Causes of Gastro-Esophageal Reflux Disease (GERD)
The lower esophageal sphincter (LES) muscle
In most cases gastro-esophageal reflux disease (GERD) is said to be caused if there is a problem with the lower esophageal sphincter (LES) muscle.

The LES is placed at the lower end of the esophagus where it joins the stomach. The esophagus is a muscular tube that contracts and pushes the food into the stomach. This movement of the food into the stomach requires opening of the sphincter.

Once the food bolus is pushed into the stomach the sphincter firmly closes again to stop the contents of the stomach from moving backwards into the gullet. In this way the LES acts as a valve.

In patients with GERD the LES becomes weakened and allows some of the stomach’s contents and acid to seep back into the esophagus. This causes symptoms of heartburn and chest pain in patients with GERD.
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