Effects of walnuts consumption on vascular endothelial function in humans: A systematic review and meta-analysis of...

Endothelial dysfunction can promote atherosclerosis pathogenesis. The aim of the present meta-analysis was to determine the effects of walnut consumption on peripheral endothelial function (EF) in adults.

PUBMED, MEDLINE and EMBASE were searched to identify studies up to August 2017. Eligible studies conducted randomized controlled trials (RCTs) on the effects of walnut consumption compared with a control on EF. Standard mean difference (SMD) and 95% confidence intervals (CI) were reported as summary statistics. Standard methods were used for assessment of heterogeneity, meta-regression, sensitivity analysis and publication bias.

Five studies comprising a total of 323 subjects were included in the meta-analysis. The results showed a significant increase in EF after walnut consumption (SMD: 0.40%; 95% CI: 0.20 to 0.62; p < 0.001) with no evidence of heterogeneity across studies. Sensitivity analysis showed that the effect size was robust and not sensitive to any single study. Meta-regression did not indicate any significant association for an increase in EF after walnut consumption with dose of treatment, duration of treatment, or baseline EF.

The available evidence from RCTs suggests there may be a clinically relevant effect of walnut consumption on EF.