Saliva and esophageal protection.

There has been much interest in recent years in the potential protective role of saliva in the esophagus. Variables such as salivary volume and neutralizing capacity have been studied both during basal conditions and in response to esophageal acid exposure, in healthy subjects and in patients with esophagitis. In addition to its known neutralizing capacity, saliva also contains growth factors. These polypeptides (of which epidermal growth factor has been studied most) have cytoprotective and healing properties in various segments of the gastrointestinal tract. Therefore, a deficiency in one or more of these growth factors might be a contributing factor in the development of gastroesophageal reflux disease (GERD) or its complication, such as Barrett's metaplasia. However, human studies have produced contradictory results regarding salivary growth factor deficiency in such patients. Current methods of investigation make it difficult to assess the importance of saliva in GERD. This may be due in part to the multifactorial nature of the disease and the difficulty in long-term, selective manipulation of salivary function in humans. Given the present data in the literature, it is therefore unknown if saliva plays an important role in esophageal protection.