A randomized study on coffee and blood pressure.

The effects of coffee on blood pressure and heart-rate and the mediating effect of two common brewing methods, were studied in a randomized trial in 107 young, normotensive adults. After a three-week run-in period, subjects were randomly assigned to one of three groups, receiving either (1) 4-6 cups filtered coffee per day, (2) 4-6 cups boiled coffee per day, or (3) no coffee at all for a period of nine weeks. Because all participants consumed filtered coffee before the trial, the group continuing on filtered coffee was considered as the reference group. Both systolic (SBP) and diastolic blood pressure (DBP) decreased in the abstinence group. Compared to the filter group, only the fall in SBP after 9 weeks was statistically significant, -6.1 mmHg (95% confidence limits -10.8, -1.4). After adjustment for SBP at baseline and body weight change during the study, the observed reduction decreased, to -3.4 mmHg (-7.1, 0.3). The patterns for SBP and DBP were remarkably similar in the groups using either filtered coffee or boiled coffee. After 9 weeks of boiled coffee, mean changes from baseline for SBP and DBP were 0.4 mmHg (-3.7, 4.5) and -0.1 mmHg (-3.4, 3.2), compared to the filter group. The heart rate showed a slight, non-significant decrease in the abstinence group. In conclusion, these findings suggest that abstinence from coffee for a period of several weeks may slightly reduce blood pressure in young normotensive subjects.

RCT Entities:   Population Interventions Outcomes