The average Canadian coffee drinker consumes about three cups of coffee a day. A significant number drink much more. Indeed, an estimated five per cent of Ontario residents drink more than is necessary to develop a physical addiction to caffeine, according to Richard Gilbert, a consultant to Ontario’s Addiction Research Foundation. And recently a medical debate has begun over whether coffee contributes to such serious illnesses as heart disease. Now, the results of a study released earlier this month by researchers at the Johns Hopkins Medical School in Baltimore have added new fuel to the controversy. The study, which documented the coffee consumption and health of 1,130 graduates of the school, concluded that there is a link between coffee and heart disease. Declared Dr. Thomas Pearson, the report’s coauthor: “I drink two cups of coffee a day. I may well give it up altogether.”
The Johns Hopkins researchers followed the medical progress of a group of men who graduated from the school
between 1948 and 1964. They correlated that data with the doctors’ coffeedrinking habits, recorded at five-year intervals after the subjects’ graduations. By the end of the 38-year followup, the incidence of coronary problems among those physicans who consumed five or more cups of coffee daily was nine per cent. By contrast, of the doctors who drank no coffee only three per cent developed heart problems. As a result, his study concluded that for people who drink a minimum of five cups a day, the risk of developing heart problems is 2.5 times greater than the rate for those who abstain.
Indeed, Pearson suggested that in order to lower the risk of heart disease coffee drinkers should consider limiting their consumption to two cups a day. Still, some scientists have said that such a recommendation is premature. For one thing, William Brooks, a spokesman for the New York-based National Coffee Association of the U.S.A., pointed out that 10 of 12 major studies carried out since the 1960s have not produced any link between coffee consumption and heart disease. And a 1974 study sponsored by the U.S. National Institutes of Health concluded that there was no relationship between coffee consumption and heart disease.
Although the Johns Hopkins study dealt only with coffee, many scientists suspect that caffeine—a mild stimulant which occurs naturally in coffee, tea and cocoa and which is added to some soft drinks and medicines—is the real enemy. Caffeine affects the central nervous system by neutralizing the effects of adenosine, a chemical which the body produces to calm the nerves. Dr. James Long, chief of the toxicological evaluations division of the Health Protection Branch in Ottawa, said that known side effects of coffee include nervousness, irritability, insomnia and even an irregular heartbeat. But Long maintains that no evidence exists to connect the beverage firmly with any disease.
For his part, Gilbert says that he is convinced too much coffee has harmful effects. In fact, he added, it is possible that large amounts of the beverage can cause birth defects, and that pregnant women should avoid more than one cup a day. Declared Pearson: “We don’t know enough yet, but there have never been any studies saying coffee is good for you.” Still, until more research is done, the body of contradictory evidence ensures that the debate will continue to brew. And a growing number of coffee drinkers may eye their morning cup, wondering if it is indeed good to the last drop.
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