The largest study to date on coffee-drinking and heart disease has found no evidence that moderate amounts of the stimulating brew increase the risk of heart attacks or stroke.
A slight increase in heart disease risk showed up among drinkers of decaffeinated coffee, but researchers said the link was not confirmed anddid not justify switching from decaf to regular.
The two-year study of more than 45,000 men seems likely to put to rest, at least for now, suspicions that caffeine -- whether in the form of coffee, tea, colas or candy -- might have adverse effects on the heart and blood vessels.
"Moderate intake of caffeine," up to six cups of coffee daily, "is unlikely to materially alter the risk of heart disease," said Dr. Meir Stampfer, an epidemiologist at the Harvard School of Public Health, which conducted the study. "It's probably not healthy to drink seven or eight cups a day," he added.
Although only men participated in the study, Dr. Stampfer said there was no reason to suspect a different outcome in women. A separate study of female nurses is also looking at this question.
The report, in today's issue of the New England Journal of Medicine, comes after years of conflicting studies, some suggesting that coffee drinkers have a somewhat higher risk of heart disease and others finding no hazard whatsoever.
Coffee also has been held suspect in a number of other health problems, including bladder and pancreatic cancer, benign breast cysts in women and ulcers.
However, Dr. Stampfer said that in his opinion, no harmful effects of coffee in moderate amounts have been confirmed. "It may make us epidemiologists seem like idiots," he said, referring to the back-and-forth results of many studies on coffee, "but I think what this means is that if there is some adverse effect, it is not strong."
Today's article in the New England Journal, written by Diederick E. Grobbee, Eric B. Rimm, Dr. Stampfer and others, cites previous efforts to determine coffee's effects on heart disease.
In one such project, 1,130 male medical students drank five or more cups of coffee a day. After being followed for up to 35 years, the men were found to have a 2 1/2 -fold greater risk of heart disease than non-drinkers.
But none of the previous studies has had as many participants as the current one, called the Health Professionals Follow-up Study, in which dentists, veterinarians and other health professionals are being observed for factors related to their risk of heart disease and cancer.
The scientists said they were surprised to find a "slight and marginally significant" increase in heart disease risk among drinkers of decaffeinated coffee: They were a little more than 1 1/2 times as likely to have heart attacks or strokes as those who did not drink coffee.
The researchers said that was not a very great additional risk and called the link statistically somewhat less reliable because the number of decaf drinkers was much lower than those who drank regular coffee.
"I don't make too much" of the finding, said Dr. Stampfer. "It definitely bears further study, but I don't think we can conclude on the basis of this study that decaffeinated coffee raises your risk of heart disease, and there's no reason to switch from decaffeinated to caffeinated coffee."
Whether it is meaningful, the finding about decaffeinated coffee falls in line with a report less than a year ago from Stanford University Medical School researchers, who said that individuals who drank decaffeinated coffee for two months had cholesterol levels 7 percent higher than those who drank regular coffee or none at all.
The number of subjects in the study, however, was small: 120 altogether.