title: The thermic effect of sugar-free Red Bull: do the non-caffeine bioactive ingredients in energy drinks play a role?
abstract: OBJECTIVE
  Consumption of energy drinks is increasing amongst athletes and the general public. By virtue of their bioactive ingredients (including caffeine, taurine, glucuronolactone, and B-group vitamins) and paucity of calories, sugar-free "diet" versions of these drinks could be a useful aid for weight maintenance. Yet little is known about the acute influence of these drinks, and specifically the role of the cocktail of non-caffeine ingredients, on resting energy expenditure (REE) and substrate oxidation. Therefore, the metabolic impact of sugar-free Red Bull (sfRB) to a comparable amount of caffeine was compared.
  
  
  METHODS
  REE and respiratory quotient (RQ) were measured in eight healthy young men by ventilated-hood indirect calorimetry for 30 min baseline and 2 h following ingestion of 355 ml of either: sfRB + placebo, water + 120 mg caffeine, or water + placebo, according to a randomized cross-over design.
  
  
  RESULTS
  sfRB and water + caffeine both increased REE to the same degree (+4%). Additionally, sfRB briefly increased RQ. Water + caffeine had no effect on RQ relative to water + placebo.
  
  
  CONCLUSIONS
  sfRB enhanced thermogenesis and marginally shifted RQ to favor carbohydrate oxidation. The stimulatory effects of sfRB on REE are mimicked by water + caffeine, indicating that the auxiliary ingredients do not influence this thermic effect. The metabolic effects of sfRB are primarily due to caffeine alone.
authors.affiliation: Laboratory of Integrative Cardiovascular and Metabolic Physiology, Division of Physiology, Department of Medicine, University of Fribourg, Fribourg, Switzerland.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Miles-Chan
authors.forename: Nathalie
authors.initials: N
authors.lastname: Charrière
authors.forename: Erik K
authors.initials: EK
authors.lastname: Grasser
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Montani
authors.forename: Abdul G
authors.initials: AG
authors.lastname: Dulloo
mesh_terms: D000328:Adult; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002110:Caffeine / Q000494:pharmacology; D002417:Cattle; D018592:Cross-Over Studies; D061215:Energy Drinks; D002149:Energy Intake / Q000187:drug effects; D004734:Energy Metabolism / Q000187:drug effects; D005965:Glucuronates / Q000494:pharmacology*; D006801:Humans; D008297:Male; D010936:Plant Extracts / Q000494:pharmacology; D012146:Rest; D013654:Taurine / Q000494:pharmacology*; D022722:Thermogenesis / Q000187:drug effects*; D014803:Vitamin B Complex / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D005965:Glucuronates; D010936:Plant Extracts; D014803:Vitamin B Complex; D013654:Taurine; C004940:glucuronolactone; D002110:Caffeine