Abstract
PurposeEnergy drinks are beverages containing vasoactive metabolites, usually a combination of caffeine, taurine, glucuronolactone and sugars. There are concerns about the safety of energy drinks with some countries banning their sales. We determined the acute effects of a popular energy drink, Red Bull, on cardiovascular and hemodynamic variables, cerebrovascular parameters and microvascular endothelial function.MethodsTwenty-five young non-obese and healthy subjects attended two experimental sessions on separate days according to a randomized crossover study design. During each session, primary measurements included beat-to-beat blood pressure measurements, impedance cardiography and transcranial Doppler measurements for at least 20 min baseline and for 2 h following the ingestion of either 355 mL of the energy drink or 355 mL of tap water; the endothelial function test was performed before and two hours after either drink.ResultsUnlike the water control load, Red Bull consumption led to increases in both systolic and diastolic blood pressure (p < 0.005), associated with increased heart rate and cardiac output (p < 0.05), with no significant changes in total peripheral resistance and without diminished endothelial response to acetylcholine; consequently, double product (reflecting myocardial load) was increased (p < 0.005). Red Bull consumption also led to increases in cerebrovascular resistance and breathing frequency (p < 0.005), as well as to decreases in cerebral blood flow velocity (p < 0.005) and end-tidal carbon dioxide (p < 0.005).ConclusionOur results show an overall negative hemodynamic profile in response to ingestion of the energy drink Red Bull, in particular an elevated blood pressure and double product and a lower cerebral blood flow velocity.
Highlights
Energy drinks refer to a category of sugary drinks that include variable amounts of caffeine, taurine and glucuronolactone as well as other ingredients that may include vitamins and minerals [1]
The blood pressure (BP)-elevating effects of Red Bull (RB) are found when compared to the water load, with the effect of the RB drink resulting in significantly higher values for systolic BP (SBP) (3.3 ± 1.0 vs. 0.3 ± 0.7 mmHg, p \ 0.005) and diastolic BP (DBP) (4.1 ± 0.7 vs. 1.3 ± 0.4 mmHg, p \ 0.005) if values were averaged over 120 min post-drink
Ingestion of water decreased cerebral blood flow velocity (CBFV) and increased Cerebrovascular resistance (CVRI) significantly over time but the effect is far less pronounced compared to RB. This is reflected in a significant difference between RB and water if values were averaged over 120 min post-drink for CBFV (-7.4 ± 0.9 vs. -2.2 ± 0.6 cm s-1, p \ 0.005) and CVRI (0.16 ± 0.02 vs. 0.05 ± 0.02 mmHg s cm-1, p \ 0.005)
Summary
Energy drinks refer to a category of sugary drinks that include variable amounts of caffeine, taurine and glucuronolactone as well as other ingredients that may include vitamins and minerals [1]. The majority of energy drinks are targeted toward adolescents and young adults [4], and the manufacturer’s publicity claims positive effects on overall performance, mental concentration, reaction speed, vigilance, metabolism and well-being if such a beverage is consumed [5]. Despite these claims for beneficial effects, there are health concerns about these energy drinks because of reported side effects like cardiovascular complications or intoxication symptoms [6,7,8].
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