Gastro-esophageal reflux, commonly referred to as acid reflux, is a very common disorder, affecting more than 7 percent of the American population. Acid reflux can occur in people of all ages, although it is more common in newborns and young children. Unlike children, which are rarely confronted with long-term symptoms of acid reflux, adults usually suffer from recurrent forms of the disorder. The process of diagnosing acid reflux is simple and it generally involves clinical examinations. Patients' reports of symptoms and physical indicators of acid reflux are usually sufficient in diagnosing the disease. However, in special cases doctors may perform additional tests in order to confirm presumptive clinical diagnoses.

The causes of acid reflux are various and of multiple natures. In most cases, chronic acid reflux disease is caused by physiological dysfunctions, on the premises of inappropriate activity of the lower esophageal sphincter or excessive pressure inside the stomach. The lower esophageal sphincter is a ring-shaped muscular valve that normally acts as a barrier between the esophagus and the stomach. In normal conditions, this valve only opens during the swallowing of food, otherwise remaining closed. If the lower esophageal sphincter is weakened or its integrity is compromised (due to physical trauma), the content of the stomach can be easily regurgitated inside the esophagus and the oral cavity.

Another common physiological cause of acid reflux is excessive pressure at the level of the abdomen, which pushes the content of the stomach upwards, in the esophageal lining. This abnormality is more common in overweight people, smokers and pregnant women.

Many cases of acid reflux are associated with hiatal hernia. Hiatal hernia generally occurs when the upper wall of the stomach moves above the diaphragm. Although this fact hasn't been confirmed, hiatal hernia is also considered to be a cause of acid reflux. An interesting fact is that while most patients with acid reflux also suffer from hiatal hernia, very few patients with hiatal hernia eventually develop acid reflux.

Medications are also a cause of acid reflux disease. A wide variety of synthetic drugs can stimulate an overproduction of gastric acid inside the stomach, thus facilitating the occurrence of acid reflux. Other medications generate relaxation of the lower esophageal sphincter or decrease the pressure at the level of the esophagus.

Diet is also a major cause of acid reflux. Acidic, irritant foods greatly contribute to the occurrence of acid reflux by generating an overproduction of stomach acid and by causing relaxation of the esophageal valve. Bad eating habits (binge eating, feasting) can also facilitate the occurrence of acid reflux. As a consequence, most symptoms of acid reflux are experienced right after meals. Smoking and the consumption of alcohol are also known to be causes of acid reflux, as they interfere with the normal activity of muscular esophageal valve.

The categories of people exposed to developing chronic forms of acid reflux disease are: pregnant women, obese people, smokers, alcoholics and people who suffer from other disorders of the gastrointestinal tract. Despite the high incidence of acid reflux in very young children and infants, these categories of patients are rarely confronted with recurrent forms of the disorder.