Could Your Thyroid be the Cause of Your Digestive Woes?
As we continue our thyroid series, remember that the thyroid is the butterfly-shaped gland in the lower part of the neck. This gland produces hormones that regulate many body functions, including metabolism, heart function, digestion, muscle control, brain development, mood regulation, and bone maintenance. It is essential to our overall bodily function and wellness, which makes it no surprise that our thyroid health can also contribute to our digestive health.
In our modern times, digestion issues are very common. However, as we often learn in functional medicine, “common” does not always define the way a body should optimally function. Before we dive into the possible digestion manifestations that a thyroid condition can contribute to, it’s important to know what digestion should look like.
Many people think they are eliminating waste regularly, but they are not. You will often see that it’s “normal” to have a bowel movement anywhere from 3 times a week to 3 times a day. However, what is “normal” is not necessarily ideal. Ideally, you should be eliminating waste 1 to 3 times a day. Your liver is responsible for clearing your body of toxins and moving them to your intestines. So if you are not emptying your waste regularly, these toxins are being reabsorbed by your body(1, 2, 3). On the other hand, if you are having frequent loose stools or diarrhea, this is also problematic, as your body is not absorbing necessary nutrients.
This brings us to the thyroid and digestive trends of both hyperthyroidism (overactive thyroid) and hypothyroidism (underactive thyroid).
Digestion and hyperthyroidism
In hyperthyroidism, patients have an overactive thyroid, which is producing too many hormones and increasing the body’s metabolism. Symptoms can include unexpected weight loss, rapid or irregular heart beat, sweating, and irritability. (For a more complete list of symptoms, see the chart below.) Because thyroid hormones help to break down low-density lipoprotein (LDL) cholesterol, the excessive amount of hormones can also cause LDL cholesterol to drop to abnormally low levels.
Causes of hyperthyroidism may include:
Graves’ disease- an autoimmune condition that often has a genetic component
Thyroiditis - inflammation of the thyroid
Toxic nodular goiter (lumps or nodules on the thyroid)
Patients with hyperthyroidism may have an increased appetite, though due to digestive issues in severe cases, increased calorie intake may not be enough to maintain a healthy weight. Patients with hyperthyroidism often have mild to moderate diarrhea and frequent bowel movements. Because patients with hyperthyroidism often have intestinal hypermotility, it decreases small bowel transit time, which can contribute to diarrhea. Oftentimes, these patients have fat malabsorption as well, which may contribute to excess fat in the stool (4).
Digestion and hypothyroidism
In hypothyroidism, patients have an underactive thyroid, which is not producing enough thyroid hormone. Your whole body may feel like it’s slowing down. Symptoms of hypothyroidism can include fatigue, lethargy, feeling cold, dry skin, trouble focusing or remembering, and weight gain. (For a more complete list of symptoms, see the chart below.) Additionally, with decreased hormone production, your body is unable to break down low-density lipoprotein (LDL) cholesterol, causing LDL cholesterol levels to build up in your blood.
Causes of hypothyroidism may include:
Hashimoto’s- an autoimmune condition in which the body attacks the thyroid
Thyroiditis- inflammation of the thyroid
Constipation is a common complaint in those who have hypothyroidism. Their motility is significantly slower when compared with healthy patients who do not have the condition (5). This may be due to the intestinal edema or swelling due mucopolysaccharide accumulation in the gastrointestinal tissue. When given thyroid hormone replacements, transit time can decrease significantly, improving constipation (6).
There is also a connection between hypothyroidism and small intestinal bacterial overgrowth, or SIBO. SIBO is an abnormally high growth of bacteria in the small intestine, and patients with SIBO often complain of symptoms such as abdominal discomfort, flatulence, and bloating. Slower motility is a risk factor for developing SIBO. Therefore, the slower motility and intestinal dysfunction that is associated with hypothyroidism may predispose a patient to SIBO. In a study with 50 patients with a history of hypothyroidism and 40 healthy control patients, 54% of the 50 patients tested positive for SIBO, compared to the 5% of 40 controls who tested positive for SIBO (7). This result was statistically significant. Though constipation is the most frequent complaint with hypothyroidism and SIBO, patients sometimes alternate between constipation and diarrhea or even have diarrhea as a primary symptom due to bacterial overgrowth (8).
Additionally, thyroid dysfunction is prevalently found in patients with irritable bowel syndrome, or IBS, specifically in those with subclinical hypothyroidism (9). When a patient has IBS, the health of the thyroid should be kept in mind.
WANT TO LEARN MORE ABOUT THYROID HEALTH?
ABIGAIL VERMEESCH, BCDHH WILL LEAD A DISCUSSION ON THYROID HEALTH AT MORGANTOWN COFFEE HOUSE ON THURSDAY, OCTOBER 24TH AT 7:00 P.M.
Chicken or the egg?
So thyroid health can affect gut health. But does gut health affect thyroid health? We know that when the gut is inflamed, this can affect nutrient absorption, which includes the malabsorption of nutrients like iodine and selenium- nutrients that are crucial for optimal thyroid health (10).
Additionally, a significant portion (20%) of the conversion of T4 into the active form of thyroid hormone (T3) occurs in the gut. When there is an unhealthy balance between beneficial and pathogenic bacteria, this conversion decreases.
Lipopolysaccharide (LPS) is a component of bacterial cell walls that can also wreak havoc on the conversion of T4 into active T3 (11). When a person has increased intestinal permeability, or “leaky gut,” LPS can leak through the intestinal walls into the bloodstream. Our bodies produce an enzyme called iodothyronine deiodinase, which is responsible for converting T4 into T3. LPS inhibits this enzyme, which in turn decreases the amount of converted T3 (12). LPS can also decrease the expression of thyroid receptors, which does not allow the messages from the thyroid to be communicated effectively (13).
As mentioned in our previous article, a leaky gut also allows the opportunity for large particles to seep through the gut lining and into the bloodstream, which can increase the chances of an autoimmune reaction, such as that in Hashimoto’s.
As you can see, gut/digestive health and thyroid health are intertwined, and it’s important to take a comprehensive approach to heal both the gut and the thyroid. This may include things such as:
Replacing inflammatory foods with nutrient-dense options
Taking probiotics/prebiotics (both in foods and supplementation)
Managing stress
Testing for and treating SIBO
To address many of the factors above, we recommend doing a comprehensive stool test to accurately assess and address gut health. We use these stool tests to look for gut health factors such as infections, enzyme status, if fat is properly digested, gliadin tolerance, inflammation in the colon, intestinal permeability, and the need for pre/probiotics.
Please contact our office for questions or more information on how we can help!
Works cited:
https://drhyman.com/blog/2017/01/13/simple-steps-dealing-constipation/
https://www.mindbodygreen.com/articles/how-often-should-you-poop-per-day-to-be-considered-healthy
https://www.gastrojournal.org/article/S0016-5085(72)80018-0/pdf
https://www.thieme-connect.de/products/ejournals/abstract/10.1055/s-0028-1094095
https://chriskresser.com/your-gut-microbes-and-your-thyroid-whats-the-connection/
https://www.physiology.org/doi/full/10.1152/ajpendo.00155.2002