- The widely held notion that light to moderate alcohol consumption confers heart protection is largely (or perhaps all) a product of confounding factors.
- Alcohol may be a direct cause of cardiovascular conditions, especially among heavy drinkers.
- No amount of alcohol is protective against cardiovascular disease.
No amount of alcohol is good for the heart, according to the latest study to weigh in on this unresolved subject matter. Published in JAMA Network Open in March, it included more than 370,000 adults in the U.K. who consumed an average of 9.2 drinks a week. As previous studies over decades have often found, those who drank lightly to moderately had the lowest risk for heart disease, followed by abstainers. But when the researchers controlled for other lifestyle factors (such as exercise, smoking, and diet), any benefit from alcohol consumption was significantly reduced. That is, light to moderate drinkers had healthier lifestyles, and that is what likely accounted for their healthier hearts—not the alcohol. Unsurprisingly, heavy drinkers still had the highest heart disease risk, even when such lifestyle factors were accounted for. In the study, light drinking was defined as 0 to 8.4 drinks a week; moderate as 8.5 to 15.4; and heavy as 15.5 to 24.5. According to the researchers, “Adjusting for only a few lifestyle factors…we observed attenuation in the apparent protective associations between modest alcohol intake and cardiovascular risk, suggesting that adjustments for yet unmeasured or unknown factors may further attenuate—if not, eliminate—the residual, cardioprotective associations observed among light drinkers.” Using a sophisticated analytical method called Mendelian randomization, the researchers further determined that people genetically predisposed to drink more were more likely to develop hypertension and coronary artery disease. This research method uses genetic data to more accurately determine whether study findings represent causation or are just associations, and it is less likely than typical observational studies to be influenced by confounding factors. And while the risk to cardiovascular health was still relatively low at the low end of alcohol consumption (up to seven drinks per week), the risk rose exponentially with heavier drinking. The researchers came to several conclusions, including: