Comparative Effects of the Branched-Chain Amino Acids, Leucine, Isoleucine and Valine, on Gastric Emptying, Plasma Glucose, C-Peptide and Glucagon in Healthy Men

Abstract

(1) Background: Whey protein lowers postprandial blood glucose in health and type 2 diabetes, by stimulating insulin and incretin hormone secretion and slowing gastric emptying. The branched-chain amino acids, leucine, isoleucine and valine, abundant in whey, may mediate the glucoregulatory effects of whey. We investigated the comparative effects of intragastric administration of leucine, isoleucine and valine on the plasma glucose, C-peptide and glucagon responses to and gastric emptying of a mixed-nutrient drink in healthy men. (2) Methods: 15 healthy men (27 ± 3 y) received, on four separate occasions, in double-blind, randomised fashion, either 10 g of leucine, 10 g of isoleucine, 10 g of valine or control, intragastrically, 30 min before a mixed-nutrient drink. Plasma glucose, C-peptide and glucagon concentrations were measured before, and for 2 h following, the drink. Gastric emptying of the drink was quantified using 13C-acetate breath-testing. (3) Results: Amino acids alone did not affect plasma glucose or C-peptide, while isoleucine and valine, but not leucine, stimulated glucagon (p < 0.05), compared with control. After the drink, isoleucine and leucine reduced peak plasma glucose compared with both control and valine (all p < 0.05). Neither amino acid affected early (t = 0–30 min) postprandial C-peptide or glucagon. While there was no effect on overall gastric emptying, plasma glucose at t = 30 min correlated with early gastric emptying (p < 0.05). (4) Conclusion: In healthy individuals, leucine and isoleucine lower postprandial blood glucose, at least in part by slowing gastric emptying, while valine does not appear to have an effect, possibly due to glucagon stimulation.

Dietary Isoleucine and Valine: Effects on Lipid Metabolism and Ureagenesis in Pigs Fed with Protein Restricted Diets

“…In the current study, HI improved the glucose clearance after the meal test. This was in line with previous studies showing that intragastric infusion of Ile and Leu in healthy males [ 76 , 77 ] or oral administration of Ile in rats [ 78 , 79 , 80 ] and healthy humans [ 81 ], but not Val, decreased the postprandial blood glucose. This is while intravenous infusion of Val in healthy humans [ 82 ] or its oral administration in rats [ 79 ] either marginally decreased or raised blood glucose concentration, respectively.…”

Postprandial Glucose and Gastrointestinal Hormone Responses of Healthy Subjects to Wheat Biscuits Enriched with L-Arginine or Branched-Chain Amino Acids of Plant Origin

“…However, a factor which has to be taken into consideration is that amino acids produce a slowing down of stomach emptying that could explain, in part, the observed metabolic responses. Certainly, intragastric administration of L-leu and L-ile in healthy men lowers postprandial blood glucose, at least in part by slowing gastric emptying [ 47 ]. Additionally, studies in Sprague-Dawley rats have shown that L-arg and other amino acids inhibit and delay gastric emptying as evaluated by a breath test using [1- 13 C] acetic acid [ 48 ].…”

Untargeted metabolomics of saliva in pregnant women with and without gestational diabetes mellitus and healthy non-pregnant women

“…Therefore, we speculate that the changes in isoleucine level in patients with GDM may be caused by changes in P-gp, ABCC8, and ABCC9 expression. Numerous studies (Doi et al, 2005;Doi et al, 2007;Ikehara et al, 2008;Guasch-Ferréet al, 2016;Ullrich et al, 2016;Newmire et al, 2019;Elovaris et al, 2021a;Elovaris et al, 2021b) have suggested that the effect of isoleucine on glucose metabolism may be related to the decreased expression of glucose-6-phosphatase (G6Pase). In the present study, we found that glucose 6-phosphate (G6P) level was elevated after pregnancy, presumably due to a decrease in G6Pase expression.…”