An MRI study from a team of cardiac radiologists found that the key ingredients in energy drinks, caffeine and taurine, cause the heart to beat more forcefully.
Consuming high amounts of caffeine can lead to rapid heartbeat, high blood pressure, palpitations, and seizure or death, according to researcher Dr. Jonas Dörner, a resident at the University of Bonn in Germany.
He says a typical energy drink has three times the caffeine of coffee or soda.
Heart researchers attempted to link tens of thousands of emergency room visits each year to energy drinks like Red Bull, Monster, and 5-Hour Energy.
Dörner and his team scanned the hearts of 15 men and three women before and after they consumed a beverage high in caffeine and taurine.
One hour later, heart strain measurements were significantly higher than before they drank the beverage.
Researchers presented the results of the ongoing study at the annual meeting of the Radiological Society of North America on Monday. Radiologists are still evaluating what the impact might be from long-term energy drink consumption and the effect of energy drinks on patients with heart disease.
"We don't know exactly how or if this greater contractility of the heart impacts daily activities or athletic performance," Dörner said. "We need additional studies to understand this mechanism and to determine how long the effect of the energy drink lasts."
Monster Beverage Corp. responded to the study on Monday calling it “alarmist and misleading.”
The energy drink maker says the study proves the benefits of the beverages, citing that taurine “helps the heart function more efficiently by improving the pumping force of the heart without any changes in blood pressure or heart rate.”
Monster says this effect “is widely considered to be beneficial.”
The company also said that some energy drinks contain less caffeine than coffee, if considered on an “ounce per ounce basis.