Selenium for Thyroid Function, Hyperthyroidism & T3/T4 Hormone Levels

Selenium plays an important role in the health and function of the body’s thyroid gland. Along with iodine, selenium is used to support the production of T3 and T4 thyroid hormones.

T3 and T4 are used by all cells in the body to facilitate energy metabolism; they play an indirect role in a number of important biological and neurological functions.

Using a selenium supplement may be recommended to individuals with certain thyroid problems, including hypothyroidism and Hashimoto’s autoimmune thyroiditis.

Selenium protects the thyroid gland from elevated iodine levels and promotes resistance to illness, inflammation and chronic infections. In addition to its roles in maintaining proper thyroid function, selenium is also important for health in several other ways.

Selenium is the base of more than two dozen selenoproteins which ae involved in DNA synthesis and repair, resisting damage from oxidative stress, promoting immune function and in reproduction. [1]

Selenium

Essential Mineral

Anti-Oxidant

Immunity

Thyroid Function

How It Works:

• Cofactor for antioxidant enzymes
• Supports thyroid function & metabolism
• Promotes immune function & fertility

Dosage:

Up to 400 mcg per day

Safety:

Rated Likely Safe at Appropriate Dosages

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Selenium and Thyroid Hormones

Selenium is important to ensure a proper balance between levels of T3 and T4 thyroid hormones.

Iodine atoms attach to a tyrosine “backbone” to produce T3 and T4 hormones.

T3 (triiodothyronine) contains 3 iodine atoms per molecule. T4 (thyroxine) contains 4 iodine atoms per molecule.

T3 is considered the active form of this hormone, used by the body to regulate metabolism. Most of this hormone is stored in the form of T4 until it is required to be active.

T4 becomes T3 via a process called deiodination. Selenium-based deiodinase enzymes are needed to facilitate deiodination.

Selenium deficiency can cause inadequate T4-to-T3 conversion; possibly leading to low thyroid activity (hypothyroidism).

This is a condition which can have a number of negative effects on the human body, including chronic low energy levels, poor skin health, impaired cognitive function and impaired detoxification function.

Selenium and Thyroid Antibodies

Selenium supplementation has been studied for its effects on certain health conditions that can impair thyroid function.

One study followed the effects of selenium supplementation in patients with inflammatory autoimmune thyroiditis over 9 months. Subjects included both selenium-deficient and selenium-sufficient patients.

Results showed that routine use of a selenium supplement reduced thyroid peroxidase antibodies significantly.

Because of this, some researchers believe that selenium supplementation might be helpful for preventing damage to thyroid tissue from various thyroid conditions. [2]

Further research is needed to be able to determine the long-term efficacy of selenium for decreasing thyroid antibodies, or preventing thyroid tissue damage in humans.

Selenium and Hypothyroidism

According to the Mayo Clinic, some of the most common symptoms of hypothyroidism include: fatigue, dry skin, constipation, irritability and increased sensitivity to cold.

Other negative effects of low T3 levels include weight gain, puffy face, weak muscles, pain, stiffness and irregular menstruation.

Those with impaired thyroid function may also experience hair loss, hoarseness, slowed heart rate, impaired memory and/or depression.

The Natural Medicines Comprehensive Database (NMCD) states that increasing selenium can make hypothyroidism worse in those who are iodine-deficient. However, selenium does not seem to have much effect on the function of the thyroid gland when iodine is adequate.

It is not recommended to take a selenium supplement without also taking an iodine supplement, especially in those with low iodine and selenium levels. [3] Doing so could exacerbate the symptoms of hypothyroidism.

Selenium and Thyroid Nodules

The American Thyroid Association (Thyroid.org), defines thyroid nodules as abnormal growth in thyroid cells that cause lumps in the thyroid gland.

Benign thyroid nodules are much more common than cancerous thyroid nodules (about 9-to-1). Most thyroid nodules cause no symptoms. Thyroid nodules are very common and have no known cause.

Hashimoto’s disease is an autoimmune disorder where the immune system attacks cells in the thyroid gland. Hashimoto’s is linked to increased risk of developing thyroid nodules. These nodules are also caused by iodine deficiency.

According to Medscape, one study showed that those with low selenium levels were more likely to develop multiple thyroid nodules greater than 10 millimeters in diameter. However, selenium supplementation did not seem to affect the development of singular thyroid nodules.

The effects of selenium supplementation on the development of thyroid nodules are not well understood yet. More research in large, randomized human-based trials is necessary.

Selenium and Thyroid Disease

The thyroid gland stores more selenium than any other organ.

Epidemiological evidence from a study of more then 1900 subjects indicated a negative relationship between “serum selenium concentrations and thyroid volume, risk of goiter, and risk of thyroid tissue damage in people with mild iodine deficiency”. [4]

Placebo-controlled, randomized human studies of selenium supplementation and thyroid disease have yielded conflicting results.

One study with 368 healthy patients between 60 and 74 years of age showed no effects of 3 different doses of selenium on thyroid function. This was true even though serum levels of selenium had increased significantly with all doses. [5]

In a different double-blind, controlled and randomized study, 159 patients with mild Graves orbitopathy were given either 200 mcg/day doses of selenium, or 1200 mg/day doses of pentoxifylline – or an inert placebo.

Relative to placebo controls, those treated with selenium reported a higher quality of life than those who received pentoxifylline.

Selenium also outperformed both pentoxifylline and the placebo agent in terms of improving ophthalmic (vision) outcomes and certain disease progression factors. [6]

More research is needed in order to determine how selenium supplementation might be helpful for preventing and/or treating thyroid dysfunction or disease.

Selenium and Thyroid Medication

Many women who use synthetic thyroid hormones replacements like Synthroid are curious about how selenium supplementation will affect their medications.

According to Drugs.com, there have not been any interactions between selenium supplements and Synthroid recorded in their database.

However, if you are considering increasing your intake of selenium-rich foods, or taking a dietary supplement, then it is best to seek medical advice first.

Ask your healthcare professional how iodine, selenium and thyroid health are related. Be sure to mention pre-existing health conditions you may have – as well as any prescription drugs you may use.

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