Background　Hot water extract of persimmon leaves（traditionally called as persimmon leaf tea）has been widely consumed in Japan and has already been found to have blood pressure （BP）lowering effect through endothelium-dependent vasodilation by our in vitro and animal studies. The aim of this study was the clinical evaluation of the BP lowering efficacy and safety of the extract.
Method　A single-blind, randomized, placebo-controlled study for 8 weeks was conducted in 27 subjects with high-normal BP（prehypertension, systolic 130/diastolic 85-139/89 mmHg） and stage�T hypertension（140/90-159/99 mmHg）. They were enrolled to three groups, to consume 350 mL/day of one of either placebo, extracts from 4 g（low-dose）, or extracts from 8 g（high-dose）of dried persimmon leaves（polyphenol contents, 0, 280, and 560 mg/day, respectively）. Primary outcome measure was change in BP after 2, 4, 6, and 8-weeks of daily intake. Secondary outcome measures included changes in flow mediated dilation（FMD）and safety evaluation for 8-weeks intake.
Results　High dose group was found to have trends toward lower systolic BP after 2, 6, and 8- weeks（P＝0.070, 0.093, 0.070, respectively）, compared with placebo group, although low dose group had no significant change. In FMD, both dose groups showed no significant change. No abnormal change caused by the test beverages was observed in the physical, biochemical and blood examinations in addition to medical interview.
Conclusions　These results suggested that the intake of persimmon leaf extract would be useful for lowering BP in subjects with high normal BP and stage�T hypertension and have no safety concern for long-term intake.