(Updates with comment from author of previous alcohol study in last two paragraphs)
July 11 (Bloomberg) -- Those who suffer from “Asian glow,” a type of facial flushing after a few drinks, should thank their genes for the side effect because it may help keep their hearts healthy.
The gene in question is alcohol dehydrogenase 1B, or ADH1B. When those with a variant of the gene drink alcohol, a chemical called acetaldehyde is produced, resulting in unpleasant symptoms such as nausea, headache and facial flushing, commonly referred to as “Asian glow” or “Asian flush.” Generally, the response among carriers is to avoid drinking too much.
Research now shows that those with the gene variation also have a lower risk of heart disease from their reduced alcohol consumption. The finding, published today in the BMJ medical journal, suggests that less drinking, with or without the gene variation, improves heart health, according to lead author Juan Pablo-Casas. It also contrasts with results from earlier studies that have shown the health benefits of moderate drinking.
“We are using the genetic variant only as a proxy, an instrument, to infer what would be the effect of alcohol for anyone, regardless of whether or not they carry the genetic variant,” Pablo-Casas, a professor of epidemiology at the London School of Hygiene and Tropical Medicine, said in a telephone interview.
Carriers of the variant are common among East Asian populations, while only seen in 7 percent of Europeans, Pablo- Casas said.
Researchers analyzed data from 56 studies involving 260,000 participants. Across the studies, those with the gene variant on average consumed 17 percent less alcohol per week than those without it. Carriers were also 22 percent less likely to engage in binge drinking.
As a result, they were on average 10 percent less likely to develop heart disease, compared with non-carriers of the gene variant. When non-drinkers were excluded, the result was even more striking: the odds of getting heart disease were 14 percent lower among carriers than among non-carriers.
Previous studies showing the possible health benefits of alcohol have limitations, Pablo-Casas said. In particular, in those studies, light and moderate drinkers are more likely to engage in other healthy behavior such as exercise and healthy eating than heavy drinkers, he said.
“So it’s very difficult to disentangle whether the beneficial aspects for cardiovascular disease is the low or moderate alcohol consumption or the other health-conscious behavior,” he said.
Non-drinkers recruited in earlier studies could also include those who had been regular drinkers before the study and therefore end up appearing to have a higher risk of disease, he said. In the new study, the researchers didn’t have to worry about these confounding factors, which were evenly distributed across the two groups -- those with the gene variant and those without.
“This impressive international study of over a quarter of a million people rightly concludes we should not accept the dogma that alcohol drinking is good for us,” Tim Spector, professor of genetic epidemiology at King’s College London said in a statement. “Gene markers are often a better way of assessing behavior than unreliable questionnaires.”
Still, the study may also have its own limitations, he said. People with alcohol intolerance may also have other unmeasured traits such as gut microbes that prevent heart disease, he said.
The study also didn’t show a link between the gene variant and lower levels of HDL, the good type of cholesterol, said Kenneth Mukamal, author of an earlier study showing moderate alcohol consumption is associated with lower risk of death from heart disease.
“The results are very intriguing but are far from conclusive about how alcohol affects heart disease,” said Mukamal, associate professor of medicine at Beth Israel Deaconess Medical Center in Brookline, Massachusetts. “As of today, they don’t seriously change the much larger bulk of data –- some of it also genetic –- that relates alcohol to lower risk of heart disease, but they do emphasize our need for continued study.”