The Role of Glutamate in the Gastrointestinal Tract

Glutamate—the principal component responsible for imparting the fifth basic taste, umami—also performs important physiological functions in our bodies, which may enhance not only food acceptance but also digestive processes.

Regarding its flavor-enhancing properties, this portal already discussed that consuming umami-rich foods is a good strategy to improve meal palatability, especially for older adults who may experience reduced taste sensitivity. This is attributed to increased salivary flow stimulated by glutamate, which enhances saliva’s role in forming the food bolus and supports both food acceptance and digestion.

Beyond stimulating salivary flow, there is evidence that glutamate increases gastric juice production and secretion, particularly when ingested alongside other amino acids. This increase promotes greater gastric motility by accelerating gastric emptying, which, in turn, may help with weight control.

Researchers have identified glutamate receptors in the stomachs of experimental animals. These receptors are associated with increased postprandial motility and faster gastric emptying, mediated by the vagus nerve. In humans, experimental data demonstrate the existence of glutamate sensors not only in the oral cavity and intestinal lining but also in the gastric wall and hepatoportal region.

These sensors increase vagal nerve activity in gastric, enteric, and hepatic branches, activating gastrointestinal and pancreatic functions that generally facilitate food digestion and promote hormone release.

Glutamate is also one of the most important energy sources for intestinal mucosal cells, accounting for half of all energy consumed during food digestion. Thus, glutamate may be indispensable for improving intestinal function in infants and maintaining the functional integrity of the intestinal mucosa in adults as well.

Researchers have found that duodenal perfusion of glutamate and inosinate promotes the release of glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide-1 (GLP-1). Because both hormones are insulinotropic, they enhance insulin release.

Therefore, activation of umami receptors by glutamate and inosinate may offer additional benefits for glucose metabolism. In another study involving conscious, resting animal models, an increase in blood insulin concentration was observed following oral glutamate infusion.

In summary, the role of glutamate extends far beyond taste identity. It effectively contributes to gastrointestinal function by supporting improved digestion through gastric juice action, controlling postprandial glycemia by stimulating insulin release, maintaining intestinal health through energy supply, and enhancing the well-being of individuals with reduced food intake due to impaired olfaction and taste.