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.
Safety and immunogenicity of S-Trimer (SCB-2019), a protein subunit vaccine candidate for COVID-19 in healthy adults: a phase 1, randomised, double-blind, placebo-controlled trial