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The Link Between IBS and Thyroid Disorders

While it is probably not a connection that instantly comes to mind, your thyroid and your gastrointestinal (GI) tract are linked in many ways. This link has effects on overall health and, specifically, irritable bowel syndrome (IBS).1

What is the thyroid, and what does it do?

The thyroid is a small, butterfly-shaped gland found inside your neck. It is part of your endocrine system, a complex network of glands that make and release hormones.1

Your thyroid makes hormones responsible for controlling metabolism. This is how your body turns food into energy. The thyroid also impacts other functions of the body, like heart rate, breathing, body temperature, and digestion.1

How does the thyroid connect to the digestive system?

Nearly every organ system in your body is affected by the thyroid and the hormones it produces. This includes your cardiovascular, nervous, and reproductive systems.

The thyroid also impacts your digestive system. It plays an active role in how food moves through your GI tract (motility). And the natural bacteria mix in your gut allows your body to process and use thyroid hormone.1,2

What happens when the thyroid stops working properly?

Sometimes the thyroid releases too much hormone (called hyperthyroidism) or not enough hormone (called hypothyroidism). Depending on your condition, you can have a range of symptoms, including:3,4

  • A faster or slower heart rate
  • Weight changes
  • Trouble withstanding cold or heat
  • Mental health problems (anxiety or depression)
  • Irregular periods
  • Changes in bowel movements (constipation or frequent bowel movements)

Overlapping symptoms of thyroid disease and GI disorders

Some signs of thyroid disease look similar to those of GI illnesses like IBS. Changes in bowel movements, problems tolerating the cold, and mental health problems are also symptoms of poor GI health.5

What scientific research reveals about IBS and thyroid disorders

Scientists are studying the connection between thyroid disorders and GI health. They have found that an underactive thyroid can slow the movement of food through the esophagus and stomach. This can lead to GI problems. They have also found that rates of small intestinal bacterial overgrowth (SIBO) are higher in those who have an underactive thyroid.2

Researchers have also discovered that certain micronutrients, like iodine and iron, play a key role in the health of your thyroid. Imbalances in the GI system can affect some of these micronutrient levels. And experts have linked IBS and SIBO to a lack of vitamins D and B12 as well as zinc.5

This shortage of nutrients can grow even worse when people with IBS avoid eating specific foods to prevent symptoms. About 13 percent of people with IBS have serious food avoidance, according to 1 review.5

Treating IBS versus thyroid disorders

So, do symptoms stem from the thyroid or digestive system? Scientific evidence suggests that GI disorders like IBS are the main cause of some symptoms thought to be caused by thyroid issues. IBS is also much more common than an underactive thyroid. This means you are more likely to have a digestive issue than a thyroid condition.5

Researchers have found that in some cases, treating GI problems also eases thyroid symptoms. But doctors may overlook GI symptoms in people with thyroid disorders. Talk to your doctor about whether a thyroid disorder may be affecting your IBS.5

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