Another chapter appears today in the unfinished, book-length work recounting the plethora of attempts to answer the question: "Is coffee bad for you--and, if so, how much is too much?"
Today's installment is from the Stanford Center for Research in Disease Prevention, part of the Stanford University School of Medicine.
It involves a controversy--brewing for several years--over whether regular long-term coffee drinking raises, possibly dangerously, critical levels of a type of fat in the blood that has been positively identified as a key cause of heart disease and heart attack. But while it reheats the controversy, it doesn't finally resolve the question--leaving key researchers split on what the findings mean and whether they plan to cut down on coffee themselves.
Specifically, the Stanford study examined the coffee-drinking habits of 77 local men, who drank an average of 2.6 cups a day and as many as 7.5. The research found an apparent association between the drinking of more than two or three cups a day and elevated cholesterol levels--even after a number of variables, from stress to diet, were taken into consideration.
In all, though, the new findings about coffee and cholesterol may say more about the problems implicit in any attempt to answer, positively and without qualification, many questions of immediate and intense interest to laymen than they say about the issue specifically at hand. The new research also illustrates, albeit indirectly, some of the pragmatic ways that scientific research evolves.
The Stanford report is being published by the Journal of the American Medical Assn. The study was funded by an unusual combination of organizations: the federal government's National Heart, Lung and Blood Institute and Apple Computer Inc.
It had its impetus in 1983 when another prominent publication, the New England Journal of Medicine, published a study by researchers in Norway who concluded that there is a relationship between the amount of coffee a person drinks and the levels of cholesterol--the umbrella term for the complex of blood fat substances common in the body. Some cholesterol is harmful, but some is highly beneficial in the body's fight to avert heart disease.
But no sooner had the U.S. Postal Service delivered copies of the June 16, 1983, issue of the New England Journal than what had been an obscure controversy over coffee's possible dangers boiled over anew. In a spirited letter-writing campaign common to scientific disputes of this type, researchers at seven other medical centers in three different countries wrote to the New England Journal protesting that the Norwegian study had not only ignored but had made no attempt to gather data on such factors as other dietary habits of the people studied or such potential variables as the levels of stress they may be exposed to in their everyday lives.
There was even criticism because the Norwegian team didn't resolve the question of whether the people studied liked their coffee with cream--the inference being that if they did, the butterfat in the cream might influence cholesterol levels without any help from the coffee. Also protested was the fact that coffee is brewed differently in Norway than it commonly is in the United States and that the Norwegian method--boiling--yields higher levels of caffeine in coffee than the most common American method, drip.
The Norwegian research--called the Tromso study, after the city where the medical school that sponsored it is located--appeared a scant two months after the coffee controversy had taken still another twist. The debate over coffee's benefits or dangers goes back at least 20 years, and probably much longer than that.
In April of 1983, Ohio researchers concluded that there might be an association of some sort between coffee and disturbances of the heart's rhythm. But when exaggerated press reports extrapolated from cautious findings a conclusion that one's morning coffee could set off potentially fatal palpitations, the question became more one of the accuracy of news media than whether the research amounted to a hill of beans.
At Stanford, a team headed by a statistician, Paul T. Williams, watched the tempest with interest. That was due, Williams said earlier this week in a telephone interview, to the fact that Stanford researchers had just finished collecting a variety of health and life-style data from a group of 77 sedentary Palo Alto area men, aged 30 to 55. Coffee drinking and cholesterol levels were two of the key areas covered by the Stanford data--which, Williams said, had not even been analyzed when the Norwegian study was published.
Quickly--at least in the context of scientific investigation--the Williams group rushed to analyze its own data, looking for clues to further resolve the coffee controversy.
Among other things, the Stanford researchers had gotten all 77 of their subjects to keep complete dietary records for a representative three-day period. That information, which specifically focused on the amount of coffee each man drank, permitted Williams to perform a variety of sophisticated statistical analyses, looking for an association between coffee drinking and three key cholesterol measures.
The researchers had also prudently gotten every research subject to submit to exercise testing to obtain a complex of blood chemistry measurements, and had even administered psychiatric tests to assess the levels of stress each man faced. When everything had finished grinding through the computer, the Williams team concluded that coffee drinking of two to three cups a day or more really is associated with increased risk of heart disease.
But, adding an important caveat, the team emphasized that while an association appears to have been clearly demonstrated between coffee and heart disease risk, it still isn't clear if coffee drinking is the cause . While association often turns out to be true causality (as in the case of tobacco use and a variety of cancers), one of the first lessons that careful scientists learn is never to presume that one follows the other.
Not to waffle, though, Williams said that the new Stanford data was enough to prompt him to alter his own coffee-drinking habits. He's down now, he says, "to two cups from about five, and I would (because of that previous coffee gusto) certainly (be biased) against our results. I would have preferred them to come out some other way. I like coffee."
Williams' recommendation: Anyone concerned with cardiovascular health should restrict coffee consumption to two cups a day or less; adopt healthier dietary habits in general, including cutting fat consumption, and initiate a regular exercise program. Smoking or any other use of tobacco, of course, is totally taboo.
But the new conclusions about coffee and cholesterol are certain to be greeted skeptically, in part because of the practical limitations on scientific research. There still hasn't been, for instance, what researchers call a prospective study of coffee and its heart effects. In a prospective study, investigators select in advance a group of people to be scrutinized, then carefully follow them for a long period of time.
In Washington on Thursday, the National Coffee Assn., a trade group, went quickly to the defense of its drink. The association issued a statement contending that the new Stanford study "is not a significant contribution to the extensive body of literature" on coffee and heart disease. The organization asserted that "the weight of evidence in medical literature shows no indication that coffee consumption causes heart attacks."
Coincidentally, Dr. Thomas B. Graboys, an authority on heart rhythms, said that he and his associates in Boston are preparing to begin this week the first prospective study of coffee and its effects on the heartbeat.
Despite the publicity the subject has received--especially since 1983--Graboys said he fears that the question of coffee and its effects on the heart is not materially closer to final resolution now than it was five years ago. "I am not impressed by any of the information that has come out in the last five years," he said, in terms of its ability "to lead to resolution of questions on coffee's significant adverse effects."
Another expert, Dr. Richard Shekelle of the University of Texas School of Public Health in Houston, agreed. "I think the evidence is not strong enough yet to warrant a recommendation (on coffee restriction to prevent heart attack) to the public in general," said Shekelle, who was associated with a famed long-term study of cardiac health among hundreds of workers at Western Electric Co. facilities in the Chicago area.
"The decision ought to be a personal one."
But still other doctors believe that the evidence against coffee is clear and convincing enough as things stand now. At the Arizona Heart Institute in Phoenix, for instance, famed surgeon Dr. Edward B. Diethrich said his program has recommended against consumption of more than two cups a day since the Norwegian study was published two years ago.
While Diethrich was concerned about the comparatively small size of the new Stanford study (77 patients is smaller than the size of many similar investigations), he said the studies he has reviewed have meant that "it's just sort of been the feeling here that we should reduce coffee intake."
Diethrich contended that a major reason that questions like this one are so hard to answer in a definitive way is the diversity of human behavior and human tastes.
"When you have human beings, it's very difficult. They're out there in society, doing what they want to do," he said.