The esophagus is the food pipe, or gullet, that carries food and liquid from the mouth to the stomach. The stomach churns the food and secretes a strong acid that aids in digestion. A specialized muscle, known as the lower esophageal sphincter (LES), is located at the end of the esophagus. This muscle normally contracts firmly and only allows food and fluid to pass from the esophagus into the stomach. The muscle maintains a certain pressure to keep the end of the esophagus closed, preventing stomach acid and digested food from moving back into the esophagus.
However the LES muscle does not always work perfectly. It can easily be overcome by a number of factors, the most common being eating a large meal. Other agents that weaken the LES muscle and allow reflux of stomach juices are:
- Nicotine (cigarettes)
- Fried or fatty foods
- Citrus fruits and juices