Saliva: its role in health and disease.

Saliva serves many functions in the upper digestive tract, with its roles in esophageal physiology, digestion, and gastric cytoprotection having been documented by many studies in the recent literature. Understanding the multiple functions of saliva and the consequences of its absence is of paramount importance to gastroenterologists. We present a clinically oriented review of the literature on the role of saliva in the upper gastrointestinal tract and review the many problems associated with lack of saliva. We also discuss the management of xerostomia.