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This Article Full Text (Publish Ahead of Print[PDF]) All Versions of this Article: 89/1/431    most recent ajcn.2008.26180v1 Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Zai, H. Articles by Mori, M. Search for Related Content PubMed PubMed Citation Articles by Zai, H. Articles by Mori, M. Agricola Articles by Zai, H. Articles by Mori, M.

Monosodium L-glutamate added to a high-energy, high-protein liquid diet promotes gastric emptying^1,2,3

¹ From the Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Maebashi, Japan (HZ, HH, AN, MM, OK, and MM), and the Department of Endoscopy and Endoscopic Surgery, Gunma University Hospital, Maebashi, Japan (MK and YS).

² The experimental diets and monosodium L-glutamate used in this study were kind gifts from Ajinomoto Co, Inc.

³ Reprints not available. Address correspondence to M Kusano, Department of Endoscopy and Endoscopic Surgery, Gunma University Hospital, Maebashi 371-8511, Japan. E-mail address: mkusano{at}showa.gunma-u.ac.jp.

ABSTRACT

Background: Free glutamate activates taste receptors on nerves in the oral cavity to elicit a unique taste known as umami. Recently, umami taste receptors were also found in the gastric mucosa. Although reports suggest that mucosal receptors may respond to free glutamate to modulate gastric function, no evidence of any effect on gastric emptying has been documented.

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 [1-¹³C]sodium acetate as a tracer. After a test meal or water was ingested, ¹³C 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.

Received for publication March 19, 2008. Accepted for publication October 8, 2008.

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