Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/103116
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Type: Journal article
Title: Intragastric administration of leucine or isoleucine lowers the blood glucose response to a mixed-nutrient drink by different mechanisms in healthy, lean volunteers
Author: Ullrich, S.
Fitzgerald, P.
Schober, G.
Steinert, R.
Horowitz, M.
Feinle-Bisset, C.
Citation: American Journal of Clinical Nutrition, 2016; 104(5):1274-1284
Publisher: American Society for Nutrition
Issue Date: 2016
ISSN: 0002-9165
1938-3207
Statement of
Responsibility: 
Sina S Ullrich, Penelope CE Fitzgerald, Gudrun Schober, Robert E Steinert, Michael Horowitz and Christine Feinle-Bisset
Abstract: Background: The branched-chain amino acids leucine and isoleucine lower blood glucose after oral glucose ingestion, and the intraduodenal infusion of leucine decreases energy intake in healthy, lean men. Objective: We investigated the effects of the intragastric administration of leucine and isoleucine on the gastric emptying of, and blood glucose responses to, a physiologic mixed-macronutrient drink and subsequent energy intake. Design: In 2 separate studies, 12 healthy, lean subjects received on 3 separate occasions an intragastric infusion of 5 g leucine (leucine-5g) or an intragastric infusion of 10 g leucine (leucine-10g), an intragastric infusion of 5 g isoleucine (isoleucine-5g) or an intragastric infusion of 10 g isoleucine (isoleucine-10g), or a control. Fifteen minutes later, subjects consumed a mixed-nutrient drink (400 kcal, 56 g carbohydrates, 15 g protein, and 12 g fat), and gastric emptying (13C-acetate breath test) and blood glucose, plasma insulin, C-peptide, glucagon, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and cholecystokinin (leucine study only) were measured for 60 min. Immediately afterward, energy intake from a cold, buffet-style meal was assessed. Results: Compared with the control, leucine-10g decreased the blood glucose area under the curve (AUC) (P < 0.05) and tended to reduce peak blood glucose (P = 0.07), whereas effects of leucine-5g were NS. Leucine-10g, but not leucine-5g, increased plasma insulin and C-peptide AUCs (P < 0.01 for both), but neither dose affected glucagon, GLP-1, GIP, cholecystokinin, gastric emptying, or energy intake. Compared with the control, isoleucine-10g reduced the blood glucose AUC and peak blood glucose (P < 0.01), whereas effects of isoleucine-5g were NS. Neither load affected insulin, C-peptide, glucagon, GLP-1, or GIP. Isoleucine-10g, but not isoleucine-5g, slowed gastric emptying (P < 0.05), but gastric emptying was not correlated with the blood glucose AUC. Isoleucine did not affect energy intake. Conclusions: In healthy subjects, both leucine and isoleucine reduced blood glucose in response to a mixed-nutrient drink but did not affect subsequent energy intake. The mechanisms underlying glucose lowering appear to differ; leucine stimulated insulin, whereas isoleucine acted insulin independently. These trials were registered at www.anzctr.org.au as 12613000899741 and 12614000837628.
Keywords: GIP; GLP-1; branched-chain amino acids; energy intake; food intake; gastric emptying; glucagon; gut hormones; humans; insulin
Rights: © 2016 American Society for Nutrition
RMID: 0030055684
DOI: 10.3945/ajcn.116.140640
Grant ID: http://purl.org/au-research/grants/nhmrc/1078471
http://purl.org/au-research/grants/nhmrc/627002
http://purl.org/au-research/grants/nhmrc/1103020
Appears in Collections:Medicine publications

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