3 superpowers of selenium for your thyroid

How the right dose of selenium can benefit your thyroid


Selenium is an important micronutrient. The amount of selenium in your body depends on the geography of where you live, and where your food comes from (1, 2). Scientists have shown selenium is crucial for maintaining a healthy immune system, hormonal balance, and metabolism.

The thyroid is the organ with the highest concentration of selenium in the body — selenium is used there as a building block of specific proteins called selenoproteins. This is where selenium has immense benefits for the thyroid gland and immune health.

1. Selenium is an antioxidant

Certain selenoproteins are antioxidants — removing free radicals (aka reactive oxygen species) that are generated during the process of building up thyroid hormones in the thyroid gland (3, 4). This is a crucial function in preventing thyroid gland damage and premature ageing.

2. Selenium helps convert T4 into T3

A subgroup of selenoproteins, deiodinases, are essential for converting an inactive T4 into its active form T3 (5).

If your body misses selenium, production of T3 will be lower — causing TSH to rise and forcing the thyroid gland to produce more T4. As a byproduct of that production, there will be more free radicals damaging the thyroid gland, and since selenium is low it won’t be able to function as an antioxidant. This will result in high T4, low T3, and higher than usual TSH. It will also create a scar tissue within the thyroid gland, deeming that part of the thyroid non-functional (6).

3. Selenium can reduce thyroid antibody levels

Research has shown that people taking 200µg of sodium in a form of sodium selenite reduces TPO antibody level by 40% after 90 days (for example, if your TPO was 200 IU/mL, after 90 days it could drop to 120 IU/mL) (7) and 55% after six months (dropping to 90 IU/mL) (8). It’s been shown if you stop taking selenium, your antibody levels will go back up (9).

Which foods contain high selenium?

Meat products, brazil nuts, fish, pasta, rice, bread, cereals, and yeast (10).

What is the best form of selenium supplements?

Selenium is available as selenomethionine, selenocysteine, selenite, and selenate (1). Selenomethionine and selenocysteine are better absorbed by the gut (11).

Low levels of selenium can still occur even when taking high doses of it — this may be caused by your lifestyle: smoking, continuously eating high quantities of eggs or white rice, drinking alcohol and/or coffee (12).

What’s the right selenium supplement dose?

400 mcg per day is considered too much, and a prolonged exposure to selenium might cause poisoning (13), it will take on average 6 weeks for the excess of selenium to leave your body once you stop taking high doses (14). If you are taking high selenium doses, you might experience skin irritation, lung irritation, diarrhea, hair loss, or nail discoloration.

See how taking selenium daily impacts your thyroid health by tracking your dosage and symptoms in BOOST Thyroid app.