Energy Drinks
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Some people trying to perk up in the morning have turned to energy drinks as an alternative to coffee, but a new study has found that these drinks can have a disruptive effect on heart function.

According to the study, which was presented on Monday at the annual meeting of the Radiological Society of North America (RSNA), drinks with high amounts of caffeine and taurine caused significant increases in heart strain one hour after consumption.

"Until now, we haven't known exactly what effect these energy drinks have on the function of the heart," said study researcher Dr. Jonas Dörner, of the cardiovascular imaging section at the University of Bonn in Germany.

"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."

The new study comes after a report published earlier this year by the Substance Abuse and Mental Health Services Administration (SAMHSA) found that the number of emergency department visits related to energy drinks in the US essentially doubled, from 10,000 to almost 21,000, between 2007 and 2011.

"Usually energy drinks contain taurine and caffeine as their main pharmacological ingredients," Dörner said. "The amount of caffeine is up to three times higher than in other caffeinated beverages like coffee or cola. 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."

In the study, the researchers used magnetic resonance imaging (MRI) to analyze the results of energy drink consumption on the heart in 18 healthy volunteers with an average age of almost 28 years. Volunteers underwent cardiac MRI scans both before and after consuming an energy drink containing taurine, at a concentration of 400 mg per 100 ml, and caffeine, 32 mg per 100 ml.

The 'after' scans showed significant measurements for contractility, or heart strain, in the left ventricle of the heart, compared to the 'before' scans. This section of the heart takes in oxygenated blood from the lungs and sends it through the aorta and on to the rest of the body.

"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."

The research team noted that they didn't see significant changes in heart rate, blood pressure or the amount of blood being sent from the left ventricle between the before and after scans.

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

He added that children and people with heart conditions should avoid energy drinks. Dörner called for additional studies involving alcoholic energy drinks.