As part of their study, researchers gave 17 subjects an energy-style drink containing 32mg per 100ml of caffeine and 400mg per 100 ml of taurine. The scientists then looked at images of the participants' hearts just one hour after they consumed the beverage. And, what they saw is kind of frightening. The contractions were so much more forceful after just one energy drink, that children, and those with certain health conditions, ought to avoid the drink altogether.
The images showed the left ventricle (responsible for pumping blood through the body) was contracting harder an hour after the energy drink was consumed than before consumption. If you think about it, your heart always pumps a bit faster when you're nervous or excited. So, it wouldn't be unlikely if the participants began with an elevated heart rate.
We already know that energy drinks contain much more caffeine than a run-of-the-mill cup of coffee or cola. But, as Dr. Jonas Dorner, a scientist on the team, points out, consuming a large amount of caffeine at once has more serious effects: "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."
While the study shows that energy drinks have a short-term impact on cardiac contractility, it remains unclear "exactly how or if this greater contractility of the heart impacts daily activities or athletic performance," or how it effects those with heart disease. Regardless of the additional research needed to comment on the effects of athleticism and pre-existing heart conditions, this preliminary study might be enough to make you rethink your energy drink habits. (BBC)