According to the British medical journal The Lancet, heartburn is pretty common. In fact, 25 percent of Americans report experiencing heartburn at least once a month, 12 percent at least once per week and 5 percent daily. So what is heart burn? And what about gastroesophageal reflux disease (GERD)? Well, here’s a guide to provide a bit more understanding of that burning sensation in your chest.

Why is it called heartburn?

“Heartburn is often sensed as a burning feeling behind the middle of the lower to middle of the chest, giving the sense that it may be coming from the heart,” Philip Jaffe, M.D., an associate professor of medicine at Yale University School of Medicine, said.

What is happening, biologically speaking?

According to David A. Peura, M.D., a professor of medicine at the University of Virginia Health System, “Acid that’s normally produced by the stomach is washing back up into the esophagus [the swallowing tube that carries food from the mouth to the stomach] and irritating [burning] its lining. This is generally because the muscle between the stomach and esophagus is weak or not working properly.”

What does heartburn feel like?

“The typical sensation is a burning in the lower chest that moves toward the neck and is often associated with a bitter taste in the back of the mouth. It typically occurs after eating a large meal, bending over at the waist, or lying down soon after eating,” Jaffe said.

What causes heartburn?

According to Jaffe, there are a variety of causes, but anything that either weakens or overwhelms the lower esophageal sphincter (the ring of muscle or “valve” at the lower end of the esophagus), decreases stomach emptying (a condition called “gastroparesis” or mechanical gastric outlet obstruction) and/or reduces the ability of the esophagus to push food down to the stomach can cause heartburn. Common causes are obesity, excessive alcohol use, fatty food intake, eating late at night, smoking, medications, hernias, pregnancy, diabetes mellitus and scleroderma.

What is GERD?

This is the condition that causes heartburn. It occurs when the lower esophageal sphincter does not close properly and stomach contents leak back into the esophagus.

Is it possible to have GERD without heartburn?

The primary symptoms are continual heartburn and “acid regurgitation”; however, you can have GERD without heartburn. Some can have pain in the chest, hoarseness in the morning, a cough or trouble swallowing, adds Jaffe.

Do spicy foods cause heartburn and/or GERD?

Spicy foods can further irritate an esophagus that has been damaged by acid reflux, and irritation of the lining of the esophagus is what causes the symptoms of heartburn, Stuart Spechler, M.D., a professor of medicine at University of Texas Southwestern Medical Center at Dallas, said.