Are energy drinks putting your heart and mind at risk?

In a recent review published in Nutrients, researchers examine the reported effects of consuming energy drinks on human health, particularly the cardiovascular and nervous systems.

Study: The Dark Side of Energy Drinks: A Comprehensive Review of Their Impact on the Human Body. Image Credit: Pheelings media / Shutterstock.com

Background

The aggressive promotion of energy drinks as a portable source of energy and stimulation by beverage companies, combined with their widespread availability in grocery stores, gas stations, and other retail outlets, has increased their consumption among young adults and adolescents. Many of these energy drinks are associated with claims that they can improve focus and concentration, increase energy levels, and enhance scholarly or physical performance.

Current popular energy drinks often include large amounts of caffeine, added sugars, and legal stimulants such as guarana, taurine, and L-carnitine. The rise of the energy drinks market among young children and adolescents has inevitably increased their caffeine consumption levels by up to 70% between 1977 and 2009.

Recent reports suggest a rising incidence of people seeking medical care after consuming energy drinks for mild adversities, such as gastrointestinal disturbances and dehydration, along with more severe outcomes like stroke. Several fatalities linked to energy drink use have also been reported.

Energy drinks likely confer some short-term benefits; however, researchers need to examine their long-term consequences on human health amid rising reports of their adverse effects.

About the study

In the present study, researchers screened PubMed, Google Scholar, and EBSCO search engines to identify original research articles and case reports/series published between January 5, 2009, and April 30, 2023, reporting the effects of acute or chronic abuse of energy drinks on humans. Case-control studies utilizing animal models were also included in the analysis. 

Study findings

A total of 96 scientific papers were included in the analysis, 35, 12, 18, seven, and two of which reported the effects of energy drink consumption on cardiac, gastrointestinal, neurologic, renal, gynecological, autoimmune, and skin systems, respectively.

Nine cases of cardiac arrest were associated with high doses of stimulants in energy drinks. Moreover, energy drink consumption was primarily associated with cardiac arrhythmias, such as ventricular fibrillation and previously unrecognized channelopathies. Several cases in which patients with no known medical conditions suffered acute cardiac events after consuming a few 250 mL cans of energy drinks were also reported.

Three individuals died due to sudden cardiac arrest, whereas six required intensive cardiopulmonary resuscitation and exhibited no cardiac abnormalities during follow-up visits.

Caffeine was often implicated in energy drink-related chronotropic and inotropic effects on the heart. At higher and very high concentrations of 10 micromolar (µM) and 100 µM, respectively, caffeine directly increased calcium uptake by increasing cyclic adenosine monophosphate (cAMP) and reduced calcium sequestration by the sarcoplasmic reticulum, respectively. 

Every 100 mg of caffeine increased systolic and diastolic blood pressure by 0.8 and 0.5 mmHg, respectively. Many previous studies have conclusively demonstrated how caffeine induces arrhythmias in people with atrioventricular conduction disorders.

The high caffeine content of energy drinks has also been associated with many adverse effects on the central nervous system (CNS), including seizures, manic psychosis, and cerebral vasculopathy. In one study, echoencephalography (EEG) demonstrated that caffeine intake from energy drinks increased left frontal activation to a greater extent than the right frontal lobe, thus suggesting that energy drinks mimic the effect of dopamine on striatopallidal neurons to reduce fatigue. 

Less than 500 mg of caffeine has been shown to increase alertness, speed of thoughts and speech, diminished fatigue, and reduced sleep. However, higher doses of caffeine likely contribute to anxiety, insomnia, tremors, and seizures.

The chronic consumption of energy drinks has been associated with stress, anxiety, and depression. These effects are likely due to the ability of taurine to mimic gamma-aminobutyric acid (GABA) and the anticonvulsant effects of glycine.

All energy drinks contain vitamins. Notably, a dose-dependent effect of vitamin B3 (niacin) has been implicated in hepatotoxicity, wherein its megadoses initially caused a mild elevation of liver enzymes, hepatic steatosis/necrosis, and, in rare cases, liver failure.

In vivo studies have similarly reported acute and chronic toxicity associated with energy drink consumption. In one study evaluating the effects of energy drinks in rabbits, a direct correlation was observed between brain, liver, kidneys, and heart tissue damage and energy drink dose.

Conclusions

The European Food Safety Authority (EFSA) has set an upper safe intake limit of 400 mg/day of caffeine in adults. Since caffeine is the main component of energy drinks, precise limits on the consumption of these drinks are warranted. 

The long-term effects of energy drinks are unclear; however, their consumption may cause psychiatric pathologies or aggravate cardiac conduction disorders in minors. Thus, although energy drinks contain legal substances, their consumption and sale should be strictly regulated, especially for minors. Pregnant or breastfeeding women should also avoid these products altogether to avert possible long-term adverse effects of energy drink consumption on their unborn child.