In a small study published in the Open Access Journal of the American Heart Association/American Stroke Association, drinking 32 ounces of an energy drink in a short timespan may increase blood pressure and the risk of electrical disturbances in the heart that affects heart rhythm.
There were 34 healthy volunteers between the ages of 18 and 40 that enrolled in the study. Individuals that participated 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 60-minute but no faster than one 16-ounce bottle in 30 minutes.
Using electrocardiogram that records the way a heart is beating, researchers measured the electrical activity of the volunteers' hearts. Also, they recorded the blood pressure of the participants. All measurements were taken at the study's start and every 30 minutes for 4 hours after drink consumption.
The two energy beverages tested contained 304 to 320 milligrams of caffeine per 32 fluid ounces. Caffeine at doses under 400 milligrams is not expected to induce any electrocardiographic changes. Other common ingredients in the energy drinks included taurine (an amino acid), glucuronolactone (found in plants and connective-tissues), and B-vitamins. The placebo drink contained carbonated, lime juice, and cherry flavoring.
The study discovered that in participants that consumed either type of energy drink, the QT interval was six 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 (lower chambers) to prepare to generate a beat again. In case 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.
Also confirmed by the results of the study were previous findings and suggested that the QT interval changes are generally sustained over the four-hour monitoring period rather than being a short-lasting effect after consuming 32-ounce of an energy drink.
Researchers also discovered a statistically significant 4 to 5 mmHg increase in systolic and diastolic blood pressure in participants who consumed the energy drinks.
The lead author of the study and professor of pharmacy practice at University of the Pacific, Thomas J. Long School of Pharmacy and Health Science in Stockton, California, Sachin A. Shah, said that they discovered a connection between consuming energy drink and changes in QT intervals and blood pressure that cannot be attributed to caffeine. Then, there was an urgency to investigate the particular ingredient or combination of ingredients in different types of energy drinks that might explain the findings seen in their clinical trial
Shah said that the public should be aware of the impact of energy drinks on their body, particularly if they have other underlying health conditions.
