Energy drinks have been found to affect the heart and blood pressure levels in a way caffeine-only drinks do not
A study published in the Journal of the American Heart Association has investigated the cardiovascular effects of energy drinks compared to caffeine-only drinks, with “concerning” results.
In the randomised, double-blind, caffeine-controlled study in healthy adults, participants in the intervention group were assigned to consume 946mL of a commercially available energy drink that contained: 320mg caffeine, sugar, vitamin B2, vitamin B3, vitamin B6, vitamin B12, taurine, panax ginseng extract, L-carnitine, glucuronolactone, inositol, guarana extract, and maltodextrin.
Those in the control group also received a 946mL drink that contained 320mg caffeine, plus 40mL of lime juice and 140mL of cherry syrup in carbonated water.
Researchers found signification prolongation of the corrected QT (QTc) interval two hours after energy drink consumption when compared with caffeine alone.
The QT interval is a measure of the time between the start of the Q wave and the end of the T wave in the heart’s electrical cycle.
Prolongation of the QT/QTc interval is a marker for life-threatening arrhythmias.
Systolic blood pressure remained significantly elevated over the caffeine control at six hours post energy drink consumption.
No difference was found between the groups in regards to heart rate, diastolic blood pressure, central systolic blood pressure, and central diastolic blood pressure at any time point.
Based on the results the researchers believe an ingredient other than caffeine, or a combination of ingredients, may be affecting the QT interval and blood pressure.
“The current literature is lacking regarding the hemodynamic profile of the ingredients contained in energy drinks, making it difficult to ascertain whether it is caffeine interacting with the other ingredients or the other ingredients alone that are driving the blood pressure effects,” they say.
Energy drinks usually consist of caffeine plus proprietary energy blends that vary between products.
“Taurine, L-carnitine, and panax ginseng are some additives found in energy drink that have conflicting physiologic effects. Guarana, another common ingredient in energy drinks, may contain 2% to 15% of its dry weight in caffeine.
“Due to the fact that multiple ingredients in energy drinks have the ability to alter electrophysiological properties, their sole and concurrent use needs further scrutiny.”
The long-term use of energy drinks also needs particular attention, they argue.
“While the degree of blood pressure chance seen in our study is generally not concerning in an acute setting, even mild sustained elevations in systolic blood pressure at the population level can increase the risk of adverse cardiovascular outcomes.”
The increased popularity of energy drinks has seen a coinciding rise in associated emergency department visits and deaths.
Those with congenital or acquired long QT syndrome should exercise caution when consuming energy drinks as they are at an increased risk for arrhythmias, the researchers say, adding that obesity has also been associated with prolongation of the QT interval.
They also warn that caution should be exercised when consuming energy drinks with alcohol.
“Combining alcohol or illicit substances with energy drinks may trigger or exacerbate untoward cardiovascular events.”