Caffeine and the Cardiovascular System of University Students

In this experiment we aimed to determine whether caffeine has any effects on the cardiovascular systems of university students who consume more than 200 mg of caffeine per day, and whether these effects differ from students who consume less than 200 mg per day. Twenty-one caffeine-consuming (e.g., coffee, energy drinks, soda, tea) juniors and seniors were investigated. All data were pooled, but most participants were female (n=17). While many influences of caffeine on the human body can be investigated, we chose to limit our observations to selected cardiovascular variables. After resting, baseline data were collected, each student consumed 200 mg of caffeine (oral tablet). Post-caffeine data were collected 60 and 120 minutes later. Blood flow to a finger was measured plethysmographically, and systemic arterial blood pressure was measured with a cuff and stethoscope. Heart rate was measured from pulsatile pressure waveforms, and peripheral vascular resistance was calculated as mean arterial pressure divided by blood flow. All data were continuously recorded on an automated data acquisition system and displayed on a desktop computer monitor. Finger volume and blood flow were markedly and consistently reduced at 60- and 120-minutes post-caffeine. Peripheral vascular resistance to blood flow was simultaneously and significantly increased. We conclude that caffeine, at 200 mg, significantly disrupts homeostasis of the young adult cardiovascular system, and consequently, is not good for the heart and circulation.