Despite its name, heartburn has nothing to do with the heart (although some of thesymptoms are similar to a heart attack). Heartburn, also called acid indigestion, isan irritation of the esophagus caused by acid that refluxes (comes back up) from the stomach.

When swallowing, food passes down the throat and through the esophagus to the stomach. Normally, a muscular valve called the lower esophageal sphincter (LES) opens to allow food into the stomach (or to permit belching); then it closes again. Next, the stomach releases strong acids to help break down the food. But if the lower esophageal sphincter opens too often or does not close tight enough, stomach acid can reflux, or seep back into the esophagus, damaging it and causing the burning sensation we know as heartburn.

Not only can stomach acid in the esophagus cause heartburn, but it can also cause esophagitis, ulcers, strictures (narrowing), esophageal spasm, and can increase the chance of cancer of the esophagus. 

Most people have felt heartburn at one time or another. In fact, the American Gastroenterological Association reports that more than 60 million Americans experience heartburn/reflux symptoms at least once each month. Though uncomfortable, heartburn does not usually present a serious health problem for most people.

However, if heartburn symptoms occur frequently and persistently, they can be an indicator of a more serious problem, such as gastroesophageal reflux disease, or GERD. Left untreated, GERD can cause a host of complications, including cancer.