Between genetic variants pinpointed in genome wide association study there is the rs1378942 near the CYP1A1/CYP1A2 locus. Coffee consumption has been associated with blood pressure (BP) but with sometimes contrasting evidences. A part of BP-coffee relationship could be mediated by genetic mechanisms: that is single nucleotide polymorphisms (SNPs) nearby the CYP1A2 gene, which metabolize caffeine, could influence BP. Indeed, smoking habit induces the expression of the CYP1A2 enzyme whereas coffee consumption itself could increase CYP1A2 activity. The aim of the present study was to explore if coffee consumption and/or smoking habit may affect BP and BP change over time (delta-BP), considering the rs1378942A > C polimorphysm.Design and method:
Coffee intake was collected by a modified diet history method and the rs1378942 was genotyped by Taqman in > 28,000 participant of the Malmö Diet and Cancer (MDC). We performed a replication in 3381 participants that were rescreened after a period (13–20 years) of follow-up (MDC-FU) and in the Malmö Preventive Project (MPP; n > 17,000).Results:
In MDC, both systolic and diastolic BP were positively associated with the rs1378942A > C, suggesting that carrying the C variant could increase BP (for SBP β = 0.397 ± 0.185, p = 0.031; for DBP β = 0.220 ± 0.100, p = 0.028). Coffee consumption as well as smoking were negatively associated with both SBP and DBP (p < 0.0001 for coffee consumption; p < 0.05 for smoke). A significant interaction between smoke and coffee was found, and both coffee and smoke interact with the rs1378942A > C (pinteraction < 0.05 for all). After stratification, in non-smokers who drink at least 600 gr/day of coffee, carriers of the rs1378942C variant had a higher BP (p_trend < 0.01 for SBP and DBP). At MDC-FU, only in non-smokers who drink less than 300 gr/day, a lesser delta-DBP was shown for rs1378942C carriers (ptrend < 0.01). In the MPP we found an interaction between the rs1378942A > C and smoking (pinteraction < 0.05; data on coffe consumption not available).Conclusions:
This study demonstrates that the effect of some genetic loci on BP could be highly influenced by voluptuary habits. In particular, coffee and smoke could influence the effect of the CYP1A1/CYP1A2 locus probably due to the metabolic action of the CYP1A2.