Heartburn and reflux

Healthy state

A sphincter at the entrance to the stomach keeps stomach acid where it belongs. Occasional reflux after a large meal is normal.

The closure is more than one muscle. The lower oesophageal sphincter has a resting pressure, and the diaphragm, which surrounds the oesophagus at an opening, squeezes from outside like a cuff, especially when breathing in, coughing and bending. In addition there is the oblique angle at which the oesophagus enters the stomach. The sphincter also opens briefly of its own accord a few times an hour, mainly after eating when the stomach stretches: that is how swallowed air escapes as a burp. If some stomach contents come up with it, that is normal.

The acid in the stomach is useful: it digests protein and kills germs before they reach the gut.

The oesophagus has its own protective mechanisms. Waves of muscle push refluxed contents back into the stomach, saliva contains bicarbonate and neutralises remains, and the lining has a protective layer and tight connections between its cells. Lying down and asleep, these mechanisms work less well because there is less swallowing and no gravity. This is why night-time reflux is particularly unpleasant. The burning comes from nerve endings in the lining that react to acid but also to stretch and heat.

Disrupted state: causes and effects

If the sphincter relaxes too often or part of the stomach slips through the diaphragm (hiatus hernia), acid regularly rises into the oesophagus. Overweight and late meals encourage this.

What weakens the closure: a hiatal hernia, permanently higher pressure in the abdomen (excess weight, pregnancy, heavy straining with constipation), very full or fatty meals that stretch the stomach for a long time and empty more slowly, and smoking and alcohol, which lower the resting pressure. In pregnancy, hormones, above all progesterone, lower the pressure of the sphincter, which is why heartburn is common then. Some medications also relax the muscle, such as certain drugs for high blood pressure or angina; others irritate the oesophagus directly, such as painkillers of the ibuprofen group or tablets swallowed lying down with little water.

Not every burning is acid. The feeling arises when nerves in the lining are irritated. That can also happen with weakly acidic or bile-containing material, or, in an oversensitive oesophagus, with a normal amount of acid. This explains why some people keep symptoms despite an acid blocker. Specialists therefore distinguish reflux disease with visible inflammation or increased acid exposure, reflux hypersensitivity and functional heartburn. This matters for treatment, because acid suppression reliably helps mainly in the first. A measurement in the oesophagus brings clarity.

The gut also acts back. Severe constipation and bloating raise abdominal pressure, delayed stomach emptying can promote reflux or cause similar symptoms, and small intestinal overgrowth with a lot of gas is also discussed as a contributor. Reflux is therefore often a clue to the whole digestive chain and not only to the stomach entrance.

Acid blockers (proton pump inhibitors Proton pump inhibitors (PPIs) Acid blockers such as omeprazole or pantoprazole. They inhibit the acid pump in the stomach lining. More in the chapter “Acid blockers (PPIs): what they change in the gut and how to stop them properly”) are very effective. In people who take them long term, however, studies find a changed gut microbiota Microbiome, gut microbiota The community of all microbes in the gut, mainly bacteria, plus viruses, fungi and archaea. Most live in the colon. More in the chapter “Building microbial diversity”: more bacteria from the mouth are found in the gut. What this means for the individual is still unclear.

Long-standing acid contact can inflame the lining (reflux oesophagitis), rarely cause narrowings and in a small share of people lead to Barrett’s oesophagus, a change in the lining that can rarely lead to cancer. Risk factors are long duration of symptoms, male sex, age over 50, smoking and excess belly fat. Reflux can also irritate the throat and airways: throat clearing, cough, hoarseness and damage to tooth enamel. Such complaints often have other causes too, so do not blame them on reflux alone.

Chest pain is not always heartburn. A heart attack can feel similar, particularly in women, older people and people with diabetes. Pressure or tightness that comes with exertion, spreads to the arm or jaw or comes with breathlessness, sweating or nausea is an emergency. Swallowing problems with food getting stuck can also point to eosinophilic oesophagitis, an inflammation with an allergic component, and should be checked by a doctor.

Warning signs that should be checked by a doctor promptly: difficulty swallowing, unintended weight loss, repeated vomiting, black stool or anaemia. New symptoms at an older age should also be checked; the age from which an endoscopy is recommended differs between countries.