Heartburn is generally caused by the stomach acid and contents traveling up into the esophagus, which is the tube that connects the mouth to the stomach. Because the esophagus is not made to deal with acid as the stomach is, this irritates the esophagus and causes a number of symptoms. You might find yourself clearing your throat over and over, feeling a burning sensation in the chest and neck, tasting a sour sensation in your mouth, coughing, or feeling bloated. It’s an unpleasant feeling and when it’s chronic, it’s called GERD (gastroesophageal reflux disease).
Heartburn is caused by the lower esophageal sphincter (LES) relaxing too much or too often. The LES is a valve that separates the esophagus from the stomach. It’s usually closed, creating a contained system in which to digest food. It does open from time to time to release gas in the form of belching. Reflux happens when the valve opens too frequently or too much, allowing stomach acid to travel up into the esophagus.
Scientists believe that the stomach’s acidity controls the LES. If the stomach is not producing enough acid, the muscles around the LES relax, which results in more reflux. This is why people may use an acidic compound like apple cider vinegar to help with heartburn—by increasing the acidity in the stomach, the muscles around the LES stop over-relaxing, and the stomach acid stays where it belongs.