title: Whey protein supplementation does not alter plasma branched-chained amino acid profiles but results in unique metabolomics patterns in obese women enrolled in an 8-week weight loss trial.
abstract: BACKGROUND
  It has been suggested that perturbations in branched-chain amino acid (BCAA) catabolism are associated with insulin resistance and contribute to elevated systemic BCAAs. Evidence in rodents suggests dietary protein rich in BCAAs can increase BCAA catabolism, but there is limited evidence in humans.
  
  
  OBJECTIVE
  We hypothesize that a diet rich in BCAAs will increase BCAA catabolism, which will manifest in a reduction of fasting plasma BCAA concentrations.
  
  
  METHODS
  The metabolome of 27 obese women with metabolic syndrome before and after weight loss was investigated to identify changes in BCAA metabolism using GC-time-of-flight mass spectrometry. Subjects were enrolled in an 8-wk weight-loss study including either a 20-g/d whey (whey group, n = 16) or gelatin (gelatin group, n = 11) protein supplement. When matched for total protein by weight, whey protein has 3 times the amount of BCAAs compared with gelatin protein.
  
  
  RESULTS
  Postintervention plasma abundances of Ile (gelatin group: 637 ± 18, quantifier ion peak height ÷ 100; whey group: 744 ± 65), Leu (gelatin group: 1210 ± 33; whey group: 1380 ± 79), and Val (gelatin group: 2080 ± 59; whey group: 2510 ± 230) did not differ between treatment groups. BCAAs were significantly correlated with homeostasis model assessment of insulin resistance at baseline (r = 0.52, 0.43, and 0.49 for Leu, Ile, and Val, respectively; all, P < 0.05), but correlations were no longer significant at postintervention. Pro- and Cys-related pathways were found discriminant of whey protein vs. gelatin protein supplementation in multivariate statistical analyses.
  
  
  CONCLUSIONS
  These findings suggest that BCAA metabolism is, at best, only modestly affected at a whey protein supplementation dose of 20 g/d. Furthermore, the loss of an association between postintervention BCAA and homeostasis model assessment suggests that factors associated with calorie restriction or protein intake affect how plasma BCAAs relate to insulin sensitivity. This trial was registered at clinicaltrials.gov as NCT00739479.
authors.affiliation: Obesity and Metabolism Research Unit, USDA, Agricultural Research Service, Western Human Nutrition Research Center, Davis, CA;
authors.forename: Brian D
authors.initials: BD
authors.lastname: Piccolo
authors.affiliation: Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, The University of California Davis Medical Center, Sacramento, CA; and Department of Nutrition.
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Comerford
authors.affiliation: Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, The University of California Davis Medical Center, Sacramento, CA; and.
authors.forename: Sidika E
authors.initials: SE
authors.lastname: Karakas
authors.affiliation: Obesity and Metabolism Research Unit, USDA, Agricultural Research Service, Western Human Nutrition Research Center, Davis, CA; Department of Nutrition.
authors.forename: Trina A
authors.initials: TA
authors.lastname: Knotts
authors.affiliation: West Coast Metabolomics Center, and Genome Center, University of California, Davis, Davis, CA.
authors.forename: Oliver
authors.initials: O
authors.lastname: Fiehn
authors.affiliation: Obesity and Metabolism Research Unit, USDA, Agricultural Research Service, Western Human Nutrition Research Center, Davis, CA; Department of Nutrition, shadams@uams.edu.
authors.forename: Sean H
authors.initials: SH
authors.lastname: Adams
mesh_terms: D000328:Adult; D000597:Amino Acids, Branched-Chain / Q000008:administration & dosage / Q000097:blood*; D001786:Blood Glucose; D015992:Body Mass Index; D031204:Caloric Restriction; D008076:Cholesterol, HDL / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005780:Gelatin / Q000008:administration & dosage; D006706:Homeostasis; D006801:Humans; D007328:Insulin / Q000097:blood; D055442:Metabolome; D008875:Middle Aged; D008894:Milk Proteins / Q000008:administration & dosage*; D015999:Multivariate Analysis; D009765:Obesity / Q000097:blood / Q000178:diet therapy*; D055105:Waist Circumference; D015431:Weight Loss; D000067816:Whey Proteins
chemical_list: D000597:Amino Acids, Branched-Chain; D001786:Blood Glucose; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D007328:Insulin; D008894:Milk Proteins; D000067816:Whey Proteins; D005780:Gelatin
keywords: BCAA; Cys; Leu; Pro; dairy; metabolic syndrome; metabolomics; obesity; protein; weight loss