Flavonoid-rich foods and vascular functions in healthy adults: a systematic review and meta-analysis of randomized...

Cardiovascular diseases (CVDs) remain the leading cause of mortality worldwide. Extensive research into preventive nutritional strategies against CVDs is needed. This meta-analysis aims to systematically evaluate the effects of flavonoid-rich foods on vascular function in healthy adults. A systematic literature search was conducted on PubMed, ScienceDirect, Scopus, Wiley, and EBSCO, and was supplemented with unpublished trials obtained from ClinicalTrials.gov until June 10, 2026. Risk of bias was assessed using the Cochrane RoB 2.0 tool. Pooled random-effects results were analysed using RStudio 4.5.3. Heterogeneity was assessed and quantified using Higgins' I² statistics. A total of 11 randomized controlled trials comprising 561 healthy participants met the eligibility criteria. The flavonoid-rich food intake group exhibited a statistically significant improvement in flow-mediated dilation compared to the control group [MD = 1.58%; 95% CI: 0.90 to 2.27%; P < 0.0001, I² = 75.7%]. The carotid-femoral pulse wave velocity also showed a statistically significant improvement in the intervention group [MD = -0.28 m s^-1; 95% CI: -0.52 to -0.04 m s^-1; P = 0.0197, I² = 0%], although findings were not robust across leave-one-out and correlation coefficient sensitivity analyses. There was no significant change in systolic blood pressure (P = 0.2210) and diastolic blood pressure (P = 0.2294) among both groups. Overall, consumption of flavonoid-rich foods improves surrogate biomarkers of vascular function in healthy adults. Further large-scale trials are needed to establish optimal flavonoid subclasses, dosages, and intervention durations.