Acid Reflux and GERD Explained: Why It's Not Always About "Too Much Acid"

Why heartburn isn't always caused by too much acid

If you've had heartburn, a burning feeling in your chest, or that sour taste creeping up your throat after meals, you've probably already tried the obvious fixes. Maybe you cut out spicy food. Maybe you're avoiding coffee. Maybe you're already on medication and still not sure why it isn't fully working.

Here's something that gets missed a lot: acid reflux is not simply "too much acid." For most people with GERD (gastro-oesophageal reflux disease), the amount of acid your stomach makes is actually normal. The real problem is usually about a valve — and what's making that valve fail.

What is GERD, really?

Between your stomach and your food pipe (oesophagus) sits a ring of muscle called the lower oesophageal sphincter, or LES. Think of it as a one-way gate. It's supposed to open to let food down into the stomach, then close tightly to keep stomach acid where it belongs.

When that gate doesn't close properly, or opens at the wrong times, stomach contents can flow back upward. That backward flow is called reflux. When it happens often enough to cause symptoms or damage, it's called GERD.

Research on GERD physiology consistently points to the same root issue: dysfunction of this valve, not excess acid production [1][2][4]. This distinction actually matters a lot for treatment, because it changes the question from "how do I make less acid?" to "how do I stop the valve from failing?"

This is a similar story to the one we covered in our piece on the migrating motor complex (MMC) — a properly functioning gut relies on muscles and valves working in a coordinated rhythm, not just on "how much" of something your body produces.

If you've been dealing with recurring acidity or reflux despite cutting out the "usual suspects," it's often worth looking at what's actually driving it, which is exactly the kind of root-cause work we do in gut health nutrition consultations at Pragmatic Nutrition.

Why does the LES fail?

There are two main patterns researchers have identified [4]:

1. The valve relaxes at the wrong time

This is called a transient LES relaxation. Even in people with a perfectly normal, strong valve, it can briefly relax on its own — often triggered by a full, distended stomach after a big meal [1][6]. This is the single most common mechanism behind reflux.

2. The valve is simply weaker than it should be

In some people, the resting pressure of the LES is lower than normal, meaning it doesn't seal as firmly even when it's supposed to be closed [4]. Certain foods, medications and habits (which we'll get to) can lower this pressure further.

There's also a third contributor worth knowing about: a hiatal hernia, where part of the stomach pushes up through the diaphragm. This can weaken how well the LES functions and is common in people with more persistent reflux [3][5].

Common myths worth clearing up

"My stomach makes too much acid." For the large majority of people with GERD, stomach acid levels are normal. The problem is acid going to the wrong place, not too much of it being made [1][2].

"Spicy food causes reflux." Spicy food can irritate an already-inflamed oesophagus and make symptoms feel worse, but it doesn't directly relax the LES the way fat, alcohol or caffeine do. It's a comfort issue for some people, not a root cause for most.

"If I just avoid every possible trigger food, I'll be fine." Not necessarily. A large population study found that smoking, alcohol, physical inactivity, high intake of sweets and desserts, low fibre intake, visceral fat and obesity were all significantly associated with increased GERD risk, while higher fibre and dairy intake were actually linked to lower odds of GERD [10]. In other words, some of the biggest drivers of reflux aren't specific "bad foods" at all — they're broader patterns like body composition, activity levels and smoking.

Not sure if it's reflux or something else? Bloating, early fullness and upper-abdominal discomfort can overlap with reflux symptoms but point to different causes.

If bloating is your main complaint, our guide on how to get rid of bloating breaks down the different mechanisms. If your symptoms show up soon after eating, our piece on stomach pain after every meal and IBS may be more relevant. Still not sure what's driving your symptoms? Book a consultation to get a proper assessment rather than guessing.

The role of weight and posture

This is one of the most consistently proven contributors to reflux, and it's mechanical, not dietary. Extra weight around the abdomen increases pressure inside the stomach. That pressure pushes upward against the LES, making it more likely to give way [9][12][13]. This is part of why reflux often improves — sometimes significantly — with modest weight loss, even without any other change [12].

Lying down soon after eating works the same way. Without gravity helping keep stomach contents down, and with a full stomach adding pressure, reflux becomes more likely. This is why avoiding meals close to bedtime is one of the most consistently useful pieces of advice for managing reflux.

What about alginates and other options beyond acid suppression?

Proton pump inhibitors (PPIs) work by reducing the amount of acid the stomach produces. That helps because it means whatever does reflux is less acidic and less damaging. But if the LES itself is still weak or relaxing too often, a PPI doesn't fix that mechanical problem — it just makes the reflux less harmful when it happens.

This is where alginates (like Gaviscon-type products) work differently. Rather than reducing acid, they form a floating gel "raft" that sits on top of the stomach contents, physically blocking material from moving back up into the oesophagus [7][8][9]. Multiple randomised controlled trials have found alginates to be effective for GERD symptoms, including in people whose symptoms weren't fully controlled by a PPI alone [7][8].

This is a good example of why "which medication is strongest" isn't the right question. Acid suppression and mechanical barrier support work through completely different pathways, and for some people, using both makes more sense than relying on either alone — always in consultation with the prescribing doctor.

If reflux symptoms keep returning despite treatment, it's also worth reading why IBS symptoms return after normal reports — a lot of the same "normal test, but still symptomatic" frustration applies to reflux too, and often points to a mechanism issue rather than something a standard test is designed to catch.

Practical, evidence-informed changes that help Acid reflux and GERD

1. Meal size and timing matter more than most people think

Since gastric distension is a direct trigger for LES relaxation, smaller, more frequent meals tend to be better tolerated than a few very large ones. Leaving 2–3 hours between your last meal and lying down gives gravity time to help, instead of working against you.

2. Focus on the mechanism, not a long "avoid" list

Instead of eliminating dozens of individual foods, it's more useful to look at whether a meal is high in fat, includes alcohol or caffeine, or is eaten late and large. These patterns explain far more of the picture than any single "trigger food."

3. Weight and activity levels are genuinely worth addressing

Given how consistently obesity and inactivity show up as GERD risk factors [10][12][13], this isn't just general health advice — it's directly mechanical for reflux specifically.

4. Elevate the head of your bed, not just your pillows

Raising the head of the bed itself (using risers or a wedge) keeps the oesophagus above the stomach contents overnight, which plain pillows often don't achieve properly.

5. Don't assume every "digestive supplement" helps reflux

Some products marketed for general digestion — particularly those containing added stomach acid (like betaine HCl) — can worsen reflux in someone with a weak LES, even though they're sometimes marketed broadly for "gut health." This is worth checking carefully with a professional rather than assuming more digestive support automatically means less reflux.

Reflux isn't a sign that your stomach is doing something wrong by making acid. It's usually a sign that the valve meant to contain that acid isn't sealing the way it should — and the fix depends on figuring out why.

Frequently Asked Questions

Is acid reflux caused by too much stomach acid?

Not usually. In most people with GERD, stomach acid levels are normal. The main problem is that the valve between the stomach and oesophagus (the LES) isn't closing properly or is relaxing at the wrong times.

What foods should I avoid with acid reflux?

Foods and drinks that directly relax the LES tend to matter most — high-fat meals, chocolate, alcohol, caffeine, mint and carbonated drinks. Spicy or acidic foods can worsen symptoms in an already irritated oesophagus but don't directly cause the underlying valve problem for most people.

Can losing weight help acid reflux?

Yes. Extra abdominal weight increases pressure on the stomach and LES, making reflux more likely. Research has found that weight loss can meaningfully improve GERD symptoms even without other treatment changes.

Do alginates work differently from PPIs?

Yes. PPIs reduce how much acid the stomach produces. Alginates form a physical gel barrier that floats on top of stomach contents and blocks reflux mechanically. They work through different mechanisms and are sometimes used together.

Can stress make acid reflux worse?

Stress doesn't directly cause reflux, but it can increase sensitivity to normal reflux episodes and affect eating habits, both of which can make symptoms feel worse.

Is it normal to have chest discomfort with reflux?

Reflux can cause chest discomfort, but chest pain should always be evaluated by a doctor first to rule out cardiac causes, especially if it's a new or changing symptom.

Medical Disclaimer

This article is for educational purposes and does not diagnose or treat GERD, acid reflux or other gastrointestinal conditions. Chest pain, difficulty swallowing, unexplained weight loss, vomiting blood, or persistent symptoms despite treatment require medical evaluation. Medication changes should only be made with the prescribing clinician.

References

1. Kahrilas PJ. Review article: the pathophysiology of gastro-oesophageal reflux disease. Aliment Pharmacol Ther. 2007. https://pubmed.ncbi.nlm.nih.gov/17593062/

2. Pathophysiology and pharmacological treatment of gastroesophageal reflux disease. https://pubmed.ncbi.nlm.nih.gov/11060472/

3. Patti MG. Gastroesophageal reflux disease: From pathophysiology to treatment. https://pubmed.ncbi.nlm.nih.gov/20698035/

4. Trudgill NJ. Pathophysiology of gastroesophageal reflux. Lower esophageal sphincter dysfunction in gastroesophageal reflux disease. https://pubmed.ncbi.nlm.nih.gov/2228162/

5. Review article: the pathophysiology of gastro-oesophageal reflux disease — oesophageal manifestations. https://pubmed.ncbi.nlm.nih.gov/15527461/

6. Gastroesophageal Reflux Disease: New Insights and Treatment Approaches. PMC. 2024. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11417972/

7. Leiman DA, et al. Alginate therapy is effective treatment for GERD symptoms: a systematic review and meta-analysis. Dis Esophagus. https://academic.oup.com/dote/article/30/5/1/3092443

8. Alginates: From the ocean to gastroesophageal reflux disease treatment. PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC6836317/

9. Meteerattanapipat P, Phupong V. Efficacy of alginate-based reflux suppressant and magnesium-aluminium antacid gel for treatment of heartburn in pregnancy: a randomized double-blind controlled trial. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5357839/

10. Risk factors for gastroesophageal reflux disease: a population-based study. https://pubmed.ncbi.nlm.nih.gov/38317085/

11. Ness-Jensen E, Lagergren J. Tobacco smoking, alcohol consumption and gastro-oesophageal reflux disease. https://pubmed.ncbi.nlm.nih.gov/29195669/

12. Role of Non-pharmacological Interventions and Weight Loss in the Management of GERD in Obese Individuals: A Systematic Review. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9524852/

13. Epidemiology, Causes, and Management of Gastro-esophageal Reflux Disease: A Systematic Review. PMC. https://pmc.ncbi.nlm.nih.gov/articles/PMC10658748/

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About Meenu Balaji

Meenu Balaji, M.H.Sc (Food Science & Nutrition), is the founder of Pragmatic Nutrition and a clinical gut-health and sports-nutrition specialist with 14+ years of experience across India, the UK and New Zealand. Her approach combines nutrition science, symptom assessment and medical-report interpretation rather than generic elimination diets.

👉 If reflux keeps coming back despite dietary changes or medication, a proper assessment can identify exactly what's driving it — and what will actually help. Work with Meenu Balaji: https://www.pragmaticnutritionist.com/contact-us