Ingestion of a protein hydrolysate is accompanied by an accelerated in vivo digestion and absorption rate when compared with its intact protein

• Published in: The American journal of clinical nutrition Vol. 90; no. 1; pp. 106 - 115
• Main Authors: Koopman, René, Crombach, Nico, Gijsen, Annemie P, Walrand, Stéphane, Fauquant, Jacques, Kies, Arie K, Lemosquet, Sophie, Saris, Wim HM, Boirie, Yves, van Loon, Luc JC
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Clinical Nutrition 01.07.2009; American Society for Nutrition; American Society for Clinical Nutrition, Inc; Oxford University Press
• Subjects: Amino acids; Biochemistry; Biological and medical sciences; blood; blood composition; Blood Glucose; Blood Glucose - metabolism; blood plasma; Carbon Isotopes; Carbon Isotopes - metabolism; Caseins; Caseins - metabolism; Cross-Over Studies; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 1 - blood; Dietary minerals; Dietary Proteins; Dietary Proteins - metabolism; digestion; Digestion - physiology; elderly; Feeding. Feeding behavior; Food and Nutrition; Fundamental and applied biological sciences. Psychology; Glucose Tolerance Test; human nutrition; Humans; in vivo studies; ingestion; Insulin; Insulin - blood; intestinal absorption; Intestinal Absorption - physiology; Kinetics; Leucine; Leucine - metabolism; Life Sciences; Male; men; metabolism; Middle Aged; muscle protein; Muscle, Skeletal; Muscle, Skeletal - metabolism; Netherlands; nutrient availability; nutrient uptake; Phenylalanine; Phenylalanine - blood; Phenylalanine - metabolism; physiology; protein hydrolysates; Protein Hydrolysates - metabolism; protein metabolism; Protein synthesis; Proteins; quantitative analysis; skeletal muscle; Sorption; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Netherlands; Human; In vivo; Absorption; Hydrolysate; Digestion; Comparative study; Protein; Ingestion; HYDROLYSAT DE PROTEINES; PROTEINE INTACTE
• ISSN: 0002-9165; 1938-3207; 1938-3207
• DOI: 10.3945/ajcn.2009.27474

BACKGROUND: It has been suggested that a protein hydrolysate, as opposed to its intact protein, is more easily digested and absorbed from the gut, which results in greater plasma amino acid availability and a greater muscle protein synthetic response. OBJECTIVE: We aimed to compare dietary protein digestion and absorption kinetics and the subsequent muscle protein synthetic response to the ingestion of a single bolus of protein hydrolysate compared with its intact protein in vivo in humans. DESIGN: Ten elderly men (mean ± SEM age: 64 ± 1 y) were randomly assigned to a crossover experiment that involved 2 treatments in which the subjects consumed a 35-g bolus of specifically produced L-[1-¹³C]phenylalanine-labeled intact casein (CAS) or hydrolyzed casein (CASH). Blood and muscle-tissue samples were collected to assess the appearance rate of dietary protein-derived phenylalanine in the circulation and subsequent muscle protein fractional synthetic rate over a 6-h postprandial period. RESULTS: The mean (±SEM) exogenous phenylalanine appearance rate was 27 ± 6% higher after ingestion of CASH than after ingestion of CAS (P < 0.001). Splanchnic extraction was significantly lower in CASH compared with CAS treatment (P < 0.01). Plasma amino acid concentrations increased to a greater extent (25-50%) after the ingestion of CASH than after the ingestion of CAS (P < 0.01). Muscle protein synthesis rates averaged 0.054 ± 0.004% and 0.068 ± 0.006%/h in the CAS and CASH treatments, respectively (P = 0.10). CONCLUSIONS: Ingestion of a protein hydrolysate, as opposed to its intact protein, accelerates protein digestion and absorption from the gut, augments postprandial amino acid availability, and tends to increase the incorporation rate of dietary amino acids into skeletal muscle protein.