Energy drinks increase heart strain, study suggests

German researchers say that energy drinks alter your heartbeat. (hero30 /shutterstock.com)

If you rely on energy drinks to give you a buzz, researchers are warning that all that caffeine can alter the way your heart beats.

A team from the University of Bonn in Germany imaged the hearts of 17 people an hour after they had an energy drink containing caffeine and taurine, with findings showing more forceful heart contractions after the drink, especially in the left ventricle, which is the chamber of that heart that pumps blood around the body.

"Until now, we haven't known exactly what effect these energy drinks have on the function of the heart," said researcher Dr. Jonas Dorner in a statement. "The amount of caffeine is up to three times higher than in other caffeinated beverages like coffee or cola."

Caffeine levels in drinks such as Monster, Red Bull and Rockstar range from about 6 milligrams to 242 milligrams per serving, and some containers have more than one serving. By comparison, a 236 mL cup of coffee has about 100 milligrams.

"There are many side effects known to be associated with a high intake of caffeine, including rapid heart rate, palpitations, rise in blood pressure and, in the most severe cases, seizures or sudden death," Dorner said.

Dorner and his colleagues are presenting their findings Monday at the annual meeting of the Radiological Society of North America in Chicago.

"We've shown that energy drink consumption has a short-term impact on cardiac contractility," he said. "We don't know exactly how or if this greater contractility of the heart impacts daily activities or athletic performance." His team advises that children and adults with an irregular heartbeat avoid energy drinks altogether.

A recent report in the journal Pediatrics found that up to 50 per cent of U.S. adolescents and young adults drink energy drinks on a regular basis.