Gerd (also known as Gastresophageal Reflux Disease) is a digestive disorder that affects the lower esophageal sphincter (LES) – muscle found between the esophagus and the stomach. This particular condition occurs when the food or liquid in the stomach leak backwards from the stomach towards (and into) the esophagus. Gerd’s effects on the esophagus can cause heartburn in many individuals. In most cases, Gerd can be treated with diet and lifestyle changes.