What is Low Stomach Acid (Hypochlorhydria)

Stomach acid is a powerful workhorse for digestion and defense. Measured on the pH scale, it has a value as low as 1 (0 being the most acidic), equivalent to the strength of battery acid. Hence, even though the gastric juice contains water and mucus, a normal stomach pH is typically between pH 1.5 and 3.5.

The human body maintains all biological equilibrium via a process called homeostasis. Low stomach acid production, otherwise known as hypochlorhydria, occurs when the stomach fails to produce adequate amounts of stomach acid. Less common, a complete loss of stomach acid production is referred to as achlorhydria. On the other hand, excessive stomach acid, a condition known as Zollinger-Ellison syndrome, is caused by the overproduction of gastrin, a hormone that stimulates gastric acid secretion. It can also be caused by H.pylori infection, autoimmune disorders, and certain medications. These imbalances can lead to various digestive problems.

Low Stomach Acid Causes

While low stomach acid production can be a normal effect of aging, stress, or nutrient deficiencies, some of the other most common causes of hypochlorhydria include certain medications used for managing acid reflux. In particular, proton pump inhibitors work by suppressing stomach acid synthesis. Pathogenic causes include the bacterium Helicobacter pylori, which survives in the gastric environment by neutralizing stomach acid, leading to inflamed gastric tissue and reduced stomach acid output. Sometimes, unfortunately, the body’s own defense mechanisms can be the issue, as seen in autoimmune gastritis, where the parietal cells that produce stomach acid are destroyed. Endocrine issues like hyper- and hypo-thyroidism are also sometimes thought to be linked to low stomach acid cases. This is particularly problematic, as adequate stomach acid is necessary to properly absorb common thyroid medications. Adequate stomach acid is needed for proper digestion and absorption of nutrients, especially vitamin B12, calcium, iron, magnesium, and zinc.

Symptoms of Low Stomach Acid

People with low stomach acid commonly experience a range of digestive issues. Low stomach acid symptoms can include a feeling of fullness soon after starting a meal, bloating, frequent belching, and general stomach discomfort that lingers long after eating or feeling like food is “sitting in your stomach.”.

The consequences of low stomach acid may extend beyond simple discomfort. It can compromise protein digestion by failing to activate pepsin, the essential digestive enzyme that functions optimally in the highly acidic environment of the digestive system. Low stomach acid also increases vulnerability to harmful bacteria, leading to intestinal bacterial infections, such as bacterial gastroenteritis and Small Intestinal Bacterial Overgrowth (SIBO). 

A common misconception is that low stomach acid would lead to less acid reflux; however, research does not support this. Stomach acid helps keep the Lower Esophageal Sphincter (LES), a muscular valve at the top of the stomach, closed. When acid levels are low, the LES may become weakened, allowing stomach contents to flow back into the esophagus. Additionally, Stomach acid is essential for breaking down food. When acid levels are low, food may take longer to digest, which can put pressure on the LES and increase the risk of reflux. The primary acid reflux treatment, like the Proton Pump Inhibitors (PPIs), induces low stomach acid, and long-term use of these medications can be a significant risk factor for developing troublesome bloating and/or SIBO, as well as various nutrient deficiencies.

Testing for Low Stomach Acid

Symptoms of low stomach acid overlap with other conditions such as functional dyspepsia, gastroparesis, and irritable bowel syndrome (IBS). Therefore, symptoms alone cannot be used to diagnose low stomach acid.

To obtain an accurate diagnosis, measuring stomach acid output is necessary. The test process typically consists of placing a capsule or probe with a pH sensor into the stomach, followed by ingestion of a standardized meal, such as a nutrient drink. This will buffer the stomach acid levels. Then the time taken for the stomach to reacidify after the meal is noted.

Despite its popularity online, the baking soda test for low stomach acid is not a 100% accurate way to diagnose, though it is sometimes used in practice as a non-invasive, less costly screening tool. The theory is that baking soda (sodium bicarbonate) reacts with stomach acid (hydrochloric acid) to produce gas (carbon dioxide), which causes belching. However, this may be unreliable, particularly because the act of drinking the solution often introduces air into the stomach, which is the most common cause of belching in this scenario. In certain cases, as long as there are no gastric ulcers present, a trial of betaine HCL/pepsin with meals (with doctor/dietitian guidance) to see if symptoms improve might be an effective option. Diluted ACV or lemon water with meals can be useful tests, as well. These are not necessarily “diagnostic tools” but they can help pinpoint if this might be an issue for someone and may prompt further testing.

How to treat low stomach acid?

There are dietary steps that can be taken, such as apple cider vinegar, which is claimed to be helpful in treating low stomach acid levels, as it has a similar pH to stomach acid, around 2.5. However, ACV does need to be diluted properly. Tests of betaine HCL/pepsin or lemon water with meals also provide insight. Working with a registered dietician such as Sarah Lynn Nutrition is a helpful step in navigating achlorhydria and related gastro-intestinal issues.

Another reported potential remedy for low stomach acid is betaine HCL tablets. Since hydrochloric acid is naturally produced by the stomach, supplementing with HCl may help lower the overall pH to a healthy stomach acid level, which is essential for digesting amino acids. While more research is needed, this is commonly used in practice due to relatively low risk and promising results.

The most effective strategy for managing low stomach acid is to target its root cause. For example, once a Helicobacter pylori infection is treated, stomach acid level often normalizes on its own. Likewise, when a patient stops taking Proton Pump Inhibitors (PPIs) under medical supervision, the body can resume its normal acid production. However, patients are advised against stopping PPIs without medical consultation, especially those who have undergone stomach surgery. These medications serve a critical protective function for the esophagus. For individuals with complications like Barrett’s esophagus, ceasing PPI therapy could elevate the risk of further damage. A healthcare provider can help create a safe treatment plan for any changes that may occur. It’s also important, when possible, to manage stress and nutrient deficiencies.

In summary, low stomach acid can disrupt digestion and increase susceptibility to intestinal infections, such as SIBO, given that gastric acid plays a key role in breaking down food and eliminating pathogens. While diagnostic tests like the stomach acid output test are available, treatment options are primarily focused on resolving the underlying condition.