Energy drinks (EDs) are marketed as ‘functional beverages’ and consist of a soda-like drink with high doses of sugar and stimulants to provide a purported energy boost (i.e., it “gives you wings”—although there are no reports of actual wing or feather growth to date). Some of the most common ED ingredients are: caffeine, taurine, glucuronolactone, guarana, ginseng, vitamin B complex, and others. Many of these compounds have not been well studied and are present in EDs at higher doses than recommended, yet EDs are reported to be the fastest growing part of the beverage industry.
The primary consumers of these EDs are young men (18-30 years old). Consumption frequency is reported at about one to three days per month in amounts of about one to three liters in a day on average in a German population, and an average of 3.1 liters per month in the UK. Commonly reported reasons for use are staying awake, boosting athletic or academic performance, and mixing with alcohol. Most users cannot define ED ingredients and are unaware of the potential adverse effects.
Beyond rare cases of cardiac arrest following overconsumption of EDs, common reported adverse effects include cardiovascular (e.g. tachycardia—rapid heart rate, high blood pressure (BP)), gastrointestinal, and neurological (e.g. anxiety, irritability) changes. Moreover, caffeine is one of the only ED ingredients with documented adverse potential, while other common ED ingredients have not been well researched. It is not clear which components or combination of ingredients in EDs contribute to the adverse effects, or whether higher doses may lead to greater adverse effects than lower doses.
The authors of the study under review aimed to examine cardiovascular and metabolic effects of EDs and their major active ingredients (caffeine, taurine, glucuronolactone, or caffeine plus taurine) to determine whether one component or a combination of them is to blame for the reported adverse effects. The putative effects of these components are laid out in Figure 1.
With their high sugar and stimulant content, energy drinks are marketed to young adults who tend to use them to stay awake, boost athletic performance, and mix with alcohol. Beyond rare cases of cardiac arrest, common reported adverse effects include cardiovascular, gastrointestinal, and neurological disturbances, but the specific ingredient or combinations of ingredients that cause these adverse effects is unknown. The study under review aimed to determine the nature of any dose-dependent influence on adverse effects and attempts to distinguish which ingredient(-combination) might be causing these effects.