Monosodium L-glutamate added to a high-energy, high-protein liquid diet promotes gastric emptying.
Objective: We hypothesized that glutamate may act as a modulator of gastric function. We studied the effects of L-glutamate enrichment of a protein-rich liquid meal, and similar enrichment of an equicaloric carbohydrate meal or noncaloric water, on gastric emptying.
Design: Ten healthy men were enrolled. Nine of the 10 subjects included in the study ingested all test meals with and without monosodium L-glutamate (MSG), and the remaining subject ingested only the protein-rich meals with and without MSG. All experimental and control liquid meals included [1-(13)C]sodium acetate as a tracer. After a test meal or water was ingested, (13)C breath tests were performed to estimate gastric emptying.
Results: MSG enrichment not only resulted in a significant decrease in the mathematically simulated half-excretion (emptying) time of a protein-rich meal, but also increased the area under the curve (%dose/h) significantly. In contrast, MSG had no significant effect on the gastric emptying of a carbohydrate meal or a noncaloric water meal.
Conclusions: Enrichment with MSG facilitated gastric emptying of a protein-rich meal exclusively, which suggests that free glutamate is important for protein digestion and may be helpful in the management of delayed gastric emptying.
Am J Clin Nutr. 2009 Jan;89(1):431-5. doi: 10.3945/ajcn.2008.26180. Epub 2008 Dec 3. PMID: 19056566.