Energy drinks packed with caffeine can change the way the heart beats, say scientists, advising children and people with some health conditions to avoid the drinks. The team, from the University of Bonn, imaged the hearts of 17 people an hour after they had an energy drink. The study showed contractions were more forceful after the drink, BBC reported Monday. The researchers told at the annual meeting of the Radiological Society of North America that children and people with some health conditions should avoid the drinks. "Until now, we haven't known exactly what effect these energy drinks have on the function of the heart," said researcher Jonas Dorner. "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." During their study, the researchers gave the participants a drink containing 32mg per 100ml of caffeine and 400mg per 100ml of another chemical, taurine.