Acid reflux, also known as heartburn, is a condition whereby acid-containing gut juices come into the esophagus from the stomach. The lower part of the esophagus contains a valve at the end, called the lower esophageal sphincter, or LES for short, which opens in order to let the food we eat get into the belly, and then shutting to keep the gastric juices and food in the stomach. When this valve relaxes too frequently or does not shut properly, it can lead to the stomach juices getting into the esophagus, which isn’t provided to handle the acidic matter. When this occurs it leads to the tell tale signs of heartburn, with a burning sensation in the area.