Energy Drinks Jolt the Heart
Popular Drinks Boost Blood Pressure, Heart Rate
Nov. 6, 2007 (Orlando, Fla.) -- Energy drinks may boost your blood pressure and heart rate as well as your
vitality, researchers say.
In a small study, they found that drinking just two cans of a popular drink
increased blood pressure and heart rate within four hours.
While the increases didn't reach dangerous levels in the healthy volunteers
studied, they could be harmful for people with heart disease or who are taking medication to control
blood pressure, says James Kalus, PharmD, senior manager of patient care
services at Henry Ford Hospital in Detroit.
"These people should avoid these drinks," he tells WebMD.
How about people at high risk of heart disease due to obesity, smoking, family history, or other factors?
"Pending more study, at least talk to your doctor about potential
risks," Kalus says.
The findings were presented at the American Heart Association's (AHA)
Scientific Sessions 2007.
Energy Drinks Raise Blood Pressure
In the study, 15 healthy young men and women drank two cans of an energy
drink that contained 80 milligrams of caffeine every day for a week. All agreed
to abstain from any other forms of caffeine for two days prior to and
throughout the study.
Within four hours of consuming the drinks on the first day, systolic blood
pressure (the top number) shot up by 9 points; on the seventh day, it rose 10
points. Diastolic blood pressure (the bottom number) rose 5 points on both
days, Kalus says.
Heart rate increased five beats per minute on the first day; seven days on
The volunteers were sitting in a chair, watching a movie, when the changes
occurred, he says.
In contrast, many young people mix the energy drinks with alcohol and
dancing. And some of the marketing for energy drinks is aimed at extreme
sports, he says.
Since it wasn't studied, Kalus says he can't say for certain that mixing
energy drinks with booze or exercise raises the risks. But some countries
advise against using energy drinks to quench thirst while playing sports,
according to the AHA.
And just yesterday, researchers reported that college students who mix
alcohol with energy drinks are at higher risk for alcohol-related injuries than
students who drink cocktails alone.
Energy Drinks Pack Caffeine Punch
Though Kalus declined to name the drink studied, most of the products on the
market pack a caffeine punch. Caffeine has been linked to increased heart rate
and blood pressure in several studies.
AHA President Daniel Jones, MD, of the University of Mississippi Medical
Center in Jackson, tells WebMD that he always cautions his patients to watch
their caffeine intake.
"Energy drinks are a new source of caffeine -- and one of which many
people aren't aware," he says.
Some energy drinks contain even higher amounts of caffeine than the product
studied. A recent review of a dozen popular drinks in Consumer Reports
found caffeine levels, which often aren't listed on the label, can top 200
milligrams per bottle or can.
While the energy drink used in the study had as much caffeine as one to two
cups of coffee, Kalus says that "comparing the two is like comparing apples
and oranges. Each contains other compounds that could have good or bad effects
on the heart."
Energy drinks contain taurine, an amino acid found in protein-rich foods
like meat and fish that generally has been found to have positive effects on
the heart, he says. And coffee has phenol, an antioxidant that has been shown
to reduce the risk of heart disease, he says.