Methylxanthines are the psycho-pharmacologically active constituents of chocolate
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.
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.
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.
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.
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”.
KeywordsChocolate Cocoa Caffeine Theobromine Mood Performance
H.J.S. was supported by a grant from Reading Scientific Services Ltd, Reading, UK.
- Barone JJ, Roberts H (1984) Human consumption of caffeine. In: Dews PB (ed) Caffeine: perspectives from recent research. Springer-Verlag, Berlin, pp 59–73Google Scholar
- Coe SD, Coe MD (1996) The true history of chocolate. Thames and Hudson Ltd, LondonGoogle Scholar
- Czok G (1974) Zur Frage der biologischen Wirksamkeit von Methylxanthinen in Kakaoprodukten. Zeitschrift Ernährungswissenschaft 13:165–171Google Scholar
- Hamilton S (1992) Why the lady loves C6H5(CH2)2NH2. New Scientist 132:26–28Google Scholar
- James A (1990) The good, the bad and the delicious: the role of confectionery in British society. Sociol Rev 38:666–688Google Scholar
- James JE (1991) Caffeine and health. Academic, LondonGoogle Scholar
- Landau SI (1986) International dictionary of medicine and biology. Wiley, New YorkGoogle Scholar
- Liebowitz MR, Klein DF (1979) Hysteroid dysphoria. Psychiatr Clin N Am 2:555–575Google Scholar
- Lorr M, McNair DM (1988) Profile of mood states Bi-polar form. Educational and Industrial Testing Service, San DiegoGoogle Scholar
- MAFF (1998) Survey of caffeine and other methylxanthines in energy drinks and other caffeine-containing products (updated). Food Surveillance Information Sheet 144Google Scholar
- Merck (1996) The Merck Index: an encyclopedia of chemicals, drugs, and biologicals, 12th edn. Merck & Co., Inc., Whitehouse Station, N.J.Google Scholar
- Reynolds JEF (ed) (1993) Martindale: the extra pharmacopoeia. Pharmaceutical Press, LondonGoogle Scholar
- Rogers PJ (1994) Mechanisms of moreishness and food craving. In: Warburton DM (ed) Pleasure, the politics and the reality. Wiley, Chichester, pp 38–49Google Scholar
- Rozin P (1987) Sweetness, sensuality, sin, safety and socialization: some speculations. In: Dobbing J (ed) Sweetness. Springer-Verlag, London, pp 99–111Google Scholar
- Smit HJ, Rogers PJ (2001) Potentially psychoactive constituents of cocoa-containing products. In: Hetherington MM (ed) Food cravings and addiction. Leatherhead Food RA Publishing, Leatherhead, pp 325–349Google Scholar
- Smit HJ, Rogers PJ (2002b) Effects of caffeine on mood. Pharmacopsychoecologia 15:231–258Google Scholar
- Tarka SMJ (1982) The toxicology of cocoa and methylxanthines: a review of the literature. CRC Crit Rev Toxicol 9:275–312Google Scholar
- Thayer RE (1989) The biopsychology of mood and arousal. Oxford University Press, New YorkGoogle Scholar