The lower esophageal sphincter (LES) is a ring of muscle that forms
a valve at the lower end of the esophagus where it joins the stomach.
The LES stays closed except during swallowing, when it allows
food to pass from the esophagus into the stomach. When the LES is closed, it
prevents the backflow (reflux) of stomach acid into the esophagus. If the LES
does not close tightly enough, stomach acid backs up into the esophagus,
causing heartburn. A weak lower esophageal sphincter is a major cause of
gastroesophageal reflux disease (GERD).
Adam Husney, MD - Family Medicine & Peter J. Kahrilas, MD - Gastroenterology
How this information was developed to help you make better health decisions.
The Health Encyclopedia contains general health information. Not all treatments or services described are covered benefits for Kaiser Permanente members or offered as services by Kaiser Permanente. For a list of covered benefits, please refer to your Evidence of Coverage or Summary Plan Description. For recommended treatments, please consult with your health care provider.