Leo Sher, M.D.
Three days ago, a research report, “Conventional and genetic evidence on alcohol and vascular disease aetiology: a prospective study of 500000 men and women in China” was published in The Lancet online ahead of print (1).
Using data from a nationwide prospective study in China, researchers investigated the relationships between alcohol and cardiovascular disease by comparing the findings from conventional epidemiology, i.e., classifying people by self-reported intake, and from genetic epidemiology, i.e., using two genetic variants to classify people by genotype-predicted mean alcohol intake. Many people in East Asia are unable to drink alcohol due to genetic intolerance. 161,498 participants were genotyped for two variants that affect alcohol metabolism, ALDH2-rs671 and ADH1Brs1229984. The ALDH2-rs671 variant, which is frequent in East Asian people, significantly slows acetaldehyde breakdown, and the subsequent buildup of acetaldehyde causes serious discomfort and distress that strongly decrease alcohol use. Since few Chinese women drink, these genetic variants were utilized to predict differences in mean alcohol intake in men, but not in women.
For stroke, genotype-predicted mean alcohol intake had a continuously positive log-linear association with risk, which was stronger for intracerebral hemorrhage than for ischemic stroke. This study shows that men who drink moderately, 10 to 20 grams of alcohol a day, increase their risk of stroke by 10 to 15 percent. Among heavy alcohol users, ingesting four or more drinks a day, blood pressure rises significantly and the risk of stroke increases by around 35 percent.
In summary, this research study demonstrates that blood pressure and stroke risk increase steadily the more alcohol people drink. Alcohol intake increases both ischemic stroke risk and hemorrhagic stroke risk. The results of this study also suggest that previous claims that one or two drinks a day might protect against stroke are not true.
The paper includes a statement that the study was funded by “Chinese Ministry of Science and Technology, Kadoorie Charitable Foundation, National Natural Science Foundation of China, British Heart Foundation, Cancer Research UK, GlaxoSmithKline, Medical Research Council, and Wellcome Trust.”
- Millwood IY, Walters RG, Mei XW, Guo Y, Yang L, Bian Z, Bennett DA, Chen Y, Dong C, Hu R, Zhou G, Yu B, Jia W, Parish S, Clarke R, Smith GD, Collins R, Holmes MV, Li L, Peto R, Chen Z. Conventional and genetic evidence on alcohol and vascular disease aetiology: a prospective study of 500000 men and women in China. Lancet, in press.