The Short Answer

Proton pump inhibitors (PPIs) used for acid reflux may increase stomach cancer risk, particularly with long-term use. The real problem isn’t too much stomach acid—it’s usually too little. For people with autoimmune conditions, including Hashimoto’s low thyroid, low stomach acid can worsen gut inflammation and immune dysregulation. Addressing the underlying cause is more effective than suppressing symptoms with acid-blocking drugs.

How stomach acid connects to autoimmune disease

Several factors contribute to stomach cancer risk, but recent research shows that regular use of proton pump inhibitors (PPIs) for acid reflux increases this risk compared to users of H2-receptor blockers like Tagamet or Pepcid. What’s particularly relevant for autoimmune patients is that low stomach acid—a common trigger for acid reflux—is often connected to immune dysfunction.

People with autoimmune conditions frequently experience acid reflux, and for many, the underlying cause is inadequate stomach acid rather than excess. This counterintuitive connection matters because how you address it determines whether you heal or worsen your condition.

Why low stomach acid causes acid reflux (not high acid)

The stomach is naturally very acidic, by design. This acidity breaks down food, kills pathogens like bacteria and fungi, and signals your digestive system to release the hormones and enzymes needed for proper digestion. Healthy stomach acid also supports mineral absorption and helps repair the gut lining.

When stomach acid is insufficient, the food entering your small intestine isn’t acidic enough to trigger the proper digestive response. The food backs up into your esophagus, where the small amount of acid present is too strong for delicate tissues. The result is a burning sensation from acid reflux, or heartburn.

This digestive dysfunction and the resulting gut inflammation can trigger or worsen autoimmune flares in susceptible people.

What causes low stomach acid

Several factors deplete stomach acid production:

Chronic stress

Bacterial infections, especially H. pylori (associated with ulcers)

Poor diet

Nutritional deficiencies in zinc, B12, magnesium, or chloride

Pernicious anemia

For autoimmune patients specifically, immune dysregulation can attack stomach acid-producing cells, creating a direct link between your autoimmunity and digestive breakdown.

Why acid-blocking drugs make the problem worse

This is the critical insight: while PPIs or H2-blockers provide immediate symptom relief, they perpetuate the underlying dysfunction. By further reducing stomach acid, these medications:

Increase susceptibility to gut infections and inflammation

Impair mineral absorption (which autoimmune patients often struggle with anyway)

Prevent proper gut repair and barrier function

May increase long-term stomach cancer risk

For autoimmune patients, this creates a vicious cycle: you’re treating the symptom while worsening the gut dysfunction that triggered your immune flare in the first place.

How to restore healthy stomach acid

Rather than suppressing acid, work to restore it. Betaine hydrochloric acid (HCl) supplements can help rebuild healthy acid levels. However, if you have active stomach ulcers or stomach-specific autoimmunity, this approach may need modification.

The goal is always to address the root cause, whether that’s an H. pylori infection, a nutritional deficiency, chronic stress, or immune dysregulation, rather than mask symptoms with acid blockers.

At RedRiver, we help autoimmune patients identify what’s driving their low stomach acid and rebuild digestive function from the foundation up.