But the news isn't totally rosy. Blood thinning could raise the risk of bleeding-type strokes, the researchers note.
So should you drink or not? The study doesn't issue a verdict. It focused on the science of how moderate drinking may affect the heart.
"The findings" should not be used by people as any reason to begin drinking," researcher Kenneth Mukamal, MD, MPH, MA, says in a news release.
Mukamal works at Boston's Beth Israel Deaconess Medical Center. His study appears in the October issue of Alcoholism: Clinical & Experimental Research.
Platelets aren't lone rangers. They cluster together to do their work. Platelet "stickiness" and activation were topics for Mukamal's team.
Mukamal's study included about 3,000 adults who didn't have heart disease. They were the children of participants from the Framingham Heart Study.
Participants gave blood samples in 1991 and 1994 as part of the Framingham Offspring Study, which began in the early 1970s. They were also surveyed about their drinking habits, smoking status, physical activity, and other health problems (such as high blood pressure and diabetes).
Participants were asked how often and how much they drank of wine, beer, and liquor. Beer was the most common drink for men; wine was women's most common drink.
"We found that among both men and women, an intake of three to six drinks per week or more was linked to lower levels of stickiness by aggregability," says Mukamal in the news release.
"Aggregability" means the ability to cluster together. It measures platelet stickiness.
"Among the men, we also found that alcohol intake was linked to lower levels of platelet activation," Mukamal continues.
"Together, these findings ... identify moderate drinking as a potential blood thinner," he says.
The type of alcohol didn't appear to change the results. The study didn't specify whether wine was red or white.
Moderate drinkers have been shown to have lower rates of heart attacks than nondrinkers, the researchers note.
"Our findings add to a large body of evidence showing that moderate drinking has effects on blood coagulation, which may have both good and bad effects, but now identify a new avenue by which this effect may occur," says Mukamal.
What's a Serving?
It's easy to get carried away with serving size, especially if you're drinking out of large wine goblets or hefty beer glasses.
What you consider "one" drink could actually be several drinks if your portions are off.
Here's how the researchers defined one serving:
- 12 ounces of beer
- 5 ounces of wine
- 1.5 ounces of 80-proof spirits
Self-reports, like those used in this study, aren't always perfect. No one was told to drink (or not drink) to directly test alcohol's effects.
Mukamal's team will evaluate other ethnic groups, according to the news release.
"If you drink, do so in moderation," states the web site of the American Heart Association (AHA).
"The incidence of heart disease in those who drink moderate amounts of alcohol (no more than two drinks per day for men or one drink per day for women) is lower than in nondrinkers. However, with increased intake of alcohol, there are increased health dangers including high blood pressure, obesity, and stroke," continues the AHA.
Of course, alcohol is not recommended for pregnant women and should not be drunk before driving.