Thyroid gland & histamine intolerance: All the important connections
The thyroid is a small, butterfly-shaped organ in the neck that is essential for metabolism and numerous bodily functions. If it is not working properly, this can have serious effects on your health. In this article, you will learn everything about overactive and underactive thyroids, their symptoms, causes, important thyroid values, and the connection with histamine.
What exactly is the thyroid?
The thyroid is a vital hormone gland located in the front of the neck. It is butterfly-shaped and lies below the larynx. It gets its shape from the two lateral lobes that wrap around the trachea. They are connected by a bridge of tissue and are usually slightly different in size.
Functions of the thyroid
The thyroid plays a crucial role in many processes in the body as it produces vital hormones that regulate human metabolism and energy balance. The most important hormones are:
- Thyroxine (T4): most important thyroid hormone; regulates metabolic activity and influences almost all organs
- Triiodothyronine (T3): is more effective than T4, especially in the cardiovascular system, and plays a key role in energy production and growth
- Calcitonin: participates in regulating the body's calcium and phosphorus balance, thereby influencing bones
T3 and T4 can even be produced by the thyroid in advance. They are stored in the follicles of the gland and can last for up to two months. Calcitonin is produced by the C-cells of the thyroid and released directly into the blood.
The production of these hormones is controlled via a feedback loop involving the thyroid and several parts of the brain. The hypothalamus is a part of the human diencephalon where the hormone TRH is formed and released when blood levels of T3 and T4 are too low.
The TRH then stimulates the pituitary gland—a gland connected to the hypothalamus—to release thyroid-stimulating hormone (TSH). This then leads to the release of T3 and T4 in the thyroid.
The TSH value is important for diagnosing thyroid disease and is normally between 0.4 and 4.0 mU/l. In women, especially during pregnancy, these values can vary slightly.
The trace element iodine is an essential building block of these hormones, which is why adequate iodine intake is important for a healthy thyroid. For adults, the daily iodine requirement is about 180 to 200 micrograms. The requirement is slightly higher for pregnant women because an accelerated metabolism demands more thyroid hormones.
Seafood, such as pollock or plaice, contains particularly high levels of iodine and is more tolerable in cases of histamine intolerance. Iodine is also found in smaller amounts in other foods.
The tasks of the thyroid in the body include:
- Metabolic regulation: controls how quickly the body burns energy
- Growth and development: particularly important for the growth of children and the development of the nervous system
- Cardiovascular system: influences heart rate and blood pressure
- Heat production: supports the regulation of body temperature
A healthy thyroid is therefore essential for physical well-being. Disorders such as an overactive or underactive thyroid can have significant health effects, ranging from fatigue and weight fluctuations to heart rhythm disturbances and mood swings.
But what types of thyroid disorders are there?
Thyroid diseases
The thyroid can be affected by various diseases that impair its function. Among the most common disorders are hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid), with hypothyroidism being more common.
Additionally, thyroid nodules can occur, which may limit thyroid function. These are detected via ultrasound. The thyroid is not immune to cancer either. Malignant thyroid tumors are relatively rare compared to other tumors (approx. 1%) and usually require surgical removal.
How do I know if I have an overactive thyroid?
Typical hyperthyroidism symptoms include:
- Weight loss despite increased appetite
- Increased body temperature
- Nervousness, tremors, and internal restlessness
- Racing heart and high blood pressure
- Sleep disturbances, concentration problems, and increased sweating
- Frequent bowel movements or diarrhea
Diagnosis and hormone levels for hyperthyroidism
Hormone levels are tested to diagnose an overactive thyroid. Here, a low TSH value and high levels of the hormones T3 or T4 indicate an overactive thyroid. An isolated low TSH value with normal T3 and T4 levels may point to the onset of hyperthyroidism.
A TSH value below 0.3 mU/l is considered a sign of an overactive thyroid.
Causes and influences on an overactive thyroid
The causes of an overactive thyroid include thyroid autonomy ("hot nodules") and Graves' disease. Autonomy means the thyroid is not being controlled normally by the pituitary gland. Often, nodules in the thyroid cause this overproduction.
Graves' disease is an autoimmune disorder in which certain thyroid structures are not recognized by the immune system as being the body's own. As a result, antibodies are formed that cause the activation of the thyroid and thus increased hormone production.
However, an excessive dose of thyroid hormone treatment can also lead to an overactive thyroid. In rare cases, the overactive thyroid is congenital.
- Excessive iodine intake, e.g., through seafood or iodine-rich dietary supplements
- Stress and heat exposure: can intensify the symptoms
What is an underactive thyroid (hypothyroidism)?
Common hypothyroidism symptoms are:
- Chronic fatigue
- Concentration problems
- Weight gain despite normal nutrition
- Heart problems
- Constipation
- Dry skin and hair loss
- Depression, mood swings, and libido disorders
- Sensitivity to cold and swollen limbs
Diagnosis and hormone levels for hypothyroidism
In the case of an underactive thyroid, the TSH value is too high and levels of the hormones T3 or T4 are too low. For this reason, hypothyroidism treatment is often carried out using the medication L-thyroxine (levothyroxine), which is intended to replace the missing hormones.
In the early stages of hypothyroidism, only the TSH value is elevated. A TSH value above 4.0 mU/l indicates hypothyroidism. Values between 4.0 and 10 mU/l are considered only slightly elevated (latent hypothyroidism), while values above 10 mU/l are clinically relevant.
Causes and influences on hypothyroidism
The causes of an underactive thyroid can be varied. Besides the wrong dosage of medication used to treat an overactive thyroid, Hashimoto's thyroiditis can also cause hypothyroidism.
What is Hashimoto's?
Hashimoto's syndrome is a chronic autoimmune disease of the thyroid. In this condition, the immune system mistakenly attacks the body's own thyroid tissue, leading to inflammation. Over the course of the disease, the thyroid tissue is increasingly destroyed and can no longer produce enough hormones.
For more information on the topic of Hashimoto's, we can also recommend the HistaFit Podcast episode "Hashimoto & Histamine: Diagnostics, Connections & Treatment" by Melina and the wonderful Ann-Katrin from Healthy Hashimoto.
But an underactive thyroid can also be congenital in rare cases.
- Iodine deficiency: In Germany and other European countries, foods traditionally consumed are lower in iodine. This is due to the low iodine content of our soil and groundwater. Therefore, you often find iodized table salt. However, this is often poorly tolerated in cases of histamine intolerance.
- Stress and sleep deprivation: can place additional strain on the hormone balance
- Incorrect diet: you can find more about forbidden foods for hypothyroidism below in the section Nutrition for thyroid diseases
Is there a connection between thyroid diseases and histamine intolerance?
There are indications that a connection may exist between the thyroid and histamine intolerance. However, the exact mechanisms are not yet fully understood.
In the area of mast cells, which are frequently involved in histamine intolerance, there are already some findings. Mast cells are the body's own cells that are responsible for, among other things, immune defense. They contain chemical messengers such as histamine and release them when triggered.
Regarding thyroid hormones, the following has already been determined:
- Mast cells can store and release thyroid hormones such as T3. They also possess receptors for thyroid-stimulating hormone (TSH). This connection suggests that thyroid function influences mast cells (and vice versa) and can thus also promote histamine release.
- Histamine in the mast cells of the thyroid promotes the inflammatory response and plays a role in the development of thyroid tumors. Furthermore, in an experimentally induced thyroid hormone deficiency, it could be shown that the number of mast cells and the histamine content in the thyroid increase.
- In diseases like Hashimoto's, antibodies can activate mast cells and release histamine, which further aggravates the autoimmune disease.
As already mentioned, thyroid dysfunction can also lead to accelerated or slowed digestion. This means that the thyroid can also have a negative effect on the gut.
For this reason, Ann-Katrin from Healthy Hashimoto says in our podcast that she frequently sees hypothyroidism and histamine intolerance occurring together. Therefore, the gut should also be a focus here. Because a gut flora dysbiosis or a leaky gut can worsen the symptoms even further.
We share this view. That is why we are always in favor of looking at and rebuilding the gut first.
If you would also like to focus on your intestinal mucosa, our MucosaFit can be easily integrated into your daily routine. The formula combines L-glutamine and flaxseed with selected vitamins and minerals such as vitamins A, C, D, and zinc. Vitamin A contributes to the maintenance of normal mucous membranes, while vitamin C and zinc support the normal function of the immune system.
MucosaFit is suitable for a low-histamine & low-fructose diet, gluten-free, lactose-free, and vegan, as well as free of unnecessary additives & laboratory-tested.
Important: If you have an existing thyroid condition or are taking medication, you should consult a doctor before taking any dietary supplements.
Nutrition for thyroid diseases
For both overactive and underactive thyroids, the same applies: a balanced, healthy diet is the key.
What is especially important for nutrition in the case of an overactive thyroid?
- Low-iodine diet: especially avoiding algae and seafood
- Avoiding high-caffeine drinks such as coffee and cola as well as alcohol, so as not to place additional strain on the overactive metabolism
What should be considered regarding nutrition with hypothyroidism and Hashimoto's?
- Iodine-richer diet
- No excessive consumption of foods that inhibit iodine uptake, e.g., onions (1), cassava, soy (2), tofu (2), walnuts and peanuts (2), or even many types of cabbage
- Avoid highly processed foods: often contain unhealthy fats and few nutrients
Conclusion
A healthy thyroid is essential for physical and mental well-being. Disorders such as an overactive or underactive thyroid can have significant health effects, which can be treated through proper diagnostics, nutrition, and, if necessary, medication therapy.
Particularly important is an adequate iodine intake, as this trace element is a central building block for thyroid hormones. Regular check-ups and an adapted lifestyle can help you detect and treat diseases early on.
A histamine intolerance and hypothyroidism can also co-occur, as thyroid hormones and mast cells influence each other.
It is important here to also focus on the gut and, if necessary, to restore it.
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