Abstract
Background:
Caffeine enhances the function of the central nervous system. Recently, the overuse toxicity of caffeine has become a social problem, therefore to reveal which factors give vulnerability to caffeine is an urgent issue. We reported that caffeine (200 mg) increased blood pressure (BP) and calculation speed and also that C allele carriers of adenosine A2A receptor (ADORA2A, rs5751876) and G allele carriers of dopamine D2 receptor (DRD2, rs55900980) may be more susceptible to caffeine by conducting a clinical trial with 359 voluntary participants. Because cytochrome P450 (CYP) 1A2 is involved in metabolism of caffeine, the polymorphisms of CYP1A2 may influence the effect of caffeine. In this study, we further investigated whether the polymorphisms of CYP1A2 affects BP and calculation speed after caffeine intake.
Methods:
We analyzed the polymorphisms of CYP1A2 (*1F, rs762551; *1C, rs2069514) using samples of the 206 participants from a former study, who had provided secondary-use consent for gene analysis, after the ethics committee approval. The data of smokers (5 in 206 volunteers) were excluded from analysis because smoking may change the expression of CYP1A2.
Results:
Polymorphisms of CYP1A2, ADORA2A and DRD2 did not influence BP or calculation speed when all volunteers' data were totally analyzed. Generally, habitual consumption of caffeine is considered to reduce the effect of caffeine. Our data showed the changes of BP in participants with relatively high caffeine consumption (≥100 mg/day) tended to be smaller than those in participants with low caffeine consumption (<100 mg/day). Therefore further analysis was conducted using only the data of participants with low caffeine consumption (<100mg/day). The results showed that the changes of systolic BP (SBP) after caffeine intake were significantly larger in CC carriers than in A allele carriers of CYP1A2*1F. G allele carriers in CYP1A2*1C and C allele carriers in ADORA2A showed slightly, but not significantly, larger changes in SBP. However, DRD2 did not influence the changes of BP. Polymorphisms of CYP1A2, ADORA2A and DRD2 did not influence the speed of calculation.
Conclusions:
CYP1A2*1F may influence the effect of caffeine on SBP in non-smoking and non-habitual caffeine drinkers.
