The impact of the gut microbiome goes far beyond just digestion, influencing areas of physiology such as immune system health, brain neurotransmitter production, and endocrine organ function. The ability of the thyroid to function well is closely tied to gut health, with many gut conditions having ties to thyroid disorders. A root cause medicine approach to managing thyroid disorders includes analyzing the gut microbiome and optimizing gut health to ensure optimal thyroid function.

[signup]

Overview of Thyroid Disorders

Classical thyroid disorders typically fall into one of two classes, hypothyroidism and hyperthyroidism. Hypothyroidism occurs when the thyroid is under-functioning relative to metabolic needs, leading to symptoms that develop over time and affect a variety of bodily systems. Common symptoms of hypothyroidism include fatigue, weight gain, constipation, dry skin, cold intolerance, puffiness in the eyes or face, depression, decreased sex drive, thinning hair, numbness or tingling in the hands, brain fog, and irregular menstrual cycles. 

Hyperthyroidism, conversely, occurs when the thyroid is over-functioning relative to metabolic needs and can appear quite different from hypothyroidism. Common symptoms of hyperthyroidism include unintentional weight loss, arrhythmias, tachycardia, heart palpitations, sweating, menstrual cycle changes, anxiety, tremors, heat sensitivity, increased frequency of bowel movements, sleep disturbances, muscle weakness, and brittle hair.

Autoimmune thyroid diseases include Hashimoto’s thyroiditis as well as Graves’ disease. Hashimoto’s disease is the most common cause of hypothyroidism in developed countries, with roughly 5% of Americans impacted. Symptoms typically overlap with hypothyroid symptoms, though some cases of Hashimoto’s may be asymptomatic, especially in the early stages of the disease. Graves’ disease, while also autoimmune, typically resembles hyperthyroidism, though the disease can also impact the eye and skin. Bulging eyes (Graves’ ophthalmopathy) and thick red skin on the tops of the shin or feet (Graves’ dermopathy) are both hallmark symptoms as the disease progresses 

Conventional treatments for any type of hypothyroidism typically involve T4 hormone replacement based on blood testing of thyroid stimulating hormone (TSH). Occasionally, T3 treatments may be used, but are not as commonly recommended as T4 hormone replacement. This treatment approach is standard for Hashimoto’s thyroiditis as well. For hyperthyroidism, including Graves’ disease, the conventional treatment approach typically includes anti-thyroid treatment, beta-blockers, and potentially radioactive iodine therapy and thyroidectomy depending on the severity of the case. Additionally, corticosteroids and, if needed, orbital decompression therapy are also used for Graves’ disease, which can impact the eye.  

The Gut-Thyroid Axis

The phrase “gut-thyroid axis” is used to refer to the relationship between the gut microbiome and thyroid function. The gut microbiome can make and regulate various compounds related to endocrine signaling and hormone function, making the gut an essential part of the overall endocrine balance. Deiodinases, the enzymes that are responsible for converting thyroxine (T4) to the active T3, are active in the intestinal wall, highlighting the close relationship between gut function and thyroid hormone production. Additionally, bacteria in the gut microbiome impact many different vitamins and minerals that are important for optimal thyroid function. This includes the production of specific vitamins such as Vitamin K, folic acid, and other B vitamins, the breakdown of dietary fiber, communication with and impact on neurotransmitter production, and overall absorption of micronutrients like zinc, selenium, and iodine. Together, all of these impact the ability of the thyroid to function optimally.  

When dysbiosis and increased intestinal permeability are present, the resultant deleterious impact on gut function also impacts thyroid health and can place individuals at higher risk of autoimmune thyroid conditions like Hashimoto’s disease. Higher levels of zonulin, a protein related to tight junctions in the intestinal lining, have been found in Hashimoto’s patients, highlighting a link between intestinal permeability and autoimmune thyroid disease. When zonulin is highly expressed, it can lead to a prolonged opening of intestinal tight junctions, setting the stage for a “leaky gut.” Additionally, short-chain fatty acids (SCFA) that are produced from fiber breakdown in the gut, such as butyrate, have been linked to immune system regulation, with higher butyrate and SCFA production protecting against autoimmune activity. Dysbiosis and poor SCFA production have also been linked to a higher rate of Hashimoto’s disease.  

Root Cause Medicine Assessment of Gut and Thyroid Health

Root Cause medicine practitioners combine a thorough personal health history, review of systems, and targeted labs to fully assess both gut and thyroid health when working with patients with thyroid disorders. Ordering thyroid labs alone is typically not enough to fully understand the root cause of a patient’s thyroid disorder, and the information gleaned from functional lab testing can help personalize a therapeutic plan to help patients feel their best.

To evaluate thyroid function, practitioners will typically order a more comprehensive thyroid panel that looks at several markers beyond just TSH. The Comprehensive Thyroid Panel by Access Medical Labs measures TSH, free fractions of both T4 and T3 hormone, as well as reverse T3 and the thyroid antibodies typical of Hashimoto’s disease, anti-TPO (thyroid peroxidase enzyme) antibodies and anti-TG (thyroglobulin) antibodies.  

Thyroid-stimulating immunoglobulins (TSI) may also be measured if a diagnosis of Graves’ disease is suspected. Understanding the full picture of thyroid health through comprehensive testing helps practitioners see if autoimmune activity plays a role in thyroid symptoms (which can’t be gleaned from TSH alone), and bring to light any potential problems with the conversion of T4 to T3, which can occur with gut and liver problems as well as in high-stress lifestyles.

To evaluate the gut microbiome, stool testing such as the GI-MAP by Diagnostic Solutions provides insight into the overall health of the gut, bringing to light any imbalances in microbes in the gut as well as any issues with digestive efficiency and nutrient absorption. This test can be particularly valuable for those thyroid patients who are dealing with autoimmune thyroid conditions, as dysbiosis is one of the main drivers of various autoimmune diseases.  

When dysbiosis and increased intestinal permeability are present, there is a higher risk of developing food sensitivities to various types of foods, with the most common foods affected being wheat, milk, eggs, soy, peanuts, and corn. Food sensitivities can serve as triggers of autoimmune activity, whether that be due to further disruption of the intestinal barrier or a phenomenon called “molecular mimicry,” in which food proteins resemble one’s tissue, leading to misguided immune responses against host tissue instead of the food protein. For example, gliadin, the protein found in gluten, has been shown to trigger the release of zonulin, highlighting the potential for gluten to increase the risk of developing increased intestinal permeability that may trigger autoimmune disease over time. 

Food sensitivity panels such as Ayumetrix’s Basic Food Sensitivity Panel look at 96 of the most common foods that may be impacting gut health and creating inflammation. Additionally, Array 10 by Cyrex Labs looks at the cooked, raw, and modified forms of various foods, providing a comprehensive evaluation of how different cooking methods of foods may impact the body’s immune response to said foods. Last, the ALCAT test by Cell Science Systems evaluates not just antigen-antibody reactions to foods, but measures white blood cell reactions to truly see how the immune system is responding to commonly consumed foods. Understanding what foods may need to be temporarily removed while supporting gut and thyroid healing helps personalize a plan and decrease the likelihood that unnecessary nutritious foods are avoided.

[signup]

Nutritional Strategies for Supporting Gut and Thyroid Health

While there are many diets marketed to help heal Hashimoto’s disease, evidence currently points to an anti-inflammatory, nutrient-dense diet that emphasizes the intake of micronutrients important for thyroid health, such as selenium, iron, zinc, and iodine. The gut microbiome plays an important role in the absorption of these minerals, so supporting optimal gut function and a healthy gut lining is an important piece of any nutritional strategy aimed at supporting better gut and thyroid health. Limiting refined sugars, incorporating fresh, whole unprocessed fruits, vegetables, and lean meats, and including gut-healing foods such as bone broth, prebiotics, and probiotic foods are all strategies to help design a personalized nutrition plan to optimize gut and thyroid function. A Mediterranean-type diet with the potential elimination of gluten and dairy (guided by functional medicine lab testing) can be a great starting place for many thyroid patients, while a Paleo or autoimmune-Paleo diet is another example of an anti-inflammatory, whole-food diet that can help achieve health goals for those dealing with thyroid conditions.  

Emphasizing specific food sources and supplements of appropriate micronutrients, as determined by micronutrient testing, can also help curate a personalized nutrition experience for each thyroid patient.  Zinc is an essential mineral for thyroid function, playing a central role in the activity of the deiodinase enzymes that convert T4 into T3. It’s also an incredibly important mineral for gut health, helping to keep the gut lining healthy and strong.  Selenium helps to activate the enzyme that makes thyroid hormones, and supplementation has been found to help reduce antibody counts in both Hashimoto’s and Graves’ disease. Last, iodine is another important mineral for thyroid hormone production, with low levels being linked to hypothyroidism. Iodine deficiency can be addressed simply by adding iodized salt back into the diet.  

Gluten-free diets may also help reduce symptoms of Hashimoto’s in some individuals. Prevalence of autoimmune thyroid disease is four times higher in those with celiac disease as compared to the general population, suggesting that there may be a potential link between gluten reactivity and increased risk of developing Hashimoto’s symptoms and higher antibody counts. Additionally, adequate protein intake, dietary fiber, and unsaturated fatty acids, especially omega-3 fats, are also recommended to help support Hashimoto’s healing.  

Additionally, probiotics can help improve immune function, decrease pathogen growth in the gut, and help heal and strengthen the intestinal barrier to help support overall gut health. Probiotics can be consumed through supplementation or foods such as yogurt, sauerkraut, pickles, tempeh, or kimchi.  

Addressing Gut Dysbiosis and Leaky Gut

Dysbiosis is associated with the development of hypothyroidism, correcting gut dysbiosis an important component of any functional medicine plan to manage thyroid disorders. Additionally, dysbiosis is also a driver of autoimmune disease, making gut-healing essential for cases of autoimmune thyroid disease as well.  

Based on lab testing, a personalized plan to correct dysbiosis and heal leaky gut syndrome can be created as part of thyroid management. Antimicrobial herbs may be recommended to help rebalance bacteria in the gut and to target specific pathogens, such as candida overgrowth. Gut-healing supplements such as zinc carnosine can be effective in repairing and strengthening the gut lining and regulating the immune system, while vitamin D supplementation can help improve dysbiosis as well as hypothyroidism.  Prebiotic and probiotic supplements are helpful to increase beneficial bacteria in the gut. Lab results from stool testing can help practitioners personalize probiotic recommendations for each patient by evaluating what the makeup of a person’s microbiome looks like. Probiotics can also improve intestinal barrier function, helping to resolve leaky gut syndrome. 

Lifestyle modifications can also help improve the function of the intestinal barrier and help to heal leaky gut syndrome. Smoking, lack of exercise, and chronic unresolved stress have all been linked to poor gut microbiome health, underlining the importance of healthy lifestyle habits and regular exercise.  High-fiber diets have also been found to improve intestinal barrier function and overall health of the gut microbiome; including a variety of fiber sources in the diet can be a good strategy for thyroid patients to support overall gut health. 

Lifestyle Modifications to Support Overall Health

In addition to nutritional strategies for supporting both gut and thyroid health, a root cause medicine approach to holistic care will also include lifestyle modifications to positively impact patient results. Lifestyle changes may be aimed at stress reduction, sleep optimization, or increasing physical activity.  

Stress can negatively impact thyroid function and may also exacerbate symptoms in autoimmune thyroid patients. The hypothalamic-pituitary-adrenal (HPA) axis and the hypothalamic-pituitary-thyroid (HPT) axis can communicate and influence each other, underlining the connection between stress response and thyroid function. Ongoing stress often leads to excess cortisol production, which can signal the thyroid to stop producing adequate thyroid hormone while also inhibiting the conversion of T4 to T3, leading to the development or worsening of hypothyroidism. Stress has also been closely linked to changes in the gut microbiome and overall gut health, increasing the risk of developing leaky gut syndrome and impacting inflammation and gut function through the gut-brain axis. Stress management strategies are therefore essential for any patient looking to optimize both gut health and thyroid function.

Regular exercise is another lifestyle change that can positively impact both gut and thyroid health. Physical activity has been associated with lower inflammation levels and decreased autoimmune activity and has also been linked to better thyroid hormone levels overall.  

Last, sleep optimization is another key lifestyle factor to consider when supporting gut and thyroid health.  Sleep quality has been found to affect thyroid function, with poor sleep quality correlating to higher TSH values and a higher risk of developing hypothyroidism. Gut microbiome diversity has been linked to sleep quality as well, with better sleep correlating to more diverse, healthy gut microbiomes. Without quality sleep, it can be difficult for both the gut and the thyroid to function optimally, placing patients at higher risk of symptomatology and ongoing health issues.  

A Root Cause Medicine Approach

Conventional and functional medicine approaches, when combined, can create effective, holistic management strategies for thyroid patients who also need to emphasize gut healing as part of their therapeutic plan. While thyroid hormone replacement is often a first-line approach to help reduce symptoms and normalize thyroid labs, supporting a patient’s nutrition and lifestyle while identifying the root causes of thyroid dysfunction can help personalize a treatment plan to maximize patient outcomes. Understanding a patient’s gut health is a key part of a combined approach, as the gut microbiome has been linked to thyroid function and may also be a driver of autoimmune activity in those patients managing Hashimoto’s or Graves’ disease. Optimizing gut health may improve a patient’s digestion and absorption efficiency, potentially improving how well they absorb medication, making it important to collaborate with prescribing physicians to monitor patient progress.  

Monitoring and Adjusting Treatment Plans

Monitoring both gut and thyroid health in patients with thyroid disorders is key to a personalized treatment plan that is effective and in the best interest of the patient. Because optimizing gut health can impact thyroid function, supporting a patient’s gut microbiome may lead to changes in how well their thyroid works, and may require modifications in medication or thyroid hormone management. Regularly monitoring complete thyroid labs, as well as re-evaluating gut microbiome health after any treatment protocols can help adjust and finetune a patient’s plan as needed. While monitoring labs is key to adjusting treatment plans, the role of patient feedback is also important. Regularly checking in with patients to assess symptoms, adherence to lifestyle changes, and monitoring patient well-being are all key parts of gauging treatment effectiveness and adjusting personal plans as needed.  

[signup]

Key Takeaways

Root Cause medicine is uniquely positioned to help identify and address the root causes of thyroid disorders, one of which is often poor gut health. Optimizing gut health can help patients better absorb nutrients, reduce inflammation, and improve the strength of the gut lining, all of which are essential for optimal thyroid function. Because the gut is so closely tied to thyroid function, patients and healthcare providers need to consider gut health as a foundational aspect of managing thyroid disorders to set patients up for best results and long-term success.