You may want to think twice before reaching for that energy-boosting caffeine and taurine drink; it may alter the way your heart functions. According to a recent study, healthy adults who consume energy drinks experience significant spikes of heart contract rates per hour after intake, which may lead to fatal heartbeat problems.

Energy drink labels typically don’t tell consumers what chemicals are in the manufacturer’s products. Despite being named “energy” drinks, these products do not provide any real energy but instead provide the popular stimulant, caffeine. The stimulating properties in the drink can boost heart rate and blood pressure, sometimes causing palpitations, that dehydrate the body and prevent sleep. The Long Island Heart Associates, an affiliate of Mount Sinai Heart, says the alteration in heart function is due to the presence of high amounts of caffeine — the equivalent of two or more cups of coffee and taurine, an amino acid known to boost heart rate.

Presented at the 2013 annual meeting of the Radiological Society of North America, German researchers observed myocardial function in a group of healthy volunteers, using cardiac magnetic resonance imaging (CMR), to show the structure of the heart and how it functions during consumption of energy drinks high in caffeine and taurine.

Eighteen participants — 15 male and three female with an average age of 27.5 — were examined by undergoing a CMR performed on a whole-body scanner before and one hour after drinking an energy drink. These drinks contained taurine (400mg/100ml) and caffeine (32mg/100ml). The researchers looked at how the left ventricle, the heart chamber that pumps oxygenated blood out of the heart and to the rest of the body, was functioning by measuring its peak strain rate during heart contraction and dilation. In addition, the participants’ heart rate and blood pressure were also recorded in the study.

Compared to the images taken before the consumption of the energy drinks and post-beverage MRIs, the researchers noted an increased in peak systolic strain rates, or heart contractions, in the heart’s left ventricle per hour after drink intake. However, the energy drink did not show a significant effect on the amount of blood being ejected from the left ventricle, heart rate, or blood. The short-term impact on heart contractions caused by energy drinks was affirmed in the small study.

"We've shown that energy drink consumption has a short-term impact on cardiac contractility,” said Dr. Jonas Dörner, study researcher of the University of Bonn in Germany, the BBC reports. "We don't know exactly how or if this greater contractility of the heart impacts daily activities or athletic performance."

The researchers do acknowledge that further studies need to be done to accurately assess the long-term effects of energy drink consumption as well as any other possible effects these drinks may have on people with a history of heart disease. Although there is a lack of knowledge about long-term risks, the German researchers recommend children and people with cardiac arrhythmias — irregular heartbeats — abstain from consuming energy drinks. The short-term impact on contractility changes may produce the onset of arrhythmias.

Dörner also warns about the risks posed by mixing energy drinks with alcohol, especially due to its popularity in the nightclub scene. Stimulants can mask how intoxicated a person is and prevent them from realizing how much alcohol they have consumed which shadows the effects of the depressant. Fatigue is usually one of the ways the body lets a person know they have had enough to drink.

The combination of energy drinks and alcohol have been under review such as the drink Four Loko. Prior to the reformulation of Four Loko products in November 2010, a 23.5-ounce can of Four Loko typically contained 12 percent alcohol — the equivalent of four to six beers or 35 milligrams of caffeine and guarana, a legal stimulant similar to caffeine, according to Brown University Health Education. In February 2013, the Federal Trade Commission announced Phusion Projects, the maker of Four Loko, is now required to print an "Alcohol Facts" panel on all containers of Four Loko after the drinks were found to be responsible for several hospitalizations and deaths. 

The Cavalier Daily reports Ramapo College in New Jersey prohibited the drink following the hospitalization of 17 students and six visitors. One student was taken to the emergency room with a 0.4 blood alcohol content — five times the legal limit in New Jersey — after consuming three cans of Four Loko, the equivalent of 12 tequila shots.

According to a 2013 report from the Substance Abuse and Mental Health Services Administration in the U.S., energy drink-related emergency department visits have doubled from more than 10,000 to approximately 21,000. Most of the cases occurred in patients between the ages of 18 and 25. For ways to naturally boost your energy, click here.

Source: Dörner J, Kuetting D, Naehle CP, et al. Caffeine and Taurine Containing Energy Drink Improves Systolic Left-ventricular Contractility in Healthy Volunteers Assessed by Strain Analysis Using Cardiac Magnetic Resonance Tagging (CSPAMM). RSNA. 2013.