What causes heartburn can vary, though it is most commonly related to ingested foods, medical conditions, or other lifestyle factors. Heartburn, contrary to what the name implies, is not linked to one’s heart. Instead, heartburn is the result of stomach acid backing up (or refluxing) into the esophagus. This happens when the lower esophageal sphincter (LES) relaxes. The LES is intended to let food pass through the esophagus and into the stomach, while preventing stomach acids from backing up into the esophagus. However, if this group of muscles becomes weak or relaxes inappropriately, the result will be the burning sensation known as heartburn. Read more »