A triple nonfat mocha may taste good, but it's likely the jolt that drives millions of people to fork over three bucks or more for the steaming cup of liquid. Between 80 percent and 90 percent of North Americans consume caffeine regularly, according to a 2004 review, with an average daily consumption equal to about two mugs of coffee or four 16-ounce bottles of soda.
The habit has become less guilt-inducing recently, with growing evidence that both coffee and tea can fight cancer, heart disease, diabetes, Parkinson's disease and more. Because most people equate these beverages with the caffeine in them, it's tempting to conclude that the stimulant is what gives these wonder drinks their powers.
That may not be the case. Caffeine's effects on health appear to be considerably more nuanced.
On the plus side, the drug does appear to help protect the brain from degenerative disease and, for many, keep the brain's gears churning, which is what drives most people to drink it in the first place. But habitual and large doses of caffeine can also stress the heart and interfere with insulin's ability to process sugar. And many of the benefits ascribed to caffeine may be due, in fact, to other chemicals that outweigh caffeine's negative effects.
"As soon as you say coffee, people think caffeine; as soon as you say caffeine, people think coffee," says Terry Graham, a metabolic physiologist at the University of Guelph in Canada, a longtime caffeine researcher who recently organized an international symposium on caffeine and health. Scientists have isolated antioxidants, polyphenols and micronutrients from coffee and tea, but there have been no long-term studies of how each ingredient, including caffeine, affects the body on its own or within a beverage.
"There are health benefits of coffee that have nothing to do with caffeine," Graham says. In fact, he adds: "There are no health benefits I've ever seen documented for caffeine."
Physical reaction
Anyone who has used a latte to get through an after-lunch meeting - or ended up with stomach-churning jitters after one too many shots of espresso - knows that ingesting caffeine has physical consequences. The molecule, which is identical in every beverage that contains it, blocks the action of a naturally produced chemical called adenosine.
