Category: Thyroid Function

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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

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    Selenium and Patients with Autoimmune Thyroid Disease

    Sufficient selenium status is necessary for good thyroid health.

    A woman's neck
    Selenium-containing drugs are effective for treating patients with autoimmune thyroid disorders [Zuo 2021].
    Zuo et al [2021] have investigated selenium status and the effects of selenium supplementation in patients with autoimmune thyroid disease.

    They analyzed the data from 17 journal articles based on studies of 1,911 subjects. Their meta-analysis results showed the following statistically significant associations:

    • Serum free triiodothyronine (FT3) levels in patients were reduced after selenium supplementation compared to placebo treatment.
    • Serum free thyroxine (FT4) levels and anti-thyroid peroxidase antibody (TPOAb) levels were reduced after selenium supplementation compared to placebo treatment.
    • Anti-thyroid peroxidase antibody (TPOAb) levels were decreased after selenium supplementation compared to placebo treatment.

    However, the thyroid stimulating hormone (TSH) levels
    and the anti-thyroglobulin antibody (TGAb) levels were not significantly different between the selenium treatment group and the control group.

    The researchers concluded that selenium-containing drugs were effective in treating patients with autoimmune thyroid disease and greatly reduced
    the levels of free triiodothyronine, free thyroxine, and anti-thyroid peroxidase antibody in these patients. read more

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    Selenium in the Prevention and Treatment of Thyroid Disorders

    Throid gland in the neck
    The thyroid gland is an endocrine gland in the front of the neck just below the Adam’s apple. It consists of two lobes connected by the thyroid isthmus. Selenium deficiency and less than optimal activity of the selenoproteins may be a factor in autoimmune thyroid diseases.  https://commons.wikimedia.org.

    A 2017 summary of the research literature supports the idea that optimal selenium levels are needed for antioxidant protection against harmful free radicals in the thyroid gland and for the normal metabolism of thyroid hormones [Ventura 2017].

    A 2018 research literature review shows that selenium supplementation can reduce anti-thyroperoxidase antibody levels and can improve thyroid ultrasound features. In addition, selenium supplementation is associated with improved symptoms and improved quality of life in patients with Graves orbitopathy [Santos 2018].

    Note: Anti-thyroperoxidase antibody levels that are too high (>500 IU/ml) are associated with an increased risk of hypothyroidism in autoimmune thyroiditis, which is the most common form of thyroid disorder [Ehlers 2016]. read more

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    Selenium Supplementation and Graves’ Disease

    Low selenium status is associated with increased risk of Graves’ Disease. Graves’ Disease is an autoimmune disease of the thyroid. It is the most common cause of hyperthyroidism. It often results in an enlarged thyroid.

    A 2018 meta-analysis of randomized controlled trials shows that adjuvant selenium supplementation may enhance the restoration of normal thyroid function in patients with Graves’ Disease [Zheng].

    Graves’ Disease is the most common cause of hyperthyroidism in adults. It is characterized by below-normal serum TSH levels and increased serum levels of free thyroxine (FT4) and/or triiodothyronine (T3). The basal metabolic status of Graves’ Disease patients is accelerated; the result is an increase in the production of harmful free radicals and reactive oxygen species [Zheng].

    Intra-cellular antioxidant enzymes such as superoxide dismutase (SOD), glutathione reductase, and glutathione peroxidase (GPx) protect against the cellular damage caused by oxidative stress. read more