The effect of four coffee types on normotensive rats and normal/hypertensive human volunteers.

Coffee is a commonly consumed beverage. The purpose of this study was to determine the effect of the four coffee types on blood pressure (BP). The caffeine percentage was tested on one cup (250 mL) of each type of coffee (Arabian, Turkish, American and an instant coffee preparation) using two methods. 65 adult male rats and 400 healthy human volunteers were used in this study. Normotensive rats were treated orally with a single dose of normal saline with varying types of coffee. Normotensive and mildly hypertensive human volunteers were administered a cup (250 mL) of any type of coffee separately. Tail cuff and a strain-gauge plethysmograph were used to measure the systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) of the rats, and volunteers, respectively before and 0.5, 1.0, 1.5, and 2 h post administration. The mean arterial pressure (MAP) was calculated mathematically using SBP and DBP. The alkaloidal percentage of different types of coffee showed the presence variable contents and amount of active materials. The study showed that Arabian, Turkish, American and instant coffee all have the potential to cause a BP lowering effect. Variable antimicrobial activities were recorded for the different types of coffee when tested bacteria.