Persons most commonly affected: All age groups and both sexes. More than one third of the population suffers from occasional heartburn, as do about one half of pregnant women. The occurrence of heartburn generally increases with age; however, it is common --and often overlooked-- in infants and children.

Organ or part of body involved: Esophagus.

Symptoms and indications: Burning in the chest, especially at night, burping, difficulty in swallowing, a sour or acid in the mouth, or a sore throat.

Causes and risk factors: Heartburn occurs when digestive juices from the stomach move back up into the esophagus, the tube connecting the throat to the stomach. The upper third of the esophagus consists of skeletal muscle that propels the food downward. The lower two-thirds of the esophagus is smooth muscle. The lower esophageal sphincter (LES) is a thick band of muscle that encircles the esophagus just above the uppermost part of the stomach. This sphincter is usually tightly closed --opening only when food passes from the esophagus into the stomach-- and prevents the contents of the stomach from moving back into the delicate esophageal tissue. The stomach has a thick mucous coating that protects it from the strong hydrochloric acid it secretes to digest food. However the much-thinner esophageal mucous coating does not protect against stomach acid. Thus, if the LES opens inappropriately or fails to close completely, stomach acids can back up and burn the esophagus, causing heartburn.

Occasional heartburn is usually harmless. However, frequent or chronic heartburn (recurring more than twice per week) is called gastroesophageal reflux disease (GERD) and requires early management. Repeated episodes of GERD can lead to esophageal inflammation (esophagitis). If the esophagus is repeatedly subjected to stomach acid and digestive enzymes, ulcerations, scarring, and thickening of the esophageal walls can result. This causes a narrowing of the interior of the esophagus that can affect swallowing and the peristaltic movements that send food downward. Repeated esophageal irritation also can result in Barrett\'s syndrome -- changes in the types of cells lining the esophagus. Barrett\'s esophagus can develop into esophageal cancer.

Prevention: It is advisable to avoid overeating or food and drink that might lead to an increased production of stomach acid. These foods include spicy curries, acid fruits, alcohol and coffee. The risk of developing heart burn increases with age, obesity, excess consumption of alcohol, poor diet and some drugs, such as aspirin and preparations taken for arthritis. Bending over or lying down after a meal tips the stomach contents and encourages reflux. It is advisable to eat meals and snacks slowly and chew food well, preferably in a stress-free environment. Large meals are best avoided, especially during pregnancy. The stomach is pushed out of positioning by the growing foetus, forcing the stomach\'s acidic contents up into the throat.