The Connection Between Thyroid and Gut Health

My Story

January is Thyroid Month, and this topic holds a special place in my heart. I have lived with a diagnosed autoimmune thyroid condition, Hashimoto’s Thyroiditis for the past 15 years. Through my own journey, I have helped many patients understand how important their thyroid is to GI health, metabolism, energy, & overall well-being.




The Thyroid

The thyroid gland is a small but very important gland for the body. It is shaped like a butterfly and sits just below the Adam’s apple. Its job is to produce hormones that are used in metabolism, which is the process that the body undergoes to turn the food that is eaten into nutrients that it can use to produce energy. These hormones are known as T3 and T4, and if the body produces too much or too little of them, it can create many problems.



Thyroid Health

Hypothyroidism is a disease that causes the thyroid gland to not make enough hormones. Hashimoto’s Autoimmune Thyroiditis is the most common cause of hypothyroidism, affecting approximately 6-8% of the population (mostly women). But other things, such as thyroid surgery, radiation or some medications can cause a lack of hormones to be produced. Additionally, deficiency of certain nutrients such as iodine, selenium and zinc can cause the thyroid gland to under-function. Stress can also prevent the hormone T4 from turning into its active form, T3. Insufficient or an imbalance of hormones then often cause weight gain, constipation, gas and bloating, as well as other symptoms including feeling sluggish, fatigued, dry skin, brittle hair and feeling forgetful.


Hyperthyroidism on the other hand, is when the thyroid gland is overactive and produces too much of these hormones. This can cause metabolism to “rev up” and lead to unwanted weight loss, anxiety and difficulty sleeping.


Gut Health

Irritable Bowel Syndrome (IBS) is a disorder that affects the large intestine. While it isn’t well understood, there are many symptoms that can result such as diarrhea, constipation, abdominal pain, bloating and gas.


SIBO, or small intestine bacterial overgrowth is when there is an overgrowth of bacteria, fungus, yeast or other organisms in the small intestine. This can lead to a variety of GI symptoms including constipation, diarrhea, bloating and gas, and nausea.


The Connection

As we have seen, the thyroid produces hormones that aid metabolism and greatly influences the rate of motility in the gastrointestinal tract. Because of this, there are many GI symptoms that can arise when things are not functioning properly. As metabolism slows down in hypothyroidism, there is often resulting slowing of movement through the digestive tract, causing constipation. If diarrhea is experienced in hypothyroidism, this could be due to SIBO arising because of the slowing down of intestinal motility.


On the other hand, metabolism is revved up in hyperthyroidism, so this means that diarrhea can be a common symptom due to the state of hypermotility and hypersecretion of hormones. In either case, diet and lifestyle can be incredibly important in prevention and treatment of autoimmune disorders as gut health and integrity is a key factor in modulating autoimmunity.


Key Nutrients

When it comes to managing both thyroid and GI disorders with nutrition, the goals are often very similar: What are the key nutrients at play and how do they need to be balanced? There are a lot of nutrients that can influence the thyroid gland. These include some B vitamins, specifically B1 (Thiamin), B6 and B12 as well as iodine, selenium, zinc and vitamin D. One of the best ways to ensure adequate consumption of these nutrients is to consume a diet consisting of whole plant foods. Here is a list of some plant-based foods that are high in each of these key nutrients:

  • Vitamin B1 (Thiamin): Legumes (beans and peas), flax seeds, sunflower seeds, whole grains and enriched grain products.

  • Vitamin B6: Garbanzo beans, bananas, avocados and potatoes.

  • Vitamin B12: Nutritional yeast and fortified cereals.

  • Vitamin D: Mushrooms and fortified plant-based milks, such as soy, rice or almond.

  • Iodine: Grain products, seaweed, kelp flakes and iodized salt.

  • Selenium: Brazil nuts and whole grains.

  • Zinc: Legumes, whole grains, cashews and pumpkin seeds.

Take Action

It is my goal to empower you to take charge of your health and make small changes that can lead to big impacts to the way you feel. Try incorporating 2-3 new foods every week from the list above into your meals, or adding a few sprinkles of iodized salt or kelp flakes to your dishes. Remember that eating a wide variety of plant foods can provide the key nutrients you need to support both gut and thyroid health so that you can decrease your symptoms and optimize your well-being.


It is important to remember that not every case is the same, and because of this, it is important to seek assistance that is tailored just for you. Talk with your primary care provider and investigate your lab values such as TSH, Total T3, T4, reverse T3, TPO, vitamins A, D, B1, B6, B12, iodine, zinc and selenium. Having this insight can provide you with direction to start optimizing the foods you eat to support your gut and thyroid. If you feel your thyroid is impacting your gut health, we are here to help! You can schedule a personalized nutrition therapy session with us. We would love to help you on your journey.


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