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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.

  • 2025-11
  • Nutrition, metabolism, and cardiovascular diseases : NMCD 35(11)
    • Behnaz Pourrajab
    • Artemiss Mirdar Harijani
    • Parastoo Asghari
    • Farzad Shidfar

Study Design

Type
Meta-Analysis
Population
participants at risk of CVD
Methods
systematic review and meta-analysis of 21 trials comparing Mediterranean diet supplemented with olive oil vs mixed nuts

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.

Research Insights

  • Olive Oil→Improved Blood Lipid Profile

    The findings indicated that the MED diet supplemented with olive oil has no significant effect on lipid indices

    Effect
    Neutral
    Effect size
    Small
  • Olive Oil→Increased High-Density Lipoprotein Cholesterol

    The findings indicated that the MED diet supplemented with olive oil has no significant effect on lipid indices and diastolic blood pressure

    Effect
    Neutral
    Effect size
    Small
  • Olive Oil→Increased Systolic Blood Pressure

    the olive oil group had slightly higher systolic blood pressure levels than the mixed nuts group, with a significant p-value of <0.001

    Effect
    Harmful
    Effect size
    Small
  • Olive Oil→Reduced Blood Cholesterol

    The findings indicated that the MED diet supplemented with olive oil has no significant effect on lipid indices and diastolic blood pressure

    Effect
    Neutral
    Effect size
    Small
  • Olive Oil→Reduced Diastolic Blood Pressure

    The findings indicated that the MED diet supplemented with olive oil has no significant effect on lipid indices and diastolic blood pressure

    Effect
    Neutral
    Effect size
    Small
  • Olive Oil→Reduced LDL Cholesterol

    The findings indicated that the MED diet supplemented with olive oil has no significant effect on lipid indices and diastolic blood pressure

    Effect
    Neutral
    Effect size
    Small
  • Olive Oil→Reduced Triglyceride Levels

    The findings indicated that the MED diet supplemented with olive oil has no significant effect on lipid indices and diastolic blood pressure

    Effect
    Neutral
    Effect size
    Small
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