Diet for Hyperthyroidism - Key Insights

The thyroid gland is one of the hormone-secreting glands located within the body. It is responsible for regulating the function of most tissues that affect the body's metabolism, thermogenesis (heat production), and calcium-phosphorus economy. The thyroid's function is monitored by the pituitary gland, which releases the thyroid-stimulating hormone (TSH), thereby stimulating the thyroid to produce T3 and T4 hormones. The synthesis of these hormones also requires the intake of iodine and amino acids through food. The function of the thyroid and pituitary glands are interdependent, a phenomenon known as feedback regulation. This mechanism operates on the principle of effective information exchange: an elevated level of thyroid hormones leads to a decrease in the signal from the brain (release of TSH by the pituitary gland), while a deficiency of these hormones results in an increase in TSH production, which in turn encourages the thyroid to produce more T3 and T4.

Thyrotoxicosis affects 1-2% of Poles, primarily women aged 20-40 years (P. Miśkiewicz, T. Bednarczuk, mp.pl). The condition involves the excessive secretion of hormones triiodothyronine and thyroxine by the thyroid gland. As a result, there is an excess amount of hormones in the body. The most common causes of thyrotoxicosis include Graves-Basedow disease and thyroid nodules. Occasionally, thyrotoxicosis is also caused by postpartum and subacute thyroiditis, which are associated with a history of viral infection.

Excessive activity of the thyroid gland means that the body is functioning at maximum capacity. As a result, symptoms such as feeling hot, excessive sweating, trembling of the hands, heart palpitations, and increased metabolism can be observed, leading to unintentional weight loss despite increased appetite. Those affected by excessive activity of the thyroid gland often experience restlessness, anxiety, irritability, difficulty sleeping, and muscle weakness, and stimulated intestinal peristalsis results in more frequent bowel movements and diarrhea. Although the symptoms associated with increased metabolism may initially be perceived as beneficial, untreated excessive activity of the thyroid gland can lead to serious complications such as heart rhythm disorders, heart failure, osteoporosis, or a thyroid storm, which is a life-threatening condition of exacerbated excessive activity of the thyroid gland.

The primary objective of nutrition in the case of hyperthyroidism, when hormone levels are not yet balanced, is to prevent weight loss. Due to accelerated metabolism, the body is in a phase of catabolism, i.e., an increased breakdown of molecules or tissues with the release of chemical energy. This results in increased utilization of all available resources and consequently higher energy requirements, but when these are not met, uncontrolled weight loss occurs. For patients with a BMI below the norm, a diet with higher caloric content is recommended (on average, 15-25%, i.e., 300-500 kcal). In cases of significant weight loss, accompanied by muscle wasting, it is advisable to consider the use of mixtures available in pharmacies. However, after achieving hormonal balance, it is necessary to return to a normocaloric diet to avoid the risk of overweight.

It is assumed that protein should constitute 12–15% of the energy value of the diet (according to D. Wolańska-Buzalska on ncez.pzh.gov.pl). However, for individuals with weight loss, a higher protein intake of approximately 90–100 g (according to P. Tuchendler and Z. Zdrojewicz, 2017) is recommended. The primary source of protein should be lean meats, eggs, seeds of leguminous plants, and occasionally fish (no more than 2–3 times a week due to its iodine content, as an excess of this element in the diet can exacerbate the condition). Fat should constitute 20–35% of the energy value of the patient's diet and be of plant origin. The polyunsaturated omega-3 fatty acids present in plant fats exhibit a protective effect on nerve cells and have an immunostimulatory effect (according to D. Wolańska-Buzalska on ncez.pzh.gov.pl). The source for this nutrient in the diet includes freshly ground or soaked flax seeds, rapeseed oil, olive oil, walnuts, pumpkin and sunflower seeds, avocado, and olives. It is also important to consume the appropriate amount of dietary fiber (20–40 g daily) and carbohydrates (at the level of 50–70% of the energy value of the diet) (according to D. Wolańska-Buzalska on ncez.pzh.gov.pl). For this reason, whole-grain products, vegetables, and fruits should be the primary source of carbohydrates in the diet.

Certain nutrients are particularly important in the diet of people with thyroid disorders, namely calcium and vitamin D, because they are involved in bone metabolism (D. Wolańska-Buzalska, pzh. gov. pl). Hyperthyroidism can lead to disturbances in calcium metabolism, which can predispose to osteopenia and osteoporosis. Women are particularly susceptible to these disorders, as the risk of bone loss increases with age and they are more likely to experience hyperthyroidism. Vitamin D also plays a key role in many bodily processes, including blood pressure regulation and the functioning of the nervous and muscular systems. Calcium and vitamin D can be found in large amounts in sardines, herring and sprat. It is also important to note that the intake of vitamin D from food is often insufficient, so year-round supplementation is recommended. The calcium requirement can be met by consuming dairy products, green leafy vegetables, white beans, soy, sesame and poppy seeds. It is also important to consider vegetables that contain goitrogens, such as raw broccoli, cauliflower, cabbage and turnip. These compounds can prevent the incorporation of iodine into the precursor molecules of thyroid hormones, which can in turn reduce the amount of hormones produced. An overproduction of thyroid hormones can also lead to an increased proportion of free radicals, so it is important to provide natural antioxidants such as vitamins A, C and E as well as certain elements such as selen.

Salted snacks and fast food are particularly high-energy foods that may seem desirable in hyperthyroidism. However, they are definitely not recommended due to their pro-inflammatory trans fat content. Energy drinks - caffeine provides an additional boost which may exacerbate symptoms such as anxiety, heart disturbances, concentration difficulties, and insomnia in patients. In cases of hyperperistalsis leading to discomfort, a light diet is recommended, including the avoidance of frying and grilling and the restriction of fiber. In the case of radioiodine therapy, a low-iodine diet is recommended (thyroid.org). Iodine is used in animal care and feeding as well as a stabilizer and safety component in food processing, therefore it can be found in varying amounts in nearly all food and beverages. In this type of treatment, the largest sources of iodine must be strictly avoided, such as iodized salt, certain bakery products (according to the European Parliament regulation, the iodine content must be listed on the packaging), seafood, shellfish, beef, poultry, milk and dairy products, eggs, seaweed, and algae.

Besides the obvious symptoms of hyperthyroidism, which significantly reduce the comfort of life, there are also other long-term effects of the disease that are not immediately apparent. Among the patients with hyperthyroidism, about half of them have impaired glucose tolerance, and about 3% of them are battling diabetes (M. Gierach, J. Gierach, R. Junik 2014). Scientific research suggests that an abnormal processing of carbohydrates is the result of liver insulin resistance, which manifests itself in increased organ activity – synthesis of lipoprotein and triacylglycerol fractions, glycogenolysis, and gluconeogenesis (P. Tuchendler, Z. Zdrojewicz 2017). As a result of accelerated tissue metabolism, the body also processes glucose, leading to a hyperthyroidism-specific postprandial hyperglycemia (M. Gierach, J. Gierach, R. Junik 2014). Glucose requires insulin as a key to enter the cell. At high glucose levels, driven by the disease, the pancreas is constantly stimulated to produce insulin, which can ultimately lead to insulin resistance in the tissues.

A mode of nutrition does not constitute treatment for thyroid dysfunction; however, it improves well-being and quality of life. An organism that is well-nourished is better equipped to counteract the disease. An appropriate nutrition plan is particularly significant prior to attaining hormonal equilibrium in the case of substantial weight loss. Throughout the entire treatment process, by adhering to the principles of a balanced diet, we prevent long-term health repercussions such as chronic diseases.