Gastroesophageal reflux disease (GERD) can have a number of causes. Exogenous causes (from outside the body) include medications and alcohol consumption, and the overuse of over-the-counter NSAIDs such as aspirin and ibuprofen are common causes of GERD. Hereditary structural issues are also possible culprits.
Primary causes. GERD occurs when acid from the stomach rises into the lower esophagus. This is usually due to incompetency of the lower esophageal sphincter (LES), the muscle that closes the upper opening of the stomach once food enters. The muscle is unable to close, allowing stomach acid to come back up. This can be due to motility problems, a hiatal hernia, stomach (gastric or peptic) ulcers, or in conjunction with a number of other maladies such as various types of cancer, diabetes and Crohn’s disease. A hiatal hernia occurs when a portion of the stomach protrudes through the diaphragm up into the chest. According to the Mayo Clinic, "It's not always clear why this happens, but pressure on your stomach may contribute to the formation of hiatal hernia." Adult ringed esophagus is still another cause of GERD. In this condition, an abnormally high number of rings in the esophagus causes difficulty in swallowing, and food may get lodged in the esophagus.
Genetics. It is estimated that approximately 30 percent to 40 percent of GERD patients have a hereditary component to their illness. This may be due to an inherited structural or muscular problem with the stomach, the esophagus, or both. Genetic factors appear to play an especially big role in susceptibility to developing a condition called Barrett’s esophagus. This condition is a pre-cancerous condition of the esophagus that generally results from chronic GERD.
Treatments for other conditions. Interestingly enough, treating people for peptic ulcers may actually aggravate GERD. Stomach ulcers are caused by a bacterium known as H. Pylori, which causes a decrease in the secretion of stomach acid. By successfully eradicating H. Pylori via antibiotic therapy, stomach acid secretion levels may actually rise.