Thyroid and Gut Health Connection

What is the Thyroid?

The thyroid is a gland in the neck, just in front of the windpipe. It is shaped like a small butterfly and produces the hormones that affect things like our heart rate and body temperature.1

The two hormones that the thyroid produces are called thyroxine (T4) and triiodothyronine (T3). These hormones are necessary for all the cells in the body to function normally.2

Unfortunately, the thyroid doesn’t always function correctly for many people. This can be a temporary problem or a lifelong issue. A thyroid issue is far more common in women but can affect anybody of any age. Approximately 1 in 20 people have thyroid dysfunction at some point.2 

The amount of hormones secreted by the thyroid gland is controlled by the pituitary gland - a small gland located underneath the brain in the skull.

This very clever little gland monitors the level of the hormones in your bloodstream and then instructs the thyroid to release more or fewer hormones to keep the levels steady through secreting a hormone called the thyroid-stimulating hormone.2

What is Thyroid Dysfunction?

The thyroid can be overactive or underactive. The hormones released by the thyroid gland influence the metabolism of your body cells - in other words, how quickly they work.

There aren’t always obvious symptoms of thyroid dysfunction, and most people require a blood test to confirm a thyroid disorder. It’s tough to self-diagnose a thyroid condition accurately due to the varying yet common symptoms that can be experienced.2 

If not enough thyroid hormones are produced, this is known as hypothyroidism. In this case, the cells and organs slow down, which can cause the intestines to work sluggishly, resulting in constipation. You may feel tired, cold, gain weight, have poor concentration or experience depression if you have hypothyroidism.2 

If too much thyroid hormone is being secreted, then the body cells work too fast. This is called hyperthyroidism. The symptoms of this condition can be a faster heart rate or frequent bowel motions/diarrhoea from increased activity of the intestines.

With hyperthyroidism, you may experience weight loss, heat sensitivity, anxiety, or sore and gritty eyes. This is the most minor common thyroid disorder.2 

Thyroid disorders can have many causes, but autoimmune thyroid disease is the most common reason. This occurs when the body’s immune system attacks the thyroid cells as it believes they are foreign cells.2

Our immune system is the function that keeps us healthy and defends us against illness and disease by attacking foreign invaders and bad cells. Still, when the immune system attacks the wrong body parts, it can cause issues like thyroid disease. It’s common for this particular cause to be genetic, as it usually runs in families. 

Is a Thyroid Dysfunction Serious?

Although an overactive or underactive thyroid can be frustrating, it is not life-threatening. What can happen, though, is a condition known as a thyroid storm.

The symptoms of a thyroid storm can be a rapid heartbeat, a high temperature, diarrhoea and sickness, jaundice, severe agitation and confusion and loss of consciousness.6

A thyroid storm can be caused by an infection, pregnancy, incorrect medication use or an injury to the thyroid gland. It is a sudden flare-up of symptoms that can be life-threatening.6

It’s unusual for a thyroid storm to occur, but it’s essential to seek immediate emergency assistance if you are concerned that you are experiencing symptoms.

Is the Thyroid Linked To Gut Health?

Yes! Thyroid issues don’t allow your body to function at the correct speed, which can cause problems directly to the digestive system. Our gut health is vital in ensuring our overall health is good, including our bowel movements.

An overactive thyroid speeds up your bodily systems, including the digestive system. This can cause diarrhoea, as your body doesn’t have enough time to digest the food.

An under-active thyroid doesn’t allow your bodily systems to function fast enough, leading to constipation.4 This is because your digestive system isn’t working at the pace needed to digest food properly; it is working much slower. 

How Do I Help Thyroid Dysfunction?

Firstly, it's essential to fix the problem at the source with thyroid issues.


If you have hypothyroidism, a thyroid replacement pill can be prescribed to give your body enough of the hormones to function correctly. This can limit constipation caused by hypothyroidism, which is a direct symptom of insufficient hormones.5

If you have hyperthyroidism, you may be given oral radioactive iodine to combat symptoms. This is absorbed by your thyroid gland, which shrinks it, fighting signs that were present from too much thyroid hormone production. 

This treatment can cause it to shrink too much, causing hypothyroidism; in this case, you may need to take a thyroid replacement pill to level it out.7 


Anti-thyroid medications can also be prescribed to combat hyperthyroidism. These prevent your thyroid from producing excessive amounts of hormones. Types of anti-thyroid medication can include methimazole or propylthiouracil, and symptoms of hyperthyroidism will usually subside after a few weeks or months.8 

How Do I Help Bowel Dysfunction Caused By Thyroid Dysfunction?

Whether you have hypothyroidism or hyperthyroidism, fibre will help your bowel movements. Fibre adds bulk to the stool and allows it to absorb water, making it easier to pass. This helps to prevent both constipation and diarrhoea.5 

It’s essential, remarkably, when increasing your fibre intake that you are suitably hydrated. It’s recommended by the NHS Eat Well Scheme to drink 6-8 glasses of fluid per day for optimum health.8 You need water to bond your stool together; if there's not enough water, your stool will be hard and challenging to pass. 

Increasing exercise levels can also help with constipation caused by an under-active thyroid. Studies have shown that exercising 150 minutes per week can help manage constipation symptoms.5 If you can increase your activity levels, it can help move the stool through the colon and relieve that backed-up feeling. 

The Gut Co’s Benefit On Thyroid Dysfunction

At The Gut Co, we created a daily probiotic supplement, “Gut Care”, that includes many ingredients that can benefit people with symptoms caused by thyroid dysfunction. Firstly, Gut Care contains a fibre-rich ingredient called Actazin - a kiwi extract. This fibre extract will help to reduce bloating and support bowel regularity. 

If you have hyperthyroidism, Gut Care may benefit you through its ingredient CRL 1505, a strain of bacteria shown to reduce episodes of diarrhoea by up to 60% in some cases. The Gut Care formula also contains a form of yeast called Saccharomyces Boulardii that may benefit people with thyroid and autoimmune conditions. 

All our formulas are vegan, organic where available and free from gluten, sweeteners, preservatives and excipients. They are packaged in sustainable, plastic-free glass jar packaging, as they are committed to designing clean products that are good for you and the planet. 

Final Thoughts

Having an overactive or under-active thyroid can be an irritating condition to live with that can impact so many sections of the body and, therefore, everyday life.

The impact the thyroid has on the bowels can be painful and uncomfortable, but luckily, lifestyle changes, medications and products can help with symptoms. 

Prev Article

What are the signs you need probiotics?

It can be pretty easy to identify when something is wrong with your body, but knowing how to fix it? Now that can be a whole lot more challenging.  There are a few tell-tale signs that your body could benefit from probiotics, and we’re here to spread that knowledge so...

Related Articles…