What is Acid Reflux? Acid Reflux is also known as GERD, Gastroesophageal Reflux Disease. So what causes it? Its cause is said to be complex. There almost certainly are numerous causes, and diverse causes may be found in many patients or even in the same individual at various times. It is characterized in that a small number of patients with GERD produce unusually large amounts of stomach acid, but this is unusual and not a contributing factor in most patients. The causes of Acid Reflux are found in the lower esophageal sphincter, hiatal hernias, emptying of the stomach, and esophageal contractions. The lower esophageal sphincter or (LES) is possibly the most significant factor for preventing reflux. The esophagus is a muscular tube that extends from the lower throat to the stomach. The LES is a particular ring of muscle that surrounds the lower-most end of the esophagus where it connects to the stomach. The muscle that makes up the LES is constantly in use, constricting and closing off access from the esophagus into the stomach. This closing of the passage prevents reflux. When food or saliva is swallowed, the LES opens for a few seconds to let the food or saliva pass from the esophagus into the stomach, and then it closes up again. For patients with GERD defects of the LES are pretty common. Two of these defects involve the function of the LES. The first is an unusually weak tightening of the LES, which decreases its capability to avoid stomach acids refluxing into the esophagus. Second is an irregular relaxation of the LES, called transient LES relaxations. Usually, they go in sync with swallowing and pause for a long time, up to a few minutes. As a result, these protracted relaxations permit reflux to take place without difficulty. The temporary LES relaxations occur in patients with GERD most frequently after meals when the stomach is swollen with food. Hiatal hernias add to reflux, even though the way in which they add to the problem is not clear. Many patients with GERD have hiatal hernias, but others do not. As a result, it is not essential to have a hiatal hernia to have GERD. Additionally, many patients have hiatal hernias but do not have GERD. It is not exactly clear how or why hiatal hernias occur. As mentioned earlier, swallowing is vital to removing acid in the esophagus. Swallowing causes a ring-like wave of tightening of the esophageal muscles, which constricts the inner cavity of the esophagus. This tightening, referred to as peristalsis, starts in the upper esophagus and moves to the lower esophagus. It thrusts food and saliva which is in the esophagus into the stomach. In patients with Acid Reflux, more than a few abnormalities of contraction have been described. Most reflux during the day takes place after to meal times. This reflux almost certainly is due to transient LES reductions that are caused by distention of the stomach with food. If you suspect you are suffering from Acid Reflux, you should first consult your primary care physician before taking other steps.