Interactions of the salivary and gastrointestinal systems. I. The role of saliva in digestion.

Considerable evidence now demonstrates that saliva and its components have multiple functions in the GI tract. Saliva aids in bolus formation; it lubricates, protects and cleanses the pharyngeal and esophageal mucosa. Salivary bicarbonate buffers esophageal acid in common reflux. Normal salivary flow decreases the duration of acid contact with esophageal mucosa, an important factor in the development of GERD. If salivary flow is depressed or if the esophagosalivary reflex is lost, a patient may be predisposed to develop GERD. Salivary EGF stimulates GI mucosal proliferation via a direct lumenal effect in the esophagus and stomach. The salivary enzymes LL and salivary amylase initiate fat and starch digestion. They are particularly significant in patients with pancreatic insufficiency such as neonates and patients with cystic fibrosis.