Stomach acid has become one of the most talked-about topics in the online wellness space, and most of what you see on social media about it is either oversimplified or outright wrong. The most common claim goes something like this: most people with bloating, reflux, and digestive discomfort actually have too little stomach acid, not too much. The recommended fix is usually apple cider vinegar before meals, or a baking soda test to diagnose yourself at home. The reality is more complicated. Low stomach acid is a real condition that affects a meaningful number of people, particularly older adults. But the self-diagnosis methods floating around the internet are not reliable, and the proposed remedies lack clinical evidence. Here is what stomach acid actually does, what happens when you do not make enough, and where the popular claims go wrong.
How stomach acid is made and what it does
Your stomach lining contains specialized cells called parietal cells, and these cells produce hydrochloric acid (HCl) through an active transport mechanism involving the hydrogen-potassium ATPase pump, often called the proton pump. This is the same pump that proton pump inhibitor medications (PPIs) like omeprazole and pantoprazole block. The acid your stomach produces is strong, typically reaching a pH of 1.5 to 3.5 in the fasting state. That is acidic enough to dissolve certain metals (Schubert, 2015).
Acid secretion is regulated by three main stimulators: histamine (released by enterochromaffin-like cells), gastrin (a hormone released by G cells in the stomach), and acetylcholine (released by the vagus nerve). All three converge on the parietal cell to drive acid production. This is why there are different classes of acid-reducing medications: H2 blockers target histamine receptors, PPIs target the proton pump directly, and anticholinergics reduce vagal stimulation.
Stomach acid serves several critical functions. First, it activates pepsinogen, an inactive enzyme precursor, into pepsin, which is the primary enzyme for breaking down proteins in the stomach. Without adequate acid, pepsinogen just sits there doing nothing, and protein digestion in the stomach is significantly reduced. Second, acid is necessary for the proper absorption of several nutrients. Iron absorption depends on acid to convert ferric iron (Fe3+) into the more absorbable ferrous form (Fe2+). Calcium absorption, particularly from calcium carbonate supplements, requires an acidic environment. Vitamin B12 absorption depends on acid to free B12 from dietary proteins so it can bind to intrinsic factor (Marcuard et al., 1994). Third, gastric acid is a first-line defense against bacteria, parasites, and other pathogens that you swallow with food and water. The acidic environment kills most organisms before they reach the small intestine.
What hypochlorhydria actually is and who gets it
Hypochlorhydria means your stomach produces less acid than normal, and achlorhydria means it produces essentially no acid at all. These are real, diagnosable conditions. The most common causes are aging (the number and function of parietal cells decline with age), autoimmune atrophic gastritis (where the immune system attacks parietal cells directly), H. pylori infection (which can cause chronic inflammation that damages the gastric lining), and long-term PPI use (which suppresses the proton pump for extended periods).
The prevalence of hypochlorhydria increases substantially with age. A study by Hurwitz et al. (1997) found that between 10 and 30% of adults over 60 had significantly reduced acid output. In patients with autoimmune atrophic gastritis, the rate is much higher. This age-related decline matters clinically because it contributes to the higher rates of B12 deficiency, iron deficiency, and certain infections seen in older adults.
Long-term PPI use is another significant cause. PPIs are among the most prescribed medications worldwide, and while they are effective and appropriate for conditions like GERD, Barrett's esophagus, and peptic ulcers, prolonged use at high doses can reduce acid output to the point of hypochlorhydria. A meta-analysis by Freedberg et al. (2017) confirmed associations between long-term PPI use and increased risk of C. difficile infection, community-acquired pneumonia, and certain nutrient deficiencies, though the absolute risk increases are relatively modest.
⚠️If you are taking a PPI prescribed by your doctor, do not stop it based on social media advice about low stomach acid. PPIs are prescribed for serious conditions including GERD, Barrett's esophagus, and ulcer prevention. Stopping abruptly can cause rebound acid hypersecretion, which means your symptoms may come back worse than before. Any changes to PPI therapy should be discussed with your prescriber.
Why the baking soda test does not work
You have probably seen this one: drink a glass of water with a quarter teaspoon of baking soda first thing in the morning, then time how long it takes to burp. If you burp within 2 to 3 minutes, your stomach acid is supposedly fine. If you do not burp, or it takes a long time, you supposedly have low stomach acid. This test is widely promoted on social media, in wellness blogs, and even by some alternative health practitioners.
The problem is that this test has never been validated in any clinical study. There is no published research correlating baking soda burp timing with measured gastric acid output. The reasoning behind it (baking soda reacts with acid to produce CO2 gas, which causes burping) is chemically sound in principle, but the variables involved make it useless as a diagnostic tool. How much baking soda you used, how much water you drank, how fast you drank it, whether you swallowed air, your stomach volume, and your individual belch threshold all influence the result. A positive or negative result tells you essentially nothing about your actual acid production (El-Omar et al., 1997).
If you genuinely want to assess gastric acid production, the clinical methods include the Heidelberg capsule test (you swallow a small pH-transmitting capsule), gastric pH monitoring, or serum markers like pepsinogen I and pepsinogen II ratios, which can indicate atrophic gastritis. These are medical tests that require a physician's involvement. They are not glamorous, but they actually measure what they claim to measure.
Apple cider vinegar: the evidence gap
The claim that apple cider vinegar (ACV) can treat low stomach acid or improve digestion is one of the most persistent in the alternative health space. The logic usually goes: ACV is acidic (pH of about 2.5 to 3.0), so drinking it adds acid to your stomach and compensates for low production. Some versions of the claim add that ACV stimulates your own acid production.
There are no randomized controlled trials demonstrating that ACV improves symptoms of hypochlorhydria, enhances nutrient absorption, or meaningfully changes gastric pH in a clinically significant way. The acid content of a tablespoon of ACV is trivially small compared to the volume and concentration of acid your stomach produces on its own. A normally functioning stomach produces roughly 1.5 to 2 liters of gastric juice per day (Schubert, 2015). A tablespoon of ACV contains about 750 mg of acetic acid. It is not in the same league.
ACV also has a downside that is rarely mentioned in promotional content. Its acidity can damage tooth enamel with regular use, irritate the esophagus, and worsen symptoms in people who actually have too much acid or damaged esophageal mucosa. A case report in the Netherlands Journal of Medicine documented esophageal injury in a woman who regularly consumed ACV tablets (Hill et al., 2005). The point is not that ACV is dangerous in normal amounts, but that recommending it as a treatment for a condition you have not properly diagnosed is not helpful.
What about betaine HCl supplements?
Betaine HCl (betaine hydrochloride) is sold as a digestive supplement and is essentially a pill form of hydrochloric acid. Unlike ACV, there is at least a mechanistic rationale here: you are directly adding acid to the stomach. A small study by Yago et al. (2013) showed that betaine HCl could temporarily lower gastric pH in people with pharmacologically induced hypochlorhydria (they were given PPIs to suppress acid, then given betaine HCl to see if it restored acidity). It did, temporarily.
However, this study involved only 10 participants, used drug-induced rather than naturally occurring hypochlorhydria, and measured pH changes rather than clinical outcomes like symptom improvement or nutrient absorption. We do not have large, well-controlled trials showing that betaine HCl supplements improve digestion, reduce bloating, or enhance nutrient status in people with naturally low acid production. The supplement may have a role in specific clinical scenarios, but it is not something to self-prescribe based on a social media diagnosis.
When to actually talk to your doctor about stomach acid
If you have symptoms that could plausibly relate to low stomach acid, it is worth discussing with a gastroenterologist rather than self-diagnosing. Persistent bloating and fullness after meals (especially protein-heavy meals), undigested food visible in your stool, iron deficiency or B12 deficiency without an obvious dietary cause, recurrent GI infections, and chronic use of PPIs that you are not sure you still need are all reasonable reasons to bring up the topic. Using a symptom tracking tool like GLP1Gut to document your meal patterns and symptoms before your appointment gives your doctor something concrete to work with, rather than a vague report of 'I feel bloated sometimes.'
Your doctor can check serum pepsinogen levels, test for H. pylori, evaluate your B12 and iron status, and refer you for further workup if needed. If you are on a long-term PPI and are not sure whether you still need it, your doctor can help you evaluate whether a trial taper is appropriate. This should be done gradually, not abruptly, because of the rebound acid hypersecretion that can occur when PPIs are stopped suddenly.
The bottom line on stomach acid
Stomach acid is essential for digestion, nutrient absorption, and defense against infection. Low stomach acid is a real condition that becomes more common with age and certain medications. But the online narrative that most digestive problems are caused by low acid, and that the fix is a home test with baking soda or a daily shot of apple cider vinegar, is not supported by evidence. The actual diagnosis requires medical testing, and the actual treatment depends on the underlying cause. If aging parietal cells are the issue, supplemental acid or dietary adjustments might help. If H. pylori is destroying your stomach lining, you need eradication therapy. If you are on a PPI you no longer need, a supervised taper might be the answer. None of these situations are well served by a one-size-fits-all social media protocol.
Can you have both low stomach acid and acid reflux at the same time?
Yes. Acid reflux (GERD) is primarily a problem of the lower esophageal sphincter not closing properly, which allows whatever acid is present to splash into the esophagus. Even a small amount of acid in the wrong place causes burning. You can have reduced overall acid production and still experience reflux if your sphincter function is impaired.
Does eating too fast reduce stomach acid?
Eating speed does not directly change how much acid your parietal cells produce. However, eating very quickly can overwhelm the stomach's ability to mix food with acid efficiently, which can lead to symptoms like bloating and fullness that mimic low acid issues. Chewing thoroughly and eating at a moderate pace helps mechanical digestion do its part.
Are there foods that naturally increase stomach acid production?
Protein-rich foods are among the strongest stimulators of acid secretion because amino acids trigger gastrin release. Bitter foods and certain spices may also mildly stimulate gastric secretion. However, no food has been shown to meaningfully treat clinical hypochlorhydria. If your acid production is impaired due to atrophic gastritis or medication effects, dietary changes alone will not fix the underlying problem.