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ORIGINAL RESEARCH COMMUNICATION |
1 From the Department of Nutritional Sciences, University of Toronto, Canada (MCC and AE-S); the Department of Nutrition, Harvard School of Public Health, Boston, MA (HC); and the Centro Centroamericano de Poblacion, Universidad de Costa Rica, San Pedro de Montes de Oca, Costa Rica (HC)
Background: Caffeine is the most widely consumed stimulant in the world, and individual differences in response to its stimulating effects may explain some of the variability in caffeine consumption within a population.
Objective: We examined whether genetic variability in caffeine metabolism [cytochrome P450 1A2 (CYP1A2) 163A
C] or the main target of caffeine action in the nervous system [adenosine A2A receptor (ADORA2A) 1083C
T] is associated with habitual caffeine consumption.
Design: Subjects (n = 2735) were participants from a study of gene-diet interactions and risk of myocardial infarction who did not have a history of hypertension. Genotype frequencies were examined among persons who were categorized according to their self-reported daily caffeine intake, as assessed with a validated food-frequency questionnaire.
Results: The ADORA2A, but not the CYP1A2, genotype was associated with different amounts of caffeine intake. Compared with persons consuming <100 mg caffeine/d, the odds ratios for having the ADORA2A TT genotype were 0.74 (95% CI: 0.53, 1.03), 0.63 (95% CI: 0.48, 0.83), and 0.57 (95% CI: 0.42, 0.77) for those consuming 100200, >200400, and >400 mg caffeine/d, respectively. The association was more pronounced among current smokers than among nonsmokers (P for interaction = 0.07). Persons with the ADORA2A TT genotype also were significantly more likely to consume less caffeine (ie, <100 mg/d) than were carriers of the C allele [P = 0.011 (nonsmokers), P = 0.008 (smokers)].
Conclusion: Our findings show that the probability of having the ADORA2A 1083TT genotype decreases as habitual caffeine consumption increases. This observation provides a biologic basis for caffeine consumption behavior and suggests that persons with this genotype may be less vulnerable to caffeine dependence.
Key Words: Caffeine ADORA2A adenosine A2A receptor gene CYP1A2 cytochrome P450 1A2 genotype epidemiology dependence
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