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The Connection Between Thyroid Disorders, Inflammation, and Your Gut Microbiome

Getting a handle on what is affecting your gastrointestinal health is key if you have a thyroid disorder

The human gut microbiome.

Many doctors believe that the key to a healthy thyroid doesn’t stop at medications to balance hormones; rather, a more holistic approach is necessary. That means also reducing possible sources of inflammation and ensuring a healthy gut. Here’s what you should know, especially if you’re taking thyroid medication but still suffer from symptoms such as weight gain, brain fog, body pain, or fatigue.

Understanding inflammation

Inflammation isn’t just a vague buzzword (although we are certainly hearing more and more about it these days as experts connect the dots). Inflammation is an important physiological process that happens inside the body.

Put simply, it’s your immune system’s response to an invader, irritant, or underlying issue. Inflammation can come from many sources, including your gut, a cut, a chemical, or a health condition or disease. (The suffix ‘-itis’ — think spondylitis, cystitis, Hashimoto's thyroiditis — usually indicates a condition marked by inflammation).

Inflammation is complicated, and that’s why it gets a bad rap. In general, short-term inflammation is a good thing. When you fall and hit your knee, that swelling you see is normal and part of the healing process.

Any sort of injury will trigger your immune system to dispatch its army of white blood cells to head toward and heal the area. The inflammation that results is made from those cells along with immune cells and cytokines, small proteins that tell the immune system to protect you.

But chronic inflammation, which is inflammation that lasts months or years, is a different story. When your body is always inflamed, those white blood cells work overtime, causing sometimes irreparable damage to tissues and organs. In fact, chronic, systemic inflammation is linked to risk of stroke, COPD, heart disorders, diabetes, and cancer.

Textbook symptoms of acute inflammation include heat, swelling, pain, loss of function, and redness, while chronic inflammation is more insidious. This sort of inflammation is often behind some not-so-obvious symptoms, or symptoms you might not attribute to anything in particular. In fact, it’s possible to have rampant inflammation without even knowing it.

Symptoms of chronic inflammation include:

  • Fatigue
  • Insomnia
  • Brain fog (trouble thinking or remembering)
  • Mood disorders such as anxiety and depression
  • Gastrointestinal issues
  • Weight fluctuations
  • Myalgia (body pain)

Blood tests, lifestyle changes, and dietary updates can help you identify whether you have inflammation and the sources of inflammation — although it’s not always easy to test for it. For example, some blood tests won’t show elevated inflammation even if it is present. Additionally, some medications can cause a false negative when testing for inflammation.

In this case, it’s important to take a holistic approach to identifying inflammation, and that’s where your gut comes into play.

Where does inflammation come from?

There are plenty of sources of inflammation. These range from infectious organisms, irritant exposure, an autoimmune disorder (in which the immune system attacks itself), an autoinflammatory disorder (in which the body’s inflammation-fighting cells are defective), recurrent short-term inflammation, oxidative stress (from free radical damage), and more.

As researchers learn more about inflammation, however, there is mounting evidence that poor gut health can also be a culprit, including in cases of thyroid disorder.

How inflammation affects thyroid function

  • Inflammation of the thyroid, also known as thyroiditis, can lead to hypothyroidism. This inflammation can cause thyroid hormone to leak into the bloodstream.
  • Michael Ruscio, Doctor of Natural Medicine and author of Healthy Gut, Healthy You, says that inflammation can interfere with the conversion of the hormone T4 into T3. It can also cause elevations in rT3 (or reverse triiodothyronine), which is thought to be released when you are ill, and can block the T3 hormone from working.
  • Inflammation can also cause issues with your mood; for example, it can interfere with your neurotransmitters (which are responsible for ‘happy hormones’), causing mood issues. As a result, many patients with hypothyroidism also suffer from depression caused by a combination of inflammation and hormonal imbalances.
  • A study in JAMA Psychiatry found that C-reactive protein (which is often elevated when inflammation is present and chronic) is associated with depression and psychological distress.

Supporting your gut microbiome

Inflammation can still be present even if you’re taking the appropriate thyroid medications, as managing the inflammation can be separate from medicating with hormones. “Thyroid medication may not address all of the causes of inflammation,” Ruscio says. 

In short, it’s possible to have strange and ongoing symptoms (such as brain fog, bloating, or fatigue) even after being treated for a thyroid condition.

Beyond not smoking, sleeping well, getting enough exercise, and managing stress, you’ll want to pay attention to your gut health, Ruscio says. The gut (or microbiome) can also play a role in whether or not patients with thyroid disorders continue to experience inflammation and the symptoms that come with it.

Ruscio says, “The gut can be a primary source of inflammation, because it houses the highest density of immune cells in the whole body.”

There is increasing evidence that gut health and thyroid health are interconnected. A new study in Clinical Medicine & Research found that there’s a link between celiac disease and thyroid disease. Another recent review in Trends in Endocrinology and Metabolism asserts: “An altered microbiota composition increases the prevalence of Hashimoto’s thyroiditis and Graves’ disease.”

"In cases of both hypothyroidism and hyperthyroidism, stomach acid levels may be low, which can open the door to bacterial overgrowth, as acid can be antimicrobial," according to Ruscio. But it also works the other way around, he says: “If you have a gut disorder, it may lead to malabsorption of thyroid hormone medication."

Beyond taking your thyroid medication, what can you do to support a healthy gut for your thyroid health?

Get your gut on track

  • Try an elimination diet
    An elimination diet is a short-term diet, lasting only a few weeks. The goal is to help you identify (and remove) foods that your body doesn't tolerate well. When you eat foods that your body doesn't tolerate well, it may trigger an inflammatory reaction.

    “An elimination diet would be a good starting point,” Ruscio says. “It might be that you are gluten sensitive or lactose intolerant, so try eliminating the foods that may be the culprits.” Try removing the foods you suspect could be pro-inflammatory and then reintroduce them gradually. Note how you feel as you remove and reintroduce the foods.
  • Try a low-FODMAP diet
    FODMAP is an easy way of saying "Fermentable oligo-, di-, mono-saccharides and polyols,” or, in other words, digestion-resistant carbs. In some people with a sensitivity to these foods, these carbs can sit in in the intestine, feeding "bad" bacteria and creating gut problems such as diarrhea, gas, and bloating. Studies have found that an excess of these "bad" bacteria can trigger inflammation and immune issues over time.

    FODMAPS include lactose, fructose, sugar alcohols (such as xylitol and sorbitol), and fructans (which are found in wheat, spelt, and barley). Try removing them and then reintroducing them to determine your personal level of sensitivity to each one.
  • Use probiotics
    Ruscio also recommends “a good, well-rounded probiotic protocol. It’s safe and relatively inexpensive, and it can help with inflammation.”

    Researchers have found that probiotics, which are considered “good" bacteria that may help balance out an overgrowth of "bad" bacteria, have the potential to decrease inflammation associated with intestinal permeability, or the passing of what’s inside our guts to the rest of our bodies. Aim for a capsule that contains one billion to 10 billion colony-forming units (CFU) daily or several times per week. Although researchers make it clear that more research is needed in the area of probiotics and thyroid health, there is mounting evidence that "good" bacteria may help keep the gut microbiome in balance.
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