The thyroid and digestion connection | Guest column

The thyroid and digestion connection

by Gavin Guard

How is your thyroid health?

Many people feel tired, run-down, and low on energy. They may feel like their gas tank is running out of fuel and they are looking for ways to increase their energy levels and sense of vitality.

A major cause of these symptoms is low thyroid (hypothyroidism). In fact, 12% of Americans will develop a thyroid condition in their lifetime. And up to 60% of people with thyroid disease are unaware of their condition. Thus, it’s important to assess thyroid status and to fix the underlying cause of any dysfunction.

What we are going to cover in this article is the key relationship between the gut and the thyroid. You may be wondering how two (seemingly unrelated) organs are related. It’s important to know that almost all body systems affect each other in one way or another. Unfortunately, this fact goes unnoticed many times in conventional medical care.

As I alluded to, a major connection between body systems is the gut and the thyroid. Many people are on thyroid medication these days. However, some still suffer from thyroid-related symptoms such as low energy, weight gain, constipation, hair loss and chronic fatigue.

What’s often missed is how gut health affects thyroid health. Instead, many patients are placed on higher doses of thyroid or switched from one medication to another. These decisions are often done prematurely without first addressing other factors that lead to thyroid dysfunction in the first place.

SIBO and Thyroid

The first connection we will make is between thyroid health and Small Intestinal Bacterial Overgrowth. Normally, gut bacteria should be high in the large intestine and low in the small intestine. SIBO is a condition where the small intestine starts to get crowded with too much or the wrong type of gut bacteria. It is characterized by symptoms such as bloating, abdominal discomfort, diarrhea and/or constipation and excessive flatulence, usually after meals.

One study concluded that 54% of those who are hypothyroid have SIBO, compared to only 5% who did not have SIBO. The authors noted that “overt hypothyroidism is a risk factor for SIBO development.”

In a study looking at 1,800 patients with confirmed SIBO, thyroid replacement therapy was the strongest predictor of having SIBO. In other words, those patients who were taking thyroid medication were also the most likely to have SIBO. PPI (e.g. Prilosec, Nexium) and opioid use were other predictors.

The correlation between SIBO and thyroid is interesting. Thyroid hormone increases gut movement which plays a large role in controlling overgrowth of bacteria in the gut. Thyroid hormone also is needed for stomach acid production which also limits bacteria growth in the small intestine. Thus, low thyroid hormone may play a role in the development of SIBO.

If you’d like to find out more information about how to heal your gut, go to