Energy drinks high in caffeine can increase heart contraction

"Until now, we haven't known exactly what effect these energy drinks have on the function of the heart," said Jonas Dorner, of the cardiovascular imaging section at the University of Bonn, Germany, which is led by the study's principal investigator, Daniel K Thomas.

Thomas said,"There are concerns about the products' potential adverse side effects on heart function, especially in adolescents and young adults, but there is little or no regulation of energy drink sales."

"Usually energy drinks contain caffeine and taurine as their main pharmacological ingredients," Dorner added.

"The amount of caffeine is up to three times higher than in other caffeinated beverages like coffee or cola.

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

For the study, which is ongoing, Dorner and colleagues used cardiac magnetic resonance imaging (MRI) to measure the effect of energy drink consumption on heart function in 18 healthy volunteers, including 15 men and 3 women with a mean age of 27.5 years.

Each of the volunteers underwent cardiac MRI before and one hour after consuming an energy drink containing taurine (400 mg/100 ml) and caffeine (32 mg/100 ml).

Compared to the baseline images, results of cardiac MRI performed one hour after the study participants consumed the energy drink revealed significantly increased peak strain and peak systolic strain rates (measurements for contractility) in the left ventricle of the heart.

The heart's left ventricle receives oxygenated blood from the lungs and pumps it to the aorta, which distributes it throughout the rest of the body.

Dorner said, "We don't know exactly how or if this greater contractility of the heart impacts daily activities or athletic performance."

Dorner said. "We need additional studies to understand this mechanism and to determine how long the effect of the energy drink lasts."

The researchers found no significant differences in heart rate, blood pressure or the amount of blood ejected from the left ventricle of the heart between the volunteers' baseline and second MRI exams.

"We've shown that energy drink consumption has a short-term impact on cardiac contractility," Dorner said.

"Further studies are needed to evaluate the impact of long-term energy drink consumption and the effect of such drinks on individuals with heart disease," Dorner added.