How Does Your Thyroid Impact Your Gut?
Have you been told something is wrong with your thyroid? Has someone mentioned that you should test your thyroid because of your digestive symptoms?
The thyroid and gut have an intimate relationship in your body and can often impact each other in a way that makes it hard to truly know what came first. Before we get to that, let’s lay a foundation of what your thyroid actually is and what it does…
Listen to The Gut Show episode on this topic on iTunes or Spotify, watch the video below, or keep reading to learn more about your thyroid!
What is your thyroid?
The thyroid is a small, butterfly-shaped gland located in the front of the neck, just below the Adam's apple. It is an essential part of the endocrine system, which is a network of glands that produce and release hormones into the bloodstream to regulate various bodily functions.
Think of hormones as office managers or wedding planners. When healthy and at their best, they take the information they are given and they make sure that information is communicated and carried out appropriately by all (organs, nerves, etc.) who should be involved, while continuing to gather information so they can alert if any issues arise.
What does your thyroid do?
The primary function of the thyroid gland is to produce two important hormones: thyroxine (T4) and triiodothyronine (T3). These hormones play a crucial role in regulating metabolism, which is the process of your body converting food into energy.
The production and release of thyroid hormones are tightly controlled by the hypothalamus and pituitary gland in the brain. The hypothalamus releases thyrotropin-releasing hormone (TRH), which signals the pituitary gland to release thyroid-stimulating hormone (TSH). TSH then stimulates the thyroid gland to produce and release T4 and T3.
Thyroid hormones influence the rate at which cells use energy and help control other processes in the body, including:
Metabolism: thyroid hormones regulate the speed at which the body's cells use energy. They can affect how quickly or slowly your organs and systems work, influencing your basal metabolic rate.
Growth and development: thyroid hormones are essential for proper growth and development stages in children and adolescents, including the development of the brain and the skeletal system.
Body temperature: the thyroid gland helps to regulate body temperature by controlling the rate at which the body produces heat.
Heart rate and blood pressure: thyroid hormones impact heart rate and heart contractions, affecting blood flow and blood pressure.
Muscle function: thyroid hormones play a role in muscle function and coordination.
What’s your poop personality? Find out here!
Where does the gut and digestive system fit into this?
The thyroid’s role in digestion:
Metabolism of nutrients: as covered earlier…
Gallbladder function: thyroid hormones can influence the production and flow of bile, which is necessary for the digestion of fats.
Gut motility: thyroid hormones affect the contraction and relaxation of the muscles in the digestive tract, including the stomach and intestines, which influences how fast or slow things move through the gut.
Acid production: thyroid hormones can influence the production of stomach acid, which then impacts the breakdown of proteins in stomach and how well food moves through the stomach.
Gut microbiome: emerging research suggests that thyroid hormones may also play a role in shaping the gut microbiome, the community of microorganisms living in the intestines, which affects digestion and overall gut health.
What happens when the thyroid malfunctions?
What can happen when the thyroid gland is not functioning properly:
Hypothyroidism: the thyroid produces insufficient hormones, leading to symptoms like fatigue, weight gain, sensitivity to cold, and depression.
In the gut, this can lead to slowed motility, poor stomach acid production, decreased bile flow, constipation, bloating, and may be associated with bacterial overgrowth.
Hyperthyroidism: the thyroid produces excessive hormones, resulting in symptoms like rapid heartbeat, weight loss, nervousness, and heat sensitivity.
This can lead to gut hypermotility, causing diarrhea, urgency, and loose stools.
Goiter: an enlarged thyroid gland, often due to iodine deficiency or other underlying causes.
Hashimoto's thyroiditis: an autoimmune disorder that leads to inflammation of the thyroid gland.
The immune system mistakenly attacks and damages the thyroid tissue, causing it to become enlarged and interfering with its ability to produce thyroid hormones. The exact cause of Hashimoto's disease is not fully understood, but it likely involves a combination of genetic and environmental factors.
This can create the same effects as hypothyroidism in the gut.
Graves' disease: an autoimmune disorder that results in the overproduction of thyroid hormones (hyperthyroidism).
How does the gut impact the thyroid?
One of the biggest influencers of thyroid function from the gut is the gut microbiome. Dysbiosis, or an unideal makeup of microbes, is a common finding in thyroid disorders. While it’s hard to know which comes first, we do know that gut microbes can influence immune system function and some microbes can inhibit TSH production.
Gut microbes also influence the absorption of minerals that are important to the thyroid, including iodine, selenium, zinc, and iron. These are essential for thyroid function and there is a clear link between thyroid dysfunction and altered levels of these minerals.
Additionally, microbes function as a reservoir for T3 and are able to prevent thyroid hormone fluctuations, which impacts overall balance and function of hormones.
Outside of gut microbes, stress is a major factor in both digestive health and thyroid health. Chronic levels of stress, which can be sparked from conditions or problems in the gut, can impact thyroid function leading to decreased or increased production of hormones. This is also true in reverse, where stress related to thyroid malfunction can impact the gut.
The good news is that the connection between the gut and thyroid also includes how we support them, meaning we can improve both with similar strategies. If you’re looking for help with this, our team of registered dietitians may be a great fit!
Are you frustrated with your IBS symptoms? Do you desire to be confident in your food choices? Do you want to have a healthier relationship with your body and diet? Are you ready to take control of your IBS?
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