Does your thyroid gland need more vitamins and minerals?

Extreme fatigue, unsuccessful attempts to lose weight, mood swings, dry skin, constipation, swollen throat, and many other symptoms may be a sign of Hashimoto’s disease that slows down the metabolic rate. This thyroid disorder that develops slowly is increasing at a rapid rate. Other thyroid disorders like Graves’ disease that cause hyperthyroidism are also a problem. In a review article published in Nutrients, researchers have looked at how nutrients such as iodine, selenium, iron, zinc, and vitamin D support the thyroid gland, the body’s production of thyroid hormones, and the regulation of chronic inflammation of the thyroid gland. Millions of people around the world lack one or several nutrients that are needed to prevent and treat these common thyroid disorders. Lack of nutrients can also explain why many people receiving medical therapy for their condition aren’t helped. The digestive system and food intolerance may also play a role.

The thyroid gland is responsible for the synthesis and secretion of thyroid hormones, which all the body’s organs and systems need in order to function properly. One of the thyroid hormones contains four iodine atoms. It is called T4 (thyroxin) and is passive. The other thyroid hormone, T3 (triiodothyronine), contains three iodine atoms and is the active thyroid hormone. It works by delivering oxygen to the cells, which is important for their ability to convert carbohydrate, fat, and protein into energy.
The body’s synthesis of thyroid hormones should always be balanced to meet its needs. Because the thyroid gland is a very active gland through which an enormous amount of blood flows, it is important that it is protected against oxidative stress. This is a condition that occurs when protective antioxidants are outnumbered by potentially harmful free radicals.
What we eat is enormously important for our metabolism. If our diet is unable to provide the thyroid gland with the nutrients it needs to produce thyroid hormones, and if the thyroid gland is exposed to oxidative stress, it increases our risk of chronic inflammation, thyroid disorders, and thyroid cancer.
In their review article, the authors have looked at the different nutrients and their role in helping the thyroid gland carry out its functions. Trawling through databases like PubMed, Scopus, and Mendeley, they have searched for relevant studies published in the period between 1986-2024 and compiled the following about nutrients and their role in the thyroid function.

Hashimoto’s disease is a widespread autoimmune thyroid disorder that causes hypothyroidism. The condition is characterized by chronic inflammation.
Graves’ disease is a less common autoimmune thyroid disorder that causes hyperthyroidism. This condition is also characterized by chronic inflammation.
Goiter is characterized by an enlarged thyroid gland.
Hypothyroidism and its early stages seen in connection with pregnancy can increase the risk of miscarriage, pre-eclampsia, preterm delivery, low birth weight, and still birth.
Postpartum thyroiditis is seen after delivery, when a phase of hyperthyroidism is followed by a phase of hypothyroidism

Iodine

Iodine plays a key role in the synthesis of the thyroid hormones, T3 and T4, that contain three and four iodine atoms, respectively. Iodine is important for pregnancy, for child growth, and throughout life. According to the European Food Safety Authority (EFSA), adults need 150 micrograms of iodine daily. Lack of iodine can cause goiter, hypothyroidism, and hyperthyroidism in rare cases. During pregnancy, iodine deficiency can result in fetal damage, and children that lack iodine are at an increased risk of mental retardation.
Iodine is mainly found in seafood (fish, shellfish, and seaweed). The amount of iodine in our diet is influenced by how much iodine is in the agricultural soil. In Denmark and many other countries, it has been custom for decades to enrich table salt with iodine to prevent goiter.
Nonetheless, there is widespread iodine deficiency in the world, especially among vegans. An estimated five billion people lack iodine. What is more, fluoride compounds (including PFAS), chlorine, and brome interfere with our iodine metabolism and may increase the need for the nutrient. It is important not to give patients with Hashimoto’s disease iodine supplements before their selenium levels are adequate.

Selenium

The inactive T4 hormone is converted into active T3 in the body’s tissues. This process requires the presence of selenium-containing enzymes called deiodinases. The enzymes remove a single iodine atom from T4, thereby converting it into T3. The T4/T3 ratio must be properly balanced in order for the metabolism to work properly.
Selenium also supports some powerful antioxidants called GPX (glutathione peroxidases) that protect the thyroid gland against oxidative damage.
Around 2.8 billion people worldwide are believed to lack selenium, mainly because of low selenium in the soil. In their review article, the authors mention several studies and meta-analyses where selenium supplementation (typically around 200 micrograms daily) has shown a positive effect on autoimmune thyroid disorders like Hashimoto’s and Graves’. It is a good idea to stick with selenium yeast that has good bioavailability.

Hypothyroidism is normally treated with synthetic T4 hormone (Eltroxin and Euthrox)
Many patients continue to have symptoms
Selenium deficiency may explain why the medicine often has limited effect. The selenium deficiency simply means there is too little selenium to support the selenoproteins that convert T4 into T3

Iron

Iron is important for the blood’s hemoglobin that delivers oxygen to all cells. Iron is also important for the functioning of the thyroid gland, including the enzyme TPO that is involved in the synthesis of thyroid hormones. During pregnancy, iron is of particular importance to fetal growth, and iron deficiency is associated with anemia and hypothyroidism.
Heme-iron from animal foods has better absorption in the body than non-heme iron from plant foods. Around 4.9 billion people are believed to lack iron, especially women in their childbearing age because of the loss of menstrual blood. Vegans are also vulnerable as a group. It is normally advised only to take an iron supplement in the case of a detected iron deficiency, which is because large amounts of circulating iron in the blood can generate harmful free radicals.

Vitamin D

Most cells in the body have vitamin D receptors (VDR), and this also goes for cells in the thyroid gland. Vitamin D is especially important for the innate immune system. Vitamin D also helps regulate the inflammatory processes, thereby preventing the inflammation from going into overdrive and becoming chronic.
Studies suggest that low vitamin D levels can increase the risk of autoimmune thyroid disorders. When taking a vitamin D supplement, it is essential to focus on optimizing blood levels of the nutrient, which means the status should be higher than 75 nmol/L, and preferably above 100 nmol/L. Our main source of vitamin D is the sun during the summer period, which enables us to synthesize vitamin D in our skin. Still, around one billion people worldwide are believed to lack vitamin D. At our latitudes where the sun is only strong enough for vitamin D synthesis during the spring and summer period, we are more likely to become deficient.

Zinc

Zinc is important for cellular gene expression, cell growth, and a variety of different enzyme processes, including the function of the thyroid gland. Zinc also supports the TPO enzyme that is involved in the production of thyroid hormones. In addition, zinc serves as a powerful antioxidant (SOD) that protects the thyroid gland against oxidative stress. Lack of zinc can impair the functions of the thyroid gland and the cellular receptors for thyroid hormones. It can also result in an enlarged thyroid gland (goiter) in both children and adults. In women with Hashimoto’s disease, there may be a link to zinc deficiency. Future studies will have to look into that.
Around 3.5 billion people have too little zinc. Good zinc sources are shellfish (oysters in particular), offal, meat, eggs, legumes, and nuts. Zinc from animal food sources has better absorption in the body than zinc from plant sources. We don’t store zinc and therefore need to get it on a daily basis.

Magnesium and copper

Magnesium controls different enzyme activities that are related to the thyroid function and the conversion of passive T4 into active T3. Magnesium is also important for the energy turnover, for vitamin D activation, for the immune system, for the regulation of inflammation, and for other functions with a direct or indirect impact on the thyroid gland and the protection against oxidative stress and chronic inflammation. We primarily get magnesium from coarse greens. Around 2.4 billion people are believed to lack magnesium.
Copper is important for many processes that are related to the synthesis and release of thyroid hormones. We get copper from food sources that also include iron, and from nuts, wholegrains, and legumes. Copper deficiencies are not all that common.

Vitamin A

Vitamin A is important for the thyroid gland. It has been seen that vitamin A deficiency, especially in combination with iodine deficiency, can damage the functions of the thyroid gland. Vitamin A is also a powerful antioxidant that protects the thyroid gland against oxidative stress. Pure vitamin A (retinol) is found in high-fat animal food sources like butter, cream, egg yolks, and oily fish. Beta-carotene, which is a precursor of retinol, is found in vegetable food sources like carrots, kale, bell pepper, and tomatoes. Around 3.6 billion people worldwide are believed to lack vitamin A, especially people living in developing countries.

Vitamin B12

Vitamin B12 is important for blood formation, the nervous system, and our energy levels. Vitamin B12 plays a key role in the thyroid gland’s functions and the body’s metabolism in general. Lack of vitamin B12 is associated with autoimmune thyroid disorders such as Hashimoto’s disease. Vitamin B12 is found in animal food sources like liver and offal, meat, fish, eggs, and dairy products. An estimated 3 billion people worldwide lack vitamin B12. Vegans and older people are especially likely to have too little vitamin B12. The same goes for those with low stomach acid and a lack of intrinsic factor, which is a protein that delivers vitamin B12 to the bloodstream.

Digestion, gut flora, and gluten intolerance

The digestion and the enormous gut flora also play a role in our metabolism. Scientists often refer to the thyroid-gut-axis, which is involved in uptake of the nutrients of importance to the functions of the thyroid gland. Thyroid hormones and the metabolism, on the other hand, can also affect the gut flora and its functions.
Unfortunately, modern refined diets, antibiotic use, NSAID preparations, and stress all tend to have a negative impact on our gastrointestinal mucosa and gut flora. Gluten intolerance has even been seen to affect the development of Hashimoto’s and Graves’.
Supplementation with probiotics may positively affect the gut flora and the thyroid hormones, but there are no studies of probiotics and their effect on autoimmune thyroid disorders.

References:

Anna-Mariia Shulhai et al. The Role of Nutrition on Thyroid Function. Nutrients. 2024

Simone Passarelli et al. Global estimation of dietary micronutrient inadequacies: a modeling analysis. The Lancet Global Health 2024

Pernille Lund. Har du problemer med stofskiftet. Ny Videnskab 2015.