# Consumption of Energy Drinks among University Students in Eastern Croatia
## 1 Introduction  
Modernized and stressful way of life today has led people to seek new solutions for overcoming fatigue just to be more productive. Therefore, they turn to various products offered on the market such as energy drinks (EDs) [1]. The ingredients of EDs have different biochemical, ergogenic, and possible additive or synergic properties which are not yet been fully clarified [1; 2]. The concentration of caffeine, which is the main ingredient of EDs, sometimes varies significantly in those drinks [3; 4; 5]. Along with highlighted beneficial effects of EDs such as an energy boost, and improvement of physical and cognitive performance, there are some adverse health effects related to the consumption of EDs such as arrhythmia, increase in blood pressure, anxiety, sleep disorders, gastrointestinal and metabolic effects, agitation, migraines [3; 6] and cardiovascular complications [3; 6; 7]. U.S. Poison Control Centers as well as U.S. Food and Drug Administration (USFDA) linked the consumption of EDs even to possibly fatal outcomes [8; 9]. [PERSON] et al. [10] noticed how moderate EDs consumption did not reveal clinically relevant cardiovascular changes in young adults while high intake (\(\geq\)1 L) could cause some adverse effects. A large study conducted on more than 52,000 participants from 16 different EU Member States revealed that 68% of adolescents, 30% of adults, and 18% of children consumed EDs at least once during the last year with the average volumes consumed being 2.1, 2.0, and 2.0 L/month. A particularly worrying fact is that around 12% of adolescent consumers were identified as so-called \"high chronic\" consumers, i.e., consuming EDs 4-5 times/week or more, with an average consumed EDs volume of 7 L/month [2]. [PERSON] et al. [11] investigated the patterns of EDs use among German adolescents and discovered that 61.7% of the respondents reported using EDs during their lifetime while 21.4% reported using EDs inthe last month. They also discovered that consumption of EDs was related to the male sex, older age, drug use, poor nutrition, higher BMI, excitement seeking, poor school achievement, and more frequent commercial exposure. Studies have also shown more frequent consumption of EDs among people who engage in physical activity as well as among people who smoke [12]. Numerous studies highlighted the growing trend of EDs consumption worldwide [13; 14; 15]. [PERSON] et al. [13] discovered a significant increase in EDs consumption over the past 12 years (from 2008 to 2019) among high school students. [PERSON] et al. [15] reported a significant increase in EDs consumption from 2003 to 2016 for three population groups in the U.S. The consumption increased in adolescents (0.2% to 1.4%, \(p\) = 0.028), young adults (0.5% to 5.5%, \(p\) < 0.001), and middle-aged adults (0.0-1.2%, \(p\) = 0.006), indicating the largest increase among young adults. A higher total caffeine intake was also noticed for all observed groups in comparison to EDs non-consumers which also indicates EDs as a major source of caffeine. Moreover, consumers often do not read the labels provided on EDs which is why they are probably not even aware of the harmful effects of EDs consumption [16]. Except for labeling caffeine concentration and highlighting warnings such as \"High caffeine content\" and \"Not recommended for children, pregnant and breastfeeding women\", EDs remain globally under-regulated [11; 17; 18]. The European Cardiac Arrhythmia Society recently issued recommendations regarding the consumption of these drinks, to prevent possible adverse effects. The consumption of EDs is not recommended for children under 14 years of age, as well as for populations at higher risk of heart disease. The daily limit of caffeine intake is emphasized to be 400 mg, while in children over 14 years the total intake should not exceed 2.5 mg/kg of body weight. Consumption of EDs before or during sports activities or mixing EDs and alcohol or illicit drugs is also not recommended [17].