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Hypochlorhydria and Heartburn: The Surprising Link

Written by Portland Clinic of Natural Health on August 8, 2023

Most people think that heartburn, or gastroesophageal reflux disease (GERD), is caused by the production of too much stomach acid. It's why antacids, which neutralize stomach acid, are a go-to remedy for many. However, emerging research suggests that the opposite may be true for a significant number of people: too little stomach acid, a condition known as hypochlorhydria, might be a leading cause of GERD.

What is Hypochlorhydria?

Hypochlorhydria refers to a deficiency of hydrochloric acid in the stomach. This acid is critical for the digestion of food, especially proteins. When the stomach doesn't produce enough hydrochloric acid, digestion slows down, leading to various digestive disturbances. (1)

Hypochlorhydria and Heartburn: Evidence for the Link

The Influence of Gastric pH on Lower Esophageal Sphincter (LES) Tone

The relationship between gastric pH and the Lower Esophageal Sphincter (LES) tone is an area of significant interest in gastroenterological research. The LES acts as a valve, controlling the flow of contents from the esophagus into the stomach. 

Research has indicated that the acidity or pH level of the stomach can influence the pressure and functioning of this valve. Specifically, changes in gastric pH have been observed to correlate with variations in the LES's intraluminal pressure. This relationship suggests that the acidity of the stomach might play a crucial role in the maintenance of the LES tone and, thus, in preventing conditions like acid reflux or gastroesophageal reflux disease (GERD). (2, 3)

Incomplete Digestion

Without adequate stomach acid, food isn't broken down as efficiently. This undigested food can ferment, producing gas and increasing intra-abdominal pressure. This pressure can force the lower esophageal sphincter (LES) to open, allowing stomach content to reflux into the esophagus, causing the characteristic burning sensation of heartburn. (4)

Bacterial Overgrowth

Adequate stomach acid acts as a defense mechanism by killing pathogenic bacteria and other microbes present in food. In a hypochlorhydric environment, harmful bacteria can proliferate in the small intestine. This overgrowth can produce gas, again leading to increased intra-abdominal pressure and potential reflux. (5)

Weakened LES Tone

The LES is a muscle that separates the stomach from the esophagus. Studies have suggested that the presence of gastric acid can help maintain a strong LES tone. Without it, the LES may weaken or relax inappropriately, allowing acid to flow back into the esophagus. (6)

Contradicting the Norm with GERD

One of the reasons the hypochlorhydria and heartburn link is surprising to many is due to the widespread use of proton pump inhibitors (PPIs) and antacids to treat GERD. These medications reduce or neutralize stomach acid. For those with hypochlorhydria, this could further reduce their already low acid levels, potentially exacerbating the underlying cause of their symptoms.

However, it's essential to recognize that GERD is a multifactorial condition. While hypochlorhydria may be a significant factor for some, others might indeed produce too much acid or have other underlying conditions contributing to their symptoms.

Hypochlorhydria as a Leading Cause of Heartburn and GERD

Recognizing hypochlorhydria as a potential cause of heartburn and GERD challenges the long-held belief about the role of acid in reflux. For those suffering from chronic heartburn, understanding this link could lead to more effective treatments and relief. 

Always consult a healthcare provider before significantly changing medications or treatment strategies.


  1. Fatima R, Aziz M. Achlorhydria. 2023 Feb 22. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–. PMID: 29939570.
  2. Kaye MD. On the relationship between gastric pH and pressure in the normal human lower oesophageal sphincter. Gut. 1979 Jan;20(1):59-63. doi: 10.1136/gut.20.1.59. PMID: 33104; PMCID: PMC1418956.
  3. Shaker R, Dodds WJ, Kahrilas PJ, Helm JF, Hogan WJ. Relationship of intraluminal pH and pressure within the lower esophageal sphincter. Am J Gastroenterol. 1991 Jul;86(7):812-6. PMID: 2058619.
  4. Dodds WJ, Hogan WJ, Miller WN, Stef JJ, Arndorfer RC, Lydon SB. Effect of increased intraabdominal pressure on lower esophageal sphincter pressure. Am J Dig Dis. 1975 Apr;20(4):298-308. doi: 10.1007/BF01237786. PMID: 1130358.
  5. Sorathia SJ, Chippa V, Rivas JM. Small Intestinal Bacterial Overgrowth. [Updated 2023 Apr 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK546634/.
  6. Usai Satta P, Oppia F, Cabras F. Overview of pathophysiological features of GERD. Minerva Gastroenterol Dietol. 2017 Sep;63(3):184-197. doi: 10.23736/S1121-421X.17.02390-X. Epub 2017 Mar 1. PMID: 28251844.

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