Visit at http://www.creatingcomforts.co.uk/infographic-gastroesophageal-reflux-disease.asp At the entrance to your stomach is a valve, this ring of muscle is called the lower esophageal sphincter (LES). Normally, the LES closes as soon as food passes through it. If the LES doesn't close all the way or if it opens too often, acid produced by your stomach to break down your food can move up into your esophagus. This can cause symptoms such as a burning chest pain called heartburn. If acid reflux symptoms happen more than a couple of times a week, you probably have acid reflux disease, also known as gastroesophageal reflux disease (GERD).