Mediterranean diet enriched with olive oil shows no consistent benefits on cardiometabolic and anthropometric parameters: a systematic review with meta-analysis of randomized controlled trials.

Purpose: Cardiovascular disease (CVD) is the primary cause of death worldwide but there is a variation in its burden across some nations that seems to be related to dietary habits. Mediterranean populations have lower rates of morbidity and mortality from CVD. Thus, this systematic review and meta-analysis aimed to assess the impacts of the Mediterranean diet (MedDiet) enriched with olive oil on blood lipids, glycemic indices, blood pressure, and anthropometric indices.

Methods: A comprehensive search of the Web of Science, PubMed (MEDLINE), Scopus, Cochrane Library, Google Scholar, Embase, and CINAHL databases until March 2024 was conducted to identify clinical trials studying the effects of MedDiet enriched with olive oil on the aforementioned parameters.

Results: In total, 3303 records were retrieved. A total of 18 clinical trials met the inclusion criteria after records were screened for eligibility. According to the pooled analysis from the random-effects model, the MedDiet enriched with olive oil significantly reduced triglycerides (TG) compared with the control group (WMD = -2.40 mg/dl; 95%CI, -4.533 to -0.262; P = 0.027). Strong heterogeneity was observed. Sensitivity analysis did not change our results and no significant effect of any trial on the overall effect sizes of all variables were found. There was a concern about the reporting bias for some studies which reported some main outcomes.

Conclusion: MedDiet enriched with olive oil showed no consistent effects on any of the reported markers of cardiovascular health except on TG.

Systematic review registration: CRD42023424641.