According to a new study in the Journal of the American Heart Association, drinking 32 ounces (about 950 ml) of an energy drink in a short timespan may raise blood pressure and increase the risk of heart function abnormalities.
Energy drinks are a growing industry with a market value predicted to reach $61 billion by 2021.
It is estimated that about 30% of teenagers between the ages of 12 through 17 years in the U.S. consume energy drinks on a regular basis.
“Energy drinks are readily accessible and commonly consumed by a large number of teens and young adults, including college students,” said University of the Pacific’s Professor Kate O’Dell, co-author of the study.
“Understanding how these drinks affect the heart is extremely important.”
The study enrolled 34 healthy volunteers between the ages of 18 and 40 years.
Participants were randomly assigned to drink 32 ounces of one of two commercially available caffeinated energy drinks or a placebo drink on three separate days. The drinks were consumed within a 60-min period but no faster than one 16-ounce (475 ml) bottle in 30 min.
Professor O’Dell and co-authors measured the electrical activity of the volunteers’ hearts by electrocardiogram, which records the way a heart is beating. They also recorded participant’s blood pressure. All measurements were taken at the study’s start and every 30 minutes for 4 hours after drink consumption.
Both energy beverages tested contained 304 to 320 mg of caffeine per 32 fluid ounces (caffeine at doses under 400 milligrams is not expected to induce any electrocardiographic changes).
In participants who consumed either type of energy drink, the team found that the QT interval was 6 milliseconds or 7.7 milliseconds higher at 4 hours compared to placebo drinkers.
The QT interval is a measurement of the time it takes ventricles in the heart to prepare to generate a beat again. If this time interval is either too short or too long, it can cause the heart to beat abnormally. The resulting arrhythmia can be life-threatening.
The results suggest that the QT interval changes are generally sustained over the 4-hour monitoring period rather than being a short-lasting effect after consuming 32-ounces of an energy drink.
The scientists also found a statistically significant 4 to 5 mm Hg increase in systolic and diastolic blood pressure in participants who consumed the energy drinks.
“We found an association between consuming energy drinks and changes in QT intervals and blood pressure that cannot be attributed to caffeine,” said University of the Pacific’s Professor Sachin Shah, lead author of the study.
“We urgently need to investigate the particular ingredient or combination of ingredients in different types of energy drinks that might explain the findings seen in our clinical trial.”
Sachin A. Shah et al. 2019. Impact of High Volume Energy Drink Consumption on Electrocardiographic and Blood Pressure Parameters: A Randomized Trial. Journal of the American Heart Association 8 (11); doi: 10.1161/JAHA.118.011318