Effect of blueberry intervention on endothelial function: a systematic review and meta-analysis

Introduction: Endothelial dysfunction indicates blood vessel injury and is a risk factor for cardiovascular diseases. Blueberry has been approved for its benefits on human health, especially on cardiovascular function. However, its effect on endothelial function remains unclear. We conducted a systematic review and meta-analysis to explore the impact of blueberries on endothelial function in adults. Methods: We searched PubMed, Web of Science, Embase, and the Cochrane Library, 16 studies were included in the systematic review, and 11 were used for the meta-analysis. Data associated with endothelial function were extracted and pooled as mean differences (MD) with 95% confidence intervals (CI). Results: Blueberry consumption significantly improved flow-mediated dilation (FMD) by 1.50% (95% CI: 0.81, 2.20; I² = 87%) and reactive hyperemia index (RHI) by 0.26 (95% CI: 0.09, 0.42; I² = 72%). A significant decrease in diastolic blood pressure (DBP) was also observed (MD: -2.20 mm Hg; 95% CI: -4.13, -0.27; I² = 11%). Subgroup analysis indicated a significant decrease in blood pressure (Systolic blood pressure [SBP]: -3.92 mmHg; 95% CI: -6.88, -0.97; I² = 20% and DBP: -2.20 mmHg; 95% CI: -4.13, -0.27; I² = 11%) in the smoking population. However, SBP levels (MD: -1.43 mm Hg; 95% CI: -3.11, 0.26; I² = 20%) and lipid status (high-density lipoprotein cholesterol [HDL-C]: 0.06; 95% CI: -0.04, 0.16; I² = 77%; low-density lipoprotein cholesterol [LDL-C]: 0.05; 95% CI: -0.14, 0.24; I² = 0%) did not significantly improve. Conclusion: Blueberry intervention improved endothelial function and DBP. Subgroup analysis revealed a notable improvement in blood pressure among the smoking population. However, no significant effects were observed on SBP, HDL-C, and LDL-C levels. Future research should delve into the mechanisms of endothelial improvement and verify blood pressure reduction in specific subpopulations through large-scale trials. Clinical Trial Registration: https://www.crd.york.ac.uk/PROSPERO/, Identifier CRD42023491277.