Eating with Gut Problems (Part 3) — the Thyroid Connection
Thyroid hormones play an important role in regulating motility in our digestive tract. Impaired motility can result in digestive symptoms like diarrhea, constipation, bloating, and gas.
If you have a thyroid disorder, do you ever wonder why you also probably experience poor digestion?
The thyroid and digestive system are connected in intricate ways. The thyroid, a butterfly-shaped gland located at the base of our neck, is the "master metabolism" controller in the body. Thyroid hormones define our basal metabolism, meaning that they act on target organs throughout the body to regulate cellular metabolism.
How thyroid dysfunction can lead to digestive issues
One particular area that thyroid hormones act on is the gastrointestinal tract [1]. For example, both thyroid hormone excess and deficiency can impact digestive motility — i.e., the transit of contents moving through the intestine.
In a typical person with an under-active thyroid, digestive motility tends to be slowed, manifesting as constipation, bloating, and/or gas [2]. Conversely, in someone who has an over-active thyroid, we tend to see diarrhea and frequent bowel movements. Without enough thyroid hormones, many of the body's functions slow down. And with too much, we see bodily functions speed up.
You may have heard of triiodothyronine (T3) and thyroxine (T4) - collectively known as the thyroid hormones. T3 and T4 have also been found to protect the intestinal lining from stress ulcers [3, 4]. They do so by promoting a healthy lining of mucous in the stomach. With a diminished or impaired mucosal layer, we see acid reflux, heart burn, and burning stomach pain.
Autoimmune thyroid disease, such as Hashimoto's and Graves' disease, has been linked to autoimmune disorders of the gastrointestinal tract, specifically celiac disease and atrophic gastritis [2]. In fact, patients with an autoimmune thyroid disease are 5-10 times more likely to develop celiac disease than the general population [2].
Was it the chicken or the egg? The thyroid-gut-immune love triangle
We also know that underlying inflammation in the gut can lead to an autoimmune thyroid disease.
Intestinal barrier permeability - a phenomenon also known as "leaky gut" - occurs when tight junction cells in the intestinal epithelium inappropriately become too permeable [5]. This leads to large protein molecules escaping from the digestive tract into the blood stream, setting off an alarm to our immune system. As a result, we mount an immune response and attack those proteins. Research has shown that such immune attacks are associated with several autoimmune diseases, including Hashimoto's — an autoimmune mediated destruction of the thyroid gland [6, 7].
Our digestive tract is home to more bacteria than the number of cells in our body. One role of our healthy gut bacteria is to support our thyroid, by converting thyroid hormone T4 into its more metabolically active form T3.
Interestingly, it has been reported that small intestinal bacterial overgrowth — a cause of irritable bowel syndrome - may be present in more than 50% of individuals with hypothyroidism [8]. So, there definitely is a relationship between our gut microbiotia composition and the thyroid — but the definition of that relationship, and its mechanism of action, is still to be ascertained.
What action can you take now?
If any of the above resonates with you, below you can find some helpful and evidence-backed tips to support normal thyroid and gut function.
Become familiar with how you feel. Do you experience front neck pain/discomfort or trouble swallowing? Hoarse voice? Dry skin and nails? Puffiness around the eyes? Constipation or diarrhea? Chronic fatigue and weight gain/loss? These are all signs and symptoms of a possible underlying thyroid disorder.
Test, test, test. Work with your primary care provider, such as a Naturopathic Doctor, to test your blood thyroid hormones. This includes TSH, triiodothyronine (T3), thyroxine (T4), anti-TPO antibodies, and sometimes anti-thyroglobulin antibodies (anti-TG). It is also known that there are certain nutrient deficiencies associated with autoimmune thyroid disorders, including low vitamin D levels, and so it is important to work with a doctor to ensure no additional issues are missed.
Reduce inflammation. For individuals with a thyroid disorder and/or leaky gut, the Autoimmune Paleo diet (or AIP) may be of benefit. The AIP focuses on healing the gut by eliminating foods that cause inflammation. The premise is that by restoring integrity of the gut, we tone down our high-alert immune system.
Self-care. Finding time to look after yourself and nourish your body can help reduce stress levels. Sometimes, it's important to put yourself first, especially for those struggling with a chronic illness.
Find benefits in botanical medicine. We know certain botanical herbs, like ashwaganda (withania), as well as vitamins and nutrients, such as zinc and selenium, have been shown through research to support either the normalization of TSH, the reduction of TPO antibodies, or the conversion of thyroid hormones T4 to T3.
Sleep. We often see persistent fatigue accompany a thyroid and/or digestive disorder. Listening to the body when it asks for sleep, and engaging in proper sleep hygiene habits, can help support both the thyroid and the gut.
When exercise does more harm than good. Vigorous and excessive exercise can actually promote cortisol production and inhibit thyroid function. To this end, I often see patients who experience a paradoxical response to exercise — the more they exercise, the harder it becomes to lose weight. For individuals with a thyroid disorder, restorative exercises in combination with "off" days may be more beneficial.
Go easy on the caffeine! Caffeine is a stimulant, and directly acts on the adrenal glands, which in response, produce stress hormones cortisol and adrenaline. Like we learned above, excess cortisol inhibits thyroid function. And, with high caffeine consumption over time, the adrenals become tired, and with tired adrenals come more fatigue.
- Dr. Dominique Vanier is a registered naturopath in Burlington, Ontario with a clinical focus on digestion and women’s hormones. Naturopath Burlington. This article is for information purposes only. It is not intended to treat or diagnose any health conditions.
References
1. Daher, R., Yazbeck, T., Jaoude, J., & Abboud, B. (2009). Consequences of dysthyroidism on the digestive tract and viscera. World Journal Of Gastroenterology, 15(23), 2834. doi: 10.3748/wjg.15.2834.
2. Maser, C., Toset, A., & Roman, S. (2006). Gastrointestinal manifestations of endocrine disease. World Journal Of Gastroenterology, 12(20), 3174. doi: 10.3748/wjg.v12.i20.3174
3. Koyuncu, A., Aydintu, S., Kocak, S., Aydin, C., Demirer, S., Topcu, O., & Kuterdem, E. (2002). Effect of thyroid hormones on stress ulcer formation. ANZ Journal Of Surgery, 72(9), 672-675.
4. Namulema, J., Nansunga, M., Kato, C., Kalange, M., & Olaleye, S. (2018). Thyroid hormones increase stomach goblet cell numbers and mucin expression during indomethacin induced ulcer healing in Wistar rats. Thyroid Research, 11(1). doi: 10.1186/s13044-018-0050-0
5. Bischoff, S., Barbara, G., Buurman, W., Ockhuizen, T., Schulzke, J., & Serino, M. et al. (2014). Intestinal permeability – a new target for disease prevention and therapy. BMC Gastroenterology, 14(1). doi: 10.1186/s12876-014-0189-7
6. Lerner, A., & Matthias, T. (2015). Changes in intestinal tight junction permeability associated with industrial food additives explain the rising incidence of autoimmune disease. Autoimmunity Reviews, 14(6), 479-489. doi: 10.1016/j.autrev.2015.01.009
7. Arrieta, M., Bistritz, L., & Meddings, J. (2006). Alterations in intestinal permeability. Gut, 55(10), 1512-1520. doi: 10.1136/gut.2005.085373
8.Lauritano, E., Bilotta, A., Gabrielli, M., Scarpellini, E., Lupascu, A., & Laginestra, A. et al. (2007). Association between Hypothyroidism and Small Intestinal Bacterial Overgrowth. The Journal Of Clinical Endocrinology & Metabolism, 92(11), 4180-4184. doi: 10.1210/jc.2007-0606