Amino Acids

, Volume 37, Issue 2, pp 333–339 | Cite as

Human insulinotropic response to oral ingestion of native and hydrolysed whey protein

Original Article

Abstract

The insulinotropic response to the ingestion of whey protein and whey protein hydrolysate, independent of carbohydrate, is not known. This study examined the effect of protein hydrolysis on the insulinotropic response to the ingestion of whey protein. Sixteen healthy males ingested a 500 mL solution containing either 45 g of whey protein (WPI) or whey protein hydrolysate (WPH). The estimated rate of gastric empting was not altered by hydrolysis of the protein [18 (3) vs. 23 (3) min, n = 16; P = 0.15]. Maximum plasma insulin concentration (Cmax) occurred later (40 vs. 60 min) and was 28% [234 (26) vs. 299 (31) mM, P = 0.018] greater following ingestion of the WPH compared to the WPI leading to a 43% increase [7.6 (0.9) vs. 10.8 (2.6) nM, P = 0.21] in the AUC of insulin for the WPH. Of the amino acids with known insulinotropic properties only Phe demonstrated a significantly greater maximal concentration [Cmax; 65 (2) vs. 72 (3) μM, n = 16; P = 0.01] and increase (+22%) in AUC following ingestion of the WPH. In conclusion, ingestion of whey protein is an effective insulin secretagogue. Hydrolysis of whey protein prior to ingestion augments the maximal insulin concentration by a mechanism that is unrelated to gastric emptying of the peptide solution.

Keywords

Amino acids Insulin Whey protein Peptide hydrolysate Gastric emptying 

Abbreviations

AA

Amino acid

EAA

Essential amino acid

Leu

Leucine

Ile

Isoleucine

Val

Valine

Phe

Phenylalanine

Lys

Lysine

Arg

Arginine

BCAA

Branched chain amino acids

GE

Gastric emptying

WPI

Whey proteins isolate

WPH

Whey protein hydrolysate

RP-HPLC

Reverse phase high performance liquid chromatography

AUC

Area under the curve

T50%

Half-time of gastric emptying

Tmax

Time of maximum plasma concentration

Cmax

Maximum plasma concentration

GIP

Glucose dependent insulinotropic polypeptide

GLP-1

Glucagon-like-peptide 1

Notes

Acknowledgments

The authors acknowledge the financial support of Enterprise Ireland (Grant IP 2004-237) and Carbery Food Ingredients.

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Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  1. 1.Human Science Research Unit, Department of Physical Education and Sports ScienceUniversity of LimerickLimerickIreland
  2. 2.Carbery Food IngredientsBallineenIreland

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