Background: Previous studies of a functional variant of the catechol-O-methyl transferase (COMT) gene, Val158Met, have provided inconsistent results with regard to blood pressure or hypertension. We examined the effect of this variant, the considering environmental factors of daily salt and energy intakes.
Methods: A total of 735 Japanese men (mean age, 47 years) were recruited from two separate occupational cohorts from Kanagawa and Kyoto prefectures. Participants were genotyped for the presence of COMT Val158Met (rs4680, G/A). Daily salt and energy intakes were evaluated by the food frequency questionnaire (FFQ).
Results: Met/Met carriers had higher adjusted systolic blood pressure (SBP) (+4.79 mm Hg, P < 0.001) and diastolic blood pressure (DBP) (+2.33 mm Hg, P = 0.001) than Met/Val or Val/Val carriers. There was a significant association between being a Met/Met carrier and having a higher prevalence of hypertension (odds ratio = 2.448, 95% confidence interval = 1.426-4.205, P = 0.001). When salt and energy intakes were dichotomized, the effect of Val158Met on hypertension was observed only in the high-energy intake group, and was equivalent between low- and high-salt groups.
Conclusion: The Met allele of COMT Val158Met is associated with higher blood pressure and higher prevalence of hypertension in Japanese men, and energy intake may interact with this effect.