Changes in Peak Expiratory Flow Rate, Blood Pressure and Pulse Rate Following Ingestion of Increased Coffee Concentrations in Healthy Male Adults

We studied the effect of different concentrations of coffee on peak expiratory flow rate (PEFR), blood pressure and pulse rate in an attempt to determine some physiological effects of coffee intake. 18 apparently healthy adult males, age range 20 to 30 years, were recruited for the study over a three day period. Varying concentrations (2g, 4g and 6g) of Nescafe Instant Coffee were administered. 2g coffee concentration was given on the first day, 4g on the second day and 6g on the third. The control measurements were taken on the first day of the experimental procedure in all subjects. The PEFR readings after coffee administration increased significantly when compared with control readings (P<0.05) 4g and 6g readings also increased significantly when compared with 2g readings (P<0.05), but there was no significant change between the 4g and 6g readings. Using 2g, no significant change in systolic blood pressure (SBP) was observed when compared with controls. SBP increased significantly at 4g and 6g when compared with the control (P<0.05). Diastolic blood pressure (DBP) increased significantly in all categories when compared with the control, but there was no significant change in DBP when the 3 coffee doses were compared. There was significant decrease in PR in all the 3 experimental doses when compared with the control reading (P<0.05), 2g decreased significantly when compared with 4g, but no significant change when 4g was compared to 6g. This study suggests that 2g of coffee does not give maximum cardio-respiratory effects. The peak effect that coffee can exhibit on PEFR and cardiovascular system was seen from 4g coffee concentration; but there was no significant difference when compared with 6g concentration. Only in DBP and PR were significant changes observed when 2g concentration was administered. It further indicates that, mild doses of coffee confer benefits on airflow in the lungs. While higher doses are also beneficial in improving airflow in the airway, such doses have the disadvantage of increasing BP.