Causes of gastroesophageal reflux

GERD is a digestive disorder affecting the lower esophageal sphincter (LES), the muscle connecting the esophagus and stomach. This muscle acts as a barrier to protect the esophagus against the backflow of gastric acid from the stomach. Normally, the LES works something like a gate, opening to allow food to pass into the stomach and closing to keep food and acidic stomach juices from flowing back into the esophagus.

The LES is a complex segment of smooth muscle under the control of nerves and various hormones. As a result, dietary substances, drugs, and nervous system factors can impair its function. Gastroesophageal reflux occurs when the LES weakens or just relaxes when it shouldn't, allowing contents of the stomach to rise up into the esophagus. Scientists aren't always sure exactly why this happens, but they have identified some contributing factors.

Digestive abnormalities. Malfunction of the LES isn't the only digestive problem that can contribute to reflux and heartburn. If stomach muscles don't contract normally, this can delay the emptying of the stomach, increasing the risk that acid will reflux back into the esophagus. In addition, esophageal contractions that should clear refluxed acid may fail to do so. There could also be a reduction in the esophageal lining's ability to resist damage, or a decrease in production of saliva (which has a neutralizing effect on acid).

Weight. Being overweight increases the risk of frequent GERD symptoms. Even if a person's body mass index (BMI, a ratio of weight to height) remains in the normal range, weight gain may bring on heartburn. The additional weight can increase pressure on the stomach, pushing its contents up.

Pregnancy. Pregnancy can promote GERD, both because of hormonal changes and because the enlarging uterus presses against other organs.

Age. As you age, esophageal contractions and the muscles of the LES may weaken. However, since the esophagus can become less sensitive to acid with age, reflux might not result in heartburn. Instead, you may feel nausea or vague chest discomfort.

Smoking. Smoking irritates the digestive tract, and nicotine relaxes the LES. In addition, frequent sucking on a cigarette can cause you to swallow air, increasing stomach pressure and encouraging reflux. People who smoke a pack or more a day are the most likely to have symptoms.

Foods and drinks. Diet can contribute to dysfunction of the LES. For example, alcohol can loosen the LES (and irritate the esophageal lining), as can coffee and other caffeine-containing products. Coffee, tea, cocoa, and cola drinks are all powerful stimulants of gastric acid production. Mints and chocolate, often served to cap off a meal to aid in digestion, can relax the LES and induce heartburn. Some people say that onions and garlic give them heartburn. Others have trouble with citrus fruits or tomato products, which can irritate the esophageal lining. High-fat and fried foods can also trigger symptoms. If you notice that a particular food leads to episodes of heartburn, by all means stay away from it.

Eating patterns. How you eat can be as important as what you eat. Skipping some meals and then eating heavily can increase pressure in the stomach and the possibility of reflux. Lying down right after eating will only make the problem worse. It is best to wait three hours after eating before going to bed. And stay away from late-night snacks.

Medications. Some prescription drugs can worsen your heartburn. Oral contraceptives or postmenopausal hormone preparations containing progesterone are known culprits. Aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin) and naproxen (Aleve, Naprosyn) may also pose problems. Corticosteroids can also cause heartburn. Osteoporosis drugs such as alendronate (Fosamax) irritate the esophagus. And some antidepressants, tranquilizers, and calcium-channel blockers (used to treat high blood pressure or coronary artery disease) can contribute to reflux by relaxing the LES.

To prevent medications from irritating your esophagus, take a few sips of water before you swallow a pill, and drink a cup of liquid afterward to speed the pill's transit through your esophagus into your stomach. If you take any drugs known to irritate the esophagus, such as alendronate, stand or sit upright for at least 30 minutes after taking the pill.

Hiatal hernia. Hiatal hernia is a common condition that develops when part of the stomach extends up through the diaphragm, the band of muscle that separates the chest from the abdomen and helps with breathing. The diaphragm has a small opening (hiatus), which should be just large enough for the esophagus to pass through. However, in a person with hiatal hernia, part of the stomach also protrudes through the diaphragm and into the chest. This may impair the LES's ability to prevent reflux.

Learn more about gut health in The Sensitive Gut, a Special Health Report from Harvard Medical School.

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