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Hypertension/High Blood Pressure Health Center

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Caffeine's Effect on Blood Pressure

WebMD Health News

May 17, 2002 -- The caffeine jolt of a java fix may cause a jump in blood pressure -- a particular problem in people who already have high blood pressure. But don't put your coffee cup down just yet. Researchers say the jury's still out on the effects on caffeine on your heart.

This new study was presented today at the annual scientific meeting of the American Society of Hypertension in New York City.

Although there has been a lot of recent interest in studying how caffeine may affect the heart and blood pressure, the authors say it's the first time an effect of caffeine has been found on the stiffness of arteries, an indicator of heart function.

In the study, caffeine quickly increased the stiffness of the large arteries in people with high blood pressure, said study author Charalambos Vlachopoulos, MD, of the department of cardiology at Athens Medical School in Greece, at a news conference.

Vlachopoulos and colleagues tested the effects of caffeine on the major arteries of 10 people who were being treated for high blood pressure and were an average of 62 years old. On alternating days, the participants were given either a pill containing 250 mg of caffeine (the equivalent of 2-3 cups of coffee) or a placebo.

Thirty minutes after the caffeine was given, there was a big jump in the stiffness of their arteries, said Vlachopoulos. The effect peaked after 60 minutes and remained significant for at least three hours.

This led to an 11 point jump in systolic blood pressure -- the top number -- and an 8 point jump in diastolic blood pressure -- the bottom number.

Researchers say this finding is only preliminary and more research is needed to determine exactly how caffeine intake may influence blood pressure as well as determine who's at risk.

Alice H. Lichtenstein, DSc, vice-chairwoman of the American Heart Association's nutrition committee, agrees this finding merits further study, but she stresses that there isn't any real cause for concern based on this very small study.

"It's hard to superimpose this scenario on everyday life," Lichtenstein tells WebMD. "It's very likely that different people respond differently to coffee. People who are habituated to drinking large amounts do not respond in the same way as people who do not drink coffee."

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