Effect of the Mediterranean diet supplemented with olive oil versus the Mediterranean diet supplemented with mixed nuts on blood pressure and serum lipid indexes among adults: a systematic review and meta-analysis of randomized controlled trials.

Abstract

Background and aim: Hypertension and dyslipidemia are major risk factors for cardiovascular disease (CVD). This systematic review and meta-analysis compared the effects of two Mediterranean (MED) dietary patterns-one supplemented with olive oil and the other with mixed nuts-on blood pressure and lipid profile.

Methods and results: Relevant studies published until April 24, 2024, were thoroughly searched in online databases, including PubMed/Medline, Scopus, Clarivate Analytics' Web of Science, Cochrane Central Register of Controlled Trials, and Google Scholar. The analysis included 21 trials with 25 effect sizes, calculated as standardized mean differences with 95 % confidence intervals (CI). The findings indicated that the MED diet supplemented with olive oil has no significant effect on lipid indices and diastolic blood pressure (DBP) when contrasted with the MED diet supplemented with mixed nuts. However, the olive oil group had slightly higher systolic blood pressure levels than the mixed nuts group, with a significant p-value of <0.001.

Conclusions: Evidence indicates no significant difference in serum lipid profile and DBP between the MED diet supplemented with olive oil and that with mixed nuts in participants at risk of CVD. However, mixed nuts significantly reduce SBP compared to olive oil. More studies on diverse populations are needed.