Black Raspberry Extract Increased Circulating Endothelial Progenitor Cells and Improved Arterial Stiffness in Patients with Metabolic Syndrome: A Randomized Controlled Trial

Administration of black raspberry (Rubus occidentalis) is known to improve vascular endothelial function in patients at a high risk for cardiovascular (CV) disease. We investigated short-term effects of black raspberry on circulating endothelial progenitor cells (EPCs) and arterial stiffness in patients with metabolic syndrome. Patients with metabolic syndrome (n = 51) were prospectively randomized into the black raspberry group (n = 26, 750 mg/day) and placebo group (n = 25) during the 12-week follow-up. Central blood pressure, augmentation index, and EPCs, such as CD34/KDR⁺, CD34/CD117⁺, and CD34/CD133⁺, were measured at baseline and at 12-week follow-up. Radial augmentation indexes were significantly decreased in the black raspberry group compared to the placebo group (-5% ± 10% vs. 3% ± 14%, P < .05). CD34/CD133⁺ cells at 12-week follow-up were significantly higher in the black raspberry group compared to the placebo group (19 ± 109/μL vs.-28 ± 57/μL, P < .05). Decreases from the baseline in interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) were significantly greater in the black raspberry group compared to the placebo group (-0.5 ± 1.4 pg/mL vs.-0.1 ± 1.1 pg/mL, P < .05 and-5.4 ± 4.5 pg/mL vs.-0.8 ± 4.0 pg/mL, P < .05, respectively). Increases from the baseline in adiponectin levels (2.9 ± 2.1 μg/mL vs.-0.2 ± 2.5 μg/mL, P < .05) were significant in the black raspberry group. The use of black raspberry significantly lowered the augmentation index and increased circulating EPCs, thereby improving CV risks in patients with metabolic syndrome during the 12-week follow-up.