Among the many products comprising the booming dietary supplement industry, a growing number of individuals are turning to supplements and drinks containing caffeine and other compounds purported to increase energy. According to some reports, the energy drink market in the United States reached more than $9.7 billion in sales in 2015.1 While many use these supplements with the aim of reducing fatigue and improving mental focus, people often seek to improve athletic performance by consuming such products.

However, experts have cautioned that, despite their popularity, caffeine-based products and other types of energy-boosting supplements could have adverse effects, especially on cardiovascular health. Because of these risks, the World Health Organization has cited consumption of energy drinks as a significant public health issue.2

While most of these risks are associated with the high levels of caffeine contained in these products, other common ingredients intended to increase energy include taurine, guarana, ginseng, glucuronolactone, and bitter orange.3 In a 2022 position statement, the European Association of Preventive Cardiology notedthat consumption of a formulation containing caffeine, taurine, and glucuronolactone “may increase arterial blood pressure, act as a platelet aggregation enhancing factor and compromise endothelial function in healthy individuals.”3


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The authors point to a range of cardiovascular side effects linked to consumption of energy drinks, including coronary disease, heart failure, cardiac arrhythmias, ventricular tachycardia, and aortic dissection, among numerous other potential cardiovascular consequences.3

In addition, in a randomized, double-blind, placebo-controlled trial published in 2019, Shah et al examined the effects of 2 different energy drinks on cardiovascular parameters compared to placebo.4 The results showed that that consumption of the energy drinks significantly prolonged participants’ QTc interval (maximum change from baseline in Bazett’s corrected QT interval: +17.9±13.9 ms for drink A, +19.6±15.8 ms for drink B, and +11.9±11.1 ms with placebo; P =.005 for ANOVA; P =.04 and P <.01, respectively, compared to placebo).

Significant increases in peripheral and central systolic and diastolic blood pressure were also observed with the energy drinks compared to placebo (all P <.001).

These risks may be especially elevated among individuals with underlying heart conditions. A 2017 study found that the risk of cardiac arrest increased by 20% in individuals with familial long QT syndrome after drinking 2 cans of an energy drink.3

Along with the cardiovascular hazards associated with these drinks and other energy supplements in general, consuming them before exercise can further compound the risks as cardiovascular demands increase with physical activity. For example, some findings suggest that intake of 200-300 mg of caffeine 1 hour prior to aerobic exercise decreased endothelial cell function in healthy individuals, as indicated by reductions in myocardial blood flow.5

To gauge clinician views on the potential cardiovascular risks of consuming caffeine and other energy supplements before exercise, Cardiology Advisor checked in with Gregory M Marcus, MD, MAS, professor of medicine in residence and associate chief of cardiology for research at the University of California, San Francisco, School of Medicine, and  Jeffrey J. Hsu, MD, PhD, assistant clinical professor of medicine in the division of cardiology at the University of California, Los Angeles, School of Medicine.

What is known thus far about the cardiovascular effects of supplements such as energy drinks containing caffeine or other substances before exercising? 

Dr Marcus: The great majority of research in this area has been conducted in artificial environments using small numbers of research participants and usually examining 1 brief moment in time rather than repeated assessments.6 Although the data there are conflicting, there is some evidence that caffeine may help bolster athletic performance. However, these studies have generally not been designed to assess the safety of this practice nor longer-term consequences beyond mainly a single workout.

It’s important to emphasize that the possible health benefits of caffeine that have been recently highlighted in the medical literature and lay press stem from large observational studies of predominately regular coffee drinkers rather than the use of high doses of caffeine or caffeine supplements specifically before exercise.7

Dr Hsu: Caffeine is a common ingredient in most energy drinks, including those taken prior to exercise. While caffeine in moderate amounts – the equivalent of 2 to 4 cups of coffee – may help to improve endurance, the concern is that higher doses of caffeine may increase the risk of adverse cardiovascular effects, including arrhythmias and severe hypertension, particularly when combined with high-intensity exercise. 

Have you observed any effects related to these drinks or supplements in your own patients?

Dr Hsu: Yes, it is increasingly common for athletes – both at the recreational and elite levels – to use caffeinated “pre-workout” supplements during their training, and I have seen young athletes present with symptoms related to arrhythmias or ectopy. These often improve or completely resolve with cessation of these supplements. 

How should clinicians advise patients regarding the use of these supplements in the context of exercise?

Dr Marcus: While clinicians should, of course, encourage regular exercise, they should likely caution their patients against using supplements or energy drinks to facilitate workouts. There is no strong evidence of clinical benefit and some observational data to demonstrate harm.

These energy drinks may include other constituents, including sugar, that are overall detrimental to health. I generally recommend avoiding supplements, as the concentrations of molecules tends to exceed those in natural foods that our bodies have evolved to consume.

In general, large randomized trials of supplements tend to show either no benefit or harm to health, often with unintended adverse consequences.7 For example, while observational studies suggest that caffeine as can be found in commonly consumed beverages like coffee does not have a meaningful negative effect on heart rhythm disturbances and may even protect against some common heart rhythm problems, there are many case reports of young, otherwise healthy individuals experiencing clinically significant heart rhythm disturbances in the context of consuming energy drinks with high levels of caffeine.8

Dr Hsu: Clinicians who care for athletes should inquire about supplement use during clinic visits. Clinicians should counsel their patients that there is no “magic bullet” for optimizing their cardiovascular fitness or athletic performance, and athletes should carefully review the components of any exercise supplement they plan to consume. Those who have a history of cardiovascular disease such as arrhythmias, hypertension, or cardiomyopathy should take extra caution and review supplements with their physician prior to use. 

What are the most pressing remaining research needs regarding this topic?

Dr Marcus: Long-term investigations examining actual health-related outcomes beyond simply immediate physical performance are needed to inform clinicians and, in turn, help us to provide the most beneficial guidance to our patients.

Dr Hsu: In my opinion, with the widespread use and marketing of these exercise supplements, we need a better understanding of whether we are clearly seeing adverse cardiovascular effects in people who use these supplements. My concern is that there is little regulation of how these supplements are marketed, and combining high doses of caffeine or other stimulants with vigorous exercise may carry undue cardiovascular risk. 

References

  1. Al-Shaar L, Vercammen K, Lu C, Richardson S, Tamez M, Mattei J. Health effects and public health concerns of energy drink consumption in the United States: a mini-review. Front Public Health. 2017;5:225. doi:10.3389/fpubh.2017.00225
  2. Breda JJ, Whiting SH, Encarnação R, et al. Energy drink consumption in Europe: a review of the risks, adverse health effects, and policy options to respond. Front Public Health. Published online October 14, 2014. doi:10.3389/fpubh.2014.00134
  3. Adami PE, Koutlianos N, Baggish A, et al. Cardiovascular effects of doping substances, commonly prescribed medications and ergogenic aids in relation to sports: a position statement of the sport cardiology and exercise nucleus of the European Association of Preventive Cardiology. Eur J Prev Cardiol. Published online January 27, 2022. doi:10.1093/eurjpc/zwab198
  4. Shah SA, Szeto AH, Farewell R, et al. Impact of high volume energy drink consumption on electrocardiographic and blood pressure parameters: a randomized trial. J Am Heart Assoc. Published online May 29, 2019. doi:10.1161/JAHA.118.011318
  5. Planning Committee for a Workshop on Potential Health Hazards Associated with Consumption of Caffeine in Food and Dietary Supplements; Food and Nutrition Board; Board on Health Sciences Policy; Institute of Medicine. Caffeine in food and dietary supplements: examining safety: workshop summary. Washington (DC): National Academies Press (US). 2014(5): Caffeine Effects on the Cardiovascular System. 
  6. Cameron M, Camic CL, Doberstein S, Erickson JL, Jagim AR. The acute effects of a multi-ingredient pre-workout supplement on resting energy expenditure and exercise performance in recreationally active females. J Int Soc Sports Nutr. 2018;15:1. doi:10.1186/s12970-017-0206-7
  7. Poole R, Kennedy OJ, Roderick P, Fallowfield JA, Hayes PC, Parkes J. Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes. BMJ. Published online November 21, 2017. doi:10.1136/bmj.j5024
  8. Mandilaras G, Li P, Dalla-Pozza R, Haas NA, Oberhoffer FS. Energy drinks and their acute effects on heart rhythm and electrocardiographic time intervals in healthy children and teenagers: a randomized trial. Cells. 2022;11(3):498. doi:10.3390/cells11030498