title: Evidence of enhanced serum amino acid profile but not appetite suppression by dietary glycomacropeptide (GMP): a comparison of dairy whey proteins.
abstract: OBJECTIVE
  There is evidence that high-protein foods increase satiety and may aid weight loss, yet little is known of differential effects of protein composition. The aim of the study was to compare the acute effects of 4 whey proteins on satiety and food intake and to evaluate possible relationships with postprandial serum amino acid concentrations.
  
  
  METHODS
  Isoenergetic high-protein shakes (∼1 MJ) containing 25 g whey protein were given to 18 lean male participants using a crossover design. Three protein fractions identified as satiating in a rat model, glycomacropeptide (GMP), beta-lactoglobulin (ß-lac), and colostrum whey protein concentrate (WPC), were compared with a WPC control. A standardized 2.5MJ breakfast was given at 0830 hours, followed by the preload beverages at 1130 hours. Participants rated appetite sensations using visual analogue scales (VAS) prior to the beverage (baseline, 0 minutes) and then at 15, 30, 45, 60, 90, 150, and 210 minutes. Energy and macronutrient intake was measured by covert weighing of an ad libitum lunch meal at 90 minutes. Repeat blood samples were collected via venous cannulation.
  
  
  RESULTS
  Serum amino acid (a.a.) concentrations differed between whey fractions (p=0.012) and were higher following GMP compared to ß-lac (p=0.051) and colostrum WPC (p=0.044) but not the WPC control (p=0.20). There was no difference in VAS-rated hunger, satisfaction, or thoughts of food between whey fractions, but fullness did differ (p=0.032) and was highest following the ß-lac beverage. Energy intake was not suppressed relative to control by any of the 3 whey fractions.
  
  
  CONCLUSIONS
  We conclude that total serum a.a. concentration was a poor indicator of satiety, with little evidence of differential satiety between these whey proteins other than a modest enhancement of fullness by ß-lac.
authors.affiliation: Human Nutrition Unit, School of Biological Sciences, Department of Medicine, University of Auckland, Auckland, New Zealand. s.poppitt@auckland.ac.nz
authors.forename: Sally D
authors.initials: SD
authors.lastname: Poppitt
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Strik
authors.forename: Brian H
authors.initials: BH
authors.lastname: McArdle
authors.forename: Anne-Thea
authors.initials: AT
authors.lastname: McGill
authors.forename: Ramon S
authors.initials: RS
authors.lastname: Hall
mesh_terms: D000293:Adolescent; D000328:Adult; D000596:Amino Acids / Q000097:blood*; D001069:Appetite Regulation / Q000187:drug effects*; D001628:Beverages / Q000032:analysis*; D002364:Caseins / Q000008:administration & dosage*; D018592:Cross-Over Studies; D002149:Energy Intake; D006801:Humans; D006815:Hunger / Q000187:drug effects; D007782:Lactoglobulins / Q000008:administration & dosage*; D008297:Male; D008894:Milk Proteins / Q000008:administration & dosage*; D010446:Peptide Fragments / Q000008:administration & dosage*; D019518:Postprandial Period / Q000187:drug effects; D012527:Satiation / Q000187:drug effects; D000067816:Whey Proteins; D055815:Young Adult
chemical_list: D000596:Amino Acids; D002364:Caseins; D007782:Lactoglobulins; D008894:Milk Proteins; D010446:Peptide Fragments; D000067816:Whey Proteins; C065989:caseinomacropeptide