What you need to know about selenium and the thyroid gland


Selenium is an essential nutrient for everyone's health. It is essential for thyroid hormone metabolism, reproduction, and DNA synthesis, and protects you from infections and oxidative stress damage.

Selenium is a mineral that occurs naturally in some foods that we eat. It is also added to foods for enrichment and can be taken as a dietary supplement. Your body does not make selenium, so the only way to get it is through food and / or supplements.

Effect of selenium on the thyroid gland.

In adults, the thyroid is the organ with the highest concentration of selenium in the body, and this mineral plays a key role in the thyroid's ability to produce thyroid hormone. The optimal amount of selenium in your diet is vital. just to prevent thyroid disease, but for your overall health.

Selenium deficiency has been linked to a variety of thyroid problems, including :

Iodine , a fundamental constituent and a key ingredient in thyroid hormone, actually requires selenium to be properly synthesized in thyroid hormone.

What the research shows

Several studies have shown key relationships between selenium supplements and thyroid function and the immune system. For instance:

  • In several studies, both excessively high and low selenium levels have been associated with an increased risk of the disease.
  • Several studies have shown that selenium supplementation reduces thyroid peroxidase (TPO) antibodies , as well as the severity of hypothyroid symptoms.
  • Several studies have shown that treating patients with mild to moderate thyroid disease (Graves' orbitopathy) with selenium supplements improved their quality of life, improved their eye condition, and dramatically slowed the progression of symptoms. The European Thyroid Association now recommends a six-month trial of selenium supplements for patients with Graves' orbitopathy.
  • Even for people who are not selenium deficient, selenium supplementation has been shown to have a significant effect on the immune system by increasing the production of activated T cells and the activity of natural killer cells, which aid in the immune response . to diseases, tumors and infections.
  • A 2016 study looked at the effect of selenium supplementation on thyroid antibody levels in people with Hashimoto's thyroiditis. The study evaluated the levels of antibodies against thyroid peroxidase (TPOAb) and thyroglobulin (TgAb) after three, six and 12 months of selenium ingestion in two groups of patients with Hashimoto: one group received replacement therapy with levothyroxine and the other with a new one. diagnosis. patients not receiving thyroid hormone replacement therapy. For those treated with levothyroxine, selenium supplementation resulted in a significant decrease in TPOAb levels at three months, which continued to decline at six and 12 months. TgAb levels did not decline until the 12-month point. In the untreated Hashimoto group, selenium supplementation resulted in lower TPOAb levels after three months, but not after six or 12 months, while TgAb decreased after three months, but not after six or 12 months. .

Selenium deficiency

While this nutrient is important to your thyroid, keep in mind that selenium deficiencies in the United States are quite rare due to the selenium-rich soil. Most Americans easily get the amount of selenium they need on a daily basis.

While the likelihood of a deficiency is quite low for most, there are people for whom the risk is higher. Some of the risk factors for developing selenium deficiency include:

  • Intestinal, digestive, or absorption problems such as Crohn's disease.
  • After gastric bypass surgery
  • Living in an area deficient in selenium in the soil.
  • Receive kidney dialysis
  • The presence of the human immunodeficiency virus (HIV)


Lack of selenium can cause a variety of symptoms. Some of the most common:

  • Sterility
  • Hair loss
  • Fatigue
  • Weight gain
  • Immune system disorder, resulting in more frequent illnesses.
  • Difficulty thinking and / or concentrating.

Of course, it is worth noting that some of these overlap with the symptoms of thyroid disease.

Selenium levels can be measured with blood tests, and hair or nail tests can assess selenium levels over months or years. Healthy blood selenium levels are 8 micrograms (mcg) / dl or higher, according to the National Institutes of Health.

While this is not a routine test, if you have a thyroid disorder (usually only done if selenium deficiency or toxicity is suspected), you or your healthcare provider may check your levels at some point to make sure that are within the normal range. limits.

Daily recommendations

It helps to know what your goal should be, especially if you have any of the symptoms mentioned above.

The Food and Nutrition Board (FNB) of the National Academies Institute of Medicine recommends that healthy people 14 years of age and older get 55 mcg of selenium daily from all sources. Recommended up to 60 mcg per day if you are pregnant and up to 70 mcg per day if you are breastfeeding. You can safely take up to 400 mcg per day between meals and supplements.

Shapes and fonts

There are two forms of selenium: organic (selenomethionine and selenocysteine) and inorganic (selenate and selenite). Both forms are good sources, but research has shown that using the organic form of selenium as a supplement may be more effective because your body absorbs more than 90% of the organic selenium, but only about 50% of the inorganic form.

Foods that are good sources of selenium include:

  • Brazilian walnut
  • Seafood such as shrimp, sardines, salmon, halibut, and tuna.
  • Meats like beef steak, beef liver, ground beef, and ham.
  • Domestic bird
  • Eggs
  • Bread
  • Scales
  • Grain

Selenium can be found alone in supplements or in multivitamins in combination formulas. Due to its general effects on the body, studies are being done to see if selenium supplements can affect glucose metabolism, as well as help prevent cancer, thyroid disease, heart disease, and cognitive decline that it happens with age.


Selenium toxicity

While low selenium levels are a concern, high levels can lead to selenium poisoning over time. Symptoms include:

  • Garlic smell from mouth
  • Metallic flavor in the mouth
  • Hair loss and brittle or brittle nails
  • Nausea
  • Acne
  • Diarrhea
  • Skin lesions
  • Fatigue
  • Irritability
  • Nervous system abnormalities

In particular, watch out for Brazil nuts; Because they contain so much selenium, up to 90 mcg per nut, you can cause selenium poisoning if you eat them too often.

Benefits and risks

Despite research, international guidelines still lack formal recommendations for treating patients with autoimmune thyroid disease with selenium supplements. For people with thyroid disease and low selenium levels, supplementation may be beneficial, but for those with normal or high selenium levels, supplementation could potentially lead to toxicity.

Get the word of drug information

Before considering adding a handful of Brazil nuts to your diet or taking selenium supplements, your healthcare professional should test your selenium levels. They can then advise whether increasing your dietary selenium or adding supplements might help.

Note that if you choose to take selenium supplements, you should calculate your dietary intake and make sure to count all selenium in multivitamins and supplements so that your daily intake does not exceed the recommended maximum daily intake of 400 mcg.

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