Mediterranean diet with high-phenolic EVOO slows kidney function decline and reduces inflammation in nondialysis CKD: a meta-analysis

Background Evidence regarding the renoprotective effect of the Mediterranean diet (MedDiet) in patients with nondialysis chronic kidney disease (CKD) remains inconsistent. This may be partly attributed to variability in the phenolic content of extra virgin olive oil (EVOO), a key bioactive component. Methods We conducted a systematic review and meta-analysis to quantify the effect of the MedDiet on renal and cardiometabolic outcomes in adults with nondialysis CKD and to explore the role of high-phenolic EVOO as a potential effect modifier. We searched multiple databases for interventional and observational studies comparing a MedDiet to control diets in adults with CKD stages 1–5. Random-effects meta-analyses were performed. Results Ten studies involving 1,073 participants were included. The MedDiet was associated with a modest improvement in estimated glomerular filtration rate (eGFR) (mean difference 2.44 mL/min/1.73 m 2 , 95% CI 0.16 to 4.72), though heterogeneity was high (I 2 = 90%). This benefit appeared more consistent in mild-to-moderate CKD (eGFR ≥ 45 mL/min/1.73 m 2 ). Notably, a significant reduction in C-reactive protein (CRP) was specifically linked to interventions using high-phenolic EVOO (mean difference −0.79 mg/L, 95% CI −1.37 to −0.21). The diet also improved body composition and reduced blood urea nitrogen, without adversely affecting serum potassium or phosphorus. No significant effects were observed on blood pressure or lipid profiles. Conclusion In patients with mild-to-moderate CKD, the MedDiet may slow kidney function decline. The benefits appear to be mediated through complementary pathways: renal protection from the overall dietary pattern and a specific anti-inflammatory effect attributable to high-phenolic EVOO. Systematic review registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420251124826 , identifier PROSPERO (CRD420251124826).