The questions seem simple and straightforward enough: Is drinking coffee bad for your heart and circulatory system, or isn't it?
How much coffee is too much? How much, if any, can you safely drink without risking your health?
Obviously, such questions are a matter of wide interest: Coffee, in the view of most scientists, is one of the most widely used drugs in human society. So the answers must be known, available, fundamental.
In data on coffee and heart disease published within the last 24 hours, prominent researchers from Johns Hopkins University have underscored the extent to which--despite decades of inquiry into its health effects--the truth about coffee remains elusive.
An Intelligent Guess
Moreover, in the absence of the financial means to conduct a long-term study (and none is currently being planned) of perhaps thousands of coffee drinkers who would be followed for as long as 25 years, it is unlikely scientists will be able to do much more than speculate intelligently and differ politely among themselves about whether coffee is bad for your cardiovascular health.
Likely as not, consumers will be left to guess, wonder and decide on their coffee habits for themselves.
The newly published study is simply the latest in a seemingly endless series of research projects examining coffee and its effects on the human body. In the last year alone, nine major studies on the effects of coffee on the heart--all of them cautious and tentative in their conclusions--have been published in major journals. Fourteen have appeared inquiring into the possible link between coffee and cancer.
For the moment at least, a relationship between coffee-drinking and cancer seems unlikely, but the issue is still unresolved. The greatest interest and suspicion about coffee is directed at its possible role as a cause of heart disease.
On that issue, two major new pieces of research have emerged recently enough that they haven't even appeared in the scientific literature.
In one, experts at Northwestern University in Chicago--who have for more than 20 years been doggedly following the lives and health of nearly 2,000 male employees of Western Electric Co.-- concluded that there appears to be an association between six cups of coffee a day and an increased risk of death from heart disease. But curiously, there was no apparent evidence of risk from coffee consumption below six cups, noted Alan Dyer, a professor of community health and preventive medicine who led part of the research.
In Boston, though, a respected team at Harvard Medical School has just finished evaluation of 50 patients, looking for some indication that coffee influences the beating rhythm of the heart--which could be key evidence of a link to heart problems. But, said Dr. Thomas Graboys, the principal researcher, the study found no coffee-heart rhythm relationship, though final analysis of the Harvard data must await completion of a full-dress report and publication of the article in a journal.
The study, Graboys noted, makes it impossible for him to justify a campaign to discourage his own patients from drinking coffee. "If they want to drink a couple of cups a day," he said, "that's perfectly all right."
The newly published Johns Hopkins study that appeared Thursday in the New England Journal of Medicine has focused even more attention on the issue of coffee and heart disease.
Although the study's major conclusions were presented last year at a scientific convention of the American Heart Assn. and were extensively covered by news media at the time, the version that came out this week includes far more detail than emerged at the medical convention.
Simply put, the project concludes that if you drink five or more cups of coffee a day, you may be opening yourself to two or three times the risk of heart disease, or possibly having a heart attack, than if you drink less or none of the brew.
"Our findings support a strong, positive, dose-responsive, independent association between the risk of . . . coronary disease and coffee consumption," the report concluded. "The magnitude of the relation suggests a twofold or threefold elevation in the risk of . . . coronary disease associated with heavy coffee drinking."
Conducted by a team at Johns Hopkins and the federal government's National Center for Health Statistics, the new research focused on 1,130 medical students who enrolled at the university between 1948 and 1964. And therein is the beginning of what even the study's investigators concede is the problem with saying too much, too definitively, about coffee.
What the Johns Hopkins team did not study could be almost as significant as what it did.
Caffeine Factor Ignored
For instance, the research subjects, noted Andrea LaCroix, the project's principal investigator, were all male and all white and the research team did not differentiate between whether the coffee they drank was caffeinated or decaffeinated.