Acid reflux, also known as acid indigestion, is extremely common. It occurs when the lower esophageal sphincter (LES)—the muscle located between the esophagus and the stomach—doesn’t close properly. This allows stomach contents such as digestive juices to enter the esophagus.
The most common symptom of acid reflux is the burning sensation just behind the breastbone, more commonly known as heartburn. Other symptoms may include regurgitation and difficulty swallowing (dysphagia). Chronic acid reflux, which occurs more than twice per week, is known as gastroesophageal reflux disease (GERD).
The thyroid is a butterfly-shaped endocrine gland located in the neck, just above the collarbone. The primary function of the thyroid is to produce hormones that regulate metabolism. Millions of Americans suffer from thyroid diseases. The two most common are hyperthyroidism and hypothyroidism.
Hyperthyroidism is caused by an overactive thyroid. People with this condition may have increased heart rates, heat sensitivity, and weight loss. Hypothyroidism is much more common, especially in women. In this condition, the thyroid gland is under-active, causing the body to use energy more slowly than it should. Symptoms of hypothyroidism include weight gain, fatigue, and difficulty adjusting to cold temperatures.
Hypothyroid and the LES
An under-active thyroid may disable the LES, allowing food and digestive acids to re-enter the esophagus from the stomach. In addition, hypothyroidism has been shown to delay gastric emptying, which allows more acid to flow upward into the esophagus.
H. Pylori, Prilosec and Thyroxine
H. pylori is the most common chronic bacterial pathogen found in human beings. It affects nearly half of all people worldwide. H. pylori suppresses stomach acid secretion, allowing it to survive in the stomach where normal bacteria would be destroyed. It’s also one of the leading causes of chronic gastritis.
Acid-reducing medications such as Prilosec—often prescribed to treat GERD—have been shown to create the ideal conditions for H. pylori to thrive. A 1996 article published in the New England Journal of Medicine found that rates of H. pylori infection in those taking Prilosec increased from 59 percent to 81 percent over the course of a five-year study. Thirty percent of the people taking part in the study who were on Prilosec developed gastritis, compared to only 4 percent of those who had surgery to relieve their GERD.
A 2006 Italian study seemed to further confirm the relationship between H. pylori and acid reflux. Researchers found that hypothyroidism patients who were also infected with H. pylori required up to 37 percent more medication to combat their condition than those without H. pylori-related gastritis. The study implicated omeprazole, a drug found in the heartburn medication Prilosec, as the cause.
Hypothyroidism and Hiatal Hernia
There appears to be an additional connection between hypothyroidism and acid reflux. A 2006 Russian study found that GERD and hiatal hernia are early signs of hypothyroidism. Hiatal hernia is a condition where part of the stomach pushes through the small hole in the diaphragm, causing symptoms of heartburn, belching, fatigue, or difficulty swallowing.
The Acid Reflux-Thyroid Connection
In short, there does appear to be a connection between hypothyroidism and acid reflux. An under-active thyroid can lead to LES dysfunction and hiatal hernia, which may lead to acid reflux and GERD.
Some medications like Prilosec (used to treat heartburn) suppress stomach acids, allowing the H. pylori bacteria to thrive. This causes chronic gastritis in some patients, which further reduces stomach acids and can cause even more chronic heartburn for sufferers.