Dr. Dana Frank fields questions almost every week from patients who have heard that drinking alcohol can be good for the heart.
One man wondered whether he should drink even though it gives him migraines. Another justified his three or four bottles of wine a week by the studies showing that alcohol can reduce the risk of heart attack.
"Therapeutically, I don't necessarily sit here and recommend that they drink alcohol on a regular basis," says Frank, an internist at Johns Hopkins' Green Spring Station clinic in Baltimore County. "It's very individualized."
Depending on how much - and how often - a person drinks, alcohol can have a wide range of effects on the body.
But experts say the evidence showing that consuming light to moderate amounts has cardiac benefits should not be viewed as a reason to start drinking - especially if you're not a drinker already.
A study published in The New England Journal of Medicine this month found that how often a person drinks is more important than how much or whether it's whiskey, wine or beer.
Marcus Allen, 29, learned about the health benefits of drinking red wine a few years ago, so he usually has a glass of merlot, cabernet or syrah about three nights a week over dinner.
The West Baltimore chiropractor's family has a history of high blood pressure and high cholesterol - two risk factors for heart disease.
"I just saw the benefits [of moderate drinking]. People don't do things in moderation, and I think moderation is the key," he says.
Alcohol in moderate amounts raises the level of high-density lipoproteins, the "good" cholesterol, in the blood. It also keeps platelets from sticking together, which can help prevent clotting and, so, heart attacks.
"Alcohol is good for the heart, but when it's prescribed at the right amount," says Dr. Michael Miller, director of the Center for Preventive Cardiology at the University of Maryland Medical Center.
Federal health guidelines define "moderate" drinking as no more than one drink a day for most women and no more than two a day for most men. A standard drink is about 12 ounces of beer, 5 ounces of wine or 1.5 ounces of 80-proof liquor.
Some people, including children and adolescents, pregnant women and those taking certain medications, are urged by doctors not to drink at all.
But there is no single formula for the "right" amount to drink: It could depend at least in part on everything from family medical history and body size to gender and ethnicity.
Women get a higher concentration of alcohol in their blood than men, even when they drink the same amount, and are more susceptible to alcohol-related organ damage, according to the National Institute on Alcohol Abuse and Alcoholism. Some Asians don't tolerate alcohol because of inactivity of an enzyme that helps break it down.
"To try to come up with a guideline that gives people a broad instruction on how much alcohol to be drinking is very difficult because those parameters - what people's susceptibility is to alcohol, what diseases they're at risk for and so forth - are so individualized," says Dr. Kenneth J. Mukamal, assistant professor of medicine at the Harvard Medical School and associate physician at Beth Israel Deaconess Medical Center in Boston.
He was lead author of the Journal study that showed that frequency of drinking mattered most in reducing heart disease. Someone who drank at least three days a week had about a third fewer heart attacks than someone who didn't drink at all.
But that study included only healthy middle-age men - so its findings might not be applicable to the general public.
"As of now, I don't know anybody who honestly drinks a certain amount because of heart disease risk, just to prevent heart disease," says Mukamal.
"I don't think that this [study] is ... a good reason to do that for the simple reason that alcohol has a myriad of health effects. It affects many, many more organs than just the heart. It's not, I think, straightforward to take results like ours and easily turn them into a prescription for a certain amount of alcohol consumption."
Generally, consuming more than two drinks daily can increase a person's risk of adverse effects, including motor vehicle accidents, high blood pressure, liver disease and some types of cancer, says Dr. Stephen W. Havas, professor of epidemiology, preventive medicine and medicine at the University of Maryland School of Medicine.
But even light or moderate drinking can impair mental function. A recent American Medical Association report said that adolescents and young adults who drink could risk long-lasting brain damage.
Paying attention to drinking patterns is important. Researchers point out that two people who consume the same "moderate" amount of alcohol in, say, a week, won't necessarily experience the same effects if one is drinking large amounts in one or two sittings - rather than small amounts more regularly. Binge-drinking is particularly harmful.
"There's meaning in the pattern," says Thomas K. Greenfield, director of the Alcohol Research Group, a federally funded alcohol research center in Berkeley, Calif. "The pattern helps determine the degree of harm."
Dr. Steve Nelson, director of the Alcohol Research Center at the Louisiana State University Health Sciences Center, who studies the impact of alcohol on the immune system, thinks the overall potential risks associated with alcohol consumption probably outweigh the benefits. He says some people forget that alcohol is a drug.
"Some drugs will have beneficial effects in one organ, say, but have harmful effects in others," he says.
Mukamal, of Harvard Medical School, wants to remind drinkers of something else: Alcohol is addictive.
"The $64,000 question in all of this is: Does encouraging moderate drinking lead to increased heavy drinking? And we don't know the answer to that right now," he says.
"If we knew for sure that a recommendation that some people drink moderately would never lead to them being problem drinkers, this would be a much easier discussion to have."