Coffee-Health Research Is Grinding On
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.
But no.
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.
More Detail
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.
Moreover, since the way caffeine is removed from coffee today is somewhat different from the process used when the study began, it isn’t at all clear whether caffeine’s role in physical harm from coffee can even be determined from the study.
Confounding the issue even further is that smoking among the medical students in question declined radically after they left their medical training and there is still at least some confusion over what problems were possibly coffee-related and which were attributable to smoking.
More confusing still is the fact that the study did not consider the dietary habits of the doctors in question and didn’t--in fact, couldn’t--grapple with the possibility that men who drink a lot of coffee more commonly consume a diet associated with heart disease than men who drink little or no coffee.
More broadly, though, LaCroix said in a telephone interview from her headquarters at the government agency, the study also could not resolve what she conceded might easily be a haunting question for lay people: Whether heavy coffee drinking is just another reflection of high-intensity personality traits that have been increasingly associated with heart disease. In other words, is coffee simply a reflection of the personality foibles that produce heart disease--and not, in itself, a cause?
Variety of Behaviors
“Coffee consumption is colored by a variety of behaviors that go along with it,” LaCroix said. “This piece (of research) is based on a cohort of medical students and one of the things that’s important is that this finding be replicated by a more heterogeneous, nationally representative population of men and women from all walks of life.
“Can it be replicated? What else is there about coffee consumption that can help us to pinpoint what is risk-producing? What is the biological (mechanism)? We have impressive data showing that coffee may increase coronary artery disease through its effects on cholesterol (levels of fat in the blood), and while we can’t close the book on that question, we’re getting closer.”
LaCroix and several other researchers noted that tracking something like coffee consumption is made especially difficult because of the large number of variables that enter into any such research. The complex situation prompts questions like: How is the coffee brewed and does drip-brewed coffee affect the heart differently than percolated? Is it possible that cream and creamer products are the villains? What about sugar?
“People who drink a lot of coffee tend to do a number of other things,” LaCroix said. “Smoking is the most well touted because we’re always bringing it up. But coffee drinkers may have more sedentary life styles than non-coffee drinkers. They may eat more atherogenic (heart disease-linked) foods. There may be all kinds of risk factors.”
“In any population that’s being studied, you have a whole host of variables and the question is how do you control (make allowances) for them while focusing on a single agent or substance in trying to answer the question,” said Graboys. “That’s been part of the difficulty.”
It’s not that researchers are giving up. LaCroix said the National Center for Health Statistics is searching for ways to develop a reliable national data base from which to examine the health effects of coffee in a group of people diverse enough to have ethnic, gender, age, race and socioeconomic balance.
Government Study Planned
It also was learned that the federal agency is seriously considering organizing a wide-ranging national health and nutrition study in which as many as 30,000 Americans would be subjected to extensive health status examinations and then followed for several years to track the ways in which their life styles influence their health.
But to Dyer, while designing a study large enough to finally resolve the questions about coffee is theoretically possible, it’s not economically likely. “I think it could be done,” he said. “It would be extremely expensive and you’d have to have a sample large enough to generate enough deaths to detect the (true significance of something) that is not a particularly large effect numerically.
“It’s possible (to conduct such a study) but it’s not likely that it will be.”
