Most people assume that heartburn and reflux are caused by excess stomach acid. In a significant number of patients, the opposite is true. Insufficient acid production leads to delayed gastric emptying, increased fermentation, and reflux of stomach contents into the esophagus. The symptoms are identical regardless of whether acid is high or low. Only a direct measurement can distinguish between them.
You feel heartburn. You assume you have too much acid. Your doctor assumes you have too much acid. You take an antacid or a PPI. This sequence happens millions of times a day worldwide and it is based entirely on an assumption that nobody tests.
The assumption seems logical. Burning in the chest and throat must mean acid is the problem. And in many patients, it is. But in a clinically significant number of patients, the mechanism is different. The burning is real. The acid is not excessive. The reflux is caused by a different set of events entirely.
Gastric acid serves as a signal. When the stomach is adequately acidic, the lower esophageal sphincter receives chemical and neural cues to close tightly. When acid levels are low, that signalling weakens. The sphincter relaxes. The barrier between the stomach and esophagus opens.
Simultaneously, low acid slows gastric emptying. Food remains in the stomach longer than it should. Bacterial fermentation of undigested carbohydrates produces gas. The stomach distends. Intra-gastric pressure rises. The weakened sphincter gives way. Stomach contents, including whatever acid is present, move upward into the esophagus.
The esophageal lining is not designed to handle any level of acid. Even a small amount causes the sensation of burning. The patient interprets this as excess acid. The doctor prescribes an acid suppressor. But the problem was never too much acid. It was too little acid creating the conditions for reflux through a completely different mechanism.
The standard workup for reflux does not include a measurement of gastric acid output. An upper endoscopy shows whether mucosal damage exists but does not measure how much acid the stomach produces. Esophageal pH monitoring (such as the Bravo capsule) measures acid exposure in the esophagus but does not assess whether the stomach is producing too much or too little. Empirical PPI trials assume the diagnosis without confirming it.
The result is a diagnostic gap. Patients with excess acid and patients with insufficient acid present with the same symptom. They receive the same treatment. Only one group benefits. The other may get worse.
Estimates of hypochlorhydria prevalence in adults over 60 range from 10% to 30%, depending on the study and population. A significant proportion of these patients experience reflux symptoms. Yet the reflexive response to reflux at any age is acid suppression. The mismatch between prevalence and treatment approach suggests that a substantial number of reflux patients are being treated for a condition they do not have.
This is not a fringe theory. The concept of low-acid reflux has been discussed in gastroenterology literature for decades. What has been missing is a practical, non-invasive way to measure acid output in the office and differentiate between the two mechanisms. That is what the Heidelberg pH test provides.
The Heidelberg pH Capsule measures gastric acid secretion in real time. The bicarbonate challenge protocol reveals whether the stomach produces acid adequately, insufficiently, or excessively. For the reflux patient, this answers the fundamental question that no symptom questionnaire, endoscopy, or empirical medication trial can answer.
If acid is genuinely elevated, acid suppression is appropriate and the patient can proceed with confidence. If acid is low, the clinical approach changes entirely. Supporting acid production, improving gastric motility, and addressing bacterial overgrowth become the priorities rather than further suppression.
If you have been living with reflux that does not improve with acid-suppressing medication, the paradox described here may be relevant to your situation. A professional gastric acid assessment can determine which side of the paradox you are on.
Take our 2-minute self-assessment quiz or find a practitioner near you who offers the Heidelberg test.
The Heidelberg pH Capsule is a Class I medical device, 510(k)-exempt, listed with the U.S. Food and Drug Administration under 21 CFR §876.1400. Listing of a device does not denote FDA approval, clearance, or endorsement.