Light-to-moderate alcohol drinking good for the heart? Maybe not

Light-to-moderate consumption of alcoholic beverages has been touted as beneficial for heart health. But a large study says otherwise, revealing that alcohol consumption in whatever amount carries increased cardiovascular risk and that its supposed benefits appear to be the upshot of favourable lifestyle factors common among light-to-moderate drinkers.

In a cohort of 371,463 UK Biobank participants (mean age 57 years, 46 percent men) who consumed a mean of 9.2 standard drinks per week, the prevalence and risk of cardiovascular diseases (CVDs)—including hypertension, coronary artery disease (CAD), myocardial infarction, stroke, heart failure, and atrial fibrillation—were lower among light-to-moderate drinkers than abstainers, consistent with previous reports. Accordingly, heavy drinkers had the highest CVD prevalence and risk. [JAMA Network Open 2022;5:e223849; BMJ Open 2021;11:e043985; Lancet 2018;391:1513-1523; BMJ 2017;356:j909; Med J Aust 2013;198:419-422]

At the same time, light-to-moderate drinkers exhibited healthier lifestyle behaviours than abstainers. The former had better self-reported overall health and were less likely to smoke, had lower body mass index, had higher levels of physical activity, and consumed vegetables more.

“Adjustment for the aforementioned lifestyle factors attenuated the cardioprotective associations with modest alcohol intake. For example, in baseline models, moderate intake was associated with significantly lower risk of hypertension and CAD, but adjustment for just six lifestyle factors rendered these results insignificant,” according to investigators from Massachusetts General Hospital, Harvard Medical School in Boston, US.

Human genetic evidence

What is more, genetic evidence from Mendelian randomization (MR) analyses supported a nonlinear, consistent association between all amounts of alcohol consumption and both hypertension and CAD. Specifically, light alcohol intake (0–7 drinks per week) was associated with minimal risk increases, whereas heavier consumption conferred exponential risk increases (much higher at 7–14 drinks per week and especially high at ≥21 drinks per week) among both men and women.

The results were replicated in an additional analysis comprising 30,716 participants in the Mass General Brigham Biobank.

These nonlinear MR analyses, according to the investigators, have at least two important clinical implications.

“First, they substantiate prior claims that no amount of alcohol is protective against cardiovascular disease; and second, they newly demonstrate that the adverse effects of alcohol unduly affect those who consume heavily, implying that for an equivalent reduction in alcohol intake, the improvements to cardiovascular health may be significant for heavier drinkers but only slight for those who consume modestly,” they pointed out.

“Although risk thresholds are inherently somewhat subjective, the findings again bring into question whether an average consumption of 2 drinks per day (14 drinks per week) should be designated a low-risk behavior,” the investigators said. [Lancet 2018;391:1513-1523; Addiction 2016;111:1293-1298; https://www.dietaryguidelines.gov/2020-advisory-committee-report]

They believe their results stress the importance of aggressive efforts to reduce alcohol intake among heavy drinkers, given that several-fold increases in risk were observed for those consuming 21 or more drinks per week.