Heartburn

The first thing you need to know if you want to understand heartburn is that it has nothing to do with the heart, according to Dr. James W. Ostroff, a gastroenterologist and professor of gastroenterology at the University of California, San Francisco. It’s called “heartburn” because it’s a burning pain in your chest, in the same general region as your heart. But what causes it is actually a malfunction of the muscle at the bottom of your esophagus, the long, narrow “food tube” that runs between your mouth and your stomach.

How Heartburn Happens

Think of this muscle as a gate between your stomach and esophagus. When you eat, food is supposed to take a one-way trip down to your tummy. It starts in your mouth and travels down your esophagus, where a muscle (known as the lower esophageal sphincter, or LES) relaxes open so that food can enter your stomach. Once food is in, the LES is supposed to close so that stomach acid can’t back up (or reflux) into your esophagus. But some people’s LES stays open, allowing acid to back up into the esophagus, where it literally burns the lining, resulting in fiery chest pain.

Heartburn is also possible even if your LES typically functions properly. Imagine that your stomach is a partly filled balloon. Pinch the end tightly enough, and no air escapes. But if you fill the balloon beyond capacity, the same pinching might not be enough to keep all the air in. Likewise, if you overstuff your belly, the quart of stomach acid you produce every day can get the better of even the strongest LES.

Don’t Stress Your LES

Beyond overeating, anything that puts pressure on your stomach can cause acid to reflux the same way that squeezing a balloon can cause air to escape. That’s why pregnancy, obesity, bending over, tight-waisted clothing or tight belts, or even abdominal exercises like crunches can trigger heartburn.

In addition, when you’re sitting or standing, gravity helps keep stomach acid down, where it belongs. But lying down eliminates the benefit of gravity and makes it more likely that acid will get past the LES. That’s why eating before bed often leads to nighttime heartburn.

Why Heartburn Matters

During the past three months, 45 percent of American adults -- or 100 million people -- have experienced heartburn. Not only can heartburn have a huge impact on quality of life, but severe, chronic reflux may damage the esophagus to the point that precancerous changes develop (a condition known as Barrett’s esophagus). If left untreated, Barrett’s can lead to esophageal cancer.

People consider heartburn an annoyance, notes Ostroff, but it should be taken seriously. So if heartburn is a problem for you, don’t ignore it: See your doctor.

Michael Castleman has been called "one of the nation's leading health writers" (Library Journal). He is the author of 11 consumer health books and more than 1,500 health articles for magazines and the Web.

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