Energy drinks could jeopardize heart health, but caffeine may not be the culprit, warns AHA

29 May 2019 --- The increased blood pressure and impacted heart rhythms that resulted from healthy volunteers drinking about two cans – 32 ounces– of energy drink in a short timespan cannot be attributable to caffeine. This is according to a small study published in Journal of the American Heart Association (AHA), the Open Access Journal of the AHA. The researchers warn that more research is needed to investigate which energy beverage ingredient causes fluctuations in heart health. They are, therefore, calling for urgent further research.

“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 lead author Sachin A. Shah, Professor of Pharmacy Practice at University of the Pacific, Thomas J. Long School of Pharmacy and Health Sciences in Stockton, California.

The AHA study is the largest controlled study of the effects of energy drinks on the heart and blood pressure in young, healthy volunteers. Such findings are significant as estimates indicate that about 30 percent of teenagers between the ages of 12 through 17 years in the US consume energy drinks regularly, which have been linked to increased emergency room visits and death, note the researchers.

“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 study co-author Kate O’Dell, Pharm.D., Professor of Pharmacy and Director of Experiential Programs at the Thomas J. Long School of Pharmacy and Health Sciences.The AHA study is the largest controlled study of the effects of energy drinks on the heart and blood pressure in young, healthy volunteers. 

Diving into the study
Regarding the ingredient composition of the energy beverages tested, both contained 304 to 320 milligrams of caffeine per 32 fluid ounces. Notably, 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 water, lime juice and cherry flavoring.

Researchers 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 beginning of the study and every 30 minutes for four hours after drink consumption.

In participants who consumed either type of energy drink, researchers 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 (the lower chambers) 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 of the study confirm previous findings and suggest that the QT interval changes are generally sustained over the four-hour monitoring period rather than being a short-lasting effect after consuming 32-ounces of an energy drink.

Researchers also found a statistically significant 4 to 5 mm Hg increase in systolic and diastolic blood pressure in participants who consumed the energy drinks.

The researchers note that the findings cannot necessarily be attributed to the presence of caffeine in the beverage, and urgent research is necessary to investigate which ingredient, or combination of ingredients, can explain the findings.

Limitations of the research
The study, however, has some limitations. Firstly, it does not provide insight into long-term effects, nor the effects of routine energy drink consumption. Additionally, energy drink consumption was evaluated alone, and it is not uncommon for energy drinks to be consumed in combination with other substances such as alcohol. Finally, the study included only healthy individuals between the ages of 18 to 40 years and the results may be different in other populations.

“The public should be aware of the impact of energy drinks on their body especially if they have other underlying health conditions,” Shah says. “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.”Consumers are increasingly attracted to clean energy claims.

“Clean energy” NPD burst
The findings come as energy drinks continue to come under increased nutritional scrutiny. Earlier this week, the British National Health Service (NHS) canned the sale of energy drinks to under 16s in Scottish hospitals, citing that high levels of caffeine are not suitable for children. 

Concern over the impact of energy beverage ingredients such as caffeine and taurine on human health has led to an NPD surge in “clean” energy ingredients, as well as cognitive boosting ingredients. Nootropics and adaptogens, for example, are particularly popular and suppliers may be keen to transmit a “caffeine-free” claim. Innova Market Insights also notes how the energy drink category is evolving, as cleaner labels, clean energy concepts and organic claims make inroads. 

Global giants have hopped on this bandwagon, including The Coca-Cola Company. In April, it unveiled its first ever energy drink, Coca-Cola Energy, which debuted in Spain and Hungary. The new product contains caffeine from naturally-derived sources, guarana extracts, B vitamins and no taurine. Aimed at 18-35-year-old consumers, Coca-Cola Energy puts the brand in direct competition with market leaders in the energy drinks space, including Red Bull, Lucozade and Monster Energy (which Coca-Cola partly owns as the company’s biggest shareholder).

Also in April, it was announced that RUNA Clean Energy – an organic energy drink made from the Guayusa leaf – would be distributed by Keurig Dr Pepper and other regional distributor partners. RUNA contains 150mg of natural caffeine from a single source and comes in a range of sweetened and zero-calorie, zero-sugar variants. It was recently acquired by All Market Inc., (AMI), the parent company of Vita Coco. 

Concerns over caffeine, taurine and sugar content have continued to inhibit developments. However, with busy lifestyles informing the nutrition choices of many consumers, there could be ample room for energy drinks and opportunities for further NPD, that can tap into trends towards healthfulness, naturalness and clean label.

By Laxmi Haigh