Although quite popular with suburban “wine moms,” the purported heart-healthy benefits of light to moderate drinking may be an illusion.

A review of 50 academic studies comprising more than 260,000 participants has found a link between reduced alcohol consumption and improved cardiovascular health, even among lighter drinkers who consume only a dozen or two drinks per week. Lower alcohol consumption was associated with a reduced risk of coronary heart disease along with a lower body mass index and lower blood pressure, say investigators from the University of Pennsylvania and University College London, along with the London School of Hygiene & Tropical Medicine.

Tellingly, people with a specific genetic variant — the A-allele of ADH1B rs1229984 — drank 17.2 percent fewer alcoholic drinks per week with fewer episodes of binge drinking. Most common among East Asians, this variant of the “alcohol dehydrogenase 1B” gene affects the metabolism of alcohol, producing unpleasant side effects for some that includes nausea and face flushing, according to senior investigator Juan P. Casas, an epidemiologist at the London School.

“While the damaging effects of heavy alcohol consumption on the heart are well-established, for the last few decades we've often heard reports of the potential health benefits of light-to-moderate drinking,” he said in a press statement. “However, we now have evidence that some of these studies suffer from limitations that may affect the validity of their findings. In our study, we saw a link between a reduced consumption of alcohol and improved cardiovascular health, regardless of whether the individual was a light, moderate or heavy drinker.”

If causal, the association suggests that lighter drinkers may improve their heart health by reducing alcohol intake, the researchers concluded.

As to the quality of the study, the investigators acknowledged the challenge of conducting a randomized, controlled study given that people often change drinking habits over time. Yet by focussing on the genetic variant, they were able to observe light to moderate drinkers specifically, according to Shannon Armoils, senior research advisor at the British Heart Foundation, which funded the study.

"Studies into alcohol consumption are fraught with difficulty in part because they rely on people giving accurate accounts of their drinking habits. Here the researchers used a clever study design to get round this problem by including people who had a gene that predisposes them to drink less,” she said in the statement. “The results reinforce the view that small to moderate amounts of alcohol may not be healthy for the heart, although the study would need to be repeated in a larger group of people for definitive results.”

Yet although the debate remains open on the heart health of light to moderate drinking, Shannon says one thing is clear: “Drinking more than the recommended limits of alcohol can have a harmful effect on the heart.”

Source: Holmes MV, Dale CE, Silverwood RJ, et al. Association between alcohol and cardiovascular disease: Mendelian randomisation analysis based on individual participant data. BMJ. 2014.