While many people blame spicy or acidic foods for their heartburn, alcohol is a major culprit, a gastroenterologist at the University of California, Los Angeles, tells NPR.

“Alcohol has a direct effect” on heartburn, said Dr. Kevin Ghassemi. He explained that alcohol relaxes the lower esophageal sphincter, a ring of muscle located at the point where the stomach and esophagus meet.

“The muscle is supposed to be closed, except when food is passing into the esophagus,” he said. Alcohol can relax the muscle, creating an opening. When this occurs, stomach acid can come back up into the esophagus, causing reflux. This leads to the burning sensation associated with heartburn.

Coffee can also relax the sphincter muscle.

Some people may be more prone to heartburn after drinking alcohol, including those with a weak or faulty sphincter muscle. Being overweight also raises the risk. While reducing alcohol and coffee consumption can help some people, others need prescription medicine to treat heartburn, Ghassemi noted.

Karthik Ravi, a Mayo Clinic gastroenterologist, said there is no clear link between heartburn and spicy foods, or acidic foods such as orange juice or tomato sauce.