BackgroundPast studies have found a strong relationship between alcohol drinking and human health.MethodsIn this study, we first tested the association of rs671 with alcohol use in 2349 participants in southeast China. We then evaluated the causal impact between alcohol use and cardiovascular traits through a Mendelian randomisation (MR) analysis.ResultsWe found strong evidence for the association of rs671 in the ALDH2 gene with alcohol drinking (p=6.08×10^-47; OR_adj G=4.50, 95% CI 3.67 to 5.52). We found that female G carriers of rs671 had a higher proportion of non-drinkers than male G carriers (88.01% vs 38.70%). In non-drinkers, the female G allele frequency was higher than the male G allele frequency (71.1% vs 55.2%). MR analysis suggested that alcohol use had a causal effect on blood pressure (increasing 9.46 mm Hg for systolic blood pressure (p=9.67×10^-4) and 7.50 mm Hg for diastolic blood pressure (p=9.62×10^-5)), and on hypertension in men (p=0.011; OR =1.19, 95% CI 1.04 to 1.36) and in pooled samples (p=0.013; OR =1.20, 95% CI 1.04 to 1.39), but not in women. We did not observe a causal effect of alcohol use on body mass index and lipid levels; further studies are needed to clarify the non-causal relationship.ConclusionsCompared to never-drinkers, current and previous alcohol use had a causal effect on blood pressure and hypertension in pooled samples and in men. These results reflect Chinese culture which does not encourage women to drink.