Gastric emptying, gastric secretion and enterogastrone response after administration of milk proteins or their peptide hydrolysates in humans.
BACKGROUND
The influence of protein fractionation on gastric emptying and rate of appearance of their constituent amino acids in peripheral blood remains unknown.


OBJECTIVE
To examine the influence of the degree of protein fractionation on gastric emptying, gastric secretion, amino acid absorption and enterogastrone response, after the intragastric administration of complete cow milk proteins or their respective peptide hydrolysates in man.


METHODS
Six healthy males were randomized to receive one of the following four solutions: whey whole protein (W), casein whole protein (C), whey peptide hydrolysate (WHY) or casein hydrolysate (CAHY). All solutions were matched for volume (600 mL), nitrogen content (9.3 g/L), energy density (1069-1092 kJ/L), osmolality (288-306 mosmol/kg), pH (6.9-7.0) and temperature (37 degrees C).


RESULTS
Solutions were emptied at similar rates, with mean half-times of (mean +/- SEM) 21.4 +/- 1.3, 19.3 +/- 2.2, 18.0 +/- 2.5 and 19.4 +/- 2.8 min, for the WHY, CAHY, C and W, respectively. The rates of intestinal absorption of water and amino acids were similar with the exception of the casein protein solution, for which the speed of intestinal amino acid absorption was slower (p < 0.05). The peptide hydrolysates elicited about 50% more gastric secretion than the whole protein solutions ( p < 0.05),which was accompanied by higher glucose-dependent insulinotropic polipeptide (GIP) plasma levels during the first 20 min of the gastric emptying process. Similar glucagon-like peptide-1 (GLP-1) and peptide YY (PYY) plasma responses were elicited by the four solutions.


CONCLUSIONS
The rate of gastric emptying and the plasma GLP-1 and PYY responses to feeding with cow milk protein solutions in humans are independent of the degree of protein fractionation and are not altered by small differences in the amino acid composition or protein solubility. In contrast, the GIP response is accentuated when milk proteins are delivered as peptide hydrolysates.
Calbet
Jose A L
JA
Copenhagen Muscle Research Center, Rigshospitalet, Copenhagen, Denmark. lopezcalbet@terra.es
Holst
Jens J
JJ
D000328:Adult; D000596:Amino Acids / Q000378:metabolism* / Q000493:pharmacokinetics; D000704:Analysis of Variance; D000818:Animals; D002364:Caseins / Q000737:chemistry / Q000378:metabolism; D002417:Cattle; D018592:Cross-Over Studies; D005746:Gastric Emptying / Q000502:physiology*; D005753:Gastric Mucosa / Q000378:metabolism*; D005768:Gastrointestinal Hormones / Q000378:metabolism; D005934:Glucagon / Q000097:blood; D052216:Glucagon-Like Peptide 1; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007408:Intestinal Absorption; D007421:Intestine, Small; D008297:Male; D008894:Milk Proteins / Q000737:chemistry / Q000378:metabolism*; D010446:Peptide Fragments / Q000097:blood; D019894:Peptide YY / Q000097:blood; D010455:Peptides / Q000378:metabolism; D011492:Protein Hydrolysates / Q000378:metabolism* / Q000493:pharmacokinetics; D011498:Protein Precursors / Q000097:blood; D015203:Reproducibility of Results; D000067816:Whey Proteins
D000596:Amino Acids; D002364:Caseins; D005768:Gastrointestinal Hormones; D008894:Milk Proteins; D010446:Peptide Fragments; D010455:Peptides; D011492:Protein Hydrolysates; D011498:Protein Precursors; D000067816:Whey Proteins; D019894:Peptide YY; D052216:Glucagon-Like Peptide 1; C073320:enterogastrone; D005934:Glucagon