The lead author of the study was Professor Sachin A. Shah, PharmD, FAHA, who is the Regional Coordinator and Director of Pharmacy Research and Education at Travis Air Force Base, Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, California, USA.

The co-author of the study was Professor Kate M. O'Dell, PharmD, BCPS, who is the Director of Experiential Programs and Vice Chair of Pharmacy Practice at the Thomas J. Long School of Pharmacy and Health Sciences, University of the Pacific, Stockton, California, USA.

Composition of the Energy Drinks

Two commercially available caffeinated energy drinks or placebo was used in the study. Both these energy drinks contained 304 and 320 milligrams (mg) of caffeine per 32 fluid ounces (fl. oz). It is known that caffeine levels below 400 mg do not produce any changes in electrocardiograms (ECG).

Besides caffeine, other ingredients included taurine (amino acid containing sulfur), glucuronolactone (a component of connective tissues and plant gums), and vitamin B-Complex. The placebo drink was composed of cherry flavored carbonated water and lime juice.

"Energy drinks are readily accessible and commonly consumed by a large number of teens and young adults, including college students. Understanding how these drinks affect the heart is extremely important," says O'Dell.

Study Procedure

• Study participants included 34 healthy volunteers aged 18-40 years
• Participants were randomly assigned to drink one of the two caffeinated energy drinks or the placebo drink
• 32 oz of the drinks were consumed on three separate days
• Drinks were consumed within 1 hour
• Rate of consumption was no more than 16 oz in 30 minutes
• Electrical activities of the participants' hearts were recorded by ECG
• The ECG recorded the QT interval, which is a measure of the total duration of ventricular activation (depolarization) and recovery (repolarization) during the pumping action or beating of the heart
• Too short or too long QT interval can cause abnormal heartbeats (arrhythmia), which can be life-threatening
• Blood pressure was also measured and recorded
• All measurements were taken at the beginning of the study and every 30 minutes for up to 4 hours after finishing the drinks

Study Findings

• In energy drink consumers, the QT intervals for the two drinks were six milliseconds or 7.7 milliseconds higher at 4 hours compared to placebo drinkers
• In energy drink consumers, there was a 4-5 mmHg increase in systolic and diastolic blood pressure, which was statistically significant
• After consuming the energy drinks, the changes in QT intervals were sustained over the 4-hour study period, rather than short-lasting, which corroborates previous studies

"We found an association between consuming energy drinks and changes in QT intervals and blood pressure that cannot be attributed to caffeine. 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," says Shah.

Limitations of the study

• The effect of long-term or regular consumption of energy drinks was not assessed
• The effect of consumption of energy drinks in combination with alcohol, which is very common, was not assessed
• The results obtained were for healthy individuals in the age-group of 18-40 years, which could be different for other populations

Concluding Remarks

Professor Sachin Shah concludes with a word of caution for energy drink consumers having underlying heart conditions or high blood pressure: "The public should be aware of the impact of energy drinks on their body, especially if they have other underlying health conditions," says Shah. "Healthcare professionals should advise certain patient populations, for example, people with underlying congenital or acquired long QT syndrome or high blood pressure, to limit or monitor their consumption."

Funding Source

The study was funded by the University of the Pacific, Stockton, California, USA.

Reference :

1. Energy drinks may increase risk of heart function abnormalities and blood pressure changes - (https://newsroom.heart.org/news/energy-drinks-may-increase-risk-of-heart-function-abnormalities-and-blood-pressure-changes?preview=2c57)

Source: Medindia