Effects of Walnut ( Juglans regia L.) on Blood Pressure and Endothelial Function in Adults: A Systematic Review and Dose–Response Meta‐Analysis

Background

Walnuts ( Juglans regia L.) are rich in bioactive compounds with anti‐inflammatory and antioxidant properties, which may benefit cardiovascular health. However, the evidence regarding their effects on blood pressure (BP) and endothelial function remains inconclusive.

Objective

This systematic review and meta‐analysis aimed to evaluate the effects of walnut consumption on systolic and diastolic BP (SBP and DBP), and endothelial function markers, including flow‐mediated dilation (FMD), intercellular adhesion molecule‐1 (ICAM‐1) and vascular cell adhesion molecule‐1 (VCAM‐1) in adults.

Methods

A systematic search of PubMed, Web of Science and Scopus was conducted through February 2026 to identify relevant randomized controlled trials (RCTs). Weighted mean differences (WMDs) with corresponding 95% confidence intervals (CIs) were estimated using a random‐effects model. Subgroup analyses were conducted based on intervention duration and walnut dosage. Dose–response associations were further examined using both linear and nonlinear modelling approaches.

Results

Pooled analysis data from 36 RCTs showed no significant overall effect of walnut consumption on SBP (WMD: −0.65 mmHg; 95% CI: −1.61 to 0.30, p  = 0.183) or DBP (WMD: −0.68 mmHg; 95% CI: −1.56 to 0.19, p  = 0.125). However, significant reductions in DBP were observed in studies lasting ≥ 12 weeks. Walnut intake significantly increased FMD (WMD: 0.93%; 95% CI: 0.27 to 1.59, p  = 0.006), but had no overall significant effect on ICAM‐1 (WMD = −0.56 ng/mL; 95% CI: −2.50 to 1.38; p  = 0.571) and VCAM‐1 (WMD: −8.68 ng/mL, p  = 0.663). Subgroup analysis indicated a reduction in ICAM‐1 in participants at high cardiovascular risk. The dose–response analysis supported a greater effect on ICAM‐1 at higher walnut intakes.

Conclusion

Walnut supplementation may improve vascular health by reducing endothelial dysfunction and promoting a dose‐dependent reduction in endothelial inflammation.

Trial Registration: International Prospective Register of Systematic Reviews (PROSPERO): CRD420261461684.