Objective: To evaluate blood pressure (BP)-lowering effects of Umezu polyphenols, polyphenols contained in Japanese plums, in a community-based sample by double-masked and placebo-controlled design.
Methods: Seventy-two Japanese community-dwellers who were interested in prevention or control of their BP (preferably high-normal BP or grade I hypertension) but without antihypertensive medication were randomized into Umezu polyphenols or placebo groups. Each subject took 800 mg/day of Umezu polyphenols or placebo for 12 weeks, followed by a 2-week washout period. Their home and office BP were monitored for 14 weeks in a double-masked manner. We analyzed 56 subjects who met the inclusion criteria.
Results: Home BP increased gradually in both the groups during the intervention period, while diastolic office BP insignificantly decreased in the intervention group. During the washout period, home systolic BP in the morning elevated only in the intervention group.
Conclusions: The study failed to collect consistent evidence of a clear persistent hypotensive effect of Umezu polyphenols.