A team from the University of Bonn in Germany imaged the hearts of 17 people an hour after they drank an energy drink, BBC News reports. The drink contained 32 mg per 100 ml of caffeine and 400 mg per 100 ml of the chemical taurine.
The results showed that heart contractions were more forceful after the drink. It caused enough of a change that the team told the annual meeting of the Radiological Society of North America that children and people with certain 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," researcher Dr. Jonas Dorner said, adding that the amount of caffeine is up to three times higher in energy drinks than in other beverages like coffee and 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," he added reassuringly.
As we reported a year ago, Monster energy drinks have been implicated in several cardiac-related deaths, including that of a 14-year-old girl.
An hour after the German participants drank the energy drink, the chamber of the heart that pumps blood around the body, the left ventricle, was still contracting harder than at the start of the study. (This had nothing to do with their being Teutonic.)
"We've shown that energy-drink consumption has a short-term impact on cardiac contractility," Dorner said. "We don't know exactly how or if this greater contractility of the heart impacts daily activities or athletic performance." The effect on people with heart disease is also unclear, but potentially problematic.
The research team advises that all children as well as people with an irregular heartbeat refrain from consuming the drinks.
Democratic Sen. Dick Durbin of Illinois has asked the Food and Drug Administration to consider caffeine limits on energy drinks after emergency room visits involving such products jumped tenfold from 2005 through 2009.
Monster, Red Bull and other such ilk aren't bound by the FDA guidelines for caffeine in sodas, because energy drinks are often sold as "dietary supplements." Most don't even list the amount of caffeine in their formulas.
Soda typically is allowed to have as much as 71 milligrams of caffeine per 12 ounces for the FDA to consider it safe. Caffeine in energy drinks often ranges from a whopping 160 milligrams to 500 milligrams per serving, the FDA said. In comparison, an 8-ounce cup of coffee contains anywhere between 95 and 200 milligrams of caffeine. A 12-ounce can of Coke contains 35 milligrams, and an 8.3-ounce can of Red Bull has 76 milligrams.
If you want your heart to explode, you know what to do.