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Hashimoto’s Thyroiditis and the importance of Selenium

Jun 14, 2023 | Autoimmunity, Blog, Supplements, Thyroid Health

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Hashimoto's Thyroiditis and the Importance of Selenium Supplementation

The THYROID GLAND is an essential part of the ENDOCRINE system, and its proper function is crucial for maintaining good health. It is responsible for producing thyroid HORMONES that help regulate metabolism, growth, and development. However, HASHIMOTO’S THYROIDITIS is a common AUTOIMMUNE condition that affects the thyroid gland and can lead to HYPOTHYROIDISM. Fortunately, there is growing evidence that suggests the importance of SELENIUM SUPPLEMENTATION can be beneficial for individuals with Hashimoto’s Thyroiditis.


What is the Role of Selenium?

SELENIUM is an essential TRACE MINERAL that has been found to have potent ANTIOXIDANT and ANTI-INFLAMMATORY properties. Interestingly, the thyroid gland has the highest concentration of selenium compared to any organ in the human body.


Selenium is involved in the production and activation of thyroid hormone and helps protect the thyroid from OXIDATIVE DAMAGE. This deficiency can cause a range of symptoms, including fatigue, weight gain, and brain fog. Selenium is also a potent DETOXIFYING mineral. For example, MERCURY is a major thyroid-disrupting chemical, but not as significant when selenium is present. So, selenium also can protect the thyroid by BINDING TO MERCURY and making it completely inert.


Selenium and Iodine

Selenium and IODINE are intricately intertwined in the thyroid gland, and they are both necessary for thyroid hormone production. However, supplementing with selenium if you are deficient in iodine can actually suppress thyroid function. Therefore, it is important to have your iodine status checked before supplementing with selenium so we can figure out the best plan forward. One clear pattern on your thyroid labs that can indicate a selenium deficiency is a high or high/normal Free T4 but low or low/normal Free T3 with a normal TSH. This indicates that your T4 isn’t CONVERTING well to T3 possibly due to a selenium deficiency. This is important since T4 is the INACTIVE hormone, while T3 is the more important, ACTIVE one.


Can Selenium Help Hashimoto’s Disease?

Selenium supplementation has been found to also protect the thyroid gland from the damaging effects of thyroid peroxidase (TPO-Ab) and anti-thyroglobulin (Tg-Ab) antibodies.


Multiple studies have shown that selenium supplementation significantly reduced thyroid antibodies, which are an indicator of thyroid autoimmunity. In fact, the higher the antibody levels were at the beginning of the studies, the greater the positive effects from selenium. It was also found that selenium improved the overall sense of well-being in these individuals. Three separate studies have shown that selenium supplementation suppresses TPO-Ab and Tg-Ab levels


Selenium and the Epstein-Barr Virus

Selenium has also been shown to inhibit the expression of the Epstein-Barr Virus, which is a virus linked to Hashimoto’s and other autoimmune diseases.


Selenium’s Role in Pregnancy

Many women develop Hashimoto’s Thyroiditis after giving birth, and selenium supplementation has been studied in pregnant women to see if it could help prevent this condition.


The results showed that women who supplemented with selenium had much lower antibody levels, and their thyroid glands were also protected as they did not change in size compared to the women who didn’t supplement.


What Is Considered Optimal Selenium Intake from Food?


Sources of Selenium

Selenium can be obtained through dietary sources, including high-protein foods such as meat, tuna, shellfish, eggs, sunflower seeds, mushrooms, and rye. The content of selenium in foods is dependent on the soil concentration of selenium, which can vary greatly in different regions. Supplementation with selenium is also an option, but it is important to choose a safe and effective form of supplementation.


The current recommended dietary intake of selenium from food is 55-75mcg/day. However, the content of selenium in foods is dependent on the soil concentration of selenium, which is very low in some areas.


Which Form of Selenium Is Best and How Much Is a Safe Dose?

Sodium selenate and selenite are the most popular forms of selenium, but only about 50% is absorbed. In addition, these forms of selenium increase the risk of selenium toxicity. SELENOMETHIONINE is the preferred form of selenium supplementation as it is the form found naturally in food, and about 90% of it is absorbed. A safe dose is 200 micrograms each day as long as it is in the form of selenomethionine.


Can Selenium Be Toxic? Symptoms of Selenium Deficiency and Toxicity

Symptoms of selenium deficiency include muscle weakness, fatigue, joint pain, and cognitive decline. In severe cases, it can lead to the development of Keshan disease, a condition that affects the heart and can be fatal. On the other hand, high doses of selenium can be toxic and cause a range of symptoms, including hair loss, hypothyroidism, depression, diarrhea, anorexia, blindness, ataxia, respiratory disturbances, liver and kidney damage, hemorrhage, nail loss, dermatitis, central nervous system disorders, and insulin resistance leading to diabetes. It is essential to work with an experienced FUNCTIONAL MEDICINE healthcare practitioner to determine the appropriate dosage and type of selenium supplementation for your specific needs to avoid toxicity.


Why Should You Avoid Brazil Nuts?

BRAZIL NUTS can contain anywhere from .2mcg to 253mcg of selenium depending on where they come from. If you were eating three Brazil nuts a day from a source that was on the higher end of this range, you could easily begin to develop selenium toxicity, and we would also have to factor in all the selenium you are getting from the rest of the food you are eating and any supplements such as a multivitamin. If you’re going to consume Brazil nuts, don’t take any selenium supplements, and it would be wise to eat them in extreme moderation such as once a week or even once a month.


Putting It All Together

If you have Hashimoto’s Thyroiditis, it is reasonable to supplement with selenomethionine under doctor supervision if your whole blood selenium test indicates you are deficient. However, you must take into account any selenium content in other supplements you are taking as well as selenium from food to be sure you don’t go above the safe range. Additionally, you must be certain that your iodine intake is adequate from food and a small amount from supplements so as not to further suppress your thyroid function.

Since you shouldn’t supplement with large doses of iodine if you have Hashimoto’s Thyroiditis, then the reasonable approach is to take a multivitamin which has about 150mcg of iodine to begin restoring any iodine deficiencies while not exacerbating your Hashimoto’s Thyroiditis. This is definitely not something you would want to do on your own without doctor supervision, so be sure to work with an experienced FUNCTIONAL MEDICINE healthcare practitioner who can perform the proper testing needed to figure out your unique health balance.


Here are some additional tips to support thyroid health:


Eat a balanced diet:

A balanced diet with a variety of nutrient-dense foods can support thyroid health. Focus on foods high in selenium, such as meat, fish, nuts, and seeds, as well as foods high in iodine, such as seaweed, fish, and dairy products.


Reduce stress:

Stress can negatively impact thyroid function. Find ways to manage stress, such as meditation, yoga, or deep breathing exercises.


Get enough sleep:

Sleep is essential for overall health, including thyroid health. Aim for 7-8 hours of sleep each night.


Exercise regularly:

Regular exercise can help improve thyroid function and reduce inflammation.


Avoid toxins:

Exposure to toxins, such as PESTICIDES and CHEMICALS, can disrupt thyroid function. Avoid exposure to toxins as much as possible by choosing organic foods and avoiding products with harmful chemicals.

Incorporating these tips into your lifestyle can help support optimal thyroid health and manage Hashimoto’s Thyroiditis effectively. Remember to always work with an experienced FUNCTIONAL MEDICINE healthcare practitioner for personalized guidance and support.



Selenium supplementation can play an essential role in managing Hashimoto’s Thyroiditis by improving thyroid function, reducing thyroid antibodies, and improving overall well-being. However, it is crucial to be careful with the dosage and type of selenium supplementation to avoid any potential toxicity. Working with an experienced FUNCTIONAL MEDICINE practitioner to determine the appropriate dosage and type of supplementation for your specific needs is highly recommended.

In summary, by understanding the intricate connection between selenium, iodine, and the thyroid gland, you can take steps to optimize your thyroid function and overall health. With the right guidance and support, you can find the right balance of nutrients and supplements to manage your Hashimoto’s Thyroiditis effectively.