title: Methylxanthines are the psycho-pharmacologically active constituents of chocolate.
abstract: BACKGROUND
  Liking, cravings and addiction for chocolate ("chocoholism") are often explained through the presence of pharmacologically active compounds. However, mere "presence" does not guarantee psycho-activity.
  
  
  OBJECTIVE
  Two double-blind, placebo-controlled studies measured the effects on cognitive performance and mood of the amounts of cocoa powder and methylxanthines found in a 50 g bar of dark chocolate.
  
  
  METHODS
  In study 1, participants ( n=20) completed a test battery once before and twice after treatment administration. Treatments included 11.6 g cocoa powder and a caffeine and theobromine combination (19 and 250 mg, respectively). Study 2 ( n=22) comprised three post-treatment test batteries and investigated the effects of "milk" and "dark" chocolate levels of these methylxanthines. The test battery consisted of a long duration simple reaction time task, a rapid visual information processing task, and a mood questionnaire.
  
  
  RESULTS
  Identical improvements on the mood construct "energetic arousal" and cognitive function were found for cocoa powder and the caffeine+theobromine combination versus placebo. In chocolate, both "milk chocolate" and "dark chocolate" methylxanthine doses improved cognitive function compared with "white chocolate". The effects of white chocolate did not differ significantly from those of water.
  
  
  CONCLUSIONS
  A normal portion of chocolate exhibits psychopharmacological activity. The identical profile of effects exerted by cocoa powder and its methylxanthine constituents shows this activity to be confined to the combination of caffeine and theobromine. Methylxanthines may contribute to the popularity of chocolate; however, other attributes are probably much more important in determining chocolate's special appeal and in explaining related self-reports of chocolate cravings and "chocoholism".
authors.affiliation: Department of Experimental Psychology, University of Bristol, 8 Woodland Road, Bristol, BS8 1TN, UK. henk.smit@bristol.ac.uk
authors.forename: Hendrik J
authors.initials: HJ
authors.lastname: Smit
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Gaffan
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Rogers
mesh_terms: D000328:Adult; D000339:Affect / Q000187:drug effects; D001288:Attention / Q000187:drug effects; D002099:Cacao / Q000737:chemistry*; D002110:Caffeine / Q000737:chemistry / Q000494:pharmacology; D000697:Central Nervous System Stimulants / Q000737:chemistry / Q000494:pharmacology; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000187:drug effects; D011930:Reaction Time / Q000187:drug effects; D013805:Theobromine / Q000737:chemistry / Q000494:pharmacology; D014796:Visual Perception / Q000187:drug effects; D014970:Xanthines / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000697:Central Nervous System Stimulants; D014970:Xanthines; D002110:Caffeine; D013805:Theobromine