TRAVIS AIR FORCE BASE, Calif. – Do energy drinks boost more than energy? That’s the question researchers at the Clinical Investigation Facility at Travis Air Force Base, California, attempted to answer in a study published in the April 27 issue of the Journal of the American Heart Association.
The study reported that energy drinks cause changes in heart rhythm and blood pressure that don’t occur with other caffeinated drinks such as soda and coffee.
“This particular study looked at blood pressure and the electrical firing of the heart,” said Dr. Bradley Williams, 60th Medical Group, assistant director of medical education and research. “Uncontrolled high blood pressure damages the heart, potentially causing heart attacks and stroke.”
According to an Air Force survey in 2012, about 75 percent of military members consumed energy drinks and 15 percent of deployed members consumed up to three cans daily.
“There are two differences between caffeine and energy drinks,” said Williams.
He explained that although both initially raise systolic blood pressure, blood pressure normalizes slower after consuming an energy drink. Also, electrical changes in the heart occur with energy drinks that don’t occur with caffeine.
Researchers at Travis found that drinking 32 ounces – two cans – of a commercially available energy drink can increase the heart’s electrical activity more than drinking 320 milligrams of caffeine – about four cups.
“We chose a dose of 32 ounces as it is possible for some consumers to consume two cans on a social night out,” said Maj. Emily Fletcher, 377th Medical Support Squadron at Kirtland AFB, New Mexico. “The caffeine content was below the general safety threshold of 400 milligrams.”
Fletcher, the pharmacy flight commander at Kirtland, designed the study while assigned to Travis.
Eighteen “healthy” active-duty men and women ages 18 to 40 years participated in the study. Half of the group were given a serving of an energy drink and the other half were given the same amount of a control drink containing caffeine, lime juice and cherry syrup in carbonated water.
Researchers switched the drinks given to each group after a six-day “wash out” period. Participants were not allowed to consume caffeine or energy drinks 48 hours before each evaluation.
Researchers found that while both the caffeine and energy drink groups had an increase in systolic blood pressure, the systolic pressure of the control group had returned closer to the original number six hours later.
“Those who consumed the energy drink still had a mild elevated blood pressure,” said Fletcher.
Additionally, the QTc interval (interval between heart beats) was longer in the energy drink group two hours after consumption when compared to the caffeine group, which can increase the risk for triggering an abnormal heart rhythm.
“The resulting arrhythmia can be life threatening,” said Fletcher.
Energy drinks may adversely affect some people because they contain ingredients other than caffeine.
“We can’t assume that energy drinks are safe for everyone,” said Williams. “People who consume energy drinks may not realize sometimes that their blood pressure is elevated or feel changes in their heart rate.”
Energy drinks also may cause dizziness, irritability, chest pain and insomnia, said Williams.
People with underlying cardiac disease or high blood pressure may want to avoid energy drinks or use caution, especially when taking part in activities that also increase blood pressure and heart rate such as exercise and sports, said Fletcher.
The researchers concluded that larger clinical trials controlling for limitations of their study are warranted.