Abstract
Background: The ingestion of whey protein and amino acids with carbohydrate (CHO) enhances the release of glucagon-like peptide-1 (GLP-1) and glucose-dependent-insulinotropic peptide (GIP) that promote insulin secretion. It is unknown if L-isoleucine (Ile) and L-leucine (Leu) have this same effect. The purpose of this study was to examine how Ile and Leu influence both GLP-1 and GIP, subsequent pancreatic hormones, and glycemia in healthy, inactive adults. Methods: Twelve adults (6F/6M; age 27.4 ± 2 years; BMI 26.3 ± 2 kg/m2; lean body mass 53.2 ± 5 kg; body fat 34.1 ± 3%) completed four conditions in a randomized, cross-over fashion. Treatments standardized (0.3 g/kg·LBM−1) (1) Leu, (2) Ile, (3) Equal (1:1 g) of Leu + Ile, and (4) placebo (Pla, 3.5 g inert stevia) ingested 30 min prior to an oral glucose tolerance test (OGTT). Samples of plasma glucose, insulin, glucagon, GIPTotal, and GLP-1Active were assessed. Results: A treatment (p = 0.01) effect comparing Ile vs. Leu (p = 0.02) in GIPTotal. Area under the curve showed an increase in GIPTotal from Ile compared to Leu and Pla (p = 0.03). No effect was found on GLP-1. The ingestion of Ile prior to CHO augmented GIP concentration greater than Leu or Pla. No correlation was found between GIP, insulin, and glucose between conditions. Conclusions: Ile impacts GIP concentration, which did not relate to either insulin or glucose concentrations. Neither Ile, nor Leu seem to have an effect on hyperglycemia ingested prior to a CHO drink.
Highlights
More than 100 million U.S adults are living with diabetes or prediabetes, with 90% to 95%diagnosed with type 2 diabetes (T2D) according to the Centers for Disease Control and Prevention (CDC), with an economic burden of up to ~$245 billion [1,2,3]
Our data suggest that L-isoleucine may play a significant role in amino acid-driven glucose-dependent-insulinotropic peptide (GIP)
In concert with previous investigations, neither L-isoleucine nor L-leucine seem to have an effect on glucagon-like peptide-1 (GLP-1) concentration
Summary
More than 100 million U.S adults are living with diabetes or prediabetes, with 90% to 95%diagnosed with type 2 diabetes (T2D) according to the Centers for Disease Control and Prevention (CDC), with an economic burden of up to ~$245 billion [1,2,3]. It has been suggested that the large amount of branched-chain amino acids (BCAAs) found in whey protein may promote hyperinsulinemia by inducing an insulinogenic effect [16,17,18] which influences the skeletal muscle uptake of glucose by potentially directly and indirectly stimulating insulin cell signaling pathways [19,20] and possibly through the incretin effect [21]. The relationship between amino acid ingestion, the incretin effect, and glycemic control is not well understood in humans. Enhances the release of glucagon-like peptide-1 (GLP-1) and glucose-dependent-insulinotropic peptide (GIP) that promote insulin secretion. It is unknown if L-isoleucine (Ile) and L-leucine (Leu) have this same effect. Results: A treatment (p = 0.01) effect comparing Ile vs Leu (p = 0.02) in GIPTotal.
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