The Gut–Thyroid Connection _Final

>> Hello again, it's great to be back. This course is all about fostering the health and vitality of the gut. Are you convinced yet that the gut is literally the center of health? In so many ways, the key to vitality involves supporting optimal gut health. In this lecture, we'll be drawing another important connection between gut health and overall health, connecting the gut and the thyroid. These days, there's a lot of talk about the thyroid, but what exactly is it? It's a butterfly-shaped gland located at the front of the throat. The thyroid is part of the endocrine system. The thyroid is small but mighty. It creates hormones that regulate the body's energy, otherwise known as metabolism. The thyroid also plays a key role in immune function, detoxification, determining your weight, determining your sex hormones, regulating blood pressure, tissue development, energy levels, and even sleep patterns. A big list of jobs for such a little gland. The thyroid is constantly in conversation with your body and the environment. As you can imagine, when it stops working properly, many functions are affected. There are two main ways that the thyroid can malfunction, hypothyroidism and hyperthyroidism. Hypothyroidism occurs when not enough thyroid hormone is produced. The most common cause is an autoimmune disease called Hashimoto's thyroiditis. Symptoms of Hashimoto's thyroiditis include weight gain, hair loss, dry skin, brain fog, mood swings, and fatigue. On the other side of the coin, hyperthyroidism occurs when too much thyroid hormone is produced. The most common cause of hyperthyroidism is another autoimmune disease called Graves' disease. Individuals with Graves' disease often experience weight loss, insomnia, brain fog, difficulty concentrating, anxiety, tremors, bulging eyes, and heart palpitations. Another common thyroid condition is goiter, which is a non-cancerous enlargement of the thyroid. Goiter can be caused by an insufficient amount of iodine in the diet, especially in developing countries. But it can also be caused by hyperthyroidism. Symptoms of goiter include hoarseness of voice, tightness or swelling in the neck, coughing or wheezing, and difficulty with breathing or swallowing. The common theme with these thyroid imbalances is that they typically emerge as autoimmune issues. Autoimmune conditions result from a combination of genetic and environmental factors. Those environmental triggers must find their way into the body. And one key entry point is the gut. When the gut is leaky, it allows even more toxins to get through. Since the gut contains a very large part of the immune system, as much as 80%, it makes sense that the gut health will affect the health of the thyroid. And it also makes sense that an issue with the immune system in the gut can play a role in thyroid autoimmune conditions. In fact, gut health is proving to be directly correlated to autoimmune disease in the thyroid. Thyroid autoimmune conditions occur at higher rates in those with celiac disease. And hypothyroidism has been correlated with heartburn. Many people with autoimmune diseases of all kinds also test positive for a leaky gut. And leaky gut can influence thyroid disease. Studies are finding that people with autoimmune disease tend to have altered gut bacteria. Let's take a deeper look at why this might be. There are two main types of hormones that thyroid releases, T3 and T4. T4 is the inactive form of the thyroid hormone. The body converts it into T3, the active form. The bacteria in the GI tract play a role in the conversion of the T4 to T3. Stress in the GI tract can negatively affect this conversion. Inflammation from gut dysbiosis and leaky gut can also impair this conversion process. It can also cause the production of an inactive form of T3, called reverse T3. This looks like T3 but it doesn't work the same. This is problematic because a person with this issue will have normal lab results unless the test specifically looks for reverse T3. Individuals with high levels of reverse T3 experience symptoms of hypothyroidism. Let's clarify, though, that reverse T3 in and of itself isn't that. It's just if there's too much, it can suppress thyroid function. Or on the other hand, if there's not enough, thyroid function may be too high. It's all part of the body's delicate balance. The thyroid is part of a feedback loop called the hypothalamic-pituitary-thyroid axis or HPT. The hypothalamus monitors the level of T3. When T3 levels are low, it signals the pituitary to release thyroid-releasing hormone, TRH for short. TRH tells the thyroid to release more T3. As you can see, there's a whole lot of teamwork going on here. Autoimmune conditions occur when there's a breakdown in the system. The HPT axis can experience a communication breakdown in any part of this process. But the most common problem in the HPT axis is often the thyroid itself. In Hashimoto's thyroiditis, the thyroid produces antibodies against its own cells, destroying thyroid tissue. With this condition, the signal from the HPT axis makes it to the thyroid, but there isn't enough thyroid hormone to meet the demand. In Graves' disease, the thyroid ignores the signal it receives to slow down thyroid hormone production, so it keeps producing more and more hormones. The HPT axis has a set point. The hypothalamus regulates production of thyroid hormones, making sure that the right amount is being produced. But inflammation can interfere with the set point. That inflammation can come from anywhere, including the gut. When the gut is inflamed, it can also lead to leaky gut. As I mentioned earlier, when the gut is leaky, all kinds of toxins can irritate the system. This can activate the immune response and irritate the immune tissue that lines the gut. When gut immune tissue is irritated, it causes cortisol to rise which in turn decreases thyroid hormone production. Lipopolysaccharide, or LPS, is a toxin that comes from gut bacteria. It can be released through a leaky gut. When LPS escapes from a leaky gut, it's thought the thyroid can become overloaded with toxins affecting hormone function. Hopefully, by now, you can see how the gut and the thyroid are intricately connected. Let's recap what we've covered so far. We established that thyroid dysfunction stems from either an overproduction or underproduction of thyroid hormones. Two types of thyroid hormones are T3, the active form and T4, the inactive form. Thyroid hormone production is tightly regulated by the HPT axis. Leaky gut and dysbiosis can throw off the HPT axis. Inflammation from a leaky gut can negatively affect the thyroid and thyroid hormone production. And conversion of thyroid hormone from T4 to T3 can malfunction if gut health is poor. The gut can influence the thyroid, and the thyroid can influence the gut both in positive and negative ways. When the thyroid is functioning well, thyroid hormones can regulate metabolism and protect the gut from inflammation. But when one of these systems is in poor health, it can affect the other. Let's take a closer look at this. In addition to the HPT system, we also have what's called the gut-thyroid axis. This is where we can really start to see the connection between gut health and thyroid health. The gut produces hormones that communicate with the thyroid through the vagus nerve. Through this conversation, gut bacteria and their hormones can affect the thyroid and the thyroid hormones can affect the gut. Poor gut health can weaken thyroid function and trigger Hashimoto's thyroiditis. And autoimmune conditions of the thyroid often go hand-in-hand with celiac disease, irritable bowel disease, and other gut conditions. This axis also has a direct impact on metabolism. There are many endocrine cells in the lining of the gut with numerous receptors for thyroid hormone. Thyroid hormones help these cells to function, grow, and divide properly. These cells produce mucus which helps to protect the gut. In the stomach, that mucus keeps the acid in the stomach from damaging the gut wall. When the body is stressed and thyroid hormone levels are low, a person may be more susceptible to ulcers in the stomach. In the small intestine and the colon, the mucus helps to prevent leaky gut by creating a barrier from gut bacteria. As I mentioned earlier in this lecture, hypothyroidism is associated with heartburn. This is because thyroid hormones are involved in triggering the production of gastric acid. Hypothyroidism can decrease stomach acid levels. Adequate stomach acid is necessary for the digestive enzymes in the stomach to do their job. It also kills most of the pathogenic bacteria before it can travel further into the system. If there isn't enough stomach acid, partially-digested food and bacteria can pass into the small intestine causing gas, bloating, and bacterial overgrowth. In addition to mucus production and gastric acid production, thyroid hormone has the added indirect effect of helping to maintain tight junctions in the intestinal lining. Tight junctions prevent undigested food and troublesome bacteria from escaping the gut. When the thyroid is underactive, AKA hypothyroidism, this can contribute to leaky gut. Hypothyroidism can also lead to reduce motility, meaning it can slow down the transit time of food through the gut. Slow motility is a contributing factor to constipation and SIBO, small intestinal bacterial overgrowth. On the other hand, hyperthyroidism can increase transit and cause diarrhea. The thyroid is like a warning system. When there are signals that it's compromised, problems can occur throughout the body. When resources are low, the thyroid downregulates many functions in the body, which makes sense, right? It's trying to conserve resources since it knows they're limited. So as a protective function, metabolism slows down, the body doesn't want to get pregnant, and many hormonal functions become too costly. The body doesn't know when resources will be available again, so it prepares for the worst-case scenario. By viewing thyroid malfunctions as an early warning sign, it might serve as a tip off to bigger problems that could occur as a result. The thyroid also seems to be the first place in the body that's affected by an overabundance of toxins. This may explain the correlation between celiac disease and the thyroid, the burden of toxins from gluten. Okay, now let's recap. In this lecture, we've discussed how gut health and thyroid health are intimately connected. Leaky gut and dysbiosis can result in either hyperthyroidism or hypothyroidism. Thyroid conditions are directly correlated with many gut issues such as celiac disease, leaky gut, heartburn, and SIBO. Have you ever worked with a client who had thyroid issues? Did they have gut issues as well? After watching this lecture, can you see a connection between the two? Share your experiences in the Facebook group. Thanks for joining me. I hope you've enjoyed learning about how the body is a dynamic interconnected system. See you soon.