The SIBO and Hypothyroidism Connection

November 8th, 2016


As with any chronic illness, hypothyroidism and Hashimoto’s have a strong connection with gut health. I cover this link in-depth in my book, The Thyroid Connection, and I spent a whole day discussing it with the world’s top gut experts in The Thyroid Connection Summit.

One of the most common gut health issues I see in hypothyroid and Hashimoto’s patients in my clinic is Small Intestinal Bacterial Overgrowth, or SIBO. And, scientific research has shown a strong correlation between the two. In this article I’ll explain what SIBO is, how SIBO and hypothyroidism are related, and how to test for and treat it.

What is SIBO

Small intestinal bacterial overgrowth occurs when the bacteria in our gut get out of balance and overgrow. I often say, “Too much of a good thing can be a bad thing.” How do we get too much of some bacteria over others? This can manifest in several different ways, and often occurs in those eating a diet high in sugar, alcohol and refined carbohydrates. Certain strains of bacteria feed off of refined carbohydrates and break them down into short-chain fatty acids, creating gas and causing bloating.

Another strain of bacteria can break down bile salts before your body has a chance to use them. Bile salts are crucial for the breakdown of fats; without them, the end result is fat malabsorption or diarrhea.

Finally, a third type of bacteria can produce toxins that damage the lining of the small intestine. This prevents your body from absorbing the nutrients you need, much like what we see with a leaky gut.

10 Signs you have SIBO:

1. Gas, bloating, and diarrhea
2. Abdominal pain or cramping
3. Constipation (much less common than diarrhea)
4. Diagnosis of irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD)
5. Food intolerances such as gluten, casein, lactose, fructose and particularly histamine intolerance
6. Chronic illnesses such as fibromyalgia, chronic fatigue syndrome, diabetes, neuromuscular disorders and autoimmune diseases.
7. Vitamin and mineral deficiency, specifically B12 deficiency
8. Fat malabsorption (signified by pale, bulky, and malodorous stools)
9. Rosacea and other skin rashes
10. Leaky gut

How Hypothyroidism Causes SIBO

Your thyroid regulates all of your metabolic processes. So if it is under-active, as is the case with hypothyroidism, all of these processes slow down, including digestion. That’s why hypothyroidism so often causes constipation. When you are constipated and food lingers in your intestines, it becomes a breeding ground for pathogenic bacteria.

Many hypothyroid patients also have a decreased level of HCL, the primary stomach acid. If you are low in HCL then you can’t properly digest your food, which allows allows bad bacteria to overgrow in your gut.

How SIBO Contributes to Hypothyroidism

Twenty percent of your T4 (the storage form of thyroid hormone) is converted to T3 (the active form) in your gut. However, if your gut flora is disrupted and it’s not functioning up to par, this conversion is reduced, leading to hypothyroidism symptoms.

The good bacteria in your gut are also critical in preventing leaky gut, or intestinal permeability. Leaky gut occurs when the tight junctions of your small intestine open up, allowing toxins, microbes, and partially undigested food particles to escape via your bloodstream. These particles are tagged as foreign invaders by your immune system, which sends a wave of inflammation to fight them off. Leaky gut is one of the primary triggers of autoimmunity, including the autoimmune form of hypothyroidism, Hashimoto’s. If your gut remains leaky, your immune system continues to attack your thyroid relentlessly, worsening thyroid dysfunction symptoms.

So Which Came First?

As you can see, thyroid function and your microbiome are an interconnected ecosystem of their own. It’s kind of a chicken or the egg situation, where hypothyroidism contributes to bacterial overgrowth, and bacterial growth worsens thyroid dysfunction. In some cases, the hypothyroidism comes first, and in others the thyroid dysfunction leads to SIBO. Since they go hand-in-hand so frequently, I highly recommend testing for SIBO if you have symptoms of both SIBO and hypothyroidism.

How to Test for SIBO

If you suspect you have SIBO, I have a symptoms quiz in both of my books, The Thyroid Connection and The Autoimmune Solution, to help you determine if you are likely positive. You can also work with my Wellness Coach, to order testing or evaluate your symptoms.

How to treat SIBO

Treating SIBO is a 3-step approach. The first step is to remove the foods that feed it, including sugar, alcohol, and carbohydrates. Similar to Candida overgrowth, those who are susceptible to SIBO may have recurrence after treatment. For this reason, it is advised to adopt a long-term diet that is low in carbohydrates and especially refined carbohydrates.

Second, you want to attack the bad bacteria. The primary antibiotics used for treating SIBO are Xifaxan and Neomycin, depending on the type of gas being produced by your gut organisms (methane or hydrogen). As a natural alternative to antibiotics, I recommend Microb Clear™, which is a blend of  magnesium caprylate, berberine, and extracts from tribulus, sweet wormwood, grapefruit, barberry, bearberry, and black walnut.

Third, you want to restore the good bacteria with probiotics. The best probiotics for SIBO are soil-based probiotics, as lactic acid-based probiotics are not well-tolerated in those with SIBO and may actually be adding fuel to the fire. The one I use with all my patients is Primal Earth™.

Get 35 Gut Recovery Recipes for Free!

Receive 74 pages of delicious recipes and tips to repair a leaky gut PLUS a $10 gift card when you join my free weekly newsletter


Your information is secure and will never be sold or rented to a third party.

Related Articles