The aim of this single centre, repeated-dose, double-blind, placebo-controlled, crossover study is to test the hypothesis that an orally ingested apple polyphenol extract rich in epicatechin and flavan-3-ol oligomers improves brachial artery endothelium-dependent vasodilation function (FMD) in volunteer subjects with borderline hypertension. FMD and endothelium-independent nitrate-mediated vasodilatation (NMD) of the left brachial artery will be investigated with ultrasonography at the start and end of both treatment periods. Biomarkers of vascular function and epicatechin (and metabolite) concentrations will be determined from blood samples taken at the start and end of both treatment periods. Diet diary data will be collected for the evaluation of the possible effects of diet on the study results. Adverse events data will be collected throughout the study. Safety laboratory determinations will be performed at the last visit of both treatment periods.
