People who drink more than five cups of coffee a day face almost three times the risk of heart disease as people who abstain from coffee, according to a long-term study by Johns Hopkins University researchers.
The new findings, presented yesterday at the American Heart Association annual meeting here, suggest that heavy coffee drinkers are more likely to have a heart attack or suffer from heart disease, such as angina pectoris, a painful condition where the heart does not receive an adequate supply of blood.
"These results suggest that coffee drinking is an independent risk factor for heart disease," said Dr. Thomas Pearson, director of Preventive Cardiology at the university and coauthor of the study.
The role that coffee plays in heart disease continues to generate debate in the scientific community. Other studies have shown no link between heart disease and coffee drinking, while a few have shown a smaller risk than in the Johns Hopkins study.
Pearson and his coauthor, Andrea LaCroix, studied 1,337 men who graduated from Johns Hopkins medical school between 1948 and 1964; all were 22 when they entered the study. Data on participants' coffee use and smoking habits were collected at five-year intervals, making the study one of the longest continuous health investigations of Americans.
What sets this study apart from earlier research is the large number of participants, the young age at which they entered the study, the length of time they were tracked and, most importantly, the fact that only 14 percent smoked.
Heavy coffee drinking is often associated with cigarette smoking, itself an important risk factor for heart disease. In earlier studies, this coffee-cigarette connection made it difficult for researchers to determine which health effect might be caused by smoking and which might be caused by drinking coffee.
Even when researchers adjusted statistically for other risk factors -- age, cigarette smoking, high blood cholesterol levels and high blood pressure -- heavy coffee drinkers "had 2.5 times the risk of developing heart disease" as those who did not drink coffee, the study found.
Pearson recommended that all coffee drinkers "quit smoking, have blood cholesterol measured and, if . . . interested in maintaining a prudent life style," cut back coffee consumption to no more than two cups a day, as he said he and LaCroix have done.
Other scientists challenged the recommendation to limit coffee consumption to two cups a day as "premature."
"There's not enough consistent evidence to make that kind of recommendation," said Dr. William Kannel, former director of the Framingham Heart Study, who said he favored following Mark Twain's advice for "moderation in all things, including moderation."
Other researchers said they are reserving judgment until they read full drafts of the paper, which has not yet been accepted by a scientific journal for publication. However, the paper was reviewed by three independent scientists before being accepted for presentation at the meeting here.
Lynn Rosenberg of the Boston University School of Medicine said, "I would conclude that a link between coffee and heart attacks has not been established. On the other hand, it has not been ruled out."
An estimated 55 percent of Americans over age 10 drink coffee each day, according to industry figures.
William Brooks, a spokesman for the National Coffee Association, a trade group representing producers, said yesterday that the bulk of the medical literature "does not support a finding that coffee is a risk factor in the development of heart disease." Of 12 major studies in this area, he said, "10 found no relationship between coffee and heart disease. And of the two that did find an association, one was criticized by other scientists and the second was later reversed by the researchers when they did further work." Caffeine, the active ingredient in coffee, is also found in tea, chocolate, cocoa and many soft drinks.