Category: Thyroid Function

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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

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Selenium and the Thyroid Gland

The thyroid gland is the organ in the body that contains the most selenium per gram of tissue [Wang 2023].

Illustration of thyroid gland from Wikimedia Commons
The thyroid gland makes and releases hormones that control our metabolism, i.e., regulate how we use energy. Source: https://www.nlm.nih.gov/medlineplus/.

In a 2023 review article, Wang et al summarize the reasons why adequate selenium intake and status are necessary for good thyroid health.

Humans cannot synthesize selenium: the daily intake of selenium depends on the contents of the individual’s diet.

  • The selenium content of food depends on the selenium content of the soil, which varies extensively from region to region of the world. Much of Europe has selenium-poor soil; much of the United States has soil considerably richer in selenium.
  • Selenium is a micronutrient that makes possible the body’s synthesis of some 25 identified selenoproteins containing the amino acid selenocysteine.
  • The best known selenoproteins – such as the glutathione peroxidases, the thioredoxin reductases, and the iodothyronine deiodinases – are expressed in the thyroid gland, where they contribute to thyroid hormone metabolism and to antioxidant defense.
  • A selenium deficiency will increase the risk of several kinds of thyroid diseases.

Selenium Supplementation and Thyroid Diseases

Wang et al [2023] report the following outcomes from clinical trials of selenium supplementation. They advise that we need more clinical evidence for the efficacy of selenium treatment of thyroid disorders.

  • Selenium supplementation slows the progression of Graves’ orbitopathy and improves the quality of the patients’ lives.
  • Selenium supplementation is associated with the decreased levels of anti-thyroid peroxidase antibodies and with improved thyroid ultrasound structure in patients with Hashimoto’s thyroiditis.
  • Selenium supplementation has shown variable anticancer activity in patients with thyroid cancer.

Strong Association Between Selenium and Thyroid Disease

Selenium and Graves’ disease

Wang et al [2023] reviewed the data from 11 clinical trials. Nine clinical trials showed that selenium supplementation results in faster achievement of normal thyroid function in patients with hyperthyroidism. Two clinical trials did not show the beneficial effect of selenium supplementation. The difference in outcomes may be related to differences in the form of the selenium supplementation, the dose, the duration of supplementation, and the nutritional status of the study participants. read more

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Chronic Fatigue Syndrome and Impaired Selenium Transport

In a considerable number of chronic fatigue syndrome patients, researchers have observed the presence of autoantibodies to the selenium transporter Selenoprotein P. These autoantibodies disturb the normal transport of selenium to the tissues  in the body. They cause lower than normal levels of the antioxidant selenoenzyme glutathione peroxidase and lower than normal levels of deiodinase enzyme activity [Sun 2023].

Tired young woman at computer
Chronic fatigue syndrome is a complicated disorder that causes abnormal fatigue lasting six months or longer. Impaired selenium transport may be a factor underlying chronic fatigue syndrome.

Note: Autoantibodies are antibodies produced by the immune system and directed against the individual’s own proteins, in this case against selenoprotein P proteins. In an earlier study, researchers have identified autoantibodies to selenoprotein P in patients with Hashimoto’s thyroiditis, in which case the autoantibodies also impair selenium transport and selenoprotein expression [Sun 2021]. read more

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Thyroid Disorders and Selenium Supplementation

Thyroid disorders.

Many clinicians treating autoimmune thyroid diseases are using selenium supplementation as one treatment modality even though, in the official guidelines, selenium supplementation is recommended only in the treatment of mild Graves orbitopathy [Winther 2020].

Thyroid gland
The thyroid gland is the butterfly-shaped organ in the front part of the neck. Thyroid hormones regulate body temperature, heart rate, and weight gain or loss. Autoimmune thyroid disorders occur when immune system cells attack thyroid gland cells. Autoimmune thyroid disorders cause overproduction of thyroid hormones (hyperthyroidism) and underproduction of thyroid hormones (hypothyroidism). Graves’ disease is the most common autoimmune hyperthyroidism. Hashimoto’s thyroiditis is the most common autoimmune hypothyroidism.

Some clinicians consider supplementation with selenium to be a pharmaceutical action that should be taken only with thyroid disorder patients with well-defined symptoms in order to alleviate the symptoms, to improve the course of the disease, or to provide a cure. Typically, in such cases, the selenium treatment is conducted for short periods, and the health benefits and side effects are evaluated and weighed [Schomburg 2020].

Other clinicians consider supplementation with selenium in a more holistic way and use selenium supplementation as a way to correct a nutritional deficiency of selenium, which is associated with thyroid disorders [Schomburg 2020]. read more

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Selenium Deficiency and Thyroid Disorders

Selenium plays an important role in optimal immune and endocrine system function. The role that selenium plays with respect to thyroid function is complex [Chmura 2022]:

Thyroid system
Good thyroid system function promotes improved metabolism, better growth and development, and increased effect of catecholamines. Note: Catecholamines are hormones released in response to emotional or physical stress. (Attribution: Mikael Häggström, Public domain, via Wikimedia Commons.)

The thyroid gland is the organ with the greatest amount of selenium per gram of tissue.

  • An adequate supply of selenium is necessary for synthesizing the enzymes – the iodothyronine deiodinases – that are involved in the metabolism of thyroid hormones.
  • Selenium supplementation may give beneficial effects to patients with autoimmune diseases of the thyroid gland.
  • There is a significant correlation between selenium deficiency and thyroid gland dysfunction. Selenium deficiency is defined as serum or plasma selenium levels below 70 mcg/L. Optimal serum/plasma selenium levels are approximately 125 mcg/L [Winter 2020].
    • Selenium Deficiency and Thyroid Dysfunction

    A 2022 review highlights the following relationships between selenium deficiency and thyroid gland dysfunction [Chmura 2022]: read more

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    Adjuvant Treatment of Graves’ Hyperthyroidism with Selenium Yeast

    Thyroid disease. Hyperthyroidism. Adjuvant treatment of thyroid disease with selenium yeast supplementation. All topics of interest. At this writing (August 2022), we await the publication of the outcomes of the GRASS clinical trial. GRASS is the acronym for the selenium supplementation for patients with Graves’ hyperthyroidism study [study protocol described by Watt 2013].

    What is Graves’ Hyperthyroidism?

    Thyroid gland
    The thyroid gland is a butterfly-shaped endocrine gland in the neck below the Adam’s apple that makes and stores hormones that help regulate blood pressure, body temperature, heart rate, and the rate at which food is converted into energy. [This image is licensed under the Creative Commons Attribution-Share Alike 4.0 International license.]
    Hyperthyroidism is an autoimmune disease. It causes overactivity of the thyroid gland, resulting in too much production of the hormone thyroxine. Hyperthyroidism can cause an acceleration of the body’s metabolism; it can cause weight loss and rapid or irregular heartbeat.

    Hyperthyroidism is caused by a number of conditions, including Graves’ disease, which is a common cause. Graves’ disease is the result of immune system disorder. It can affect anyone, but it is more common in women and in individuals under the age of 40. read more

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    Hashimoto’s Disease Patients Benefit from Selenium Supplementation

    Hypothyroidism is the medical condition caused by an underactive thyroid gland that is not producing sufficient quantities of thyroid hormones. It is the failure of the thyroid gland to function normally.

    Jan Olav Aaseth
    Endocrinologist Jan Aaseth, M.D., Ph. D., ERT, explains that, in Norway, the diagnosis of Hashimoto’s disease is made after a clinical examination that involves determination of the patient’s circulating levels of the thyroid hormone thyroxine (T4), thyroid stimulating hormone, and thyroperoxidase antibodies [Aaseth 2022].
    The most common form of hypothyroidism is related to Hashimoto’s disease. Hashimoto’s disease is an autoimmune disorder most common among middle-aged women. Symptoms include anxiety, dry skin, fatigue and lethargy, muscle aches and muscle stiffness, negative mood, sensitivity to cold, slow thinking and poor memory.

    The standard treatment for Hashimoto’s disease is twofold:

    1) treatment with a synthetic hormone called levothyroxine, which works like the T4 hormone that is naturally produced by the thyroid gland read more

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    Selenium Supplementation and Autoimmune Thyroiditis

    Autoimmune thyroiditis is the umbrella term for various types of thyroiditis in which the immune system mistakenly attacks the thyroid gland.

    Endocrine glands placement
    The thyroid gland is the butterfly-shaped endocrine gland in the lower part of the neck. It plays an essential role in the regulation of our basic metabolism.

    The result is often hypothyroidism, the insufficient functioning of the thyroid gland.

    The two major types of hypothyroidism are Hashimoto’s disease and atrophic thyroiditis.

    Thyroiditis is the medical term for inflammation of the thyroid gland.

    Immune system disorder can also cause an overactive thyroid, called hyperthyroidism; Graves’ disease is the most common form.

    Selenium Supplementation to Prevent Hypothyroidism

    In a 2021 review article, Filipowicz et al assert that many European endocrinologists prescribe selenium supplements to autoimmune thyroiditis patients.

    For example, a 2016 survey of 815 doctors (91% endocrinologists) has shown that almost 80% of the surveyed doctors prescribe selenium supplementation to autoimmune thyroiditis patients. The rationale for the selenium supplementation is the delay of the hypothyroidism or a decrease in thyroid antibodies [Filipowicz 2021]. read more