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https://hdl.handle.net/2440/131402
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Type: | Journal article |
Title: | Suppression of energy intake by intragastric L-tryptophan in lean and obese men: relations with appetite perceptions and circulating cholecystokinin and tryptophan |
Author: | Hajishafiee, M. Ullrich, S.S. Fitzgerald, P.C. Horowitz, M. Lange, K. Poppitt, S.D. Feinle-Bisset, C. |
Citation: | The Journal of Nutrition, 2021; 151(10):2932-2941 |
Publisher: | Oxford University Press (OUP) |
Issue Date: | 2021 |
ISSN: | 0022-3166 1541-6100 |
Statement of Responsibility: | Maryam Hajishafiee, Sina S Ullrich, Penelope CE Fitzgerald, Michael Horowitz, Kylie Lange, Sally D Poppitt, and Christine Feinle-Bisset |
Abstract: | Background: L-Tryptophan reduces energy intake in healthy men. The underlying mechanisms, including appetite, plasma cholecystokinin (CCK), tryptophan (Trp), and the ratio of Trp to large neutral amino acids (Trp:LNAAs ratio), and whether responses differ in lean and obese individuals, are uncertain. Objectives: We evaluated the effects of intragastric Trp on energy intake (primary outcome) and their potential mechanisms, pre- and postmeal, in lean men and those with obesity. Methods: Twelve lean men [mean ± SD age: 30 ± 3 y; BMI (in kg/m2): 23 ± 1] and 13 men with obesity (mean ± SD age: 31 ± 3 y; BMI: 33 ± 1) received, on 3 separate occasions, in double-blind, randomized order, 3 g (“Trp-3”) or 1.5 g (“Trp-1.5”) Trp, or control (“C”), intragastrically, 30 min before a buffet-meal. Energy intake from the buffet-meal, hunger, fullness, and plasma CCK and amino acid concentrations were measured in response to Trp alone and for 2 h postmeal. Data were analyzed using maximum likelihood mixed-effects models, with treatment, group, and treatment-by-group interaction as fixed effects. Results: Trp alone increased plasma CCK, Trp, and the Trp:LNAAs ratio (all P < 0.001), with no difference between groups. Trp suppressed energy intake (P < 0.001), with no difference between groups (lean, C: 1085 ± 102 kcal, Trp-1.5: 1009 ± 92 kcal, Trp-3: 868 ± 104 kcal; obese, C: 1249 ± 98 kcal, Trp-1.5: 1217 ± 90 kcal, Trp-3: 1012 ± 100 kcal). Postmeal, fullness was greater after Trp-3 than after C and Trp-1.5 (all P < 0.05), and in men with obesity than in leanmen (P < 0.05). Plasma Trp and the Trp:LNAAs ratio were greater after Trp-3 and Trp-1.5 than after C (all P < 0.001), and tended to be less in men with obesity than in the lean (P = 0.07) (Trp:LNAAs ratio: lean, C: 1.5 ± 0.2, Trp-1.5: 6.9 ± 0.7, Trp-3: 10.7 ± 1.4; obese, C: 1.4 ± 0.1, Trp-1.5: 4.6 ± 0.7, Trp-3: 7.8 ± 1.3). There were inverse correlations of energy intake with plasma Trp and the Trp:LNAAs ratio in both groups (lean, both r = −0.50, P < 0.01; obese, both r = −0.40, P < 0.05). Conclusions: Intragastric Trp has potent energy intake–suppressant effects, in both lean men and those with obesity, apparently related to the Trp:LNAAs ratio. |
Keywords: | Amino acids; food intake; obesity; tryptophan to large neutral amino acids ratio; hunger; fullness |
Rights: | © The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com |
DOI: | 10.1093/jn/nxab218 |
Grant ID: | http://purl.org/au-research/grants/nhmrc/1158296 http://purl.org/au-research/grants/nhmrc/1103020 |
Published version: | http://dx.doi.org/10.1093/jn/nxab218 |
Appears in Collections: | Aurora harvest 8 Medicine publications |
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