What Causes Acid Reflux?

A Chronic Condition

While reflux of liquids from the stomach occurs even in normal, healthy people, the problem arises when the liquid contains higher levels of acids from the stomach and “backs up” farther into the esophagus than usual. Acid reflux is considered to be a chronic medical condition, and once it begins, it typically will last for the remainder of the sufferer’s life, although it can be controlled with medication. Injury to the esophageal lining is also a chronic condition as symptoms of esophagitis recur shortly after treatment is stopped.

Causes of Acid Reflux

Acid reflux is a complex condition that has multiple possible causes, including:

• Abnormalities of the lower esophageal sphincter or LES. The LES is an important muscle that lies in the lower part of the esophagus, where the stomach and esophagus join and works by contracting and closing the passage-way from the esophagus into the stomach (which, coincidentally, prevents the reflux of fluids). When LES contractions are weak or abnormal, reflux of stomach fluids can occur. The acid reflux due to abnormalities of the LES is common when the stomach is distended with food after eating.
• Hiatal hernia. The majority of acid reflux sufferers also have Hiatal hernia, although the exact contribution of the Hiatal hernia is unclear. The esophagus and the stomach normally join obliquely, which means at a 90 degree angle or not straight on. When joining at this angle, a flap of tissue is formed between the esophagus and the stomach that is thought to act like a valve to shut off the esophagus from the stomach, thus preventing the reflux of liquids and acid into the esophagus. In Hiatal hernia, the entry of the esophagus into the stomach is pushed up and into the chest, distorting the flap/valve so that it can no longer prevent refluxed liquids from entering the esophagus.
• Defective esophageal contractions. The contraction of the esophageal muscles is known as peristalsis, and occurs when food, liquids, saliva, etc., are swallowed. Peristalsis begins high in the esophagus and pushes what is being swallowed into the stomach. When the contractions of peristalsis are abnormal, defective or fail to reach the stomach, acid is not pushed back into the stomach and has an opportunity to reflux into the esophagus.
• Abnormal digestion of the stomach. Sufferers of acid reflux will usually note that they have the most incidences of acid reflux during the day, following meals. Acid reflux of this type is usually due to transient relaxations of the LES by a distended stomach. In addition, around one in five sufferers have stomach that tend to empty too slowly following a meal, which makes the stomach remain in a distended state for a prolonged time period, making the reflux of acid more likely.