When liquid or food from the stomach flows back into the esophagus, the tube connecting the stomach to the mouth, it is frequently referred to as acid reflux. Almost everyone experiences mild forms of reflux in the form of heartburn or indigestion. Gastroesophageal reflux disease (GERD) describes a chronic condition where reflux of stomach acid occurs frequently and can lead to irritation and inflammation of the esophagus through exposure to corrosive stomach contents.
Constant inflammation of the esophagus can cause more serious conditions to develop such as esophagitis, ulceration, or stricture and may lead to Barrett's esophagus and some forms of cancer.
At the junction of the esophagus and the stomach is a small circular ring of muscle called the lower esophageal sphincter or LES. Acting like a one-way valve, the LES prevents food that enters the stomach from flowing back into the esophagus.
When you swallow, the LES relaxes, allowing food to pass into the stomach. The remainder of the time, the LES is shut tight and the acidic liquid contents of the stomach cannot travel back through it.
Several factors can affect the function of the LES. Medications, nerve and muscle abnormalities, too much pressure on the stomach such as in obesity or pregnancy, and other medical conditions such as asthma are all implicated in GERD.
While the stomach lining is designed to be unaffected by corrosive stomach contents, the esophagus is not. Reflux of stomach acid and contact with the lining of the esophagus causes the pain and other symptoms associated with acid reflux disease. Damage is not restricted to the esophagus. Other structures such as the throat, larynx (voice box), tongue, and teeth can also be damaged by corrosive stomach acid.
Long-term irritation of the esophagus lining can cause ulceration and scarring of the esophagus. Scarring can cause narrowing or esophageal stricture that makes it more difficult to swallow.
Acid entering the airway can cause bronchospasm, chronic cough, and pulmonary fibrosis, and there is an increased incidence of asthma in people who suffer from GERD. It is not clear if the asthma is caused by GERD or vice versa.
GERD patients have a higher chance of developing a condition called Barrett's esophagus. With this condition, over time, the cells in the lining of the esophagus are replaced by cells similar to those found in the intestines. The size and shape of these cells are different than normal esophagus cells. Although Barrett's esophagus does not cause any symptoms, the condition slightly increases your chances of developing a deadly cancer called esophageal adenocarcinoma.