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Rethinking alcohol use and heart disease

New research explores how genes may affect your drinking habits and heart health.

If you enjoy a glass of wine with dinner, perhaps you’ve toasted the notion that you’re doing your heart a favor. For decades, news reports have heralded the heart-protecting effects of light to moderate drinking. (Moderate drinking means no more than one drink daily for women and two for men.)

In an effort to better understand alcohol’s role in heart disease, researchers reviewed more than 50 studies that linked drinking habits and heart health in over 260,000 people. The report, published in The BMJ in July, looked at the effects of a gene called alcohol dehydrogenase 1B, or ADH1B, which affects how quickly people break down alcohol. ADH1B has several different variants, and everyone has two copies of the gene, one from each parent.

“People with two copies of a particular variant of this gene tend to drink less alcohol than people without the variant,” says Dr. Kenneth Mukamal, associate professor of medicine at Harvard-affiliated Beth Israel Deaconess Medical Center and a co-author of the study. The reason? Their bodies break down alcohol at a faster-than-normal pace, which causes unpleasant symptoms such as nausea, headaches, and irritability, he explains. (A different version of the ADH1B gene that has similar effects occurs in about 30% of people of Asian ancestry, but this study included only people of European ancestry.)

Fewer drinks, less heart disease?

The study’s other key finding was somewhat surprising. “If alcohol is good for your heart and this gene makes you drink less alcohol, you’d expect people with the variant to have a higher risk of heart disease,” says Dr. Mukamal. But they didn’t—in fact, their risk was slightly lower.

Does this mean that even light or moderate drinkers should drink less—or that alcohol might not be good for your heart? Dr. Mukamal calls such conclusions a “leap of faith.” Like many studies, this one provides new insights but not definitive advice on alcohol’s health benefits and risks for the average person. That would require randomly assigning many people to abstinence or light or heavy drinking and following them for at least a decade—an experiment that’s unlikely to be done in the near future.

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The evidence that drinking alcohol is good for your heart isn’t as strong as you might think.

Unavoidable limitations

One limitation of this new research stems from the fact that the particular ADH1B variant studied is quite rare and found mainly among people of Jewish descent. That creates a possible bias, because this group may have a lower risk of heart disease for other reasons, such as their other genes or lifestyle habits.

A similar problem affects much of the earlier research on alcohol’s potential benefits. The majority of the studies are observational, which means that scientists observe and measure outcomes like heart attack or stroke among a large group of people. Over all, these studies suggest that moderate drinking lowers a person’s risk of developing and dying from heart disease by about 25%. But such research is subject to what scientists call “confounding”—an association between two things that is actually caused by something else.

Common confounders

Here’s how confounding could affect the alcohol-heart association: People who
are ill or taking certain medications often don’t drink alcohol. So, when
researchers compare drinkers and nondrinkers, the drinkers seem to have fewer health problems and live longer. But that might well be because they’re healthier
in general, not because they drink alcohol. Similarly, light to moderate drinkers tend to be educated and relatively wealthy—and to have some heart-healthy habits that could explain their lower risk of heart disease. But they’re also more likely to smoke than nondrinkers, which further clouds the picture.

If you’re seeking ways to lower your risk of heart disease, drinking alcohol should be way down at the bottom of the list, says Dr. Mukamal. Other habits like not smoking, getting regular exercise, and eating a healthy diet top the list because they’re good for your entire body, not just your heart.

That’s not the case with alcohol. The odds of developing cancer rise with alcohol intake, and heavy or regular drinking can lead to liver, breast, colon, and other cancers. Excessive drinking also has potentially fatal short-term risks, such as car crashes and other injuries, as well as many long-term heart-related risks. These include a higher risk of high blood pressure, atrial fibrillation, and stroke.

The bottom line: Drink for pleasure if you enjoy it, but don’t start drinking to help your heart. And always limit yourself to moderate amounts. 

Posted by: Dr.Health

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