Study: Cardiac MRI Reveals Energy Drinks Alter Heart Function

03 Dec 2013 --- Healthy adults who consumed energy drinks high in caffeine and taurine had significantly increased heart contraction rates one hour later, according to a study presented at the annual meeting of the Radiological Society of North America (RSNA).

"Until now, we haven't known exactly what effect these energy drinks have on the function of the heart," said radiology resident Jonas Dörner, M.D., of the cardiovascular imaging section at the University of Bonn, Germany, which is led by the study's principal investigator, Daniel K. Thomas, M.D. "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."

Energy drinks represent a multibillion dollar industry that is growing every day. While teenagers and young adults have traditionally been the largest consumers, in recent years more people of all demographics have begun consuming energy drinks.

A 2013 report from the Substance Abuse and Mental Health Services Administration stated that in the U.S. from 2007 to 2011, the number of emergency department visits related to energy drink consumption nearly doubled, increasing from 10,068 to 20,783. Most of the cases were identified among patients aged 18 to 25, followed by those aged 26 to 39.

"Usually energy drinks contain taurine and caffeine as their main pharmacological ingredients," Dr. 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."

For the study, which is ongoing, Dr. Dörner and colleagues used cardiac magnetic resonance imaging (MRI) to measure the effect of energy drink consumption on heart function in 18 healthy volunteers, including 15 men and three women with a mean age of 27.5 years. Each of the volunteers underwent cardiac MRI before and one hour after consuming an energy drink containing taurine (400 mg/100 ml) and caffeine (32 mg/100 ml).

Compared to the baseline images, results of cardiac MRI performed one hour after the study participants consumed the energy drink revealed significantly increased peak strain and peak systolic strain rates (measurements for contractility) in the left ventricle of the heart. The heart's left ventricle receives oxygenated blood from the lungs and pumps it to the aorta, which distributes it throughout 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," Dr. Dörner said. "We need additional studies to understand this mechanism and to determine how long the effect of the energy drink lasts."

The researchers found no significant differences in heart rate, blood pressure or the amount of blood ejected from the left ventricle of the heart between the volunteers' baseline and second MRI exams.

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

Dr. Dörner said that while long-term risks to the heart from drinking energy drinks remain unknown, he advises that children, as well as people with known cardiac arrhythmias, should avoid energy drinks, because changes in contractility could trigger arrhythmias. He also cautions that additional study is needed to address risks posed by the consumption of energy drinks in combination with alcohol.

Other co-authors are Daniel Kuetting, M.D., Claas P. Naehle, M.D., and Hans H. Schild, M.D.

In response to “Caffeine and Taurine Containing Energy Drink Improves Systolic Left-ventricular Contractility in Healthy Volunteers Assessed by Strain Analysis Using Cardiac Magnetic Resonance Tagging,” a paper presented at the Radiological Society of North America’s annual meeting, the American Beverage Association issued the following statement:

“The fact remains that most mainstream energy drinks contain only about half the caffeine of a similar size cup of coffeehouse coffee. Caffeine is a safe ingredient and is consumed every day in a wide variety of foods and beverages, including energy drinks which have been enjoyed safely by millions of people for nearly three decades. Also, this paper, which looks at only 18 adults, has not been peer-reviewed or published.”

The group presented the following additional background:

•Energy drinks have been enjoyed safely by millions of people around the world for more than 25 years, and in the U.S. for more than 15 years.
•Many of the ingredients found in energy drinks occur naturally and in other foods that we enjoy regularly.
•Taurine is an amino acid found naturally in the human body, as well as in common food items such as seafood, scallops and poultry.
•Caffeine has been safely consumed, in a variety of foods and beverages, around the world for hundreds of years.
•A vast body of available and reliable science supports the safety of caffeine, including at the levels found in mainstream energy drinks.
•According to a report from the U.S. Food and Drug Administration (FDA), on average, 14 to 21 year olds consume about one-third the amount of caffeine consumed daily by people over 21, with most of that amount coming from coffee, tea and soft drinks.