A monthly report on personal health, life and leisure
It is the world’s most popular drug, and millions of Canadians contribute to its popularity. On a recent sunny Sunday afternoon, scores of caffeine addicts crowded the 10 coffee shops along a short block of Vancouver’s trendy Robson Street, sipping espresso, cappuccino, café au lait and even, occasionally, regular brewed coffee. Many of the imbibers were aware that caffeine, the main ingredient that gives java its jolt, has been linked to health problems ranging from cancer to birth defects—but few seemed overly concerned. “There are a lot of other things you can die from,” said Danijella Kaufman, who was nursing a single espresso while her husband,
Oblak Jurisin Kaufman, downed a quadruple. “Coffee is just one of them, and not so important.” Sean Watts, who was in the process of satisfying his seven-cup-a-day habit, acknowledged that he consumes caffeine for “the kick.” He adds: “I’m very health conscious, but one bad thing isn’t really going to hurt you.”
Or can it? Over the decades, scientists and medical researchers have conducted thousands of studies in an effort to answer that very question. All that scrutiny, says David Wilkes, president of the Coffee Association of Canada, has made caffeine the most widely studied ingredient in the daily diet. (Caffeine can also be found in tea, cola soft drinks, cocoa and chocolate products, and some prescription and over-the-counter medications, but most Canadians get their fix from drinking coffee.) With that much research, it is perhaps understandable that there are conflicting views on the health effects of caffeine. In addition to being suspected of causing cancer and birth defects, some studies have implicated caffeine in contributing to miscarriages, heart disease and high blood pressure. It has also been linked to migraine headaches, insomnia, anxiety and depression, stomach ulcers and osteoporosis. On the positive side, caffeine has been shown to relieve headaches, aid in the absorption of pain-relievers, enhance mental alertness and postpone fatigue. In fact, caffeine’s ability to provide a quick boost is so well recognized that last week the Washington-based Institute of Medicine recommended that the U.S. military find ways to add caffeine to the rations of fatigued soldiers. Anne Kalvik, a staff pharmacist with the Addiction Re-
search Foundation in Toronto, says it is only right that caffeine is the subject of so much study: “When you have a substance that is used by so many people, it is a public-health issue.”
Some of the most recent—and contradictory—studies have examined the impact of caffeine consumption during pregnancy. In February, 1993, The Journal of the American Medical Association reported that expectant women who consumed moderate amounts of caffeine—up to 300 mg daily, which is the equivalent of between two and four cups, depending on strength—had no higher rates of miscarriage than women who avoided caffeine. The study, by the National Institute of Child Health and Human Development in Bethesda, Md., also concluded that moderate coffee drinkers did not give birth to smaller babies or infants with reduced head circumference, side-effects that had shown up in some previous animal studies.
But just 10 months later, the same journal published the results of a study that indicated that women who consumed the equivalent of just a half a cup of coffee a day (48 mg of caffeine) during pregnancy increased their risk of miscarriage by 15 per cent. The researchers who conducted that study, led by Dr. Claire Infante-Rivard of Montreal’s McGill University, also made the startling assertion that consumption of as little as half a cup a day in the month before conception boosted a woman’s risk of miscarriage by 29 per cent. In an accompanying editorial, the Journal noted that the conflicting results could be explained, in part, by different study methods. Still, the editors wrote that doctors should “err on the side of caution” by advising pregnant patients to reduce their caffeine intake. “In contrast to many other potential reproductive toxicants,” the Journal noted, “caffeine use is under the control of the consumer.”
Contradictions and caution have long been the bywords surrounding caffeine use. A white, water-soluble, bittertasting substance, caffeine was first isolated from coffee in 1820. When researchers isolated it from tea leaves in 1827, they believed it was a different compound and named it “theine.” Even now, many consumers remain confused about which beverage, coffee or tea, contains more caffeine. According to Danielle O’Rourke, president of the Tea Council of Canada, a pound of tea leaves actually contains more caffeine than a pound of coffee beans (2.5 to 4.5 per cent and 1.1 to 2.5 per cent respectively). On the other hand, a pound of leaves produces much more tea than the amount of coffee produced by a pound of beans. As a result, a cup of tea contains, on average, one-third to one-half the caffeine in a cup of coffee, O’Rourke says.
The amount of caffeine in a serving of coffee can also vary
widely, depending on the type of beans, where they were grown, how they were roasted and how the coffee was prepared. Beans from Coffea arabica, grown mostly in Central and South America, contain about half the caffeine of beans from the Cojfea robusta plant, which grows mostly in Indonesia and Africa. And, contrary to popular opinion, many strong-tasting coffees actually contain less caffeine than weaker-tasting swills. Alton McEwen, the Toronto-based president of The Second Cup chain of nearly 200 coffee shops across Canada, says that when beans arrive from overseas they are still green. Roasting the beans helps to bum off some of the caffeine—with the result that stronger, darker coffees often have less caffeine than milder varieties. As for espresso and other espresso-based drinks such as cappuccino, McEwen says that hot water is forced under high pressure through the ground beans so quickly that it picks up little caffeine.
All those factors make it difficult, if not impossible, for health-care authorities to declare with any certainty how much coffee or tea a person may safely drink in a day. An individual’s sensitivity to caffeine can also vary greatly. Many people can expect to experience toxic symptoms—such as agitation, restlessness and insomnia—if they consume more than about 650 mg a day, although in some they may appear in levels as low as 250 mg a day. The lowest known fatal dose of caffeine was 3,200 mg—an intravenous dose. In all, researchers have traced at least seven deaths to caffeine, but Kalvik notes they probably resulted from individuals ingesting dmgs laced with caffeine and other stimulants.
For most healthy people, moderate consumption of coffee, tea, cola or chocolate would appear to pose no serious health threat. A background document to Canada’s Food Guide to Healthy Eating states that “individuals do not face an increased risk of heart disease, hypertension, or adverse effects on pregnancy or on the fetus, provided that the total daily exposure to caffeine does not exceed 400-450 mg.”
And at least one leading researcher says that the link to heart disease and cancer has been vastly overstated. Dr. Martin Myers, a cardiologist at Sunnybrook Medical Centre in Toronto, says that the early studies were skewed against caffeine because they did not isolate all the different lifestyle factors. “Heavy coffee drinkers also tend to be smokers, but there is no stigma attached to drinking coffee,” says Myers. “People would admit to drinking 20 cups of coffee a day, but they would say that they smoked only one pack of cigarettes a day when they really smoked two.”
BARBARA WICKENS with CHRIS WOOD in Vancouver
CAFFEINE HIGHS AND LOWS
Although researchers are still debating the health effects of caffeine consumption, one recent study found that drinking as little as half a cup of coffee a day—about 48 mg of caffeine—increases a woman’s risk of miscarriage by 15 per cent. Other studies have shown that caffeine users suffer withdrawal symptoms, such as headaches and irritability, when they try to give up as little as 235 mg a day.
decaffeinated (6 ounces) less than 1 mg
instant (6 ounces) 60-100 mg
drip or brewed (6 ounces) 80-175 mg
espresso (6 ounces) 60-120 mg
cappuccino (6 ounces) 60-120 mg
(6 ounces) 30-80 mg
COLA DRINK (12 ounces) 30-65 mg
BAR (2 ounces) 3-20 mg
A DOSE OF CAFFEINE
Caffeine content in an adult dose (two pills or tablets) of various brandname medicines:
Excedrin .........130 mg
Fiorinal ...........80 mg
Empirin ...........64 mg
Darvon ...........60 mg
Most often, Canadians who drink a cup or two of coffee in the morning suffer their nastiest symptoms when they are unable to get their brew. Virtually all caffeine is eliminated from the body 12 to 24 hours after it was last consumed. After that, withdrawal symptoms, including debilitating headaches, drowsiness, irritability and fatigue, may occur. The cure? A fresh cup of coffee. The old coffee advertisements were only half right when they declared that caffeine “picks you up and never lets you down.”
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