Purpose: To determine the acute effects of a variety of recognized energy drinks on medical students, based on the hypothesis that these beverages may affect negatively cardiovascular parameters, stress levels and working memory.
Methods: Eighty young healthy medical students were included in the study. 62.5 % of the participants were male, and the age mean was 21.45 years. Each person was evaluated via measurement of systolic and diastolic blood pressure, electrocardiogram (ECG), heart rate, oxygen saturation, breath rate, temperature, STAI score (to assess anxiety state), salivary cortisol and N-back task score (to determine cognitive enhancement). These evaluations were performed before and following the intake of either carbonated water or one of three energy drinks containing caffeine in similar concentrations and an undetermined energy blend; A contained less sugar and no taurine.
Results: Thirty-minute SBP increased significantly in the A and C groups. The B group exhibited a diminution of the percentage of the 1-h SBP increase, an increase of 1-h DBP and QTc shortening. HR showed an increase in the percent change in the A and C groups. Cortisol salivary levels increased in the B group. The STAI test score decreased in the C group. The percent change in N-back scores increased in the A group.
Conclusions: The data reinforce the need for further research on the acute and chronic effects of energy drinks to determine the actual risks and benefits. Consumers need to be more informed about the safety of these energy drinks, especially the young student population.
Keywords: Blood pressure; Caffeine; Cortisol; Energy drink; Medical students; Taurine.