Study: Gene make-up boosts alcohol's heart value
BOSTON, Massachusetts (CNN) -- In what is considered a groundbreaking study on genetics, alcohol, and heart disease, Harvard researchers found that while moderate drinking can be good for everyone, it's particularly good for one out of six people with a particular genetic make-up.
People with a variation in the alcohol dehydrogenase type 3 (ADH3) gene metabolize alcohol more slowly than others. When they have a drink or two a day, they are 82 percent less likely to have a heart attack than a person without the variation who drinks the same amount.
"This is a very important message and one that takes us into the 21st century," said Dr. Robert Eckel, chairman of the American Heart Association's nutrition committee.
Eckel and other experts in the fields of genetics and heart disease said that while it's not practical now to get this test, the study is a sign of what medicine will be like in the future: making recommendations to people based on their particular genetic make-up.
"If this observation is confirmed, I can see a scenario where a physician does genetic testing and says 'Mrs. Jones, you have (this genetic variation) and you don't drink much. Maybe we ought to increase your consumption," Eckel said.
But doctors add that no matter what the genetic make-up, they would have to be very careful before encouraging someone to drink, even if it were just a drink or two a day.
"I think we'll be finding many more new examples of interactions of genetics with diet and other lifestyle factors," said Dr. Meir Stampfer, one of the study's co-authors and chairman of the department of epidemiology at the Harvard School of Public Health.
Genetics will also help explain why some people respond well to drugs while others don't, said Jeffrey Long, a geneticist at the National Institute on Alcohol Abuse and Alcoholism, a part of the National Institutes of Health.
"One of the leading causes of death is adverse responses to drugs that work well in most people," he said.
In the Harvard study, published in the New England Journal of Medicine, researchers identified 396 men who had had heart attacks and matched them with men who had not. All the men were doctors and part of the Physicians' Health Study.
The researchers found that the men who had not had heart attacks were more likely to have two genes -- one from each parent -- for slow metabolism of alcohol. The heart attack victims were more likely to have either two genes for fast alcohol metabolism or one fast gene and one slow gene.
The men with the two slow genes were more likely to have higher levels of HDL cholesterol, the so-called "good" cholesterol. About 16 percent of the Caucasian population has the "slow-slow" genetic make-up, but it's very rare among people of Asian or African heritage.
The study showed that all the men, no matter what their genetic make-up, had a lower risk of heart disease when they had a drink or two a day. Numerous other studies have shown that alcohol raises HDL levels and decreases the blood's propensity to clot, making a heart attack less likely.
The paper's co-authors theorize that when alcohol is metabolized more slowly, it has more time in the body to have good effects.
Stampfer said this research shows it's the alcohol, rather than some other factor, that gives drinking its beneficial effects. Other factors, such as the tannins in red wine, have been used to explain why people who have a drink or two a day have lower rates of heart disease.
"Some people have claimed that moderate drinkers are the same ones who jog, and maybe it's the jogging that protects against heart disease," Stampfer said. "But since this genetic variation is distributed evenly without regard to anyone's lifestyle, the fact that we see an impact on the risk of heart disease tells us it's the alcohol."
The men in the study were between the ages of 40 and 84. Another co-author, Eric Rimm, associate professor of epidemiology and nutrition at the Harvard School of Public Health, said it's not known at what point in life one would have to start drinking to have the beneficial effects. "That's the million dollar question," he said.
Another study, done on nurses, indicates that the results would be similar in post-menopausal women, Rimm said, adding that pre-menopausal women already have a very low risk of heart disease.
The article was written originally as the doctoral thesis of the lead author, Lisa Hines.
Some geneticists criticized the study, saying the results, while interesting, are barely statistically significant. "This in no way means the conclusions are invalid, but they may be perhaps a bit premature," said Joseph Terwilliger, a geneticist at the Columbia Genome Center.
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