Researchers at Henry Ford Hospital in Detroit studied a small sample of 15 healthy people with average age of 26. Participants had to abstain from any other form of caffeine two days prior to the study and during the study.
They drank two cans of an energy drink with 80 milligrams of caffeine each day for a week.
Findings showed that drinking just two cans of energy drink in a day increased blood pressure and heart rate in just four hours.
On the first day, participants found their systolic blood pressure rise by nine points; by the end of the study, it had risen to 10 points. Both times their Diastolic blood pressure (the lower number) had risen 5 points.
Their heart rates had also gone up by five beats per minute on the first day and on the last day, when they were relaxing watching a movie, it had gone up by seven beats per minute.
Although these findings are not of much concern for healthy individuals, they could pose risk to high risk individuals who are obese, smoke or have a family history of heart disease or are on medication for blood pressure.
Earth Times reports study leader James Kalus saying: "These people should avoid these drinks. Pending more study, at least talk to your doctor about potential risks."
According to WebMD, Kalus says that although the unnamed energy drink used in the study had as much caffeine as one to two cups of coffee, "comparing the two is like comparing apples and oranges. Each contains other compounds that could have good or bad effects on the heart."
The American Beverage Association Industry refutes the findings and issued a statement which said: "While the amount of caffeine in energy drinks or coffee may cause a slight and temporary increase in blood pressure, it would have no greater effect than walking up a flight of steps."
The study was reported at the American Heart Association's (AHA) Scientific Sessions 2007.
