Hypothyroidism and IBS

Your gut and thyroid impact each other in different ways. When one system is disrupted, the other is also affected and disease can occur. In this article, we’ll review the relationship between hypothyroidism and IBS, and explain some treatment options we recommend for individuals with both of these conditions.

Commonly referred to as an “underactive thyroid”, hypothyroidism occurs when your thyroid gland does not make enough thyroid hormones to meet the body’s demand. Thyroid hormones control many bodily functions like metabolism, body temperature, your menstrual cycle, heart rate, and more. 

An autoimmune condition called Hashimoto’s is the most common cause of hypothyroidism in the United States. Common symptoms of hypothyroidism include brittle nails, thinning hair, fatigue, weight gain, constipation, and cold intolerance. 

Irritable bowel syndrome (IBS) is a gastrointestinal disorder in which people suffer from a variety of digestive symptoms like gas, bloating, abdominal pain, constipation and/or diarrhea. Some studies suggest that IBS is caused by dysbiosis—an imbalance of gut bacteria. Small intestinal bacterial overgrowth (SIBO) is one type of dysbiosis that may be responsible for many IBS symptoms. Read more about SIBO and hypothyroidism.

If you have IBS, you may be more likely to also have hypothyroidism. One small study found that 19 percent of people with IBS also had a thyroid disorder (1). Interestingly, the majority of these people suffered from subclinical hypothyroidism. This occurs when your thyroid labs (like TSH) appear to be “normal” for conventional medicine standards, yet you continue to suffer from symptoms of hypothyroidism. In functional medicine, we use a narrower, more optimal, range of TSH to capture individuals with subclinical hypothyroidism. 

Hypothyroidism and IBS may commonly occur together because they both share a possible root cause: dysbiosis. As mentioned earlier, dysbiosis is a general term that refers to an imbalance of gut bacteria. People with dysbiosis may have too many bad bacteria, not enough good bacteria, or a mixture of the two. Studies have found over half of patients with hypothyroidism also have dysbiosis (2). 

Because of the major role it plays in various health conditions, we assess gut health for every single client at Root. Treating IBS can be tricky and individualized. Alternatively, conventional treatment for hypothyroidism may seem relatively straight-forward with a simple prescription for thyroid hormone replacement. However, since the most common cause of hypothyroidism is Hashimoto’s (an autoimmune disease), we also focus on supporting the immune system in addition to gut health.

Here are a few of the most common interventions we may use for an individual with both IBS and hypothyroidism.

Added sugar is one of the biggest culprits of dysbiosis because it can feed the harmful bacteria and starve the good bacteria. Removing or reducing added sugar and artificial sweeteners in your diet is key in preventing and fighting against dysbiosis. The largest sources of added sugar in the American diet are sugar-sweetened beverages (like soda, juice, or coffee drinks), pastries, and desserts.

If you also suffer from IBS, you may consider trialing a low-FODMAP diet. This is a short-term elimination diet that helps you identify which foods worsen your GI symptoms. By eliminating the foods highest in FODMAPs (like wheat, dairy/lactose, onions, and garlic), you may experience less digestive symptoms. 

Many individuals with hypothyroidism and IBS suffer from constipation due to slow gastric motility. Increasing the amount of fiber in your diet may help promote bowel regularity as it provides bulk to your stool and softens it for easier passage. Fiber is also the main fuel source for your healthy gut bacteria. Fruits, vegetables, whole grains, nuts, and seeds all contain adequate amounts of fiber. However, it’s essential to increase fiber slowly. Some individuals with IBS may experience worsening GI symptoms when increasing fiber in their diet. If this consistently happens to you, we recommend trialing a low-FODMAP diet as discussed above. As you increase the fiber in your diet, you also need to drink more water. Aim to drink at least 2 liters of water per day or about half of your body weight in fluid ounces. 

We may also recommend our Motility Support supplement for individuals suffering from constipation. This supplement contains a combination of artichoke leaf and ginger root extract in clinically proven doses to improve digestion and restore proper gastric motility.

Unsurprisingly, chronic stress negatively affects both IBS and hypothyroidism. First of all, unmanaged stress causes the body to redirect thyroid hormone (T4) into an alternative and unusable form called reverse T3. Your body requires a delicate balance of reverse T3. Too much of this hormone as a result of chronic stress can slow metabolism and make hypothyroidism worse. Furthermore, stress negatively impacts individuals with IBS by affecting digestion, GI motility, and worsening IBS symptoms (3). 

Take some time to reflect on the stressful aspects of your life. Is it possible to reduce or eliminate these triggers? Sometimes, stress is unavoidable. Therefore, we must introduce healthy ways to manage stress by implementing mind-body practices like yoga, meditation, journaling, walking, or deep breathing exercises. 

Hypothyroidism occurs when your thyroid gland does not produce enough thyroid hormones to meet the body’s demand. IBS is a GI disorder in which individuals suffer from a variety of digestive symptoms. Hypothyroidism and IBS may occur together because they both have dysbiosis as a potential root cause. You can support optimal gut and thyroid health by eliminating gut disruptors (like added sugar and FODMAPs), slowly increasing your fiber and fluid intake, improving gastric motility with effective supplementation, and lowering stress levels. 

Want to learn more? We teach you how to heal the gut and treat the root causes of hypothyroidism in our functional medicine membership program.