WEDNESDAY NOV 7, 2007 (Foodconsumer.org) -- People with cardiovascular disease or taking medicines for such a condition may consider avoiding use of energy drinks, a new study reported at the American Heart Association's (AHA) Scientific Sessions 2007 suggests.

The study led by James S. Kalus, Pharm.D., of the Henry Ford Medical Center in Detroit, Michigan and colleagues found energy drinks boost blood pressure and heart rate in a group of young and healthy people.

The increase in blood pressure may not be big enough to cause harm in most young patients, but regular consumption of energy drinks would have an impact on people, particularly those with cardiovascular disease such as hypertension, Dr. kalus was cited by Medpage as saying.

"If you know you have cardiovascular disease or are taking medication to lower blood pressure, it is important to avoid energy drinks until we learn more about what they do," he was quoted as saying.

It should not be a surprise that energy drinks boost blood pressure because these beverages contain caffeine and taurine that have been found to have an impact on cardiovascular system, according to Dr. Kalus.

The study was small and involved only 8 women and 7 men at an average of 25.9 years who were healthy and abstained from intake of caffeine for two days prior to entering the study.

Blood pressure and heart rate were measured at baseline, and the measurements were repeated 30 minutes, one, two three and fours hours after consumption of two cans of an energy drink containing 80 mg caffeine and 1,000 mg taurine.   During the time frames, participants sit watching movies.   Two cans a day were assigned to all participants.

On day one, diastolic blood pressure increased 7 percent two hours after using the energy drink and on day seven, the increase was up to 7.8 percent.  

All other measurements peaked at four hours after consuming the energy drinks. Systolic blood pressure increased on day one and on day seven by 7.9 percent and 9.6 percent, respectively.   Heart rate increased by 7.8 percent and 11.0 percent respectively and Corrected QT-interval rose 4.5 percent and 5.5 percent.

Because caffeine and taurine are commonly used in this type of beverage, all energy drinks may have the same effect on blood pressure and heart rate.