Energy drinks: the BfRshort forGerman Federal Institute for Risk Assessment updates its assessment of the health risks to children and adolescents associated with acute and chronic consumption

With this opinion, the Federal Institute for Risk Assessment (BfRshort forGerman Federal Institute for Risk Assessment) is revising Opinion No. 018/2019, ‘External Link:Children and adolescents: Excessive consumption of energy drinks increases the risk to cardiovascular health’ (in German).

In this regard, the BfRshort forGerman Federal Institute for Risk Assessment has conducted a new assessment of the body of research since the publication of BfRshort forGerman Federal Institute for Risk Assessment Opinion No. 018/2019 in External Link:2019.In particular, results from relevant studies such as the EDUCATE and EDKAR studies were taken into account. Once again, primarily the focus was on the potential cardiovascular risk that could arise from the consumption of energy drinks. As children and adolescents (as well as young adults) are the main target group of the energy drink market, the update focused primarily on the cardiovascular effects of energy drinks in children and adolescents. In addition to the acute effects previously considered, new data has now made it possible to examine the long-term effects of chronic high consumption. This analysis was based on current consumption data on energy drink intake among children and adolescents in Germany. Studies on adults were not re-examined.

2.1 Effects of acute moderate consumption of energy drinks

Taking into account the current scientific evidence, the BfRshort forGerman Federal Institute for Risk Assessment reaches the result that, in the case of acute, moderate consumption of energy drinks with caffeine intakes that do not exceed the intake level of 200 mgshort formilligram as a single dose – which is still considered safe by the European Food Safety Authority (EFSAshort forEuropean Food Safety Authority) – namely 200 mgshort formilligram as a single dose – are not expected to cause any health effects in healthy adults. However, the BfRshort forGerman Federal Institute for Risk Assessment points out that individuals with predispositions, including to certain heart conditions, may react much more sensitively to caffeine intake than healthy individuals.

There are very few intervention studies, involving only a small number of participants, on the acute effects of energy drinks in children and adolescents. The results of these studies show that acute moderate consumption of energy drinks, involving a caffeine intake deemed safe by EFSAshort forEuropean Food Safety Authority, leads to temporary changes in various cardiac parameters. Overall, the evidence regarding the effects of acute, moderate consumption of energy drinks in children and adolescents is limited.

To date, there is no evidence to suggest that health effects are to be expected at the acute caffeine intake level of 3 mgshort formilligram per kgshort forkilogram of body weight (bw), which EFSAshort forEuropean Food Safety Authority still considers safe for healthy children and adolescents.

2.2 Effects of acute high consumption of energy drinks

Health risks may arise from acute high consumption of energy drinks resulting in caffeine intake exceeding the EFSAshort forEuropean Food Safety Authority limit values. In intervention studies involving healthy young adults, in which energy drinks were administered as a single acute dose in amounts that exceeded the caffeine intake level still considered safe by EFSAshort forEuropean Food Safety Authority, moderate to severe adverse effects were observed in some participants, such as palpitations, shortness of breath, severe tremor, severe nausea, anxiety and nervousness (Section 3.5.2). Furthermore, significant prolongations of the QTc interval were observed in some intervention studies involving healthy young adults who consumed an amount of energy drinks of approximately one litre (l) (Section 3.5.1.3).

There are currently no intervention studies available for children and adolescents involving higher amounts of energy drinks in which the caffeine intake considered safe by EFSAshort forEuropean Food Safety Authority has been exceeded. This would also be unjustifiable on ethical grounds.

However, in light of the adverse effects identified following acute high intakes of caffeine or energy drinks in young, healthy adults, the BfRshort forGerman Federal Institute for Risk Assessment assumes that the sensitive group of children and adolescents – some of whom are not yet accustomed to caffeine – would react at least as sensitively to such acute high intakes as adults. Data for Germany show that some children and adolescents consume such high amounts, and even more (in some cases up to four litres on a single day of consumption), thereby in some cases significantly exceeding the caffeine intake level still considered safe by EFSAshort forEuropean Food Safety Authority (3 mgshort formilligram per kgshort forkilogram of body weight as a single dose or spread over the day).

Due to the sometimes very acute high consumption of energy drinks, children and adolescents in particular therefore represent a risk group for adverse health effects.

Adults, too, sometimes drink such large amounts (one litre or more) on specific occasions; however, the proportion of adults exhibiting such consumption patterns is lower (5% of all respondents).

2.3 Effects of chronic moderate consumption of energy drinks

To date, there have been no studies involving children and adolescents that have investigated the long-term health effects of chronic moderate energy drink consumption, i. e., no more than 3 mgshort formilligram of caffeine per kgshort forkilogram of body weight per day.

2.4 Effects of chronic high consumption of energy drinks

The results of the EDKAR study showed that, in the adjusted model, there were no significant and/or clinically relevant differences in any of the measured cardiac parameters between the group of chronic high consumers and the control group among the adolescents studied (aged 15–18 years).

However, the study does not allow conclusions to be drawn as to whether differences would arise if the group of chronic high consumers were to continue consuming large amounts of energy drinks.

Furthermore, in the EDKAR study, almost half of the chronic high consumers reported having experienced unpleasant physical sensations after drinking energy drinks at some point. The most commonly reported symptoms were palpitations/rapid heartbeat, poor sleep, headaches and a feeling of pressure or tightness in the chest.

No data are available on the effects of chronic high consumption of energy drinks in younger children under the age of 15.

Although no effects on cardiovascular health were initially observed, the EDKAR study does not allow to draw any conclusions regarding the health consequences of long-term high consumption of energy drinks.

2.5 Other aspects

2.5.1 Case reports

In addition, there are a large number of published case reports relating to the consumption of energy drinks. The main symptoms observed were cardiovascular complaints (chest pain, tachycardia, heart attack, cardiac arrhythmias, cardiac arrest, etc.), but psychiatric disorders (anxiety, psychosis, hallucinations), epilepsy and reversible acute kidney failurewere also reported. Although no causal links can be derived from case reports, the sheer number of reports does give cause for concern that excessive consumption of such drinks – particularly in conjunction with other high-risk behaviours (e.g. heavy alcohol consumption) or pre-existing medical conditions – could be associated with adverse health effects.

2.5.2 Risk awareness

A study on the need-based consumption of energy drinks has shown that awareness of the potential health risks associated with acute, excessive consumption of energy drinks – particularly in conjunction with intense physical activity or alcohol consumption – is low or insufficient among adolescents and young adults in Germany. The BfRshort forGerman Federal Institute for Risk Assessment therefore assumes that, among children too, awareness of the risks associated with excessive consumption of these drinks – particularly in conjunction with intense physical activity and/or high alcohol consumption – is generally too low, or that these population groups are not sufficiently informed about the potential risks of excessive energy drink consumption.

2.6 Possible courses of action

The BfRshort forGerman Federal Institute for Risk Assessment recommends minimising the potential health risks associated with excessive energy drink consumption among children and adolescents, particularly in view of the known risks associated with acute excessive consumption. Through measures tailored to specific target groups in the domains of health education and health promotion, children and adolescents’ awareness of the risks associated with excessive consumption of energy drinks could be raised. This could help prevent health risks and encourage them to take personal responsibility for leading a healthy lifestyle.

Educational programmes could be developed to raise awareness amongst children, adolescents, parents and educational professionals regarding the potential risks associated with such consumption patterns. Social media, in particular, could be utilised for this purpose, as it is used more extensively by children and adolescents than traditional media. It is recommended that existing educational and information materials (leaflets, videos, etc.), which are made available on the website of the Federal Centre for Diet (BZfE), amongst other places, be used more extensively in information campaigns in schools, thereby better reaching the actual at-risk group.

In view of the identified adverse effects associated with acutely high intakes of caffeine or energy drinks (see sections 3.1.3, 3.5.1.3 and 3.5.2), which can already occur in young, healthy adults, further management measures may also need to be considered where appropriate.

Energy drinks are caffeinated soft drinks which, in Germany, are defined in accordance with Section 4(2) of the Fruit Juice and Soft Drinks Regulation (FrSaftErfrischGetrV, 2012), may contain, in addition to caffeine, a maximum amount of 320 mgshort formilligram/l of one or more of the substances listed in Annex 8, Part B of the aforementioned Regulation in the ready-to-eat food. Accordingly, ready-to-eat food may contain taurine up to a maximum level of 4,000 mgshort formilligram/l, glucuronolactone up to a maximum level of 2,400 mgshort formilligram/l and inositol up to a maximum level of 200 mgshort formilligram/l.

In the following, the potential ingredients are first assessed as individual substances and then the energy drinks as a whole.

3.1 Caffeine

3.1.1 ModeClose dialogModeModeTo glossary of action

The effects of caffeine are primarily based on antagonistic activity at the adenosine receptors A1 and A2 (Ferre, 2008; Fisone et al.short foret alii (lat. "and others"), 2004). The neuromodulator adenosine is believed to have a sleep-promoting effect, as it inhibits, amongst other things, the release of glutamate and dopamine, which are thought to contribute to increased cortical activity and motor neuron activity, respectively (Ferre, 2010). The stimulant effect of caffeine is primarily due to the fact that, by binding to the adenosine receptor, caffeine prevents adenosine from interacting with its receptor. This allows glutamate and dopamine to be released in greater quantities once more, enabling them to exert their activating effects (Ferre, 2010; Nieber K., 2007). Caffeine thus acts differently to cocaine, which directly inhibits the reuptake of dopamine (Lane et al.short foret alii (lat. "and others"), 2014). Caffeine is also thought to lead to increased plasma concentrations of adrenaline and noradrenaline (Riksen et al.short foret alii (lat. "and others"), 2009).

Following repeated intake, tolerance to caffeine may develop, though not to all of its effects. Tolerance to the effects of caffeine on blood pressure and heart rate develops within days and is accompanied by a reduced caffeine-induced release of adrenaline, noradrenaline and renin (Fredholm et al.short foret alii (lat. "and others"), 1999). The exact mechanism underlying the development of tolerance is not yet fully understood; however, it is suggested that this may be due to increased expression of adenosine receptors (Ammon, 1991; Fredholm et al.short foret alii (lat. "and others"), 1999).

Withdrawal symptoms that may occur following caffeine abstinence after regular high caffeine consumption include headaches, tiredness, reduced activity/energy, reduced alertness, drowsiness, reduced satisfaction, a depressed mood, difficulty concentrating, irritability and a ‘foggy’ state (Juliano and Griffiths, 2004).

3.1.2 Bioavailability, distribution and elimination

According to EFSAshort forEuropean Food Safety Authority, studies show that caffeine is rapidly and completely absorbed following oral intake (Blanchard and Sawers, 1983) and can then pass unhindered across the blood-brain, placental and blood-testis barriers (Arnaud, 1993; Weathersbee and Lodge, 1977). In the human liver, caffeine is mainly metabolised to paraxanthine (70–80%), which is then further broken down and shedded via the kidneys. Metabolism to paraxanthine is mediated by the cytochrome P450 monooxygenase CYP1A2, which accounts for 95% of caffeine clearance (Berthou et al.short foret alii (lat. "and others"), 1991; Miners and Birkett, 1996).

In adults, caffeine has a plasma half-life of 2 to 8 hours (Abernethy and Todd, 1985; Abernethy et al.short foret alii (lat. "and others"), 1985; Balogh et al.short foret alii (lat. "and others"), 1995; Knutti et al.short foret alii (lat. "and others"), 1981).

Pregnant women have an increased plasma half-life for caffeine, which can be as long as 18 hours at the end of pregnancy in non-smoking women (Aldridge et al.short foret alii (lat. "and others"), 1981). The prolonged half-life of caffeine in pregnant women is explained by the fact that oestrogens and progestogens can inhibit CYP1A2 activity (Abernethy et al.short foret alii (lat. "and others"), 1985; Balogh et al.short foret alii (lat. "and others"), 1995; Rietveld et al.short foret alii (lat. "and others"), 1984). As neither the foetus nor the placenta can metabolise caffeine, foetuses of women who consume caffeine are exposed to caffeine for a longer period (Grosso et al.short foret alii (lat. "and others"), 2006).

Newborns, too, do not yet exhibit any significant CYP1A2 activity and therefore have a caffeine half-life of 50 to 103 hours (Ginsberg et al.short foret alii (lat. "and others"), 2004; Grosso et al.short foret alii (lat. "and others"), 2006). However, the half-life of caffeine decreases dramatically as the baby gets older. By the third to fourth month, it falls to 14 hours, and by the fifth to sixth month to 2 to 3 hours (Aranda et al.short foret alii (lat. "and others"), 1979). During childhood, the half-life of caffeine remains stable at 2 to 3 hours, before rising again in adolescents and adults (Meltzer H. M., 2008).

3.1.3 Adverse effects

The hazard potential associated with caffeine has already been intensively and comprehensively investigated and described in numerous publications (EFSAshort forEuropean Food Safety Authority, 2015; Nawrot et al.short foret alii (lat. "and others"), 2003; Wikoff et al.short foret alii (lat. "and others"), 2017).

According to this, known adverse effects of caffeine – which may potentially occur depending on the dose ingested or individual sensitivity – include, amongst others, nervousness, increased anxiety, excitability, insomnia, gastrointestinal complaints, increased diuresis, increased respiration, elevated body temperature, arrhythmias, tachycardia, elevated blood pressure, reduced myocardial blood flow, and, in pregnant women, reduced foetal growth (EFSAshort forEuropean Food Safety Authority, 2015; Nawrot et al.short foret alii (lat. "and others"), 2003; Wikoff et al.short foret alii (lat. "and others"), 2017).

3.1.4 Safe levels of caffeine intake

The opinion published by the European Food Safety Authority (EFSAshort forEuropean Food Safety Authority) in 2015 on the safety of caffeine (EFSAshort forEuropean Food Safety Authority, 2015) addresses the potential adverse health effects of both acute and habitual consumption of caffeine from food in the general healthy population. It did not consider possible adverse health effects of caffeine on particularly sensitive population groups, such as people with certain pre-existing medical conditions or those who take certain medicines and/or drugs in combination with caffeine, or who consume large amounts of alcohol.

The EFSAshort forEuropean Food Safety Authority concluded that, for healthy adults, single doses of caffeine of up to 200 mgshort formilligram or the equivalent amount consumed within a short period of time (corresponding to 3 mgshort formilligram/kgshort forkilogram body weight) from all sources are safe for health, even if caffeine is consumed less than two hours before intense physical activity under normal (environmental) conditions. According to EFSAshort forEuropean Food Safety Authority, the occurrence of clinically relevant changes in blood pressure, myocardial blood flow, hydration status or body temperature is unlikely with intakes up to this amount (EFSAshort forEuropean Food Safety Authority, 2015).

For habitual caffeine consumption, EFSAshort forEuropean Food Safety Authority derived a safe intake of up to 400 mgshort formilligram (equivalent to 5.7 mgshort formilligram/kgshort forkilogram body weight), spread throughout the day, for healthy adults.

According to the EFSAshort forEuropean Food Safety Authority opinion, a daily intake of up to 200 mgshort formilligram of caffeine, spread throughout the day, is safe for the foetus and the breastfed child in pregnant and breastfeeding women. For breastfeeding women, a single dose of 200 mgshort formilligram is also considered safe for the breastfed child (EFSAshort forEuropean Food Safety Authority, 2015).

In its opinion, the EFSAshort forEuropean Food Safety Authority points out that, for children and adolescents, the available data regarding a link between caffeine intake and health effects are insufficient to derive a safe intake level (as an acute single dose or for habitual consumption spread throughout the day). However, EFSAshort forEuropean Food Safety Authority concludes that the acute single dose of caffeine of 3 mgshort formilligram/kgshort forkilogram body weight, which is considered safe for adults, can also be regarded as safe for children and adolescents, as the rate at which children and adolescents metabolise caffeine is at least equivalent to that of adults. For the habitual consumption of caffeine by children and adolescents, the EFSAshort forEuropean Food Safety Authority therefore also proposes a safety level of 3 mgshort formilligram/kgshort forkilogram body weight per day (EFSAshort forEuropean Food Safety Authority, 2015).

3.2 Taurine

Taurine (2-aminoethanesulfonic acid) is a substance that has a high prevalenceClose dialogprevalencePrevalenceTo glossary in food, particularly in seafood and meat, and also as an endogenous metabolite in humans. In the human body, taurine is formed as a metabolic end product, mainly from the amino acid cysteine in the liver. Intake via the normal diet varies between 10 and 400 mgshort formilligram per day (EFSAshort forEuropean Food Safety Authority, 2009). Taurine is found in particularly high concentrations in the heart and skeletal muscle (Schaffer et al.short foret alii (lat. "and others"), 2010).

3.2.1 Health effects of taurine

3.2.1.1 Effect on blood pressure

Several studies have shown that taurine has a blood pressure-lowering effect in hypertensive animal models (Abebe and Mozaffari, 2011; Hano et al.short foret alii (lat. "and others"), 2009; Nara et al.short foret alii (lat. "and others"), 1978; Sato et al.short foret alii (lat. "and others"), 1987; Trachtman et al.short foret alii (lat. "and others"), 1989). A clinical, randomised, double-blind, placebo-controlled study in humans also supports this finding (Sun et al.short foret alii (lat. "and others"), 2016). In this study, 120 prehypertensive individuals (aged 18 to 75 years) received either 1.6 g of taurine per day or a placebo over 12 weeks. Taurine significantly reduced ambulatory 24-hour blood pressure, particularly in individuals with high-normal blood pressure. Ambulatory systolic blood pressure fell by 3.8 mmHg in the taurine group, whilst only a reduction of 0.3 mmHg was measured in the placebo group. Ambulatory diastolic blood pressure fell by 3.5 mmHg in the taurine group and by only 0.6 mmHg in the placebo group.

3.2.1.2 Effect on calcium homeostasis and muscle contraction

In particular, it is suggested that taurine plays a role in calcium homeostasis within muscle. It has been demonstrated that physiological concentrations of taurine increase isometric force in denervated muscle fibre preparations derived from atrial and ventricular cardiac muscle cells of the pig, as well as from the slow abdominal muscles of the crab. It was hypothesised that this is due to increased Ca²⁺ sensitivity contractile myofilaments (Galler et al.short foret alii (lat. "and others"), 1990). Furthermore, based on studies of denuded tissue fragments from rat hearts, it was hypothesised that taurine interacts directly with the sarcoplasmic reticulum and that taurine enhances caffeine-induced contraction (Steele et al.short foret alii (lat. "and others"), 1990). In human denuded vastus lateralis muscle fibre preparations, obtained via biopsy from 11 healthy individuals, taurine increased the intake of Ca²⁺ into the sarcoplasmic reticulum in both type 1 and type 2 fibres (Dutka et al.short foret alii (lat. "and others"), 2014). In a further study, taurine treatment of denervated muscle fibres from the rat extensor digitorum longus significantly increased the depolarisation-induced response amplitude. Here, too, increased Ca²⁺ accumulation in the sarcoplasmic reticulum was measured, as well as increased taurine-induced Ca²⁺ release, leading to the assumption that taurine interacts with the Ca²⁺ release channels. Furthermore, it was shown that taurine increased both the peak and the rate of rise of a caffeine-induced response (Bakker and Berg, 2002).

3.2.1.3 Effect on cardiac muscle contractility

In a double-blind crossover study, 13 trained endurance athletes were given, 40 minutes before training, either

(a) a 500-mlshort formillilitre placebo drink (energy drink containing no taurine, no glucuronolactone, no caffeine, with glucose (10.5 g) and sucrose (43 g)) or

(b) a 500-mlshort formillilitre control drink (energy drink containing no taurine, no glucuronolactone, containing caffeine (160 mgshort formilligram), glucose (10.5 g) and sucrose (43 g)) or

(c) a 500-mlshort formillilitre verum drink (the original energy drink containing taurine (2,000 mgshort formilligram), glucuronolactone (1.2 g), caffeine (160 mgshort formilligram), glucose (10.5 g) and sucrose (43 g)) (Baum and Weiss, 2001).

The placebo and control drinks, like the original drink, were produced by the energy drink manufacturer. Echocardiographic examinations were carried out before consumption of the drink, 40 minutes after consumption, immediately before exercise (cycling) and during the recovery phase following cycling.

Heart rate increased significantly after the exercise session in all three intervention groups, which is presumably attributable to the physical activity. However, a significant increase in fractional shortening and a significant reduction in left ventricular end-systolic diameter (LVESD) were observed only in the active treatment group following the ‘drink containing taurine, glucuronolactone and caffeine plus exercise’ condition. As these ventricular effects were not observed in either the placebo group or the control/caffeine group, the authors conclude that the combination of taurine and caffeine in the original energy drink enhanced left ventricular contractility (Baum and Weiss, 2001). It should be noted, however, that a drink containing taurine but without added caffeine was not tested; consequently, it cannot be determined to what extent taurine alone might be responsible for the ventricular effects. Furthermore, in addition to caffeine and taurine, the energy drink also contained glucuronolactone, although it is unlikely that glucuronolactone contributed to the observed effects.

In a study involving 32 healthy participants (20 men, 12 women, meanClose dialogmeanMeanTo glossary age: 28 years), all participants drank an amount of a commercially available energy drink (168 mlshort formillilitre/m²) with a typical concentration of caffeine (0.03%) and taurine (0.4%) (Doerner et al.short foret alii (lat. "and others"), 2015). According to the authors, for a typical participant, this corresponded to an intake of 105 mgshort formilligram of caffeine and 1,304 mgshort formilligram of taurine in a volume of 326 mlshort formillilitre. Ten of the participants were selected as a control group, who consumed a commercially available caffeinated drink (34 mgshort formilligram/100 mlshort formillilitre) without taurine on a different day (more than one week apart). The participants were examined using cardiac magnetic resonance spectroscopy before consuming the drink and one hour afterwards. Consumption of the energy drink led to a small but significant increase in the peak systolic strain rate, which is a parameter for regional contractility (Sinning, 2009). This effect was not observed in the caffeine group. In contrast, global left ventricular function remained unchanged (Doerner et al.short foret alii (lat. "and others"), 2015). It should be noted, however, that no details were provided regarding which components, apart from caffeine and taurine, were contained in the commercial energy drink or, apart from caffeine, in the commercial caffeinated drink, nor to what extent these are otherwise comparable. It cannot therefore be ruled out that other ingredients may also have influenced the observed effect. However, given the effects of glucuronolactone and inositol, it seems unlikely that these would produce such effects.

The studies presented provide evidence that taurine may have a blood pressure-lowering effect in prehypertensive individuals and could increase myocardial contractility, although this may occur via a Ca²⁺-dependent mechanism.

3.2.1.4 Taurine deficiency and cardiac function in animal models

In animal studies, Ito et al.short foret alii (lat. "and others") demonstrated that taurine transporter knockout mice (TauTKO) – which have reduced taurine concentrations in the heart and skeletal muscle compared with wild-type mice – exhibit structural and functional changes in the heart ventricles: dilated ventricles with reduced wall thickness, cardiac muscle atrophy associated with smaller cardiomyocytes, and a reduced cardiac output. The skeletal muscle cells of TauTKO mice exhibited reduced cell volume and structural damage (Ito et al.short foret alii (lat. "and others"), 2008; Ito et al.short foret alii (lat. "and others"), 2010).

In a further study, male Wistar rats were administered a taurine transporter antagonist (3% beta-alanine) for 30 days (T(-); n = 17), whilst the control group (C; n = 17) did not receive this antagonist (Pansani et al.short foret alii (lat. "and others"), 2012). The treated rats showed a clear decrease in taurine concentration in the left ventricle compared with the control group (C = 1.8 ± 0.8 µmol/mgshort formilligram tissue; T(-) = 0.4 ± 0.1 µmol/mgshort formilligram tissue). The authors observed a reduction in ventricular wall thickness, posterior left ventricular wall thickness and left ventricular weight in the taurine-deficient rats. In terms of cardiac function, the ejection fraction, fractional shortening and cardiac output were reduced. Overall, Pansani et al.short foret alii (lat. "and others") concluded that taurine deficiency in rats led to cardiac atrophy, particularly of the left ventricle, although the exact mechanisms were unknown.

3.2.1.5 Adverse health effects of taurine supplementation

The published human studies on taurine focus primarily on the potential beneficial effects of taurine, meaning that adverse effects are scarcely considered. However, as part of a risk assessment on taurine, the Norwegian Scientific Committee for Food and Environment (VKM) (VKM, 2015a) identified a small number of studies which also reported adverse effects of taurine supplementation.

An open-label study was designed to test the effects of taurine on adaptive behaviour and tolerability in patients with succinate semi-aldehyde dehydrogenase deficiency (a congenital metabolic disorder affecting GABA breakdown) (Pearl et al.short foret alii (lat. "and others"), 2014). The taurine doses were gradually increased from 50 mgshort formilligram/kgshort forkilogram to 200 mgshort formilligram/kgshort forkilogram. The 18 participants were aged between 0.5 and 28 years. A total of 16 participants took part in the study for between 3 and 50 months. The taurine supplementation did not result in any clinically relevant refinements in the condition. However, one participant (aged 30) experienced a serious adverse effect – hypersomnia – at a dose of 200 mgshort formilligram/kgshort forkilogram body weight (16 g/day), which required hospital treatment. As a result, the maximum daily dose of taurine was limited to 10 g. Other adverse effects reported included severe fatigue and drowsiness, as well as mild to moderate effects relating to the occurrence of cognitive changes, ataxia and insomnia (Pearl et al.short foret alii (lat. "and others"), 2014). However, it should be noted that the participants in this study had a medical condition and/or were, in some cases, infants; consequently, no conclusions regarding the general healthy population can be drawn on the basis of this study.

In a crossover study (two 7-day periods) involving eight healthy men (mean age (SD): 22 ± 1 years), which investigated whether taurine supplementation could increase muscle taurine concentration or alter substrate metabolism during prolonged exercise, one participant reported muscle cramps during the taurine period (2 capsules containing 0.83 g of taurine three times daily ≙ 5 g daily), one participant complained of muscle cramps (Galloway et al.short foret alii (lat. "and others"), 2008). These mild adverse effects could be explained by the potentially possible effects of taurine on muscle contractility described above.

In a double-blind, randomised, cross-over study, Brons et al.short foret alii (lat. "and others") (2004) investigated the effect of taurine on insulin secretion in 20 overweight men with a predisposition to type 2 diabetes mellitus (Brons et al.short foret alii (lat. "and others"), 2004). The participants were treated with either taurine or a placebo for 8 weeks. Taurine was administered at a daily dose of 1,500 mgshort formilligram. Eighteen participants completed the study. The participants reported no adverse effects.

A double-blind, randomised study involving 51 women (aged 18–22) with iron-deficiency anaemia investigated whether oral administration of taurine enhances the efficacyClose dialogefficacyPositive Predictive ValueTo glossary of oral iron sulphate supplementation in the treatment of iron deficiency (Sirdah et al.short foret alii (lat. "and others"), 2002). The participants were treated with iron sulphate for 20 weeks. In addition, one group (n = 26) received one capsule containing 1,000 mgshort formilligram of taurine daily, whilst another group received a placebo (n = 25). The authors reported that no adverse effects of taurine were observed.

3.2.1.6 Safe levels of taurine intake

The VKM refers to the human studies (Brons et al.short foret alii (lat. "and others"), 2004; Sirdah et al.short foret alii (lat. "and others"), 2002) in which no adverse effects occurred following taurine intakes of up to 1,500 mgshort formilligram per day. Based on these studies, the VKM considers it unlikely that taurine intakes of up to 21 mgshort formilligram/kgshort forkilogram body weight per day (corresponding to approximately 1,500 mgshort formilligram per day for a 70 kgshort forkilogram adult) would cause adverse health effects (VKM, 2015a).

Based on a 13-week (subchronic) neurotoxicity study in rats, the EFSAshort forEuropean Food Safety Authority derived a No Observed (Adverse) Effect Level (NOAEL) of 1,000 mgshort formilligram/kgshort forkilogram body weight per day for pathological changes and 1,500 mgshort formilligram/kgshort forkilogram body weight for behavioural changes. The Panel concluded from this that there are no health concerns regarding daily intakes of up to 1,400 mgshort formilligram of taurine per day in humans (the intake level at the 95th percentile of chronic energy drink consumption, which, according to EFSAshort forEuropean Food Safety Authority, corresponds to 350 mlshort formillilitre per day) (EFSAshort forEuropean Food Safety Authority, 2009; SCF, 2003).

The BfRshort forGerman Federal Institute for Risk Assessment points out that, in most of the studies discussed here, taurine was assessed as a single substance and that potential interactions between taurine and other ingredients in energy drinks, such as caffeine, were not considered – apart from those relating to diuretic effects, which were deemed unlikely (EFSAshort forEuropean Food Safety Authority, 2009). However, in its opinion on the safety of caffeine, the EFSAshort forEuropean Food Safety Authority concluded that taurine, at concentrations typically found in energy drinks (4,000 mgshort formilligram per litre), does not affect the safety of single doses of caffeine up to 200 mgshort formilligram (EFSAshort forEuropean Food Safety Authority, 2015). Possible interactions at higher levels of caffeine or taurine intake were not assessed.

3.3 Glucuronolactone

Glucuronolactone is also produced naturally in the body as a metabolite of glucose (EFSAshort forEuropean Food Safety Authority, 2009; McLellan and Lieberman, 2012) and is also a component of fibrous connective tissue. Only small amounts of glucuronolactone are taken up through the diet (1 to 2 mgshort formilligram per day) (EFSAshort forEuropean Food Safety Authority, 2009). Ingested glucuronolactone is completely absorbed, hydrolysed and shedded in the urine as glucuronic acid, xylitol and L-xylulose (Dowben, 1956; EFSAshort forEuropean Food Safety Authority, 2009).

3.3.1 Health effects of glucuronolactone

In an older study in which rats were injected with 100 mgshort formilligram per kgshort forkilogram body weight of glucuronolactone or other sugar substances three times daily, positive effects on swimming performance, blood glucose concentration and liver glycogen concentration were observed following glucuronolactone administration, whereas these effects were not observed with the other sugar substances (Tamura et al.short foret alii (lat. "and others"), 1968). However, similar observations were made in other studies following the injection of glucose and galactose (Coyle et al.short foret alii (lat. "and others"), 1986; Coyle et al.short foret alii (lat. "and others"), 1983), suggesting that these effects are attributable to the well-known ergogenic effects of carbohydrates (McLellan and Lieberman, 2012).

3.3.2 Safe intake levels of glucuronolactone

According to EFSAshort forEuropean Food Safety Authority, a 13-week (subchronic) study in rats involving intake levels of up to 1,000 mgshort formilligram of glucuronolactone per kgshort forkilogram body weight per day revealed no adverse effects, with particular attention paid to renal toxicity (EFSAshort forEuropean Food Safety Authority, 2009).

Unlike primates, including humans, rodents can synthesise vitamin C endogenously from glucuronic acid and can therefore also produce vitamin C from exogenous glucuronolactone. However, it was noted that, according to the literature, glucuronolactone is primarily metabolised via the pentose pathway, whilst the vitamin C pathway plays only a minor role; consequently, the rat model appeared to be applicable (EFSAshort forEuropean Food Safety Authority, 2009).

The EFSAshort forEuropean Food Safety Authority Panel concluded that there are no health concerns regarding daily intakes of up to 840 mgshort formilligram of glucuronolactone. This corresponds to the glucuronolactone intake at the 95th percentile of chronic energy drink consumption, which, according to EFSAshort forEuropean Food Safety Authority (2009), is 350 mlshort formillilitre per day (EFSAshort forEuropean Food Safety Authority, 2009; SCF, 2003).

3.4 Inositol

The sugar alcohol inositol is a white, crystalline, odourless powder with a slightly sweet taste (EFSAshort forEuropean Food Safety Authority, 2014). Inositol is naturally synthesised by almost all plants and animals. It exists in nine possible stereoisomers, four of which are physiologically active. It is mainly present in the form of myo-inositol. In nature, inositol occurs in both bound and unbound forms. Over 90% of free inositol is absorbed in the small intestine. The bioavailability of myo-inositol from phytic acid (inositol hexaphosphate) is very limited and depends on a variety of factors, such as phytate solubility and the presence of minerals, plant phytases, microbial intestinal phytases, dietary phytases and food processing (EFSAshort forEuropean Food Safety Authority, 2016).

Endogenous inositol is mainly synthesised in the kidneys, and the concentration of free inositol in the renal medullary cells is 1,000 times higher than in the blood. It is estimated that approximately 4 g are produced per day in humans. Plasma levels are regulated in the kidneys by glomerular filtration, reabsorption and catabolism or excretion (EFSAshort forEuropean Food Safety Authority, 2014).

3.4.1 Adverse health effects of inositol

As part of its risk assessment on inositol, the VKM (VKM, 2015b) identified various human studies and a review in which adverse effects following inositol administration were reported:

One review examined 12 controlled clinical trials involving a total of 250 adults who received 4 to 30 g of inositol per day (corresponding to 57 to 429 mgshort formilligram per kgshort forkilogram body weight per day for a 70 kgshort forkilogram person) over a period of 1 to 12 months (Carlomagno and Unfer, 2011). The most commonly reported and dose-dependent adverse effects were nausea, flatulence, loose stools and diarrhoea. At a dose of 4 g of inositol per day, mild adverse effects such as mild insomnia and flatulence were reported.

An open-label study investigated the safety and maximum tolerated dose of myo-inositol in smokers (24 men, 2 women) with bronchial dysplasia (Lam et al.short foret alii (lat. "and others"), 2006). To determine the maximum tolerated dose, the administered dose of myo-inositol was initially increased from 12 to 30 g per day over the course of one month in 16 participants. Adverse effects included flatulence, loose stools or diarrhoea. A NOAEL of 18 g per day was determined. In a second phase, this dose was then administered to 10 participants for three months. Mild gastrointestinal symptoms during the first month of treatment were reported as adverse effects. There was also a statistically significant, albeit clinically insignificant increase in haemoglobin following the intake of 18 g per day of myo-inositol over more than 4 weeks (Lam et al.short foret alii (lat. "and others"), 2006).

In a clinical trial in Israel comparing inositol with fluvoxamine for the treatment of panic disorder in otherwise healthy individuals (N = 21; 9 men, 12 women, mean age 39 years) (Palatnik et al.short foret alii (lat. "and others"), 2001), the following adverse effects were observed following the administration of 12 g of inositol per day (week 1) up to 18 g of inositol per day (weeks 2 to 4): nausea (8 participants) and fatigue (1 participant).

3.4.2 Safe intakes of inositol

The quality of the available human studies is insufficient to derive safe intake levels for inositol. However, studies involving a daily dose of 4 g of inositol (equivalent to 57 mgshort formilligram per kgshort forkilogram body weight per day) showed either no adverse effects or only mild adverse effects in a very small number of participants (Carlomagno and Unfer, 2011).

With regard to animal studies, no conventional toxicological studies were available; however, according to EFSAshort forEuropean Food Safety Authority, the results of studies in rodent models with chronic diseases suggest that the toxicity of inositol is low (EFSAshort forEuropean Food Safety Authority, 2014). In mice in which tumours had been induced by other substances, no adverse effects of inositol were observed across a dose range of 450–9,000 mgshort formilligram per kgshort forkilogram body weight per day. Only one study involving diabetic and non-diabetic rats showed an adverse effect at 1,800 mgshort formilligram per kgshort forkilogram body weight per day (thickening of the basement membrane of the capillaries in the retina and the glomeruli in non-diabetic rats) (EFSAshort forEuropean Food Safety Authority, 2014).

3.5 Energy drinks as ‘complete products’

In addition to the assessment of individual ingredients in energy drinks carried out in sections 3.1 to 3.4, energy drinks will now be considered as complete products.

3.5.1 Effects of energy drinks on the cardiovascular system

For its opinion published in 2019, the BfRshort forGerman Federal Institute for Risk Assessment carried out a comprehensive literature review of published intervention studies involving energy drinks in which cardiovascular parameters had been investigated (non-systematic search up to January 2018). The intervention studies identified at that time analysed exclusively the acute effects of energy drink consumption in almost exclusively young, healthy adults (aged 18 to 45). Only one study also included adolescents aged 15 to 18; however, the evaluations were not conducted separately for adolescents and adults (Hajsadeghi et al.short foret alii (lat. "and others"), 2016).

Since then, results have been published from two intervention studies involving children and adolescents on the acute consumption of energy drinks, as well as from a cross-sectional study involving adolescents from Berlin on the chronic high consumption of energy drinks. No further search was conducted for studies involving adults.

General characteristics of the studies included in the assessment

The studies included in the assessment, together with a meta-analysis, are listed in Table 1 in the Appendix, along with their respective study designs. One study was conducted with patients who had a familial long QTc syndrome (Gray et al.short foret alii (lat. "and others"), 2017). The participants in the intervention studies usually consumed the energy drinks as a single dose within a short period (within a maximum of three hours), i. e. only acute effects were investigated. In two studies, the acute energy drink dose was administered two or more times a day (Franks et al.short foret alii (lat. "and others"), 2012; Shah et al.short foret alii (lat. "and others"), 2016b). The observation period generally ranged from 0.5 hours to 24 hours. Two studies extended the energy drink exposureClose dialogexposureExposureTo glossary and observation period to seven days; however, acute effects were measured on specific days within this period (Shah et al.short foret alii (lat. "and others"), 2016b; Steinke et al.short foret alii (lat. "and others"), 2009). Where specified, the caffeine doses administered via energy drinks to adults were mainly between 80 mgshort formilligram and 320 mgshort formilligram per day. The children and adolescents in the EDUCATE study were administered a single dose of 3 mgshort formilligram of caffeine per kgshort forkilogram of body weight via energy drinks. In contrast, during the intervention phase of the Israeli study, adolescents who already consumed energy drinks regularly were given only 250 mlshort formillilitre of energy drink, which corresponds to an estimated caffeine content of 80 mgshort formilligram (the caffeine content was not specified). The taurine doses for adults, where specified at all, ranged between 1,000 mgshort formilligram and 4,000 mgshort formilligram per day (one study used 100 mgshort formilligram of taurine). There was little information on the amounts of glucuronolactone consumed (84 and 1,200 mgshort formilligram per day) and almost none for inositol.

The design of the three studies on children and adolescents published since 2019 is briefly outlined below.

Intervention study: Energy drinks ‘Unexplored Cardiovascular Alterations in TEens and TwEens’ (EDUCATE):

The EDUCATE study is a randomised, prospective, single- or double-blind (for the study participants) and placebo-controlled crossover study. It investigated the acute effects of energy drink consumption on cardiovascular function in healthy children and adolescents. It was conducted from April to October 2021 at Ludwig Maximilian University in Munich (Lishort forlithium et al.short foret alii (lat. "and others"), 2022; Mandilaras et al.short foret alii (lat. "and others"), 2022; Mandilaras et al.short foret alii (lat. "and others"), 2026; Oberhoffer et al.short foret alii (lat. "and others"), 2023b; Oberhoffer et al.short foret alii (lat. "and others"), 2022a, b). The study population comprised up to 27 healthy children and adolescents aged between 10 and 18 years (mean age (SD): 14.5 ± 2.4 years). The following exclusion criteria were established: chronic cardiovascular diseases, a family history of sudden cardiac death, allergies to ingredients in the drinks, regular use of medication with potential effects on the cardiovascular system, regular use of drugs, alcohol and smoking, and pregnancy.

As part of the crossover design of the EDUCATE study, participants were given either a commercially available, caffeinated energy drink or a placebo drink without the ingredients typically found in energy drinks on two consecutive days. The amount of the energy drink administered was adjusted for body weight and resulted in a maximum acute caffeine intake that, according to EFSAshort forEuropean Food Safety Authority, is safe for healthy children and adolescents (3 mgshort formilligram of caffeine per kgshort forkilogram of body weight). The amount of the placebo drink administered corresponded to that of the energy drink. Both drinks had a similar sugar content and taste.

Various echocardiographic and electrocardiographic parameters were measured both at the start and 30, 60, 120, 180 and 240 minutes after beverage consumption on each study day. In addition, blood pressure and heart rate were measured at these time points and over a 24-hour period.

Intervention study from Israel:

In an Israeli study, the first phase involved surveying energy drink consumption among adolescents at schools in the city of Nazareth and its northern surroundings, whilst the second phase investigated the acute effects following energy drink consumption after a placebo-controlled intervention (Mansour et al.short foret alii (lat. "and others"), 2019). A total of 375 school pupils aged between 16 and 18 took part in the survey. Of these, 206 participants reported consuming energy drinks. For the second phase of the study, 41 adolescents who regularly consumed energy drinks (at least two doses per week) and 40 adolescents who had never consumed energy drinks were invited to a clinic for an examination. The regular energy drink consumers were given a 250 mlshort formillilitre energy drink (the caffeine content was not specified, but standard energy drinks contain 80 mgshort formilligram of caffeine per 250 mlshort formillilitre), whilst the control group was given 250 mlshort formillilitre of water. Heart rate, respiratory rate and blood pressure, as well as subjective well-being, were recorded before and after consumption at intervals of 15 to 30 minutes, 1 hour and 2 hours.

Cross-sectional study: ‘Study on the chronic high consumption of energy drinks and cardiovascular risk in adolescents aged 15–18 years’ (EDKAR):

The BfRshort forGerman Federal Institute for Risk Assessment, in collaboration with Charité – Universitätsmedizin Berlin, conducted the EDKAR study from March 2022 to May 2024 (Menzel et al.short foret alii (lat. "and others"), 2025). Designed as a cross-sectional study, this research aimed to investigate how frequently and in what amounts adolescents aged 15 to 18 consume energy drinks, and whether excessive, long-term consumption of energy drinks has an impact on the formation of cardiovascular diseases.

The study was carried out in two phases. In the first phase, an online survey on the consumption of energy drinks and other caffeinated beverages, as well as on leisure and health behaviours, was conducted in 359 classes at 29 schools in Berlin (grammar schools, integrated secondary schools, upper secondary centres; 156 schools were approached). A total of 5,100 pupils completed the questionnaire in full. Using the data collected during this ‘screening phase’, individuals with chronically high consumption and a control group were identified and invited to undergo a cardiological examination. Around one third of each group responded to the invitation and subsequently underwent a cardiological examination at the Charité during the second phase of the study. Chronic high consumption of energy drinks was defined as follows: consumption of energy drinks on at least 4 days per week for at least one year, at a level so high that this alone results in the EFSAshort forEuropean Food Safety Authority limit value of 3 mgshort formilligram of caffeine per kilogram of body weight (kgshort forkilogram BW) per day being exceeded. The control group was defined as follows: no consumption of energy drinks in the past 12 months and no more than 80 mgshort formilligram of caffeine per week from other caffeinated drinks.

In phase 2 of the study, the identified adolescents from both groups were invited to the Charité – Universitätsmedizin Berlin for a cardiological examination. There, parameters from echocardiography and the electrocardiogram, as well as blood pressure and heart rate, were measured, and the results of the high consumers of energy drinks (n = 97) were compared with those of the control group (n = 160).

3.5.1.1 Effects of energy drinks on blood pressure

Background

Certain fluctuations in blood pressure are normal and should be regarded as an adaptive response to exogenous and endogenous demands. Hypertension is a disease of the vascular system in which blood pressure readings are persistently too high (NIH, 2024; Raven and Chapleau, 2014). Threshold values for the diagnosis of high blood pressure in Germany are specified for adults in the S3 guideline ‘National Care Guideline on Hypertension’ (BÄK/KBV/AWMF, 2023) and for children and adolescents in the S2k guideline ‘Arterial Hypertension in Childhood and Adolescence’, whereby for children under 16 years of age, gender-, age- and height-specific reference values should be used to calculate blood pressure percentiles. For adolescents aged 16 and over, the limit values defined for adults apply (BÄK/KBV/AWMF, 2023; DGPK, 2018, 2022).

In adults, an acute and marked rise in systolic or diastolic blood pressure (SBP; DBP) (> 180 mmHg systolic or > 110 mmHg diastolic) is defined as a ‘hypertensive emergency’ if it is associated with impending or progressive organ damage, or as a ‘hypertensive decompensation’ if it occurs without acute accompanying symptoms (BÄK/KBV/AWMF, 2023). The guideline does not specify any specific thresholds for a ‘hypertensive emergency’ in children and adolescents (DGPK, 2022).

In the intervention studies identified here, which examined blood pressure following energy drink consumption as an endpoint, only acute effects were analysed (for a maximum of 7 days as a single acute dose) and not the possible chronic consequences of long-term energy drink consumption.

Adults:

When an acute dose of caffeine of no more than 200 mgshort formilligram was administered via energy drinks, the changes in systolic blood pressure relative to baseline were approximately +3 mmHg to +9 mmHg (Elitok et al.short foret alii (lat. "and others"), 2015; Franks et al.short foret alii (lat. "and others"), 2012; Grasser et al.short foret alii (lat. "and others"), 2015; Grasser et al.short foret alii (lat. "and others"), 2014; Majeed et al.short foret alii (lat. "and others"), 2017; Marczinski et al.short foret alii (lat. "and others"), 2014; Miles-Chan et al.short foret alii (lat. "and others"), 2015; Ragsdale et al.short foret alii (lat. "and others"), 2010; Steinke et al.short foret alii (lat. "and others"), 2009), whilst diastolic blood pressure increased by approximately +2 to +5 mmHg (Elitok et al.short foret alii (lat. "and others"), 2015; Grasser et al.short foret alii (lat. "and others"), 2014; Hajsadeghi et al.short foret alii (lat. "and others"), 2016; Majeed et al.short foret alii (lat. "and others"), 2017; Marczinski et al.short foret alii (lat. "and others"), 2014; Miles-Chan et al.short foret alii (lat. "and others"), 2015; Steinke et al.short foret alii (lat. "and others"), 2009). Even with acute caffeine doses of up to 320 mgshort formilligram, no increases above 9 mmHg were measured (Basrai et al.short foret alii (lat. "and others"), 2019; Fletcher et al.short foret alii (lat. "and others"), 2017; Kurtz et al.short foret alii (lat. "and others"), 2013; Phan and Shah, 2014; Rashti et al.short foret alii (lat. "and others"), 2009; Shah et al.short foret alii (lat. "and others"), 2016c; Svatikova et al.short foret alii (lat. "and others"), 2015). An uncontrolled open-label study showed no significant changes in SBP with caffeine doses above 200 mgshort formilligram (240 mgshort formilligram) (Higgins et al.short foret alii (lat. "and others"), 2017). Marked changes in blood pressure were observed in an open-label study from the USA in which 960 mlshort formillilitre of an energy drink was consumed (Kozik et al.short foret alii (lat. "and others"), 2016). In this study, systolic blood pressure rose by almost 20 mmHg following consumption (from 132 ± 7.83 to 151 ± 11.21 mmHg; p = 0.001). However, no control group was included, and no caffeine content was specified. The BfRshort forGerman Federal Institute for Risk Assessment points out that the USA has not set any statutory maximum levels for caffeine and other ingredients in energy drinks.

Studies identified in which caffeine doses of around 100 mgshort formilligram or less were administered showed no significant changes in blood pressure (Al-Fares et al.short foret alii (lat. "and others"), 2015; Alford et al.short foret alii (lat. "and others"), 2001; Doerner et al.short foret alii (lat. "and others"), 2015).

Overall, it can be concluded that the acute consumption of energy drinks can significantly increase blood pressure. The rise in blood pressure is thought to be due to the ingredient caffeine, although taurine may mitigate this increase. Based on the identified intervention studies, moderate acute consumption of energy drinks (a single acute dose containing up to 200 mgshort formilligram of caffeine and taurine (in the studies cited here: no more than 2,000 mgshort formilligram, where specified)) led to maximum changes in blood pressure of approximately 10 mmHg systolic and 5 mmHg diastolic in adults.

The resulting acute increases in blood pressure in healthy adults can be considered physiological and harmless to health, provided their occurrence is occasional or temporary and under normal (environmental) conditions. Even caffeine doses of more than 200 mgshort formilligram up to 320 mgshort formilligram from energy drinks did not lead to a clinically significant rise in blood pressure in the identified studies involving young, healthy adults. However, it should be noted that in individuals with high blood pressure, such increases could already pose a health risk.

Children and adolescents:

In the EDUCATE study, which was designed as an intervention study, children showed, 30 minutes after consuming energy drinks containing weight-adjusted amounts of caffeine that are considered safe for health according to EFSAshort forEuropean Food Safety Authority (3 mgshort formilligram per kgshort forkilogram body weight), an average increase in systolic blood pressure (SBP) by 3.59 mmHg from an initial value of 112.74 ± 8.67 mmHg (time 0) to 116.33 ± 7.69 mmHg (Oberhoffer et al.short foret alii (lat. "and others"), 2022b). This increase persisted for up to 60 minutes and then decreased slightly after two hours (120 minutes: 113.59 ± 8.25 mmHg; 240 minutes: 114.30 ± 8.01 mmHg).

The significant differences in SBP values between the two groups at the 120- and 240-minute time points are primarily due to the fact that the control group showed a greater decrease in SBP values compared with the energy drink group, whilst the decrease in SBP was smaller in the energy drink group (Oberhoffer et al.short foret alii (lat. "and others"), 2022b).

The mean diastolic blood pressure (DBP) in the energy drink group was also significantly higher (+ 3.29 mmHg) after consumption of energy drinks compared with the placebo group. The individual DBP readings at the respective time points were not reported (Oberhoffer et al.short foret alii (lat. "and others"), 2022b).

In the EDUCATE study, Oberhoffer et al.short foret alii (lat. "and others") also investigated the effects of energy drinks on 24-hour blood pressure in 17 children (Oberhoffer et al.short foret alii (lat. "and others"), 2023b). 24-hour monitoring revealed a significantly higher systolic blood pressure following consumption of the energy drink compared with the placebo group (SBP) (+5.26 mmHg; 115.90 vs. 110.64 mmHg), diastolic blood pressure (DBP) (+3.45 mmHg; 66.08 vs. 62.63 mmHg) and mean arterial pressure (MAP) (+4.63 mmHg; 89.75 vs 85.12 mmHg), central systolic blood pressure (cSBP) (+2.59 mmHg; 101.77 vs 99.18 mmHg) and central diastolic blood pressure (cDBP) (+4.48 mmHg; 68.47 vs 63.99 mmHg).

A further endpoint was the calculation of the relative proportion of SBP and DBP measurements (Hypertensive SBP and DBP measurements (%)) classified by the authors as hypertension, for the day, the night and the entire 24-hour period. For these parameters, no significant differences were observed at night or over the 24-hour period between the energy drink group and the placebo group, whilst during the day a significant increase in the relative proportion of hypertensive median DBP readings was reported (ED group vs. placebo group: 10.71% (8.09–26.14%) vs. 10.64% (4.17–16.89%), p = 0.049).

Overall, based on the EDUCATE study, it can be concluded that the acute intake of a caffeine dose deemed safe by EFSAshort forEuropean Food Safety Authority (3 mgshort formilligram per kgshort forkilogram body weight) via energy drinks can lead to an increase in blood pressure in children with a mean age of approximately 14 years.

In the Israeli study, regular energy drink consumers already had a significantly higher mean systolic blood pressure compared with the control group prior to the intervention (119.10 vs. 111.85 mmHg; p < 0.05) (Mansour et al.short foret alii (lat. "and others"), 2019). Following acute consumption of the energy drink, systolic blood pressure changed only slightly within the energy drink group (15–30 minutes: +2.75 mmHg; 60 minutes: + 2.49 mmHg; 120 minutes: – 1.27 mmHg); however, the significant difference between the groups persisted across all three measurement points following consumption. Diastolic blood pressure did not differ significantly between the two groups at any measurement point. Overall, however, it should be noted that this study did not adjust for potential confounders, meaning that the pre-existing differences in systolic blood pressure between the two groups at the start of the study cannot be clearly assessed. In contrast to the EDUCATE study, it can be assumed that the EFSAshort forEuropean Food Safety Authority limit value was not reached in adolescents aged 16 to 18 who consumed a 250 mlshort formillilitre energy drink (presumably containing 80 mgshort formilligram of caffeine).

In the EDKAR cross-sectional study, which investigated the long-term effects of chronic high energy drink consumption, no statistically significant difference was found in adolescents aged 15 to 18 between chronic high female consumers and high male consumers (n=97) and the control group (n=160) with regard to systolic and diastolic blood pressure, both in the unadjusted model and when various confounders were taken into account (Menzel et al.short foret alii (lat. "and others"), 2025). It should be noted that, as an observational study, the EDKAR study did not specify whether and/or when energy drinks should be consumed. Participants were asked to behave as they normally would in their everyday lives.  Consequently, the short-term effects of acute consumption were not investigated.

3.5.1.2 Effects of energy drinks on heart rate

Background

An elevated resting heart rate is associated with a higher risk of cardiovascular disease and mortality (Cooney et al.short foret alii (lat. "and others"), 2010). According to the S2k guideline on the use of heart rate and heart rate variabilityClose dialogvariabilityVariabilityTo glossary in occupational medicine and occupational science, the resting heart rate in adults is generally between 60 and 80 beats per minute (bpm). In individuals with well-developed endurance, resting heart rates significantly below 50 bpm may be measured (DGAUM/GfA/DGSP/DPG, 2021; Sammito et al.short foret alii (lat. "and others"), 2024). However, a resting heart rate of 60 to 100 bpm is also considered normal for adults by medical societies. It is, however, difficult to make a clear statement regarding the threshold above which an increased health risk exists (Stoschitzky, 2011).

In infants and young children, resting heart rates are higher than in adults; in adolescents, heart rate readings begin to approach those of adults (Fleming et al.short foret alii (lat. "and others"), 2011).

Adults

In studies involving adults in which no more than 200 mgshort formilligram of caffeine had been taken up acutely via energy drinks, an increase in heart rate was observed (between +2 and 8 bpm, +16 bpm during exercise) (Alford et al.short foret alii (lat. "and others"), 2001; Baum and Weiss, 2001; Elitok et al.short foret alii (lat. "and others"), 2015; Franks et al.short foret alii (lat. "and others"), 2012; Grasser et al.short foret alii (lat. "and others"), 2015; Grasser et al.short foret alii (lat. "and others"), 2014; Steinke et al.short foret alii (lat. "and others"), 2009), no change (Al-Fares et al.short foret alii (lat. "and others"), 2015; Doerner et al.short foret alii (lat. "and others"), 2015; Menci et al.short foret alii (lat. "and others"), 2013) and a decrease in heart rate (Hajsadeghi et al.short foret alii (lat. "and others"), 2016; Ragsdale et al.short foret alii (lat. "and others"), 2010). For caffeine doses ranging from more than 200 mgshort formilligram up to 320 mgshort formilligram, the studies by Basrai et al.short foret alii (lat. "and others") and Fletcher et al.short foret alii (lat. "and others") showed an increase in heart rate (albeit not significant in Fletcher’s study) of approximately 3 to 4 bpm (Basrai et al.short foret alii (lat. "and others"), 2019; Fletcher et al.short foret alii (lat. "and others"), 2017), whilst in other studies, heart rate was scarcely affected (Higgins et al.short foret alii (lat. "and others"), 2017; Kurtz et al.short foret alii (lat. "and others"), 2013; Phan and Shah, 2014; Rashti et al.short foret alii (lat. "and others"), 2009; Shah et al.short foret alii (lat. "and others"), 2016b; Shah et al.short foret alii (lat. "and others"), 2016c; Svatikova et al.short foret alii (lat. "and others"), 2015). A meta-analysis also found no significant changes in heart rate following energy drink consumption (Shah et al.short foret alii (lat. "and others"), 2016a).

The evidence regarding the extent to which acute consumption of up to one litre of energy drinks affects heart rate is contradictory, meaning that no clear conclusions can be drawn in this regard.

Children and adolescents

The publications by Mandilaras et al.short foret alii (lat. "and others") from 2022 and 2026 state that, in the EDUCATE study, heart rate in the energy drink group was significantly lower than in the placebo group two hours after acute consumption (–3.11 bpm, p = 0.012), however, after three and four hours, it was approximately 2 bpm higher than in the placebo group, albeit not significantly so (Mandilaras et al.short foret alii (lat. "and others"), 2022; Mandilaras et al.short foret alii (lat. "and others"), 2026).

Oberhoffer et al.short foret alii (lat. "and others") (2022) report that the maximum change in heart rate from baseline following acute consumption of energy drinks did not differ significantly from that in the placebo group (Oberhoffer et al.short foret alii (lat. "and others"), 2022b). Furthermore, 24-hour monitoring also revealed no significant difference in heart rate between the energy drink and placebo groups (Oberhoffer et al.short foret alii (lat. "and others"), 2023b).

The Israeli study also found no significant difference in heart rate between the energy drink and control groups (Mansour et al.short foret alii (lat. "and others"), 2019).

From the BfR’s perspective, given the limited data available to date – as is the case with adults – no clear conclusions can be drawn as to whether the acute consumption of energy drinks, at caffeine intake levels still considered safe by EFSAshort forEuropean Food Safety Authority, affects heart rate.

With regard to the long-term effects of chronic high consumption of energy drinks on heart rate, the EDKAR cross-sectional study found no statistically significant difference between chronic high consumers (n = 97) and the control group (n = 160), both in the unadjusted model and when confounders were taken into account (Menzel et al.short foret alii (lat. "and others"), 2025).

3.5.1.3 Effects of energy drinks on the QTc interval

Background

The QT interval is a parameter used in the evaluation of the electrocardiogram and represents the duration of ventricular systole, i. e. the time interval required for the completion of both ventricular depolarisation and repolarisation (Kautzner, 2002). A significant prolongation of the QT interval indicates delayed cardioventricular repolarisation, which can be the cause of life-threatening ventricular tachycardia; in the worst-case scenario, this can lead to torsades de pointes, which may progress to ventricular fibrillation and thus result in sudden cardiac death (FDAshort forFood and Drug Administration, 2005). QT interval prolongations can be congenital (genetic) or acquired and have many causes, such as ion channel disorders, myocarditis, medication use, etc. (Lazzerini et al.short foret alii (lat. "and others"), 2015; Thomas and Behr, 2016; Yap and Camm, 2003). As the duration of ventricular repolarisation shortens with increasing heart rate, a heart rate-corrected QT interval (QTc) must be calculated using a correction formula (FDAshort forFood and Drug Administration, 2005; Haverkamp, 2002). According to the S2k guideline ‘Tachycardic cardiac arrhythmias in children, adolescents and young adults (EMAH patients)’, which is, however, currently being revised, the following thresholds indicate a prolonged QTc interval: > 460 ms for children (aged 1 to 15 years), > 450 ms for male adolescents and men (> 15 years) and > 470 ms for female adolescents and women (> 15 years) (DGPK, 2018).

Adults

In the intervention studies listed in Table 1 in the Appendix, in which no more than 200 mgshort formilligram of caffeine was taken up acutely via energy drinks, no significant effect on the QTc interval was observed (Brothers et al.short foret alii (lat. "and others"), 2016; Elitok et al.short foret alii (lat. "and others"), 2015; Hajsadeghi et al.short foret alii (lat. "and others"), 2016; Ragsdale et al.short foret alii (lat. "and others"), 2010; Steinke et al.short foret alii (lat. "and others"), 2009). Only in one study involving overweight individuals was a QTc prolongation observed at these doses; however, the overweight individuals already had longer QTc intervals at baseline than the normal-weight individuals (Alsunni et al.short foret alii (lat. "and others"), 2015). Of the studies in which 320 mgshort formilligram of caffeine was taken up via energy drinks, two showed a significant prolongation of the QTc interval compared with pre-consumption levels (+3 to 8 ms) (Basrai et al.short foret alii (lat. "and others"), 2019; Shah et al.short foret alii (lat. "and others"), 2016c). In the study by Fletcher et al.short foret alii (lat. "and others"), a significant difference in the QTc interval was observed 2 hours after consumption compared with the caffeine group (960 mlshort formillilitre of energy drink containing 320 mgshort formilligram of caffeine), this was, however, due to a reduction in the QTc interval in the caffeine arm, whilst the QTc interval in the energy drink arm showed hardly any difference compared to before consumption (Fletcher et al.short foret alii (lat. "and others"), 2017).

A marked increase in the QTc interval was observed in the open-label study conducted in the USA by Kozik et al.short foret alii (lat. "and others"), in which 14 participants consumed 960 mlshort formillilitre of an energy drink (Kozik et al.short foret alii (lat. "and others"), 2016). Here, the QTc interval lengthened by approximately 80 ms, from 423 ± 22.74 ms to 503 ± 24.56 ms (p < 0.001), which by definition corresponds to a prolonged QTc interval and may therefore pose a risk. However, no control group was included in this study and caffeine intake was not specified.

In an intervention study involving patients with a pre-existing familial long QT syndrome, moderate acute consumption of energy drinks (containing 160 mgshort formilligram of caffeine and 2,000 mgshort formilligram of taurine) led to a severe QTc prolongation (> 50 ms) up to a maximum value of 557 ms. However, the increase in the QTc interval was not significant for the energy drink group as a whole (Gray et al.short foret alii (lat. "and others"), 2017).

Overall, acute moderate intake of energy drinks with a caffeine intake of up to 200 mgshort formilligram does not appear to affect the QTc interval in young, healthy adults. It can therefore be assumed that occasional moderate intake of energy drinks under normal (environmental) conditions does not pose a health risk to healthy adults in terms of changes to the QTc interval. In connection with the consumption of one litre of an energy drink, three out of four studies showed a significant increase in the QTc interval. In one of these studies, serious QTc prolongations – which could pose a potential health risk – were induced in young, healthy adults by high consumption of energy drinks (the amount of caffeine was not specified). Furthermore, in patients with pre-existing long QTc syndrome, even moderate consumption could lead to the occurrence of increases in the QTc interval, posing a potentially serious health risk (Gray et al.short foret alii (lat. "and others"), 2017).

Children and adolescents

In the EDUCATE study, no significant differences in the QTc interval were observed at any time point following acute administration of 3 mgshort formilligram of caffeine per kgshort forkilogram body weight via energy drinks (Mandilaras et al.short foret alii (lat. "and others"), 2022). However, a significant reduction in the QT-RRshort forrelative risk ratio was observed two hours after consumption in the energy drink group compared with the placebo group; according to Mandilaras et al.short foret alii (lat. "and others"), this could be attributed to the significantly reduced heart rate at that time. As with heart rate, however, the QT-RRshort forrelative risk ratios at later time points after consumption were elevated in the energy drink group, albeit not significantly, compared with the placebo group (Mandilaras et al.short foret alii (lat. "and others"), 2022).

There are no data available for children and adolescents regarding the possible acute effects on the QTc interval following higher intakes of energy drinks.

In the EDKAR study, no statistically significant differences in the QTc interval were found between chronic heavy consumers of energy drinks and the control group, either in the unadjusted model or when confounders were taken into account (adjusted for age, gender, physical activity, smoking status, cannabis use and alcohol consumption, and school type) (Menzel et al.short foret alii (lat. "and others"), 2025). This also applied to other electrocardiogram parameters measured, such as the PQ interval or the QRS duration.

3.5.1.4 Effects of energy drinks on cardiac output (e. g. inotropic effects)

Background

Cardiac function is influenced by myocardial contractility (Authenrieth et al.short foret alii (lat. "and others"), 1984). An increase in contractility leads to an increase in cardiac output or cardiac minute volume. Cardiac minute volume (L/min) is the volume of blood that the heart pumps in one minute and is calculated as the product of stroke volume and heart rate (beats per minute = bpm) (Vincent, 2008). Certain changes in cardiac output can be regarded as a temporary adaptive response to the varying oxygen requirements of the heart muscle and skeletal muscle in response to different exogenous and endogenous stimuli (e. g., exercise) (Duncker and Bache, 2008; Evans, 1985).

Other parameters used to assess myocardial contractility include, amongst others, the fractional shortening (FSshort forfood supplements), the peak systolic strain rate and the left ventricular end-systolic diameter (LVESD).

Adults

In some intervention studies listed in Table 1 in the Appendix, parameters for assessing cardiac output following energy drink consumption were recorded. In all relevant studies, at least some of the measured parameters indicated that myocardial contractility or cardiac output was increased following acute energy drink consumption (Baum and Weiss, 2001; Doerner et al.short foret alii (lat. "and others"), 2015; Grasser et al.short foret alii (lat. "and others"), 2015; Grasser et al.short foret alii (lat. "and others"), 2014; Menci et al.short foret alii (lat. "and others"), 2013; Miles-Chan et al.short foret alii (lat. "and others"), 2015).

The studies that included a caffeine control group suggest that these effects may be due in particular to the overall composition of the energy drinks, as the caffeine control had no effect on these parameters. The intervention studies with caffeine controls are therefore listed in more detail below.

The study design by Baum and Weiss has already been explained in section 3.2.1.3 (Baum and Weiss, 2001). In contrast to the control drink containing caffeine (160 mgshort formilligram) (but without taurine) and the placebo, acute consumption of 500 mlshort formillilitre of the original energy drink (containing 160 mgshort formilligram of caffeine and 2,000 mgshort formilligram of taurine) following exercise resulted in a significant increase in stroke volume and the fraction of shortening (fractional shortening), as well as a significant reduction in left ventricular end-systolic diameter (LVESD). The authors concluded that the combination of taurine and caffeine in the original drink could enhance left ventricular contractility (Baum and Weiss, 2001).

The study design of Doerner et al.short foret alii (lat. "and others") has also already been explained in section 3.2.1.3 (Doerner et al.short foret alii (lat. "and others"), 2015). Acute consumption of an energy drink (corresponding to 105 mgshort formilligram of caffeine and 1,304 mgshort formilligram of taurine for a typical participant) led to a small but significant increase in the peak systolic strain rate, which is a parameter for regional contractility (Sinning, 2009). This effect was not observed in the caffeine group, which is why the authors conclude that energy drinks containing caffeine and taurine may influence myocardial contractility (Doerner et al.short foret alii (lat. "and others"), 2015). However, it cannot be definitively ruled out that other ingredients in the energy drink might also have influenced the observed effect.

The study by Miles-Chan et al.short foret alii (lat. "and others") investigated how the acute consumption of caffeinated drinks or energy drinks affects blood pressure or cardiac output (Miles-Chan et al.short foret alii (lat. "and others"), 2015). In this controlled, randomised crossover study, 18 healthy young men (25.4 ± 1.3 years) were randomly assigned in a blinded manner on four different days to receive either 355 mlshort formillilitre (1) an energy drink (containing 114 mgshort formilligram caffeine, 1,420 mgshort formilligram taurine, 85 mgshort formilligram glucuronolactone, 39 g sugar) + a placebo capsule (not further defined); (2) a sugar-free energy drink + a placebo capsule; (3) water + 120 mgshort formilligram caffeine or (4) water + placebo capsule within 4 minutes. The amount of caffeine in the energy drink was comparable, though slightly lower. Cardiovascular monitoring took place for 30 minutes at baseline and for 120 minutes following consumption of the respective drink. The energy drink, the sugar-free energy drink and the ‘caffeine + water’ drink all led to a comparable increase in blood pressure (3–4 mmHg) compared with the ‘water + placebo’ drink (p < 0.001), following the consumption of which only negligible occurrences of changes occurred. However, different effects were observed on parameters of cardiac function. Unlike the other three drinks, only the sugary energy drink significantly increased heart rate, stroke volume (SV), cardiac output (CO) (heart rate × stroke volume), the contractility index (representing aortic peak flow) and the double product (systolic blood pressure × heart rate; a surrogate marker for myocardial oxygen demand) (p < 0.01 for all parameters). Total peripheral resistance (TPR) was reduced following consumption of the energy drink, whilst the sugar-free energy drink and the ‘water + caffeine’ drink caused an increase in peripheral resistance compared with the placebo. The authors conclude that the observed changes in blood pressure may have been triggered by different haemodynamic pathways: by the energy drink via changes in myocardial output, and by caffeine as a single substance via vascular effects. As the sugar-free energy drink did not affect cardiac parameters, the authors suggest that this could be an effect of the combination of caffeine and sugar, mediated via insulin, to which inotropic effects are attributed (Klein et al.short foret alii (lat. "and others"), 2010; Klein and Visser, 2010). In contrast to the two previous studies, it is not assumed here that taurine or the combination of taurine and caffeine could be responsible for the effects on cardiac output, as the sugar-free energy drink also contained the same amounts of taurine and caffeine as the sugary version, yet did not have the same effect on cardiac output.

There is therefore evidence to suggest that the acute consumption of energy drinks could influence contractility and, consequently, cardiac output. The three studies with caffeine controls indicate that energy drinks may need to be assessed differently in this respect from other caffeinated foods that do not contain the ingredients typical of energy drinks. However, the evidence is contradictory regarding which ingredients or which combination of ingredients (sugar, taurine) might be responsible for these potential effects.

With regard to the endpoint of myocardial contractility, the intervention studies listed examined only the acute, moderate consumption of energy drinks (105 to 160 mgshort formilligram of caffeine) in healthy young adults. At these intake levels, the observed changes in these parameters, which reflect contractility, appear to be physiologically and health-wise harmless, provided their occurrence occurs occasionally and under normal (environmental) conditions in healthy adults.

It remains unclear whether, in the event of potentially long-term high consumption of energy drinks and the resulting potential long-term increase in myocardial contractility, any effects on human health are to be expected. The effects of high acute consumption also remain unclear.

Children and adolescents

The EDUCATE study investigated the acute effects of energy drink consumption on left ventricular (LV) dynamics and efficiency (N = 24) (Oberhoffer et al.short foret alii (lat. "and others"), 2022a): The measured conventional echocardiographic parameters of the ventricle, such as stroke volume (SV) and ejection fraction (EF), showed no significant differences between the energy drink and placebo groups following consumption. However, after four hours, a significantly lower cardiac efficiency (CE) (140.72 mmHg vs. 135.60 mmHg, p < 0.01) was observed in the energy drink group compared with the placebo group.

In the EDKAR cross-sectional study, various echocardiographic parameters were examined: LVEF, LVEDd, IVSd, PWED, LVMI, LAVES (four-chamber view, two-chamber view, mean), LAVI, TAPSE, MAPSE, E-wave, A-wave, E/A, lateral e’, septal e’, mean e’, lateral E/e’, septal E/e’, mean E/e’, and global longitudinal strain. In the unadjusted model without Bonferroni correction, it initially appeared that chronic heavy users had statistically significantly higher IVSd values and lower values for the parameter e’ septal compared with the control group. However, when the recommended Bonferroni correction was applied, this group comparison lost its statistical significance. Even after further adjustment for key confounders (adjusted for age, gender, physical activity, smoking status, cannabis use and alcohol consumption, and school type), no significant differences were observed between the two groups for any of the echocardiographic parameters (Menzel et al.short foret alii (lat. "and others"), 2025).

Further cardiological parameters measured in children and adolescents

Extrasystoles:

The authors of the EDUCATE study pointed out that the acute consumption of energy drinks containing caffeine intakes deemed safe by EFSAshort forEuropean Food Safety Authority was associated with a significant increase in supraventricular extrasystoles (Mandilaras et al.short foret alii (lat. "and others"), 2022).

To assess supraventricular extrasystoles (SVES), the number of observed heartbeats without arrhythmias was compared to the number of ‘extrasystoles’ in the period from 0 to 240 minutes after beverage consumption (incidence rate ratio, IRR: 1.7 (95% confidence interval: 1.058; 2.732), p = 0.028). An IRR of 1.7 indicates that the occurrence of supraventricular premature beats increased by 70% in the group that consumed an energy drink compared to the group that consumed a placebo. However, the absolute number of SVES in both the placebo group and the energy drink group remained within a low domain.

Arterial stiffness:

As part of the EDUCATE study, Lishort forlithium et al.short foret alii (lat. "and others") also investigated the effects of acute energy drink consumption on carotid artery stiffness (Lishort forlithium et al.short foret alii (lat. "and others"), 2022). To this end, the endpoints circumferential strain (CS), strain rate (SR) and arterial distensibility were measured. Compared with placebo intake, energy drink consumption led to a significantly lower maximum circumferential strain (CS) in both common carotid arteries (CCA) (11.78 ± 2.70% versus 12.29 ± 2.68%, p = 0.043) in the participants; however, no significant effect was observed over time following energy drink intake. The CS parameter is used as a marker for local vascular stiffness. A reduced CS value indicates increased stiffness of the arterial wall.

No significant differences were found between the energy drink group and the placebo group with regard to the parameters SR and arterial compliance.

Heart rate variability

The EDUCATE study also investigated how acute energy drink consumption affects the function of the autonomic nervous system (in particular the balance between sympathetic and parasympathetic activity) by measuring heart rate variability (HRV) (Mandilaras et al.short foret alii (lat. "and others"), 2026).

To this end, HRV was monitored using a 24-hour ECG by measuring the standard deviation of normal RRshort forrelative risk intervals (Standard Deviation of N-to-N intervals, SDNN), the root mean square of successive differences (RMSSD), and the low-frequency (LF) and high-frequency (HF) components. Whilst the SDNN parameter can be used to assess general autonomic flexibility, the RMSSD indicates the current state of recovery (parasympathetic regulation).

One hour after consuming the drink, a significant difference was observed in the SDNN parameter between the energy drink group and the placebo group (ED = 133.346 ± 50.217 ms vs. placebo = 115.654 ± 47.583 ms, p = 0.023). However, no significant differences in SDNN were observed in the subsequent time intervals (up to 240 minutes).

An increase in SDNN indicates that the overall variability of heartbeats has increased. Mandilaras et al.short foret alii (lat. "and others") interpret this increase as an acute response of the autonomic nervous system, in the sense of a stress response of the adolescent heart to the ingredients contained in the energy drink, such as caffeine (Mandilaras et al.short foret alii (lat. "and others"), 2026).

No significant differences were observed for the other parameters measured.

3.5.2 Additional adverse effects of energy drinks recorded

3.5.2.1 Human studies

Adults

In the intervention studies on energy drinks considered here, which focused on cardiovascular parameters (Table 1 in the Appendix), a maximum of one litre of energy drink was administered to adults, and only the acute effects of energy drink consumption were examined.

In two studies involving acute administration of 80 mgshort formilligram of caffeine via energy drinks, the participants reported no adverse effects (Franks et al.short foret alii (lat. "and others"), 2012; Hajsadeghi et al.short foret alii (lat. "and others"), 2016).

In the study by Steinke et al.short foret alii (lat. "and others") (n = 15), 200 mgshort formilligram of caffeine and 2,000 mgshort formilligram of taurine were administered via energy drinks over seven days (Steinke et al.short foret alii (lat. "and others"), 2009). Mild adverse effects were reported, such as restlessness (n = 4), gastrointestinal complaints or abdominal cramps (n = 3), increased urination (n = 1), disturbed sleep (n = 1) and a faster heart rate (n = 1). No control group was included.

In the study by Kurtz et al.short foret alii (lat. "and others") (n = 20), up to approximately 215 mgshort formilligram of caffeine was administered via an energy shot (Kurtz et al.short foret alii (lat. "and others"), 2013). The following adverse effects were reported: restlessness (n = 2), nausea (n = 1), palpitations (n = 1), sweating (n = 1) and abdominal pain (n = 1). However, participants in the control group (decaffeinated energy shot) also reported headaches (n = 1), restlessness (n = 1), palpitations (n = 1), drowsiness (n = 3) and abdominal pain (n = 1).

Phan et al.short foret alii (lat. "and others") also administered 215 mgshort formilligram of caffeine via energy shots to 10 participants. One participant complained of dizziness and another of palpitations. However, one participant who had consumed a decaffeinated energy shot also reported a headache (Phan and Shah, 2014).

In the study by Basrai et al.short foret alii (lat. "and others"), the acute consumption of 750 or 1,000 mlshort formillilitre of a control product, an energy drink (320 mgshort formilligram/L caffeine, 4,000 mgshort formilligram/L taurine, 308 mgshort formilligram/L glucuronolactone, 92 mgshort formilligram/L inositol), a control product plus caffeine or a control product plus taurine, caused moderate to more severe symptoms in some participants across all four interventions (Basrai et al.short foret alii (lat. "and others"), 2019). However, when 1,000 mlshort formillilitre was administered, the largest proportion of participants (7 out of 19) were affected after consuming the energy drinks, whilst after the administration of 750 mlshort formillilitre, the largest proportion of participants were affected after consuming the control product plus caffeine (6 out of 19). Severe symptoms, which occurred in five out of 38 individuals, were induced only following the administration of the energy drinks (severe tremor, severe nausea) or the control product plus caffeine (severe tremor, severe restlessness).

In the study by Fletcher et al.short foret alii (lat. "and others"), 15 participants (n = 18) reported the following adverse effects following the acute consumption of 960 mlshort formillilitre of energy drink (320 mgshort formilligram caffeine; taurine and glucuronolactone unknown): anxiety (n = 3), difficulty falling asleep (n = 4), dizziness (n = 3), dyspepsia/upset stomach (n = 4), nosebleeds (n = 1), headaches (n = 2), nervousness (n = 8), nausea (n = 2), palpitations (n = 4) and shortness of breath (n = 1). However, 13 participants in the caffeine group (n = 18) also reported similar adverse effects (Fletcher et al.short foret alii (lat. "and others"), 2017).

In the other intervention studies reviewed (see Table 1 in the Appendix), adverse effects were not addressed; that is, it is unclear to what extent these were even investigated.

Overall, young, healthy adults reported very few adverse effects following acute, moderate consumption of energy drinks containing up to 200 mgshort formilligram of caffeine. The acute consumption of higher amounts (up to one litre) led to moderate to severe adverse effects in some participants. However, some individuals also experienced effects after taking up higher amounts of caffeine via a control drink they had brought with them, which did not contain the other typical ingredients found in energy drinks. This suggests that caffeine alone may be primarily responsible for the adverse effects. In some studies, a few participants also reported adverse effects following the consumption of a caffeine-free drink. It is unclear whether this was due to other ingredients in this drink or to a possible sense of excitement regarding their participation in the study.

No data were available for even higher intake (more than one litre of energy drinks).

Children and adolescents

In the EDUCATE study, sleep duration, time taken to fall asleep, time taken to wake up and sleep quality were also recorded using self-reports (Oberhoffer et al.short foret alii (lat. "and others"), 2023b). Compared with the placebo group, the energy drink group had a significantly shorter duration of sleep (7.55 ± 0.92 h vs. 8.43 ± 1.70 h, p = 0.041) and woke up significantly earlier (7:00 am (6:30–7:30 am) vs. 8:00 am (7:00–8:00 am), p = 0.027). There was no significant difference in the time taken to fall asleep or in sleep quality (Oberhoffer et al.short foret alii (lat. "and others"), 2023b).

In relation to chronic heavy consumption, the EDKAR cross-sectional study investigated unpleasant physical sensations following the consumption of energy drinks. Almost half of the chronic heavy consumers reported having experienced unpleasant physical sensations after drinking energy drinks at least once. The most commonly reported symptoms were palpitations/rapid heartbeat, poor sleep, headaches and a feeling of pressure or tightness in the chest (Menzel et al.short foret alii (lat. "and others"), 2025). Furthermore, the EDKAR study showed that people with chronically high energy drink consumption slept for shorter periods on weekdays (less than 6 hours: 53.6%) than those in the control group (12.7%). The control group mainly slept for 7–8 hours (39.2%). A similar pattern was observed for sleep duration at the weekend, although in both groups around 20% reported sleeping longer than on weekdays (10 hours or more) (Menzel et al.short foret alii (lat. "and others"), 2025).

3.5.2.2 Case reports

The BfRshort forGerman Federal Institute for Risk Assessment has searched PubMed for a large number of published case reports relating to the consumption of energy drinks. The main symptoms observed were mostly cardiovascular complaints (chest pain, tachycardia, heart attack, cardiac arrhythmias and cardiac arrest, etc.), but also psychiatric disorders (anxiety, psychosis, hallucinations), epilepsy and kidney damage (see Table 2 in the Appendix).

Similarly, the Food and Drug Administration (FDAshort forFood and Drug Administration) has compiled a large number of voluntary reports from doctors, family members and consumers regarding adverse effects associated with the consumption of energy drinks in a database. The FDAshort forFood and Drug Administration points out that these event reports relating to specific products do not constitute a conclusion by the FDAshort forFood and Drug Administration regarding a causal link (External Link:https://www.govinfo.gov/content/pkg/GOVPUB-HE20_4000-PURL-gpo31531/pdf/GOVPUB-HE20_4000-PURL-gpo31531.pdf) (FDAshort forFood and Drug Administration, 2012).

The French Agency for Food, Environmental and Occupational Health & Safety (ANSES) has also recorded reports of adverse effects following the consumption of energy drinks as part of its nutrivigilance system (ANSES, 2013). ANSES has used various criteria (e. g. two Rapporteur Members States, temporal association, re-challenge, exclusion of other possible causes) to derive causal links, such as very likely, likely, possible, unlikely or excluded. In 95 of the cases investigated, for example, cardiovascular manifestations were reported. According to ANSES, the causality analysis yielded the following results: very likely in 5 cases; likely in 9 cases; possible in 25 cases; unlikely in 55 cases; and ruled out in one case.

Although causal relationships cannot be derived from case reports, the large number of reports of adverse effects following the consumption of energy drinks, particularly after excessive consumption, gives cause for concern that excessive consumption of such drinks may be associated with adverse health effects.

3.6 Exposure

As the BfRshort forGerman Federal Institute for Risk Assessment considers children and adolescents to be the main target group for energy drinks, and as potential risks arising from high caffeine intake – for example, through high consumption of energy drinks – must be taken into account particularly for these age groups, the following section primarily presents current data on children and adolescents.

3.6.1 Data from national consumption studies

In its opinion on the safety of caffeine (2015), EFSAshort forEuropean Food Safety Authority determined, amongst other things, the contribution of energy drinks to caffeine intake, based on consumption data from the Member States. For Germany, data from the NVS-II and EsKiMo-I studies, which were available in the Comprehensive European Food Consumption Database, were used for this purpose (EFSAshort forEuropean Food Safety Authority, 2015).

In the BfR’s view, the amounts of caffeine consumed from energy drinks were underestimated, partly because there was no code for energy drinks when the NVS II data were incorporated into this database, the EsKiMo-I study only took 11-year-old children into account, and because the survey methods used in NVS II and EsKiMo I did not adequately capture foods consumed irregularly.

EsKiMo-II study

EsKiMo II is a representative study of the dietary habits of 6- to 17-year-olds in Germany (survey period 2015–2017). The dietary intake of the younger children (aged 6–11, n = 1,188) was documented prospectively by their parents or carers using weighing logs on three consecutive days and one independent day. For adolescents (aged 12–17, n = 1,353), their usual intake over the previous four weeks was retrospectively assessed in a face-to-face interview using modified dietary history interviews with the aid of the DISHES software (Dietary Interview Software for Health Examination Studies). The frequency and amount of individual foods consumed at each meal were recorded. In a separate analysis, caffeine intake was determined on the basis of the consumption data collected in this way (RKI, 2019). This special analysis revealed that the mean caffeine intake across all caffeinated foods identified in EsKiMo II was 8.8 mgshort formilligram per day for children (aged 6 to 11 years) and 40.9 mgshort formilligram per day for adolescents (aged 12 to 17 years). Similarly, the average caffeine intake for all caffeinated drinks is 4.8 mgshort formilligram and 36.5 mgshort formilligram per day.

Energy drinks accounted for around 1% of total daily caffeine intake among children aged 6 to 11 years and around 4% among children and adolescents aged 12 to 17 years. The main sources of caffeine intake among adolescents were coffee and tea drinks (RKI, 2019).

However, it should be noted in this evaluation that the DISHES questionnaire, which was used for adolescents, does not allow for the quantification of acute energy drink consumption on a specific day. DISHES only records habitual consumption, but not energy drink consumption on individual days or ‘occasions’, e. g., on special occasions. Furthermore, in the DISHES interviews, specific questions about energy drinks were only asked after a screening question. Overall, it can be assumed that the consumption of energy drinks not consumed as part of regular meals is significantly underestimated by the DISHES interviews used in the EsKiMo-II study.

3.6.2 Targeted surveys on energy drink consumption among children, adolescents and adults in Germany

3.6.2.1 Survey study in 16 EU Member States (Zucconi et al.short foret alii (lat. "and others"), 2013)

In a survey commissioned by EFSAshort forEuropean Food Safety Authority and carried out in 16 Member States of the European Union in 2012 (Zucconi et al.short foret alii (lat. "and others"), 2013), 60% of the 1,068 respondents were children and adolescents (aged 10 to 18; 49.9% male, 47.5% female) in Germany stated that they had drunk energy drinks at least once in the past year (at the time of the survey). These were defined as energy drink consumers. Of these energy drink consumers, 17% stated that they drank energy drinks in amounts of one litre or more on certain occasions (in a ‘single session’). Relative to the total number of respondents who were children and adolescents in Germany, 10% reported drinking such amounts in a ‘single session’. Even at the 75th percentile, the acute caffeine intake from energy drinks during a single session among all children and adolescents who responded to the survey in Germany stood at 3.05 mgshort formilligram per kgshort forkilogram body weight; amongst energy drink consumers, the figure was as high as 4.52 mgshort formilligram per kgshort forkilogram body weight (Zucconi et al.short foret alii (lat. "and others"), 2013).

Furthermore, 9% of energy drink consumers among children and adolescents in Germany reported consuming energy drinks on 4 to 5 days a week or more frequently. In relation to the total number of children and adolescents who responded to the survey in Germany, this meant that around 5% reported consuming energy drinks on such a regular basis. However, the study did not address the amount consumed when presenting the frequency of energy drink consumption.

Among adults, 30% of the 1,553 respondents in Germany (aged 18 to 65; 49.6% male, 50.4% female) stated that they had consumed energy drinks at least once in the past year (at the time of the survey). Of those who consume energy drinks, 19% stated that they drink one litre or more of energy drinks on certain occasions (in a ‘single session’). Relative to the total number of respondents in Germany, this meant that around 5% had stated that they drink such amounts in a ‘single session’.

Furthermore, 11 per cent of energy drink consumers amongst the German adults who responded stated that they consumed energy drinks on 4 to 5 days a week or more frequently. Based on the total number of adults who responded in Germany, this meant that around 3 per cent reported consuming energy drinks on such a regular basis. As with the children, however, the presentation of consumption frequencies did not address the amounts consumed, meaning that chronic caffeine intake from energy drinks cannot be quantified.

The Zucconi study is therefore generally well suited to illustrating acute energy drink consumption on a specific occasion. It is not suitable for quantifying chronic caffeine intake from energy drinks, as the amounts of energy drinks consumed were not recorded in relation to regular consumption.

It should also be borne in mind that the survey period (February to November 2012) was more than ten years ago and that consumption patterns and amounts may have changed since then.

3.6.2.2 The BfRshort forGerman Federal Institute for Risk Assessment study on need-based consumption of energy drinks

A study on need-based consumption of energy drinks, initiated by the BfRshort forGerman Federal Institute for Risk Assessment in 2013, also provides evidence that energy drinks are consumed in large amounts by some people on certain occasions (BfRshort forGerman Federal Institute for Risk Assessment, 2013). In this study, visitors to LAN parties, sporting events, music festivals and clubs were interviewed who, at the time of the survey – based on the previous 24 hours – had consumed more than 500 mlshort formillilitre of energy drinks or more than 60 mlshort formillilitre of energy shots. A total of 508 interviews were conducted (489 interviews were included in the evaluation following data cleaning). Given the nature of the events in question, the majority of participants were aged between 15 and 30. Only a few of the respondents were over 30, with the exception of sporting events, where the average age of respondents was 33. The results therefore relate primarily to young adults and only partly to adolescents.

The individuals interviewed reported consuming, on average, around one litre of energy drink neat or 1.5 litres mixed with alcoholic drinks. Participants reported drinking particularly large amounts of energy drinks at LAN parties involving long periods of staying awake: on average, around 1.5 litres of energy drink neat or around 2.5 litres mixed with alcohol.

The survey also showed that awareness of the potential health risks associated with excessive consumption of energy drinks – particularly in conjunction with intensive sport or alcohol consumption – was very low amongst heavy consumers (BfRshort forGerman Federal Institute for Risk Assessment, 2013).

3.6.2.3 DAK Report: Prevention Radar Survey (“Präventionsradar”), 2016/17 school year (DAK, 2017)

A survey initiated by the health insurance provider DAK, carried out in schools across six German federal states (“Laender”) during the 2016/17 school year amongst pupils in Years 5 to 10 (aged 10 to 18 years) (N = 6,902), also asked about the consumption of energy drinks (DAK, 2017). However, the questions on energy drinks were not very detailed, as this was not the primary aim of the study. Of the pupils who had ever drunk energy drinks, 74% reported current consumption, of whom 60% did so occasionally (less than once a week) and 14% frequently (at least once a week). The highest frequency of consumption was reported by male respondents in Years 9 and 10 (aged 13 to 18), where the rate of consumption at least once a week stood at 20 per cent. With regard to the amounts consumed, 21% of pupils in Years 9 and 10 (aged 13 to 18) who consumed energy drinks and 11% of those in Years 7 and 8 (aged 11 to 16) reported drinking more than one can per occasion. No details were provided on how many doses were consumed when more than one dose was drunk. When asked on what occasions they had drunk energy drinks in the last 30 days, 20 per cent of pupils stated ‘before’ or ‘during school hours’ and 28 per cent stated ‘whilst gaming’ (DAK, 2017).

3.6.2.4 DAK Report: Prevention Radar Survey, 2021/22 school year (DAK, 2022)

In a further survey initiated by the DAK health insurance fund during the 2021/22 school year, carried out in schools across thirteen German federal states (“Laender”) among pupils in Years 5 to 10 (aged 11.1 to 14.9 years) (N = 17,877), the consumption of energy drinks was also investigated. Overall, 9% of pupils reported drinking these drinks at least once a week, whilst around 4% drank them daily. Broken down by year group, in years 5/6 (approx. 11 years old), 4% of pupils reported drinking energy drinks at least once a week, whilst around 2% drank them daily. In years 7/8 (approx. 13 years old), 9% of pupils reported drinking energy drinks at least once a week, whilst around 4% drank them daily. In years 9/10 (approx. 15 years old), 14% of pupils reported drinking energy drinks at least once a week, whilst around 6% drank them daily.

3.6.2.5 Survey in schools across six German federal states

A total of 6,902 children and adolescents from randomly selected schools in six German federal states ("Laender") took part in this survey. The ages of the respondents ranged from 9 to 19 years (mean: 13.1 years), with over 80% of participants aged between 11 and 15 years. Around 62% of adolescents who had consumed energy drinks within the last 30 days stated that, on a typical day of consumption, they drank one 250 mlshort formillilitre can. For 23%, the figure was two to three doses, and for around 3%, four or more, i. e. 1 litre or more. Regarding frequency of consumption, around 61% of energy drink consumers stated that they consumed energy drinks on approximately one day per month. For 31%, it was once a week, and for 8%, daily (Galimov et al.short foret alii (lat. "and others"), 2019).

3.6.2.6 Forsa survey

In a Forsa survey conducted between 3 July and 20 September 2024, 1,000 adolescents aged between 14 and 18 were questioned about their consumption of energy drinks. Among 14-year-olds, 3% stated that they consumed energy drinks daily and 6% stated that they did so several times a week. Among 15-year-olds, 11% stated that they consumed energy drinks several times a week. Among 16-year-olds, 1% reported consuming these drinks daily and 8% reported doing so several times a week. Among 17-year-olds, 2% reported consuming energy drinks daily and 4% several times a week (Foodwatch, 2024). No conclusions can be drawn from this study regarding the amounts consumed.

3.6.2.7 EDKAR study

The amount and frequency of chronic energy drink consumption – i. e. habitual (daily) consumption as well as consumption on a specific day – were recorded in the EDKAR study. This study, conducted by the BfRshort forGerman Federal Institute for Risk Assessment and the Charité University Medicine Berlin, on chronic high consumption of energy drinks and cardiovascular risk (EDKAR) among adolescents aged 15 to 18, investigated how frequently and in what amounts adolescents consume energy drinks and whether excessive, long-term consumption of energy drinks has an impact on the cardiovascular system.

Designed as a cross-sectional study, the research was carried out in two phases from March 2022 to May 2024. In the first phase of the study, an online survey on energy drink consumption, as well as leisure and health behaviours, was conducted in 359 classes at 29 schools in Berlin (grammar schools, integrated secondary schools, upper secondary centres; 156 schools were approached). Based on the data collected, individuals with chronically high consumption and a control group were identified, who were then examined by cardiologists at the Charité during the second phase of the study.

A total of 4,893 participants from the online survey in study phase 1 were included in the subsequent evaluation. Individuals were defined as energy drink consumers if they had consumed energy drinks in the past year. Adolescents were defined as non-consumers if they had either never drunk energy drinks, had drunk them only once in their lives, or had not drunk an energy drink in the past 12 months. The respondents were divided into different groups based on their respective energy drink consumption:

1. no energy drink consumption (n = 1,685),
2. occasional energy drink consumption (1 to 3 times a month; n = 1,714),
3. moderate energy drink consumption (1 to 3 times a week; n = 875),
4. regular energy drink consumption (≥ 4 times a week for less than 1 year; n = 80),
5. chronic low energy drink consumption (≥ 4 times a week for at least 1 year, ≤ 3 mgshort formilligram of caffeine per kgshort forkilogram of body weight per day; n = 252),
6. chronic high energy drink consumption (≥ 4 times per week for at least 1 year, > 3 mgshort formilligram caffeine per kgshort forkilogram body weight per day; n = 287).

Individuals with responses deemed implausible by the BfRshort forGerman Federal Institute for Risk Assessment, such as energy drink consumers who reported drinking 0 millilitres or more than 5 litres, were excluded from further evaluation.

The results showed that the median usual daily energy drink intake across all energy drink consumers was 82.9 mlshort formillilitre (20.5–286 mlshort formillilitre) per day. When considering only those with chronically high consumption (n = 287), the median usual daily energy drink intake was 818 mlshort formillilitre (571–1250 mlshort formillilitre) per day. With the assumption that commercially available energy drinks generally have a caffeine concentration of 320 mgshort formilligram/litre, the median usual daily caffeine intake across all energy drink consumers was 26.5 mgshort formilligram (6.6–91.4 mgshort formilligram) per day. When considering only those with chronically high consumption (n = 287), the median typical daily caffeine intake from energy drinks alone was 262 mgshort formilligram (183–400 mgshort formilligram) per day.

When looking at consumption on a specific day, 11.6% (n = 371) of energy drink consumers (across all groups) reported drinking more than one litre on a particular day. In the group of chronic heavy consumers, 44.9% (n = 129) reported drinking more than one litre on a given day. Furthermore, among chronic heavy consumers, 31% (n = 89) reported drinking up to two litres, 9.1% (n = 26) up to three litres, 2.4% (n = 7) up to four litres and 2.4% (n = 7) more than four litres of energy drinks on a consumption day.

Conclusion: With regard to acute energy drink consumption, the BfRshort forGerman Federal Institute for Risk Assessment considers – based on data from the study by Zucconi et al.short foret alii (lat. "and others") (2013) and the data collected by the BfRshort forGerman Federal Institute for Risk Assessment (2013), high consumption within a short period of time – for example, on a specific occasion – poses a risk of high caffeine intake exceeding the EFSAshort forEuropean Food Safety Authority limit value of 3 mgshort formilligram/kgshort forkilogram body weight. The amounts reported by participants in the EDKAR study as having been consumed on a particular day also indicate, in some cases, very high consumption of energy drinks with a correspondingly high caffeine intake. However, it is not possible to distinguish whether these amounts were consumed within a few hours or spread out over the course of the day.

3.7 Risk characterisation

3.7.1 Acute moderate consumption of energy drinks

Adults

In summary, it can be concluded that the acute moderate consumption of energy drinks in amounts that do not exceed the safe intake of caffeine as defined by EFSAshort forEuropean Food Safety Authority (200 mgshort formilligram of caffeine for healthy adults) does not pose a health risk to the cardiovascular system for healthy adults. This also applies to the other ingredients in energy drinks, such as taurine, glucuronolactone and inositol, at the current amounts added. The observed changes in blood pressure, the QTc interval, heart rate or myocardial contractility in conjunction with moderate energy drink consumption appear to pose no health risk, provided their occurrence is occasional and under normal (environmental) conditions. Furthermore, adverse effects associated with moderate energy drink consumption in young, healthy adults have been reported only very rarely.

Thus, even taking into account recent literature and in view of the mechanisms of action that have not yet been assessed by EFSAshort forEuropean Food Safety Authority (e. g., the potential inotropic effects of energy drinks and their impact on the QTc interval), it is confirmed that the acute intake of up to 200 mgshort formilligram of caffeine – including in the form of energy drinks containing other ingredients – does not pose a health risk to healthy adults.

Children and adolescents

There are very few intervention studies, involving only a small number of participants, on the acute effects of energy drinks in children and adolescents. The results of these studies show that the acute moderate consumption of energy drinks, with a caffeine intake deemed safe by EFSAshort forEuropean Food Safety Authority, leads to temporary changes in various cardiac parameters. Overall, however, the current evidence on the acute moderate effects of energy drinks in children and adolescents is insufficient to allow a clear health risk assessment to be derived.

To date, there is no clear evidence to suggest that the caffeine intake of 3 mgshort formilligram per kgshort forkilogram body weight – which EFSAshort forEuropean Food Safety Authority still considers safe for healthy children and adolescents – is unsafe.

3.7.2 Acute high consumption of energy drinks

Adults

In the identified intervention studies with cardiovascular endpoints in combination with acute high energy drink consumption, a maximum intake of up to one litre was investigated, which generally corresponds to a caffeine intake of around 320 mgshort formilligram. No intervention studies involving higher energy drink consumption were identified for adults. However, intervening in studies involving such excessive amounts is not justifiable on ethical grounds.

Based on the available study data, it is not possible to draw any conclusions regarding the extent to which acute high energy drink consumption affects heart rate or myocardial contractility in adults, as the data were either contradictory (heart rate) or the studies were not conducted with energy drink intake levels that resulted in an intake of more than 200 mgshort formilligram of caffeine (myocardial contractility). It should be noted, however, that there is evidence to suggest that energy drinks may have a greater effect on myocardial contractility than other caffeinated drinks without the typical ingredients found in energy drinks (Baum and Weiss, 2001; Doerner et al.short foret alii (lat. "and others"), 2015; Miles-Chan et al.short foret alii (lat. "and others"), 2015).

Caffeine doses ranging from more than 200 mgshort formilligram up to a maximum of 320 mgshort formilligram from energy drinks significantly increased blood pressure, although the changes were only moderate in young, healthy adults. However, consuming this amount of energy drink (or more) could potentially lead to a more pronounced increase in blood pressure in susceptible individuals, particularly when combined with intense physical activity and/or very high alcohol consumption. EFSAshort forEuropean Food Safety Authority also takes up the view that caffeine and exercise have an additive effect on blood pressure (EFSAshort forEuropean Food Safety Authority, 2015).

With regard to the QTc interval, acute high consumption of one litre of energy drinks led to significant prolongations of the QTc interval in healthy young adults in three out of four studies that analysed this endpoint (Basrai et al.short foret alii (lat. "and others"), 2019; Kozik et al.short foret alii (lat. "and others"), 2016; Shah et al.short foret alii (lat. "and others"), 2016c). This effect was not observed in combination with moderate energy drink consumption. In one of these studies, which was conducted in the USA, the induced increases in the QTc interval in healthy young adults were so substantial that they could pose a health risk (Kozik et al.short foret alii (lat. "and others"), 2016). However, the amount of caffeine consumed was not specified in this study.

Furthermore, in the identified studies involving acute caffeine doses of more than 200 mgshort formilligram via energy drinks, moderate to severe adverse effects such as palpitations, shortness of breath, severe tremor, severe nausea, anxiety and nervousness were reported in some participants (Basrai et al.short foret alii (lat. "and others"), 2019; Fletcher et al.short foret alii (lat. "and others"), 2017; Kurtz et al.short foret alii (lat. "and others"), 2013; Phan and Shah, 2014). These adverse effects appear to become more frequent and severe as the amount of energy drink consumed increases. However, comparable adverse effects were also observed following consumption of the caffeine control (where one was used), suggesting that caffeine may be responsible for most of these adverse effects. Some participants also reported adverse effects after consuming a control drink without caffeine. It is not clear whether this is due to other ingredients in the drink or to possible nervousness about taking part in the study.

Children and adolescents

There are no intervention studies available for children and adolescents involving higher amounts of energy drinks that would have led to the caffeine intake exceeding the level still considered safe by EFSAshort forEuropean Food Safety Authority. Nor would this be justifiable on ethical grounds.

However, in view of the adverse effects identified following acutely high intakes of caffeine or high acute consumption of energy drinks in young, healthy adults, the BfRshort forGerman Federal Institute for Risk Assessment assumes that children and adolescents – some of whom are not yet accustomed to caffeine – are at least as sensitive to such high intakes as adults.

The consumption of large amounts of energy drinks within a few hours is common among a substantial proportion of children, adolescents and young adults on certain occasions (BfRshort forGerman Federal Institute for Risk Assessment, 2013; Zucconi et al.short foret alii (lat. "and others"), 2013), particularly at certain events such as music festivals and in nightclubs (the BfRshort forGerman Federal Institute for Risk Assessment, 2013). In the 2012 survey on energy drink consumption in 16 EU Member States, 17% of children and adolescents in Germany who consumed energy drinks reported drinking an amount of one litre or more of energy drinks during a ‘single session’. Of the total number of respondents, around 10% reported drinking such amounts in a ‘single session’ (Zucconi et al.short foret alii (lat. "and others"), 2013). Even at the 75th percentile, the acute caffeine intake from energy drinks during a ‘single session’ among all children and adolescents who responded to the survey in Germany stood at 3.05 mgshort formilligram/kgshort forkilogram body weight; amongst those who consumed energy drinks, the figure was as high as 4.52 mgshort formilligram per kgshort forkilogram body weight (Zucconi et al.short foret alii (lat. "and others"), 2013).

More recent surveys conducted as part of the EDKAR study between 2022 and 2024, in which energy drink consumption among children and adolescents was specifically investigated, show that more than 10% of energy drink consumers reported drinking more than one litre (in some cases up to four litres) on a given day, thereby in some cases significantly exceeding the caffeine intake level deemed safe by EFSAshort forEuropean Food Safety Authority. However, this survey does not allow us to distinguish whether the amounts reported were taken up within a short period of time or spread out over the course of the day (unpublished data from the BfRshort forGerman Federal Institute for Risk Assessment).

It should be borne in mind that, depending on body weight, children and adolescents may exceed the acute caffeine intake level still considered safe by EFSAshort forEuropean Food Safety Authority even when consuming less than one litre of energy drink. Consequently, the proportion of children and adolescents who exceed the EFSAshort forEuropean Food Safety Authority limit value for caffeine through the consumption of energy drinks alone could in fact be slightly higher.

The reasons cited for consuming energy drinks by the majority of children, adolescents and young adults who drink them included the taste, the belief that energy drinks provide them with energy, the belief that they lead to increased performance, improved concentration and alertness, as well as the visual design and the influence of idols and celebrities (BfRshort forGerman Federal Institute for Risk Assessment, 2013; Maschkowski, 2016; Zucconi et al.short foret alii (lat. "and others"), 2013).

In summary, it can be said that a potential health risk has been identified for a significant proportion of children and adolescents due to excessive acute consumption of energy drinks. The same applies to adults with such consumption patterns; however, the proportion of adults who drink excessive amounts of energy drinks is presumably lower than among children and adolescents.

The potential health risks may depend on an individual’s sensitivity to the effects of caffeine. It can therefore be assumed that some children, in particular, may not yet be accustomed to caffeine and could therefore be especially sensitive to caffeine intake. Individual sensitivity may also be influenced by caffeine intake from other sources and possibly by accompanying factors, such as alcohol consumption or strenuous physical or sporting activity.

Furthermore, it has been shown that, amongst adolescents and young adults, awareness of the potential health risks associated with excessive consumption of energy drinks – particularly in conjunction with intensive sport or alcohol consumption – was low or insufficient (BfRshort forGerman Federal Institute for Risk Assessment, 2013). The BfRshort forGerman Federal Institute for Risk Assessment therefore assumes that, even among children and adolescents in general, awareness of the risks associated with excessive consumption of these drinks is not always sufficient.

3.7.3 Chronic moderate consumption of energy drinks

To date, there are no studies that have investigated the long-term health effects of chronic moderate energy drink consumption, or of no more than 3 mgshort formilligram of caffeine per kgshort forkilogram of body weight per day, in children and adolescents.

3.7.4 Chronic high consumption of energy drinks

The results of the EDKAR study showed that, in the adjusted model, there were no significant and/or clinically relevant differences in any of the measured cardiological parameters between the chronic high-consumption group and the control group among the adolescents studied (Menzel et al.short foret alii (lat. "and others"), 2025).

However, the study does not allow conclusions to be drawn as to whether differences would arise if the group of chronic high consumers were to continue consuming high amounts of energy drinks, as the EDKAR study defined chronic consumption as lasting at least one year. Furthermore, adolescents with chronic high energy drink consumption reported significantly higher alcohol consumption, higher smoking rates and shorter sleep duration compared with the control group (Menzel et al.short foret alii (lat. "and others"), 2025).

Furthermore, in the EDKAR study, almost half of the chronic heavy consumers reported having experienced unpleasant physical sensations at some point after drinking energy drinks. The most commonly reported symptoms were palpitations/rapid heartbeat, poor sleep, headaches and a feeling of pressure or tightness in the chest (Menzel et al.short foret alii (lat. "and others"), 2025).

3.8 Other aspects

The BfRshort forGerman Federal Institute for Risk Assessment study on the need-based consumption of energy drinks has shown that awareness of the potential health risks associated with acute excessive consumption of energy drinks – particularly in conjunction with intense physical activity or alcohol consumption – was low or insufficient amongst adolescents and young adults. The BfRshort forGerman Federal Institute for Risk Assessment therefore assumes that, among children too, there is generally too little awareness of the risks associated with excessive consumption of these drinks, particularly in conjunction with intense physical activity and/or high alcohol consumption, or that these population groups are not sufficiently informed about the potential risks of excessive consumption of energy drinks.

The BfRshort forGerman Federal Institute for Risk Assessment recommends minimising the potential health risk posed by excessive consumption of energy drinks among children and adolescents, particularly in view of the identified risks associated with acute high consumption.

Given the insufficient awareness of the risks associated with excessive consumption of energy drinks, target-group-specific measures in the domains of health education and health promotion could be implemented to raise awareness among children and adolescents, prevent health risks and support responsible behaviour with regard to a healthy lifestyle.

For example, educational programmes could be developed to raise awareness among children, adolescents, educational professionals and parents regarding the potential risks associated with high consumption. Social media could be utilised in particular, as children and adolescents use it more intensively than traditional media. It is recommended that existing educational and information materials (leaflets, videos, etc.), which are made available on the website of the Federal Centre for Diet (BZfE), amongst other places, be used more extensively in information campaigns in schools, thereby better reaching the actual at-risk group.

Particularly in view of the identified adverse effects associated with acutely high intakes of caffeine or energy drinks (sections 3.1.3, 3.5.1.3 and 3.5.2), which may occur in young, healthy adults, further measures should, where appropriate, be considered with the aim of fundamentally counteracting the potential excessive consumption of energy drinks, particularly among children and adolescents.

BD Blood pressure

bpm beats per minute

ED Energy drink

DBP diastolic blood pressure

FSshort forfood supplements fractional shortening

GLS global longitudinal strain

HF heart rate

HRV heart rate variability

HMV Cardiac output

LV left ventricular

LVEDV left ventricular end-diastolic volume

LVEF left ventricular ejection fraction

LVESD left ventricular end-systolic diameter

LVESV left ventricular end-systolic volume

LVSV left ventricular stroke volume

MAPSE mitral annular systolic plane systolic excursion

PSS Peak systolic strain

PSSR peak systolic strain rate

RV right ventricular

RVLS right ventricular longitudinal strain

SBP systolic blood pressure

SV stroke volume

TAPSE tricuspid annular plane systolic excursion

Tp-e electrocardiographic T wave

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