The Essential Thyroid-Gut Connection

By: Jill Grunewald, HNC, FMCHC

Average Read Time: 3 minutes

Over the last few years, the studies linking a healthy digestive system to our overall health have been staggering. We’re talking about the mighty microbiome: our 100 trillion-strong ‘mini ecosystem’. The evidence of the importance of gut health is head-spinning. And exciting.

Let’s take a closer look at the mighty microbiome, and what it means for your thyroid and overall health.

The Gut Is a Huge Piece of the Health Puzzle

Addressing digestive function may not be the single solution for what ails us, but it’s a huge (and often missing) piece of the puzzle for many conditions.

You read that right. Your digestive environment is the first thing to address if you have or suspect a thyroid condition. How is it that this little butterfly-shaped gland in our neck is so affected by our gut?

Before we get into the whys and hows of the thyroid-gut connection, let’s look at the relationship between the two.

Low thyroid function, known as hypothyroidism (I discuss hyperthyroidism below), can cause impaired digestive health, and poor digestive health can exacerbate hypothyroidism and Hashimoto’s (the autoimmune component of low thyroid function). See the negative cycle there?

As long as you struggle with gut issues, it’s unlikely—perhaps impossible—that you’ll ever experience optimal thyroid function. Examples of gut problems include:

There is a bright side! Given the cyclic nature of the gut-thyroid relationship, addressing both can benefit both, too.

up next: 10 Simple Ways to Improve Your Gut Health

Three Considerations:

1. A Healthy Gut Can Help Reduce Antibodies

Considering that 70–80 percent of our immune system is housed in our digestive tract, it’s easy to see how tuning up the gut can, in turn, tune up our thyroid. Optimal digestion helps to tame the autoantibodies associated with Hashimoto’s and Graves’. (Ditto with any autoimmune antibodies, really!)

*It’s important to note here that the vast majority of those with hypothyroidism have Hashimoto’s, an autoimmune condition.*

2. A Healthy Gut Affects Production and Conversion of Thyroid Hormones

Twenty percent of healthy thyroid function depends on an abundant supply of healthy gut bacteria (a mighty microbiome) to convert T4 (the inactive form of thyroid hormone) to T3 (the active form). In order for the body to utilize thyroid hormones properly, the wheels that grease the T4 to T3 conversion need to be well oiled with ‘friendly flora’ and ‘good bugs’.

An overgrowth of unfriendly bacteria (SIBO, for instance) can inhibit thyroid hormone production. According to Dr. Datis Kharrazian, “Studies have shown that bacterial gut infections reduce thyroid hormone levels, dull thyroid hormone receptor sites, increase the amount of inactive T3, decrease TSH, and promote autoimmune thyroid disorders.”

3. A Healthy Gut Helps Us Absorb Nutrients and Minerals from Our Food

The thyroid is very nutrient-dependent. It’s especially fond of minerals. Oh, how I love talking about minerals and the thyroid.

When our intestinal lining is compromised, the subsequent inflammation can create tiny fissures where we should see tight cellular junctions. Dr. Mark Hyman refers to them as, “chinks in the gut’s armor.” These chinks can inhibit our ability to properly absorb and assimilate micronutrients from our food, which can have a significant impact on the thyroid.

These chinks also allow undigested food and pathogens (bacteria, yeast, etc.) into the bloodstream, causing the immune system to go, “Whoa, invaders! These aren’t supposed to be here.” Thus, a full throttle immune attack could ensue.

One symptom of hyperthyroidism and Graves’ is an overactive bowel. When our trains are moving too quickly, it’s common to have a nutrient malabsorption issue. (To be clear, an overactive bowel can also be a symptom of Hashimoto’s due to the digestive issues often associated with any autoimmune condition.)

While we may not consider ‘thyroid-supportive nutrition’ to be of utmost importance for those looking to tame an overactive thyroid, the reality is that many people transition from having Graves’ to having Hashimoto’s, or they have both Graves’ and Hashimoto’s simultaneously (weird, I know).

Work with your doctor on your unique situation and needs, but the bottom line is that the thyroid—and the immune system, as in Graves’ or Hashimoto’s—is dependent on whole foods nutrition. Most Americans need some level of gut repair, which (among other reasons) is why I’m convinced we’re seeing such a spike in autoimmune conditions. Click here for 10 Simple Ways to Improve Your Gut Health

Given that both the thyroid and immune system are reliant on whole foods nutrition for proper functioning, some sound nutritional interventions can be just what you need to keep your thyroid, immune system, and gut in good repair.


About the Author

Jill Grunewald, HNC, FMCHC, Integrative Nutrition and Hormone Coach, is a thyroid health and autoimmunity specialist and co-author of The Essential Thyroid Cookbook. Jill has suffered from alopecia (autoimmune hair loss), off and on, since 1982 and in early 2008, was diagnosed with Hashimoto’s thyroiditis. In her coaching practice, Healthful Elements, Jill specializes in hypothyroidism, Hashimoto’s, Graves’, and adrenal dysfunction. She has written for Huffington Post, MindBodyGreen, and Experience Life magazine and has contributed articles to Self and Shape magazines. She lives in Minneapolis with her husband and daughter.