The Impact of Berries on Macro- and Microvascular Function: A Systematic Review of Randomized Studies

CONTEXT: Several studies have investigated the effect of berries high in polyphenol content on vascular function. Polyphenols have antioxidant properties and enhance nitric oxide bioavailability. However, existing reviews investigated the effects of polyphenols on vascular health without distinguishing between micro- and macrovascular function. OBJECTIVES: This review explores the impact berries high in polyphenols (containing ≥200 mg of total polyphenols per 100 g or 100 mL) on macro- and microvascular function to better understand their role in vascular health. DATA SOURCE: A systematic search was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines across the PubMed, SciELO, and Web of Science databases using the following combined keywords: ("Berries" OR "Polyphenol-rich foods" OR "Polyphenols") AND ("Arterial stiffness" OR "Blood flow" OR "Macrovascular function" OR "Microcirculation" OR "Vascular function"). DATA EXTRACTION: Randomized controlled trials evaluating the effects of polyphenols derived from berries on macro- and microvascular function were included. Data extraction was performed independently by 2 researchers, and the risk of bias was assessed using the Cochrane risk-of-bias tool. DATA ANALYSIS: A total of 35 studies were included and analyzed. Among these, 26 studies evaluated the effects of polyphenols from berries on macrovascular function, 6 studies evaluated their effects on microvascular function, and 3 studies examined both macro- and microvascular function. CONCLUSION: The findings suggest berries containing high levels of polyphenols may improve vascular function in both the micro- and microvasculature. However, the supplementation protocol (ie, single dose vs multiple dose) appears to have a more pronounced effect on microvascular function. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42023408362.