It only weighs between 20 and 60 grams and yet it is responsible for so many processes in our body - the thyroid is an organ that many people only think about when they have problems with it. In this article, you will find out why the thyroid gland is so important and what you can do to keep it healthy.
Contents
The structure and function of the thyroid gland
The thyroid gland is located at the front of the neck, directly under the thyroid cartilage of the larynx. It consists of two flaps of skin that are connected to each other via a bridge in front of the windpipe. This results in a shape reminiscent of a butterfly. There are two parathyroid glands on each of the two lobes, which are about the size of a grain of rice. The exact number of these glands varies. In 90% of people there are four, but some people even have up to ten parathyroid glands. They produce the parathyroid hormone, which regulates the concentration of calcium and various trace elements in the blood.
The two most important thyroid hormones are thyroxine, also known as T4, and triiodothyronine or T3. The two differ in the number of iodine atoms they contain, namely four and three respectively. In the thyroid gland, they are formed from the amino acid tyrosine and iodine atoms. The so-called C-cells produce the hormone calcitonin, which regulates bone, calcium and phosphate metabolism as a counterpart to the parathyroid hormone. The TSH (thyroid stimulating hormone) produced in the pituitary gland stimulates the production of thyroid hormones.
Which functions are regulated by the thyroid gland?
T3 and T4 act primarily on the pituitary gland and the hypothalamus and regulate the production of hormones in these glands. This interaction is also known as the thyrotropic control loop. The thyroid hormones are therefore significantly involved in basic bodily functions. Hormone balance, energy levels, blood sugar levels, metabolism, regulation of body heat, fat, protein and carbohydrate metabolism, sexuality, psyche, healthy development of the embryo during pregnancy and much more are regulated by them. The thyroid plays a key role in all of these processes. If it is not working properly, a lot of things in our body can get out of balance. Researchers even see a connection between thyroid diseases such as Hashimoto's and the gut microbiome. It is possible that a balanced gut flora promotes thyroid health and, conversely, thyroid problems could promote chronic inflammatory bowel diseases such as leaky gut syndrome. The latter is a disorder of the intestinal mucosa that allows toxins from the intestine to enter the bloodstream.1
What happens if the thyroid is not healthy?
Just as the list of bodily functions that the thyroid regulates is long, so is the list of symptoms that can occur when it is out of balance. Everything from metabolism to libido, heat sensation, heart rate, brain function and energy levels can suffer when thyroid function is disrupted. The cause of thyroid dysfunction can lie in genetics, but external factors are also cited as possible causes, such as smoking and psychological stress, iodine or selenium deficiency.2
Hypothyroidism
As the name suggests, the thyroid gland produces too few hormones when it is underactive. This means that the metabolism of people suffering from this condition runs at a low level. Those affected are often tired or listless, get cold very easily and suffer from poor memory or concentration. In addition, they often have water retention and suddenly put on weight even if their diet remains the same. Due to the more general symptoms, hypothyroidism in women is often confused with symptoms of menopause and not recognised. However, even mild hypothyroidism can cause long-term damage. For example, the slow metabolism increases the risk of deposits in the blood vessels and therefore also of a heart attack. It is therefore worth taking a look at your thyroid levels if you feel tired or listless.
Hyperthyroidism
Hyperthyroidism is the exact opposite. In this case, the gland produces significantly more hormones than usual. Although a very active metabolism may not sound bad to many people at first, this disorder also causes some problems for those affected. For example, they suffer from palpitations and increased blood pressure, heavy sweating and heat intolerance, weight loss despite eating normally, concentration and sleep disorders or inner restlessness. Here too, diagnosis is not as simple. The symptoms often first appear between the ages of 20 and 40. This is the age at which most heart problems first become noticeable. The cause is therefore often sought in the heart, not the thyroid gland.
In most cases, hyperthyroidism is caused by Graves' disease. This is an autoimmune disease in which antibodies are formed that act on the TSH receptors. This leads to an increased production of thyroid hormones and often to an enlargement of the thyroid gland. Psychological stress, smoking and being female are cited as favouring factors. Vitamin D or selenium deficiency are also possible factors that can cause hyperthyroidism.3
What does the thyroid gland need to function?
Thyroid hormones are made from the amino acid L-tyrosine and iodine atoms. This means that the smooth functioning of the organ depends primarily on the supply of these building blocks. The trace element selenium is also significantly involved in the conversion of T3 into T4. Amino acids are contained in proteins, i.e. mainly in meat, fish and eggs, but also in nuts and dairy products. Iodine is also found in higher quantities in fish (especially sea fish) and seaweed. Eggs and milk contain the trace element as well. As iodine-poor soil prevails in European latitudes, vegetables, cereals and fruit do not contain significant amounts of iodine. Selenium is also found in large quantities in meat, fish and eggs. However, mushrooms, cabbage, lentils and nuts do contain selenium, although the content here is quite low as the soils in our latitudes tend to be low in selenium. The recommended daily intake for adults is 150µg iodine and 55µg selenium. This is the amount of iodine contained in 100-150g of saithe, for example. To get the recommended amount of selenium, you could eat 150g of mackerel, for example.4 With plant-based foods, the amount is significantly higher to get your daily dose. You would have to eat 750g of mushrooms, for example.5
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Ensure your iodine supply
Since the 1980s, table salt has been fortified with iodine in many Western countries in order to prevent iodine deficiency nationwide. As a result, the number of people with a goitre (enlarged thyroid gland) has decreased significantly. However, the supply of iodine to young people has been on the decline again since 2004. The WHO suspects that one of the reasons for this is the reduced use of iodised salt in food production. Researchers are in favour of supplementation with iodine if other sources of iodine are not included in the diet. One advantage of this is that the quantity can be controlled, unlike the content of various foods.6
People who do not eat meat or fish should therefore ensure their iodine and selenium supply by other means. Iodised salt alone cannot cover the requirement, or at least such a large amount of salt would not be healthy. However, if you want to ensure your iodine supply with the help of food supplements, you should always speak to a doctor, as an oversupply of iodine can also be harmful.
Sources:
- Danailova Y, Velikova T, Nikolaev G, Mitova Z, Shinkov A, Gagov H, Konakchieva R. Nutritional Management of Thyroiditis of Hashimoto. Int J Mol Sci. 2022 May 5;23(9):5144. doi: 10.3390/ijms23095144. PMID: 35563541; PMCID: PMC9101513. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9101513/
- Weetman AP. An update on the pathogenesis of Hashimoto's thyroiditis. J Endocrinol Invest. 2021 May;44(5):883-890. doi: 10.1007/s40618-020-01477-1. Epub 2020 Dec 17. PMID: 33332019; PMCID: PMC8049926. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8049926/
- De Leo S, Lee SY, Braverman LE. Hyperthyroidism. Lancet. 2016 Aug 27;388(10047):906-918. doi: 10.1016/S0140-6736(16)00278-6. Epub 2016 Mar 30. PMID: 27038492; PMCID: PMC5014602. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5014602/
- Bundeszentrum für Ernährung: Jodliefernde Lebensmittel. https://www.bzfe.de/ernaehrung-im-fokus/wissen/jodliefernde-lebensmittel/ , aufgerufen am 05.06.2024
- Deutsche Gesellschaft für Ernährung: Selen. https://www.dge.de/gesunde-ernaehrung/faq/selen/#c2940, aufgerufen am 05.06.2024.
- Hatch-McChesney A, Lieberman HR. Iodine and Iodine Deficiency: A Comprehensive Review of a Re-Emerging Issue. Nutrients. 2022 Aug 24;14(17):3474. doi: 10.3390/nu14173474. PMID: 36079737; PMCID: PMC9459956. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9459956/
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