Acid reflux, also known as GERD or acid indigestion, is extremely common. It occurs when the lower esophageal sphincter (LES) doesn’t close properly. The LES is the muscle located between the esophagus and the stomach. It’s a one-way valve that normally opens for limited amounts of time when you swallow. When the LES fails to close completely, stomach contents and digestive juices can come back up into the esophagus.

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The most common symptom of acid reflux is heartburn, which causes a burning sensation in the chest. Other symptoms may include regurgitation and difficulty swallowing. When acid reflux occurs more than twice per week, it is known as chronic acid reflux, or gastroesophageal reflux disease (GERD).

How the Thyroid Affects Acid Reflux

The thyroid is a butterfly-shaped gland located in the neck, just above the collarbone. It’s part of a collection of glands that make up the endocrine system. The endocrine system produces hormones that regulate growth and development, reproduction, and sleep, among other things. The thyroid gland is responsible for manufacturing hormones that regulate the body's metabolism, or the body’s process of creating and using energy. These hormones include tetraiodothyronine (T4) and triiodothyronine (T3). There are several different disorders that can occur when the thyroid produces too many or too few hormones.

Millions of Americans suffer from thyroid diseases. The two most common diseases are hyperthyroidism and hypothyroidism.

Hyperthyroidism is caused by an overactive thyroid, which means the thyroid produces too much hormone. This can cause rapid heart rate, high blood pressure, and unexpected or sudden weight loss.

Hypothyroidism is caused by an underactive thyroid, which means the thyroid doesn’t produce enough hormones. This interferes with the body’s ability to perform normal metabolic functions, such as effectively using energy from food products. Symptoms of hypothyroidism include weight gain and fatigue. Hypothyroidism is much more common than hyperthyroidism, especially in women.

In people with hypothyroidism, the underactive thyroid may disable the LES. This allows food and digestive juices from the stomach to re-enter the esophagus. Hypothyroidism has also been shown to delay gastric emptying, or the way the stomach contracts and moves food into the intestines. This means more acid can flow upward into the esophagus.

Bacteria and Acid Reflux

The presence of the Helicobacter pylori bacterium may also contribute to acid reflux. H. pylori are a common type of bacteria that usually infects the stomach. It affects more than half of all people worldwide. The bacteria grow in the digestive tract and attack the stomach lining. 

H. pylori can thrive in the harsh, acidic environment of the stomach. These bacteria can change the environment around them and reduce its acidity so they can survive. The spiral shape of H. pylori allows them to penetrate your stomach lining, where the mucus protects them from your body’s immune cells. H. pylori is one of the leading causes of chronic gastritis.

H. pylori may also cause excessive stomach acid. The bacteria stimulate the stomach to produce extra quantities of acid, which then come back up into the esophagus. The increased amount of acid may also cause the stomach to empty more slowly, leading to acid reflux.

It’s believed that acid-reducing medications — which are often prescribed to treat H. pylori — may contribute to reflux. Certain medications, such as Prilosec, can actually increase stomach acid and create an ideal environment for the bacteria to thrive. In some cases, this can lead to chronic gastritis, which may cause even more heartburn for people with acid reflux. These medications may also interfere with other drugs used to treat thyroid diseases, such as hypothyroidism.

The Acid Reflux-Thyroid Connection

In short, there does appear to be a connection between the thyroid and acid reflux. When the thyroid doesn’t produce a sufficient amount of hormones, it can cause LES dysfunction. This allows stomach contents and digestive juices to enter the esophagus, which may lead to GERD. Other factors, such as an H. pylori infection, can also contribute to your acid reflux.

You should contact your doctor if you have a thyroid disease and are experiencing acid reflux. Your doctor can help you find ways to relieve your acid reflux without impairing your thyroid function. You should also speak with your doctor if you suspect you may have a thyroid problem. They can conduct various tests to make a diagnosis and prescribe the proper treatment for your condition.

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