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Purpose: Energy 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. Methods: Twenty-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 20min baseline and for 2h following the ingestion of either 355mL of the energy drink or 355mL of tap water; the endothelial function test was performed before and two hours after either drink. Results: Unlike 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). Conclusion: Our 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.

Background & aimsAn important consequence of ageing is a tendency for postprandial blood pressure to decline, which can lead to fainting. As a possible countermeasure, we investigated in healthy older adults the impact of drinking water before a breakfast meal on postprandial cardiovascular and autonomic functions.MethodsAfter a stable cardiovascular baseline recording for at least 20 min, twelve older adult (67 ± 1 y) test subjects ingested, in a crossover study design, either 100 mL or 500 mL of tap water over 4 min, which was followed by the consumption of the test breakfast meal (1708 kJ) over a period of 15 min. Then, cardiovascular recordings were resumed for 90 min after the meal. Eleven young (25 ± 1 y) and healthy subjects served as a control group. Measurements included beat-to-beat blood pressure, heart rate, impedance cardiography and autonomic variables.ResultsIn older adults, systolic and diastolic blood pressure started to decline around 30 min after the meal, with the lowest values around 60 min; these effects were not observed in the young control group. Postprandial systolic blood pressure decreased between 30 and 90 min to a greater extent in response to 100 mL than to 500 mL (−6.4 vs. −3.3 mmHg, P < 0.05). Drinking 500 mL of water tended to increase stroke volume, cardiac output and vagal markers to a greater extent than 100 mL.ConclusionsOur data suggest that drinking a large volume (500 mL) of water before a meal may attenuate postprandial hypotension in older adults.