The number of people with thyroid health conditions continues to rise each year, although many of us are unaware we are affected as symptoms can be wide-ranging and non-specific and are often mistaken for something else. According to the British Thyroid Foundation, 1 in 20 people in the UK suffer from thyroid disorders with women six times more likely to suffer than men. However, the actual incidence is estimated to be much higher.
So why are we seeing this increase? In this week’s blog we will take a look at some of the underlying mechanisms that might be contributing to the rise in thyroid dysfunction and also at some of the nutritional and lifestyle interventions to help support our thyroid health.
Overview of the thyroid
The thyroid gland is an endocrine gland located at the base of the throat and is responsible for making two important hormones – thyroxine (T4) and triiodothyronine (T3). Firstly, the hypothalamus releases thyroid hormone releasing hormone (THRH), which stimulates the pituitary to release thyroid stimulating hormone (TSH). TSH triggers the thyroid to produce T4 which needs converting to the active T3. These hormones are transported in the blood where they control metabolic rate, growth and many other vital functions.
Every cell in the body has receptors for thyroid hormone as it is necessary for all cells in the body to function normally. Any one or more of these pathways can be interrupted leading to hypothyroidism.
Primary hypothyroidism – low T4 or T3 and high thyroid stimulating hormone (TSH) – it can also be high T4 but low T3 because of poor conversion, lack of cofactors etc
Secondary hypothyroidism – low T4 and TSH, poor pituitary release
Tertiary hypothyroidism – low production of thyroid hormone releasing hormone (THRH) from hypothalamus
Autoimmune – production of antibodies against the thyroid gland (Hashimoto’s)
Wilson’s syndrome – normal levels of T4 and T3 but high levels of rT3 (an inactive molecule, which can inhibit the action of T3)
Hyperthyroidism is an overactive thyroid, meaning that the thyroid gland makes more thyroid hormones than the body needs. This can speed up the body’s metabolism and lead to symptoms such as weight loss, increased heart rate and irritability.
Conversely, hypothyroidism is an underactive thyroid and occurs when the thyroid gland is not producing and secreting enough thyroid hormones. This is the most common thyroid condition and will be the primary focus of this blog.
Prevalence of thyroid health disorders
Hypothyroidism affects up to 5% of the population according to European prevalence estimates1, while as many as 5% of the population may be undiagnosed.
However, some experts estimate that as much as 25-40% of the adult population has suboptimal thyroid function.
It is common to have subclinical hypothyroidism, where no diagnosis is made based on blood tests results within the normal range. However, thyroid function is not optimal and therefore individuals can still experience vague symptoms. Suboptimal thyroid function is a possible factor in many conditions than are currently realised and should be considered particularly in patients who do not respond well to interventions for other conditions.
Symptoms of hypothyroidism
Symptoms of low thyroid function include (but are not limited to):
- weight gain
- mental slowing
- dry skin
- hair loss/thinning
- brain fog
- muscle pain and stiffness
- low mood
- menstrual problems
- intolerance to the cold
The full implications of hypothyroidism however are not completely appreciated or defined.
Factors affecting thyroid health
The rise in thyroid disorders is hard to disentangle from rising life expectancies, improved testing and increases in those seeking help. However, there are many factors that can impact the health of our thyroid, which are also increasing, such as chronic stress, metabolic syndrome and insulin resistance.
The thyroid is also influenced by many body systems which are all interconnected including the gut, liver, immune and reproductive system, which are all impacted by various modern-day factors. Support for thyroid function therefore needs to be multifaceted.
Poor adrenal health
Overwhelming or unremitting stress can lead to poor adrenal function and increase the risk of poor thyroid function. In modern society, our stressors are often not survival based and can come in many forms such as financial worries, relationship problems, health concerns, or just busy schedules, and are often ongoing.
There are other scenarios which our bodies may also perceive as stress – pain, over-exercise, nutrient deficiencies, blood sugar imbalances, anti-nutrients (caffeine and alcohol), food intolerances and toxins, as well as our thoughts and perceptions – an extensive list!
Stress can impact on the thyroid through multiple mechanisms including:
Disruption of HPA/HPT axis
The HPA axis describes the interaction between the hypothalamus, pituitary gland, and adrenal glands. Stress sensed in the brain leads to the release of hormones that ultimately cause the adrenal glands to secrete the stress hormones – adrenaline and cortisol.
The process of thyroid hormone synthesis and secretion is regulated by the hypothalamic-pituitary, thyroid (HPT) axis. Chronic stress can fatigue the pituitary gland so that the signals to the thyroid are impaired and inadequate thyroid hormone is released.
Reduces conversion of T4 to T3
Increased cortisol due to high stress can shift the thyroid into a more inactive state, elevating rT3 levels rather than converting T4 to T3. Too much however can slow metabolism and cause other detrimental effects in the body. It is thought that rT3 blocks the T3 receptor sites on cells. During stress, inflammatory cytokines are released which are known to suppress the conversion of T4 to T3.
Promotes leaky gut
Stress can increase gut barrier permeability through various mechanisms such as impacting bacterial populations and suppressing the immune system. Chronic disruption of the gut barrier can lead to translocation of microbial components into the body, producing systemic, low-grade inflammation.2 This can trigger immune complexes which can produce antibodies against proteins similar to our own, potentially leading to autoimmune disease.
Insulin resistance/blood sugar imbalance
According to Diabetes UK, new figures show that 4.3 million people are now living with a diagnosis of diabetes and more than 2.4 million are at a high risk of developing it. Furthermore, an estimated 850,000 are undiagnosed. This brings the overall UK-wide figure to over 5 million for the first time.3 Furthermore, Metabolic Syndrome is estimated to affect 1 in 3 older adults in the UK and is increasing.4 It has been shown in a number of studies that insulin resistance, diabetes, or metabolic syndrome are associated with:5-8
- a significant reduction in T4 to T3 conversion
- an intracellular deficiency of T3
- an increased conversion of T4 to rT3 (further reducing intracellular T3 levels)
Furthermore, dysglycaemia has been shown to:
- weaken and inflame the gut
- cause hormone imbalances
- exhaust the adrenal glands
- impair overall metabolism
Each of these effects significantly weakens thyroid function.9
Poor liver health
Most conversion of T4 to T3 occurs outside of the thyroid gland, particularly in the liver. A sluggish liver can therefore impact thyroid health adversely. Obesity, poor diet, medications, alcohol and toxin overload can all contribute to poor liver health.
Poor gut health
Converting T4 into T3
Your gut is another location where the conversion of T4 to T3 occurs. Approximately 20% of T4 is converted to T3 in the digestive tract by healthy gut bacteria in the forms of T3 sulphate (T3S) and triidothyroacetic acid (T3AC). The conversion of T3S and T3AC into active T3 requires an enzyme called intestinal sulphatase, which comes from beneficial gut bacteria. Dysbiosis and poor gut health is characterised by a reduction in the numbers of beneficial bacteria in the gut.
Onset of Hashimoto’s disease has been associated with coeliac disease as well as non-coeliac gluten sensitivity. Gluten has been shown to cause local inflammation of the enterocytes that line the digestive tract, which can increase the risk of leaky gut and hence autoimmune disease.9
Inflammation is at the heart of most chronic diseases, particularly autoimmune diseases. Infections, leaky gut, poor diet and stress can lead to immune dysregulation and inflammation. Inflammation:
- suppresses the HPT axis and decreases the conversion of T4 to T3
- It also affects receptor function as it decreases the number and sensitivity of thyroid receptors
- Pro-inflammatory cytokines have been shown to depress levels of circulating T3 and may interfere with the HPT axis
Minerals such as iodine, iron, selenium and zinc play many important roles in thyroid health, including the conversion of T4 to T3. Those with a poor diet, digestive health issues causing poor absorption of nutrients (Crohn’s / Coeliac disease) or those with inflammation due to chronic infection or various other factors are at an increased risk of deficiency.
Diet and lifestyle support for thyroid health
Many nutrients can be used to support thyroid health, but the following are directly involved in the production of thyroid hormones:
Tyrosine – An amino acid that is a major constituent of T4. (Should not be supplemented along with thyroid hormone replacement medications e.g., thyroxine unless under the supervision of a qualified medical practitioner.)
Iodine – four iodine molecules are combined with tyrosine to produce T4 (should not be supplemented along with thyroid hormone replacement medications unless under the supervision of a qualified medical practitioner)
Selenium – a cofactor for the enzyme which manufactures T4, and the enzyme which converts T4 into T3. Selenium has been shown to lower auto-antibodies to thyroid hormones.10,11
Zinc and copper – cofactors for the conversion of T4 to T3.
Iron – deficiency has been shown to significantly reduce T4 to T3 conversion, increase rT3 levels, and block the thermogenic (metabolism boosting) properties of thyroid hormone.12
A note on goitrogens
Goitrogenic foods including soy and raw brassica vegetables (in large quantities) can bind to iodine, making it unavailable to the thyroid, thus inducing an iodine deficiency. Cooking inactivates this action therefore it is not necessary to avoid these foods, but they should not be consumed raw in excess.
Stress management/adrenal support
This is vital when supporting the thyroid. The adrenal glands need to be looked at holistically as psychological factors, supplementation, a good diet and quality sleep can play an important role.
- Stress can deplete many nutrients and can also increase our need for others. Vitamins C, B5 and B6support normal adrenal function and cortisol production. Vitamin C is abundant in fruit and vegetables and the B vitamins are found in many foods including wholegrains, legumes, meat and fish.
- Magnesiumis considered a natural tranquiliser due to its function to relax both skeletal and smooth muscle. It is also an essential cofactor for many enzymes involved in the production of adrenal hormones and therefore is depleted in times of stress
- Aim to avoid or limit caffeine and alcohol, which are stimulants and can stress the adrenals
- Adaptogenic herbs such as Ashwagandha, Siberian ginseng, Panex ginseng and Rhodiola all help to modulate the stress response
- Practicing stress management or relaxation techniques such as meditation, mindfulness, yoga and walking can help to support the body in stressful times
- Stabilise blood sugar levels (see below)
Balance blood sugar levels
- Avoid or minimise sugary, processed foods and refined foods as they are rapidly converted into glucose and raise blood levels quickly
- Consume plenty of healthy protein sources such as meat and poultry, fish, and eggs
- All green vegetables/salads are recommended. Those vegetables that grow above the ground will have significantly lower carbohydrate (and higher healthful nutrients) than those that are grown below the ground
- Choose healthy fats such as olive oil, avocado, nuts, seeds and oily fish. Fat in a meal will slow down the release of glucose into the bloodstream.
In terms of lifestyle:
- Regular exercise can support blood glucose levels by building muscle and therefore increasing glycogen storage, so that more glucose can be taken out of the blood
- Stress is an independent risk factor for developing diabetes, and stress reduction techniques such as yoga, mindfulness or meditation can improve insulin sensitivity
- Sleep deprivation can contribute to type 2 diabetes so ensure you try to get 7-8 hours a night
Support immune system/decrease inflammation
You can do this by following an anti-inflammatory diet (the Western diet and lifestyle tends to promote inflammation):
- Increase intake of fresh fruit and vegetables – obtaining 6-8 per day, including dark leafy greens high in anti-inflammatory phytonutrients and antioxidants
- Reduce consumption of omega 6 fatty acids found in seed oils and processed foods
- Increase sources of omega 3 from oily fish and flax, chia seeds and/or a take a supplement containing EPA. Omega 3 plays a crucial role in reducing inflammation
- Curcumin – found in turmeric, has been shown to inhibit Cox-2 enzymes which produce inflammatory prostaglandins.
Support gut health / autoimmunity
If the cause is autoimmunity, then removing the triggers and healing the gut is important. Autoimmune triggers include:
- gluten and casein, which have been shown to have a detrimental effect on gastro-intestinal permeability
- leaky gut
- environmental toxins
- Glutamine, found in bone broths or as a supplement, supports the repair of the gut lining
- Vitamin D3 is an essential part of the innate immune system. Th1 dominance is associated with tissue specific autoimmune diseases such as Hashimoto’s. Research has shown that D3 can reduce Th1 dominance.13
- Reduce exposure to xenobiotics which have been shown to increase thyroid autoantibodies
- Increase prebiotic and fermented foods such as chicory, apples, Jerusalem artichoke, dark green leafy vegetables, olives, plain yoghurt, kefir, raw sauerkraut and kimchi
- Include a live bacteria supplement, containing a wide variety of beneficial strains
Support liver health
Supporting Phase II liver detoxification will help to prevent a sluggish liver and your body to remove excess steroid hormones, such as oestrogen and cortisol, if they are known to be a problem. Vitamin B6 and magnesium are important for sulphur amino acid metabolism, as are foods containing sulphur such as: eggs, meat, poultry, nuts and legumes.
Cruciferous vegetables such as cauliflower, cabbage, kale, broccoli and Brussels sprouts are a rich source of sulphur-containing phytochemicals called glucosinolates, which offer antioxidant and anti-inflammatory properties and support detoxification. Ensure your water intake is adequate.
Thyroid health key takeaways:
- The number of people with thyroid conditions continues to rise each year
- Hypothyroidism is an underactive thyroid and occurs when the thyroid gland is not producing and secreting enough thyroid hormones
- Symptoms of low thyroid function include weight gain, mental slowing, fatigue, dry skin, hair loss/thinning, brain fog, infertility, muscle pain and stiffness, low mood
- The thyroid is influenced by many body systems which are all interconnected including the gut, liver, immune and reproductive system
- Overwhelming or unremitting stress can lead to poor adrenal function and can disrupt the HPA/HPT axis, reduce conversion of T4 to T3 and promote leaky gut
- Insulin resistance, diabetes, and metabolic syndrome are associated with poor thyroid function
- Poor liver function and gut health can impact thyroid health
- Inflammation is at the heart of autoimmune disease
- Minerals such as iodine, iron, selenium and zinc play many important roles in thyroid health
- Adrenal glands need to be looked at holistically as psychological factors, supplementation, a good diet and quality sleep can play an important role
- Balancing blood sugar levels, supporting gut and liver health and following an anti-inflammatory diet can help to support thyroid health
- Thyroid refs Chiovato, L., (2019). Hypothyroidism in Context: Where We’ve Been and Where We’re Going. Advances in therapy, 36(Suppl 2), 47–58.
- Martel, J., Chang, S. H., Ko, Y. F., Hwang, T. L., Young, J. D., & Ojcius, D. M. (2022). Gut barrier disruption and chronic disease. Trends in endocrinology and metabolism: TEM, 33(4), 247–265.
- Diabetes UK, Number of people living with diabetes in the UK tops 5 million for the first time [online]. Accessed 19th June 2023.
- Metabolic syndrome – NHS (2019). Available at: https://www.nhs.uk/conditions/metabolic-syndrome/ (Accessed: 19 June 2023).
- Farasat, T., Cheema, A. M., & Khan, M. N. (2012). Hyperinsulinemia and insulin resistance is associated with low T₃/T₄ ratio in pre diabetic euthyroid Pakistani subjects. Journal of diabetes and its complications, 26(6), 522–525.
- Khatiwada, S., Sah, S. K., Kc, R., Baral, N., & Lamsal, M. (2016). Thyroid dysfunction in metabolic syndrome patients and its relationship with components of metabolic syndrome. Clinical diabetes and endocrinology, 2, 3.
- Biondi, B., Kahaly, G. J., & Robertson, R. P. (2019). Thyroid Dysfunction and Diabetes Mellitus: Two Closely Associated Disorders. Endocrine reviews, 40(3), 789–824.
- Kalra, S., Aggarwal, S., & Khandelwal, D. (2019). Thyroid Dysfunction and Type 2 Diabetes Mellitus: Screening Strategies and Implications for Management. Diabetes therapy : research, treatment and education of diabetes and related disorders, 10(6), 2035–2044.
- Kresser, C. Thyroid Disorders. Available at: https://chriskresser.com/thyroid/ Accessed 20th June 2023.
- Hu, Y., Feng, W., Chen, H., Shi, H., Jiang, L., Zheng, X., Liu, X., Zhang, W., Ge, Y., Liu, Y., & Cui, D. (2021). Effect of selenium on thyroid autoimmunity and regulatory T cells in patients with Hashimoto’s thyroiditis: A prospective randomized-controlled trial. Clinical and translational science, 14(4), 1390–1402.
- Gärtner, R., Gasnier, B. C., Dietrich, J. W., Krebs, B., & Angstwurm, M. W. (2002). Selenium supplementation in patients with autoimmune thyroiditis decreases thyroid peroxidase antibodies concentrations. The Journal of clinical endocrinology and metabolism, 87(4), 1687–1691.
- Zimmermann, M. B. and Köhrle, J. (2002) ‘The Impact of Iron and Selenium Deficiencies on Iodine and Thyroid Metabolism: Biochemistry and Relevance to Public Health’, Thyroid, 12(10), pp. 867–878.
- Soleimani, M., Jameie, S. B., Mehdizadeh, M., Keradi, M., Masoumipoor, M., & Mehrabi, S. (2014). Vitamin D3 influence the Th1/Th2 ratio in C57BL/6 induced model of experimental autoimmune encephalomyelitis. Iranian journal of basic medical sciences, 17(10), 785–792.
If you have questions regarding the topics that have been raised, or any other health matters, please do contact our team of Nutritional Therapists.
Last updated on 6th July 2023 by cytoffice