title: Effects of theobromine and caffeine on mood and vigilance.
abstract: Like caffeine, theobromine crosses the blood-brain barrier and binds to adenosine receptors, suggesting it might share caffeine's beneficial effects on mood and vigilance. Therefore, the purpose of this study was to assess the effect of theobromine doses commonly found in foods on mood and vigilance parameters sensitive to caffeine. Caffeine was tested as a positive control. Twenty-four men (age, 23 [3] years) completed 6 double-blind trials during which they consumed experimental beverages, assessed their mood using standardized self-report questionnaires, and completed a 2-hour visual vigilance task. Three experimental doses (100, 200, and 400 mg theobromine) were delivered in a cocoa-based beverage; 3 matched control treatments (0 mg theobromine, 400 mg theobromine, and 100 mg caffeine) were delivered in a non-cocoa beverage. Mean salivary concentrations of theobromine exhibited significant dose-dependent differences (400 mg trials > 200 mg trial > 100 mg trial > 0 mg trials; P < 0.005). At every dose tested, theobromine failed to consistently affect mood state or vigilance (P > 0.05), but 100-mg caffeine significantly decreased lethargy/fatigue and increased vigor (P = 0.006 and 0.011, respectively). These findings indicate theobromine does not influence mood and vigilance when administered in nutritionally relevant doses, despite sharing many of caffeine's structural characteristics.
authors.affiliation: Department of Kinesiology, California State University, Fullerton, Fullerton, CA 92834, USA. djudelson@fullerton.edu
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Judelson
authors.forename: Amy G
authors.initials: AG
authors.lastname: Preston
authors.forename: Debra L
authors.initials: DL
authors.lastname: Miller
authors.forename: Colleen X
authors.initials: CX
authors.lastname: Muñoz
authors.forename: Mark D
authors.initials: MD
authors.lastname: Kellogg
authors.forename: Harris R
authors.initials: HR
authors.lastname: Lieberman
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000339:Affect / Q000187:drug effects*; D000704:Analysis of Variance; D001143:Arousal / Q000187:drug effects*; D001288:Attention / Q000187:drug effects; D001628:Beverages; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology*; D002140:California; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000494:pharmacology*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006801:Humans; D008297:Male; D015394:Molecular Structure; D009483:Neuropsychological Tests; D057566:Self Report; D013329:Structure-Activity Relationship; D013805:Theobromine / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors; D055815:Young Adult
chemical_list: D000697:Central Nervous System Stimulants; D002110:Caffeine; D013805:Theobromine