The physical cause of heart burn is the improper functioning of the LES (lower esophageal sphincter). This ringed muscle at the bottom of the esophagus, relaxes in order to allow food to enter the stomach. This muscle then retracts in order to keep the digestive fluids where they belong. It is when this muscle is too relaxed or damaged, that the stomach fluids can escape up into the esophagus thereby causing reflux.
There are many possible causes of reflux. The foods that we eat play an important role. Food that is too acidic can aggravate this ailment. Not chewing food properly, eating meals that are too large and lying down within three hours of eating can all contribute to reflux.
Certain foods and beverages can cause the LES to become lazy. These culprits include smoking, drinking alcohol and prescription drugs. Raw onions and garlic, fried foods, chocolate and foods that are too spicy can also cause the LES to relax.