Role of berries in vascular function: a systematic review of human intervention studies

CONTEXT: Berries are a source of polyphenols with recognized health-promoting activities. Several studies suggest that consumption of berries may improve vascular function. OBJECTIVE: The aim of this systematic review is to provide evidence of short- and long-term benefits of berries on outcomes of vascular function. DATA SOURCES: Human intervention studies were collected from PubMed and Scopus databases. STUDY SELECTION: Studies were eligible if they investigated the effects of acute or chronic berry consumption on one or more markers of vascular function in humans and provided a characterization of the berry polyphenolic content. Only randomized controlled trials were included, and studies were excluded if berries were combined with other foods. DATA EXTRACTION: After selection, 22 randomized controlled trials were included and analyzed, most of which were performed in healthy individuals or patients with cardiovascular risk factors. RESULTS: The overall results seem to suggest a protective role of berries in vascular function, likely dependent on the time of exposure, the type and dose of berry, and the biomarkers analyzed. Flow-mediated dilation and reactive hyperemia index (markers of vascular reactivity) improved following short-term interventions, while pulse wave velocity and augmentation index (markers of arterial stiffness) improved only after medium- to long-term intervention. CONCLUSIONS: Current evidence suggests that berries, at physiological relevant doses, may have a role in the modulation of vascular function and stiffness. High-quality human intervention trials are encouraged in order to strengthen these findings and to better elucidate the mechanisms involved in such modulation.