title: Influence of carbohydrate on serum caffeine concentrations following caffeine ingestion.
abstract: OBJECTIVE
  To examine the effect of a high carbohydrate meal on serum caffeine concentration following caffeine intake.
  
  
  METHODS
  Randomised, double-blind, crossover.
  
  
  METHODS
  Fourteen healthy males randomly completed 4 trials, each separated by 5 days. Participants either remained fasted (on 2 occasions) or ingested a high carbohydrate meal (2.0gkg(-1) carbohydrate, 42.4±0.6kJkg(-1)) prior to consuming either 6 or 9mgkg(-1) anhydrous caffeine. Venous blood was sampled for the analysis of serum caffeine at baseline and at 6 time-points over 4h following caffeine intake.
  
  
  RESULTS
  Peak caffeine concentration occurred 60min following ingestion for both the 6 and 9mgkg(-1) fasted (p<0.001) trials compared to 120 and 180min following ingestion for the 6 and 9mgkg(-1) fed trials, respectively (p<0.001). Peak concentration was greater in the 9mgkg(-1) fasted trial than the corresponding fed condition (70±9μmolL(-1) and 56±6μmolL(-1), respectively) and both were greater than the 6mgkg(-1) conditions (44±8μmolL(-1) and 38±8μmolL(-1) for 6mgkg(-1) fasted and fed, respectively). Area under the caffeine curve was significantly greater (p<0.001) in the 9mgkg(-1) fasted trial (3262μmolL(-1)h(-1)), whilst areas were lowest in the 6mgkg(-1) fed trial (1644μmolL(-1)h(-1)).
  
  
  CONCLUSIONS
  A high carbohydrate meal consumed prior to caffeine ingestion significantly reduced serum caffeine concentrations and delayed time to peak concentration. Differences in research findings between caffeine supplementation studies may, at least in part, be related to variations in postprandial timing of caffeine intake. The influence of postprandial timing should be considered when athletes consume caffeine with the aim of enhancing performance.
authors.affiliation: The University of Queensland, School of Human Movement Studies, Australia. tskinner@hms.uq.edu.au
authors.forename: Tina L
authors.initials: TL
authors.lastname: Skinner
authors.forename: David G
authors.initials: DG
authors.lastname: Jenkins
authors.forename: Jennifer
authors.initials: J
authors.lastname: Folling
authors.forename: Michael D
authors.initials: MD
authors.lastname: Leveritt
authors.forename: Jeff S
authors.initials: JS
authors.lastname: Coombes
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Taaffe
mesh_terms: D000328:Adult; D002110:Caffeine / Q000008:administration & dosage / Q000097:blood*; D050260:Carbohydrate Metabolism; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000097:blood*; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004311:Double-Blind Method; D005215:Fasting / Q000097:blood*; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D004040:Dietary Carbohydrates; D002110:Caffeine