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]:
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].
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?
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
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.
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 glandread more
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
Sufficient selenium status is necessary for good thyroid health.
Zuo et al  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
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].
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
The Su.Vi.Max. study — SUpplementation en VItamines et Minéraux AntioXydants — was a big randomized, double-blind, placebo-controlled study carried out with typical French efficiency. Even though I have written the name of the study in French, there are so many English cognates that I am sure you can read the full name of the study.
The study was designed to test the health benefits of daily supplementation with a number of vitamins and minerals at nutritional dosages (roughly, one to three times the daily recommended dietary intakes) [Hercberg 1998]:
selenium, 100 micrograms
vitamin C, 120 mg
vitamin E, 30 mg
beta-carotene, 6 mg
zinc, 20 mg
In particular, the French researchers wanted to see the effect of the daily supplementation over a long period, approximately 7.5 years, from 1994 to 2002, on the prevention of cancer and cardiovascular disease, both of which have been linked to oxidative stress and oxidative damage and might, therefore, be affected by supplementation with antioxidants.read more
Selenium is an essential micronutrient. We need only small quantities of it, but we do need selenium as a component of the amino acid selenocysteine. We need the selenocysteine, in turn, for the body’s synthesis of 25 identified selenoproteins that have a variety of biological functions [Bellinger].
The thyroid is the small butterfly-shaped gland at the base of our necks, just above our breastbones. For such a small gland, the thyroid gland is very important. When it is healthy, it produces the hormones that regulate many bodily functions:
the body’s metabolism rate
the body’s heart function
the functioning of the digestive system
the body’s muscle control
the brain’s development
the maintenance of good bone health
Diseases inhibiting thyroid gland function
The most prevalent diseases of the thyroid gland are the following [Iddah]:read more
Selenium is a trace element. It exists only in rare quantities in the world. It is produced primarily as a by-product of the process of mining copper. It is not recyclable. It is very unevenly distributed in the soils of the earth.
Consequently, the availability of selenium in grasses and grains and, at the next stage of the food chain, in animals, varies considerably from region to region in the world. The human dietary intakes of selenium vary accordingly around the world.
Selenium a vital nutrient for humans Selenium is a necessary micronutrient that our bodies do not produce. We get our selenium primarily from our diets. Selenium is important for good immune system function, good thyroid function, good reproductive function, and good protection of our cells’ DNA.read more
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