Low vs. Higher-Dose Dark Chocolate and Blood Pressure in Cardiovascular High-Risk Patients

Background Dark chocolate may have blood pressure-lowering properties. We conducted a prospective randomized open-label blinded end-point design trial to study a potential dose dependency of the presumed antihypertensive effect of dark chocolate by directly comparing low vs. higher doses of dark chocolate over the course of 3 months. Methods We enrolled a total of 102 patients with prehypertension/stage 1 hypertension and established cardiovascular end-organ damage or diabetes mellitus. Patients were randomly assigned to receive either 6 or 25g/day of flavanol-rich dark chocolate for 3 months. The difference in 24-h mean blood pressure between groups was defined as the primary outcome measure. Results Significant reductions in mean ambulatory 24-h blood pressure were observed between baseline and follow-up in both groups (6g/day: −2.3mmHg, 95% confidence interval −4.1 to −0.4; 25g/day: −1.9mmHg, 95% confidence interval −3.6 to −0.2). There were no significant differences in blood pressure changes between groups. In the higher-dose group, a slight increase in body weight was noted (0.8kg, 95% confidence interval 0.06 to 1.6). Conclusions The findings are consistent with the hypothesis that dark chocolate may be associated with a reduction in blood pressure (BP). However, due to the lack of a control group, confounding may be possible and the results should be interpreted with caution.