It's the Coffee Break That Lasts . . . and Lasts . . . and Lasts
Study says caffeine lingers in body, compounds stress
MONDAY, Aug. 5, 2002 (HealthDayNews) -- Stressed out? Try kicking caffeine for a week, and you will see your blood pressure, adrenaline levels and overall stress drop, according to a study by Duke University Medical Center.
The new research found that the effects of caffeine stay in the body all day long, amplifying any feelings of stress. Moreover, the perception of stress increased for the 47 study participants after they took caffeine tablets.
"On the day they had caffeine, their blood pressure was higher throughout the day. And we also found that adrenaline goes up by about 32 percent," says lead researcher James D. Lane, who has studied caffeine for 15 years. "The measurable effects of drinking four cups of coffee are the difference between working a stressful job at a hospital and spending the day at home."
An estimated 85 percent of Americans drink coffee, tea or soft drinks, Lane says, but most people don't accept that there is a downside to caffeine consumption.
"Caffeine may be the most popular drug in the world, but a growing body of evidence suggests that its adverse effects are not inconsequential," Lane concluded in the study, which was funded by the National Institutes of Health and is published in the current issue of the journal Psychosomatic Medicine. "Almost all of the major diseases have stress as a contributing factor."
To link caffeine to stress, the researchers gave half the study participants 250 milligrams of caffeine twice a day; the other half were given inactive placebo tablets. All participants wore blood pressure monitors and were electronically instructed to check their blood pressure an average of four times per hour. They also wrote down what they were doing each time they checked in, and they kept urine samples so the scientists could measure adrenaline levels.
The participants who were given caffeine showed a 3 percent rise in blood pressure, a difference which clinical studies have tied to a 20 percent increase in coronary heart disease, Lane says. And with adrenaline levels elevated by more than 30 percent, the increased heart rate and associated stress can cause long-term damage to the heart, he said.
The results correspond with one of Lane's past studies, in which he found that drinking four or five cups of coffee a day rather than just one increases the chances of a person developing heart disease later on by boosting heart rate and blood pressure.
Researchers from the Johns Hopkins Medical Institutions, however, argue that the effects of caffeine are more difficult to calculate.
In a study of 1,000 coffee drinkers released this spring, the Johns Hopkins scientists found that people who drink at least five cups of coffee a day are 60 percent more likely than non-coffee drinkers to develop high blood pressure.
But after considering other common characteristics of coffee drinkers, such as the consumption of alcohol or cigarettes, they found the effects of coffee were overstated.
"Overall, coffee drinkers had higher blood pressures than people who did not drink coffee, but there was no set 'dose-response' relationship," says the lead author of that study, Michael Klag, who adds that risks of high blood pressure were only slightly higher for coffee drinkers.
Still, the Johns Hopkins study emphasizes that people who struggle with high blood pressure should consider limiting their caffeine intake.
And that's the main point of Lane's work, he says. He still drinks coffee and isn't trying to get everyone to quit cold turkey; he just wants to offer health information.
"We all have risks in our lives, whether it's eating too much ice cream or not exercising enough, and we all make choices about what we want to do," he says. "My point is not that people need to quit, but that we need to realize how it can aggravate stress in their lives. People who have a lot of stress in their lives should consider cutting back to see how that works."
Another benefit of cutting your caffeine intake is that you won't go through the cycles of withdrawal that occur for regular coffee drinkers. When a person wakes up groggy in the morning, desperate for caffeine, it is a sign she is going through withdrawal from taking caffeine the day before, he says.
Lane is working on another study about people ceasing to drink coffee for a week. But since most people get headaches for a couple of days when they stop all at once, he recommends that they cut back over a couple of weeks or begin to mix decaffeinated coffee with regular coffee. In many cases, those who stopped didn't want to begin again, he adds.
"It's a simple thing to try for a week or so," Lane says. "If it doesn't work, you can go back to Starbucks and load up again."
What To Do