Then, Dr. Gary D. Friedman, an epidemiologist and colleague who was computer-savvy years before it was commonplace, told him about a study he wanted to do. Using the large patient database afforded them by Kaiser Permanente in Northern California, a health maintenance organization where they both worked, they'd plug reams of information into the computer and possibly find new associations between habits and heart health.
Klatsky agreed to the idea. Together, they inputted the information. Many of the risk factors of heart disease were already known at the time; the idea, Klatsky recalled recently, was "to see what we could find that wasn't known."
The idea paid off.
"One of the things that came out was that abstainers [of alcohol] seemed to be at high risk for heart disease," Klatsky says. "That hadn't been reported from an epidemiological standpoint." The theory was around, tossed about by experts.
But now Klatsky and Friedman had convincing proof that moderate drinking -- when cigarette smoking was controlled -- decreased the risk of heart attacks. Their study was published in the Annals of Internal Medicine in late 1974.
In the nearly 30 years since, Klatsky, who says Friedman was his mentor, has been unearthing more details about why and how alcohol might protect the heart. He's also found how it might protect your health in myriad other ways, staving off stroke, gallstones, possibly diabetes and vascular disease in the extremities.
In late 2001, Friedman, Klatsky and others presented an updated analysis of more than 128,000 patients and found that those who drank one or two alcoholic drinks a day had a 32 percent lower risk of dying from heart disease than did abstainers.
The road hasn't been easy at times. "There have been people who got very upset and said it is going to promote alcoholism," says Klatsky, a senior consultant in cardiology and adjunct investigator at the division of research at the Kaiser Permanente Medical Center in Oakland, Calif.
On that point, Klatsky is clear. He's not suggesting anyone take up drinking based on his research to improve health. In fact, that's the trickiest part -- a doctor trying to tell his or her patient whether they should or should not drink for health benefits.
The answer, Klatsky says, is complicated and very individual.
Suppose a woman, 40, has had children, is at low risk of breast cancer (which has been linked with drinking in some studies), eats a healthy diet, does not smoke, has low cholesterol and no family history of heart disease and no moral reasons not to drink. Should she drink for health benefits?
"I would say she can choose to drink for pleasure," Klatsky says. "The data don't show a net benefit [for health] until a woman reaches menopause [when heart disease risk rises]."
But a man of the same age, with basically the same habits and background, would probably net health benefits from a drink or two a day, he says, because he is more at risk for having a heart attack than the woman, Klatsky says.
As convincing as the data are about alcohol and heart health, drinking must be put into perspective, Klatsky says. "The important thing is, there are lots of lifestyle measures useful to prevent heart attack -- not smoking, exercising, proper diet, getting blood pressure under control if it is high, getting cholesterol under control. All of those things are more important than light drinking."
Klatsky, now 73, practices what he preaches. "I have a little wine with dinner," he says. He's a six-time marathoner, but knee problems have forced a switch to walking, logging four miles a day.
Friedman, now 69, says he is happy the first cardiologist he asked to join his research project three decades ago was too busy and he turned to Klatsky. "He's primarily a clinician who is very bright and got interested in the alcohol field and became a very well-respected researcher," Friedman says.
It took the computerized data to sort it all out, but Friedman says both he and Klatsky had lots of hints about the health effects of alcohol, even way back in their residency days. They both served at Boston City Hospital as house officers, though Klatsky preceded Friedman by about four years.
Later, they talked about some of their patients, Friedman recalls. "We used to see a lot of alcoholics who had cirrhosis -- but very clean arteries."