Rethinking the Cause of Heartburn

Most people—and even many healthcare providers—assume that heartburn is caused by too much stomach acid. That’s why acid-blocking medications like proton pump inhibitors (PPIs) and antacids are prescribed so often.

But in functional medicine, we’ve seen that low stomach acid (hypochlorhydria) is actually a more common cause of chronic heartburn.

This may sound surprising—how can low acid cause a burning sensation? Let’s break it down.

How Low Stomach Acid Triggers Heartburn

Your stomach acid (hydrochloric acid) plays a vital role in digestion. When levels are low, food doesn’t break down as quickly. This delayed digestion allows food to sit in the stomach longer, creating more pressure.

That pressure can cause the lower esophageal sphincter (LES)—the valve between your stomach and esophagus—to open at the wrong time. When it does, even the small amount of acid present can reflux into the esophagus, causing that familiar burning sensation.

In short: it’s not always too much acid—it’s acid in the wrong place, at the wrong time, often because there’s not enough of it to begin with.

The Hidden Causes of Low Stomach Acid

Low stomach acid can develop for several reasons, including:

• Chronic stress – Stress reduces digestive secretions.
• Frequent antacid or PPI use – These medications suppress acid production.
• Aging – Natural acid production often declines after age 40.
• Poor diet – Low protein diets, excess processed foods, and nutrient deficiencies can impair stomach acid secretion.
• H. pylori infection – This common bacterial infection can damage acid-producing cells.

Why Stomach Acid Is Essential for Nutrient Absorption

Stomach acid is more than just a digestive aid—it’s the first step in unlocking key nutrients from your food. Without adequate acid, your body can’t absorb certain vitamins and minerals effectively.

Here are some of the nutrients most affected by low stomach acid:

1. Vitamin B12

B12 is bound to protein in food. Stomach acid helps release it so it can bind to intrinsic factor for absorption in the small intestine. Low acid means poor B12 release—leading to fatigue, brain fog, nerve issues, and anemia.

2. Iron

Non-heme iron from plant foods needs an acidic environment to convert into its absorbable form. Low acid can contribute to iron deficiency and symptoms like weakness, shortness of breath, and brittle nails.

3. Magnesium

Magnesium plays a role in over 300 biochemical processes in the body. Acid suppression has been shown to lower magnesium levels over time, leading to muscle cramps, sleep disturbances, and heart rhythm issues.

4. Calcium

Acid helps solubilize calcium for absorption. Chronic low acid can contribute to bone loss and osteoporosis.

5. Zinc

Zinc is critical for immune health, wound healing, and hormone production. Low acid impairs its absorption, which can weaken immune defenses and slow tissue repair.

The Downstream Effects of Low Acid

When nutrient absorption is compromised, it can lead to:

• Immune weakness – More frequent infections due to low zinc or vitamin C absorption.
• Anemia – From poor B12 or iron absorption.
• Bone loss – From reduced calcium and magnesium absorption.
• Hair loss and skin changes – Linked to zinc, protein, and iron deficiencies.
• Hormonal imbalances – Many hormones rely on adequate minerals for production and regulation.

This is why, at Sheen Vein & Cosmetics, we view heartburn as a possible symptom of a deeper digestive imbalance—not just something to be “quieted” with acid suppression.

A Functional Medicine Approach to Heartburn

Instead of simply masking symptoms, we focus on identifying the root cause. For patients with suspected low stomach acid, we may use:

• Comprehensive digestive testing to look at enzyme levels, microbiome balance, and infection markers.
• Nutrient testing to identify deficiencies caused by low absorption.
• Dietary adjustments to support natural acid production, such as including more protein and reducing processed foods.
• Targeted supplementation such as betaine HCl (when appropriate) to restore healthy stomach acidity.
• Lifestyle changes including mindful eating, stress reduction, and avoiding excessive fluid intake with meals.

What Happens When We Correct Low Stomach Acid

Many of our St. Louis functional medicine patients are amazed at what happens when their digestion is restored:

• Heartburn symptoms improve or disappear.
• Energy returns as nutrient absorption improves.
• Hair, skin, and nails get healthier.
• Immune function strengthens.

One patient even reported that after years of “indigestion” and fatigue, just a few months of improving her stomach acid levels completely transformed her digestion and energy.

The Bottom Line

Heartburn isn’t always about too much acid—often, it’s the opposite. Low stomach acid can not only trigger reflux but also silently rob your body of essential nutrients. Over time, this can lead to widespread health issues far beyond the digestive tract.

If you’ve been relying on acid-blocking medications for years, or if you have both heartburn and unexplained nutrient deficiencies, it’s worth taking a deeper look.

At Sheen Vein & Cosmetics, we offer functional medicine consultations—both in-person in St. Louis and via telemedicine—so you can finally get to the root of your digestive concerns and reclaim your health.

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