jan Alexander. MD, PhD, Eurotox Registered Toxicologist, and Professor at the Norwegian Institute of Public Health in Oslo. Co-author, together with Professor Urban Alehagen and Professor Jan Aaseth, of many articles about selenium and Coenzyme Q10.

There are three types of deiodinase enzymes. In normal thyroid function, these deiodinases regulate the activation and inactivation of the T4 and T3 thyroid hormones, as needed. Abnormal thyroid hormone function is closely associated with diminished health-related quality of life and with increased risk of cardiovascular morbidity and mortality.

In many selenium-poor regions of the world, including much of Europe and the Middle East, low selenium intake and status may cause sub-optimal synthesis of deiodinase enzymes and, consequently, sub-optimal thyroid gland function. Selenium is an essential trace element found in soil, and humans must get it from their food. read more

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Selenium and Graves’ Hyperthyroidism

Thyroid disease. What is the role of the micronutrient trace element selenium in thyroid disease? The thyroid gland is the organ in the body that contains the greatest amount of selenium per gram of tissue [Wang 2023]. Even in times of low dietary selenium intakes, the thyroid gland has high priority for the supply of selenium in the body [Schomburg 2020].

Endocrine system depicted
The thyroid gland is part of the endocrine system. It plays an important role in the body’s metabolism. It has high priority for the supply of selenium in the body.

Dietary selenium intakes vary considerably from region to region in the world. There are large differences in the soil content of selenium and in the factors that influence the bioavailability of selenium to plants. As a consequence, individuals’ plasma/serum selenium status varies accordingly [Winther 2020]. Thus, widespread sub-optimal selenium status has been reported throughout Europe, the United Kingdom, and the Middle East [Stoffaneller & Morse 2015]. read more

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Selenium and Hypothyroidism

In the CATALYST study, researchers found that selenium supplements and placebo supplements improved the quality of life of patients with hypothyroidism to an equal extent. Accordingly, the researchers have now emphasized a need for more research into the effect of selenium supplementation on immune system function, on oxidative stress, and on low-grade inflammation in patients with thyroid diseases [Larsen 2024].

Thyroid system depicted
Depiction of the thyroid system. Attribution: Mikael Häggström, Public domain, via Wikimedia Commons. The CATALYST study (Chronic Auto-immune Thyroiditis Quality of Life Selenium Trial) sought to establish whether selenium supplementation improves quality-of-life in patients with autoimmune thyroiditis .

The CATALYST study was a multi-center randomized, double-blinded, placebo-controlled clinical trial conducted in Denmark. The study participants were patients aged 18 or more years with serum thyroid peroxidase antibody (TPOAb) levels equal to or greater than 100 IU/mL. 82% of the study participants were women [Larsen 2024]. read more