By Dr. Paul Deglmann
Edited by Meghan Feir Walker

Almost everyone knows someone with a thyroid condition, whether it’s hypothyroidism, hyperthyroidism, Grave’s disease, or Hashimoto’s thyroiditis. Hypothyroidism, where the thyroid gland is underactive, is the most common form. According to the American Thyroid Association, over 20 million Americans have some type of thyroid disease, and more than 12 percent of the population will develop a thyroid condition at some point during their lifetime. However, what many people aren’t concentrating on is the thyroid-gut connection.

Read on to find out how your thyroid and gut greatly influence each other’s health and behavior.

To watch the accompanying video, click below.

What is the difference between thyroid conditions?

Shaped like a butterfly, the thyroid gland is located on the front of the neck and controls the body’s regulation of energy and the effectiveness of other organs in the body.

There are four common types of thyroid conditions that affect thyroid hormone production and the rest of the body’s functions.

Hypothyroidism describes an underactive thyroid and is the most common thyroid condition in the United States. In this case, the thyroid isn’t producing enough thyroid hormone. This can cause a slower heart rate, lower body temperature, and decreased metabolism. While this condition is most common in older women, it can affect women and men of all ages.

Main symptoms of hypothyroidism:
  • Fatigue
  • Depression
  • Cold sensitivity
  • Constipation
  • Dry skin
  • Unexplained weight gain/difficulty losing weight
  • Low libido
  • Muscle aches and weakness
  • Brittle hair and nails

Hyperthyroidism describes a thyroid in an overactive state. This is when the thyroid makes too much thyroid hormone, which speeds up the metabolism causing an array of unpleasant symptoms.

Main symptoms of hyperthyroidism:
  • Weight loss: 
  • Increased appetite
  • Rapid or irregular heartbeat
  • Nervousness, irritability, trouble sleeping, fatigue
  • Shaky hands
  • Muscle weakness
  • Sweating or trouble tolerating heat
  • Frequent bowel movements
  • Brittle hair 
  • Diarrhea
  • Needing to urinate more often than usual
  • Persistent thirst
  • Itchiness
  • Low libido
  • Difficulty swallowing if the thyroid gland is enlarged 

It has been estimated that up to 90% of all thyroid conditions are autoimmune in nature, which means that the immune system is the culprit that is causing the thyroid issue. Two distinct thyroid conditions that are also autoimmune diseases are Hashimoto’s thyroiditis and Grave’s disease. 

The Thyroid and Gut Connection

Hashimoto’s thyroiditis/chronic thyroiditis is the autoimmune form of hypothyroidism and is often the cause of hypothyroidism. This condition causes the body to attack the cells in the thyroid gland, which causes major inflammation and harm to the thyroid gland, limiting its ability to produce enough hormones. This condition can grow worse over time, even if symptoms aren’t noticeably growing worse. Anyone can develop this autoimmune condition, but it’s most prevalent in middle-aged women.

Main symptoms of Hashimoto’s:
  • Fatigue 
  • Extra sensitivity to cold
  • Dry skin
  • Constipation
  • Muscle weakness
  • Thyroid swelling
  • Depression
  • Muscle and joint aches
  • Tenderness and stiffness

Grave’s disease is the autoimmune form of hyperthyroidism. In the case of Grave’s disease, the body’s immune system creates an antibody to a specific area on the surface of thyroid cells, causing the thyroid to produce too much thyroid hormone. This condition is most prevalent among women 40 and younger, but it can affect anyone.

Main symptoms of Grave’s disease:
  • Bulging eyes (exophthalmos)
  • Heat intolerance
  • Increased energy
  • Difficulty sleeping
  • Diarrhea 
  • Anxiety
  • Hand tremors
  • Unexplained weight loss
  • Enlarged thyroid gland
  • Low libido
  • Fast or irregular heartbeat

How Does the Thyroid Impact the Gut?

As with most conditions that cause inflammation or are autoimmune in nature, the gut is, in turn, affected. 

Active thyroid hormone, called T3, activates gut motility to move food and stool down the GI tract. Thyroid hormones also impact the speed at which the stomach empties digested food.

T4, or inactive thyroid hormone, promotes a healthy mucous lining in the stomach to protect against inflammation of the stomach lining (called gastritis) and ulcers.

When these hormones are out of balance, many symptoms can arise.

In hypothyroidism, it’s more common to see slow motility, slow stomach emptying, and constipation. The slow stomach emptying can also contribute to acid reflux or heartburn because of this delay.

In hyperthyroidism, it is more common to see fast motility, diarrhea/loose stools, and fast stomach emptying. Due to the fast stomach emptying and faster motility, hyperthyroidism can lead to malabsorption of nutrients. This can increase the risk of developing nutritional deficiencies.

The Thyroid and Gut Connection

How Does the Gut Impact the Thyroid?

Just as other problems in the body can greatly influence digestive processes, the health of the gut greatly impacts the health of the rest of the body.

Since up to 90% of thyroid conditions are autoimmune, we need to ask “Where does most of the immune system live?” It’s estimated that 70-80% of the immune system lives in the gut. The GALT (Gut-Associated Lymphoid Tissue) is where the immune cells live. When you learn this, you have to wonder if improving gut health can alter thyroid health as well, and guess what? It does influence the health of the thyroid.

When it comes to autoimmune conditions, the body’s immune system mistakes its own healthy tissues as foreign invaders and attacks them. In up to 90% of thyroid conditions, the body’s immune system mistakes the thyroid gland for a foreign invader.

Another way the gut impacts the thyroid is through thyroid hormone conversion. Thyroid conversion is the body’s process of taking the inactive (or less active) thyroid hormone, T4, and converting it to active thyroid hormone, T3. An estimated 20% of thyroid conversion is dependent on healthy beneficial gut bacteria—the probiotics in your microbiome

Inflammation of the gut, which can be triggered by inflammatory foods, an imbalance of the gut microbiome from a lack of beneficial bacteria, or an overgrowth of other microbes such as opportunistic bacteria, yeast/candida, parasites, toxins/chemicals/mold/heavy metals, can also negatively impact the thyroid.

Poor gut absorption can also lead to nutritional deficiencies. Certain deficiencies like selenium, iodine, tyrosine, magnesium, zinc, and vitamin A, along with other vitamins and minerals are needed for optimal thyroid function.

The Thyroid and Gut Connection

What thyroid testing can you do?

In order to determine whether your thyroid is over or underproducing thyroid hormone, it’s imperative you get tested accurately. Many doctors will only test TSH, T4, and maybe T3, but that provides an incomplete picture of thyroid health. We recommend having a full thyroid panel done and seeing a doctor who knows how to interpret the results effectively.

Full thyroid panel:

  • TSH
  • Free T4
  • Total T4
  • Free T3
  • Total T3
  • Reverse T3
  • Thyroglobulin Antibodies
  • Thyroid Peroxidase Antibodies (TPO)

We also want to test anything that can impact the health and performance of your gut. Some of the common tests we run in our clinic include the following:

Gut health tests:

  • Food allergy/food sensitivity panels
  • Stool test
  • Organic Acids Test (OAT)
  • Nutritional deficiencies panel
  • Adrenal/cortisol panel

Test, don’t guess!

If you know what’s causing the problem, you can more easily find a solution. Because knowledge is power, we always encourage our patients to “Test, don’t guess!” By combining the test results with your history and symptoms, we can create a personalized plan to get to the root cause of your symptoms. 

These plans usually consist of the following:

  • Suggesting a personalized diet (based off of your results, history, and symptoms)
  • Making lifestyle modifications
  • Using specific supplements to address the findings of the test results with a goal of improving function and outcomes

We’re here to help

Trying to take your health back on your own can feel overwhelming. This is why at RHS, we offer free 15-minute phone consultations to go over your individual case and see if we are a good fit for you.

If you or anyone you know is having health issues with little to no answers, give us a call today at 952-479-7801.



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