Dietary polyphenols have been shown to have a beneficial impact on blood pressure. To investigate the effect of daily consumption of a low calorie cranberry juice beverage (a rich source of polyphenols) on blood pressure of healthy adults (n=56), we conducted a parallel arm, double-blind, randomized, placebo-controlled trial. Volunteers were men (n=26) and women (n=30), aged 51+11 years, with a body weight of 79.3+8.8 kg and BMI of 28.4+4.3 (mean+SD). Treatments were a low calorie cranberry juice beverage or a color/flavor/calorie-matched placebo beverage, both of which were incorporated into a controlled diet for 8 weeks. During the controlled diet, volunteers consumed a base diet, consisting of typical American foods, scaled to meet their individual energy requirement such that body weight did not change during the study. Blood pressure was measured by a standardized protocol at the beginning of the intervention, after 4 weeks of treatment, and after 8 weeks of treatment. Systolic and diastolic blood pressure values for placebo and cranberry juice treatments at 4 weeks and 8 weeks were compared with a mixed model ANOVA. Blood pressure measures at 4 and 8 weeks of treatment for placebo and cranberry juice were also compared to baseline using a repeated measures ANOVA. After 8 weeks, diastolic blood pressure was significantly lower for the cranberry juice group compared to the placebo group (LSmeans + SEM of 72.2+1.1 mm Hg for placebo vs. 68.6+1.1 mm Hg for cranberry juice, respectively, p=0.029). When 8 week blood pressure values were compared to baseline, cranberry juice was associated with a significant decrease in diastolic BP (73.9+1.6 mm Hg at baseline vs. 70.9+1.6 mm Hg at 8 wk, p=0.049) and a trend toward decreased systolic BP (121.9+3.2 mm Hg at baseline vs. 118.6+3.1 mm Hg at 8 wk, p=0.12), while the placebo was associated with no change from baseline (systolic of 111.5+2.4 mm Hg at baseline vs. 112.3+2.2 mm Hg at 8 wk, p=0.89; diastolic of 68.1+1.5 mm Hg at baseline vs. 68.6+1.5 mm Hg at 8 wk, p=0.37). In conclusion, incorporation of a low calorie cranberry juice beverage into the diet of healthy adults appears to result in improvements in blood pressure.
Standard reference values of weight and maximum pressure distribution in healthy adults aged 18–65 years in Germany
