Systematic Literature Reviews

Health Effects of Olive Oil and the Mediterranean Diet

A review of recent systematic literature reviews

Prepared for Olive Wellness Institute

July 2018

Prepared by Nutrition Research Australia

Aim

 

The aim of this project was to:

  • Search the literature for systematic literature reviews (SLRs) or meta-analyses on olive oil and/or the Mediterranean Diet
  • Provide a brief summary of the SLRs for ten health outcomes to be used to update the Olive Wellness Institute (OWI) website

Methodology

The following methodology was used to obtain all SLRs on olive oil and/or the Mediterranean diet:

  • PUBMED and Web of Science databases were searched for studies published from the year 2000 to June 2018.
    • The search was limited from the year 2000, as all previously published reviews would be outdated, and all previous studies would be captured in more recent reviews of the literature.
  • Search terms included: Mediterranean diet OR Mediterranean OR Olive oil OR Extra virgin olive oil OR Virgin olive oil OR EVOO OR VOO AND Review OR Systematic review OR Systematic literature review OR SLR OR Meta-analysis OR Meta-analyses.
    • Limited to reviews in English and in humans (children or adults).
  • Titles and abstracts were scanned for the following inclusion criteria:
    • Systematic reviews or meta-analysis.
      • Expert/narrative reviews or individual studies were not considered.
    • Reviews focused specifically on the Mediterranean diet or on olive oil (any type)
      • This included reviews that looked at the Mediterranean diet alongside other diets.
    • Any health outcome or related measure (e.g. adherence, cost-effectiveness, etc.).
  • Studies were categorised into 14 health outcomes, and ten outcomes were included in this summary report.
    • Asthma (excluded)
    • Blood pressure
    • Bone health (excluded)
    • Cancer risk (excluded)
    • Cardiovascular disease
    • Cholesterol and lipids
    • Cognitive health and impairment
    • Depression and mental health
    • Type 2 diabetes (prevention and management)
    • Frailty in the elderly (excluded)
    • Inflammation
    • Metabolic Syndrome
    • Mortality (excluded)
    • Rheumatoid arthritis
    • Weight and anthropometric measures
  • The most recent and relevant review was selected and summarised for each of the ten health outcomes.
    • Studies were chosen based on:
      • Diet: Studies specifically on olive oil were prioritised over those on the Mediterranean diet, when available
      • Publication date: Studies with the most recent publication date
      • Outcomes: Studies that reported the largest range of measures relevant to the outcomes of interest (i.e. more than one risk factor for cardiovascular disease)
      • Quantitative assessment: Studies that performed a meta-analysis
      • Quality of evidence: Highest quality of evidence (i.e. RCTs prioritised over cross-sectional studies)
      • Impact factor: Studies published in a journal with the highest impact factor of the journal
      • Citations: When studies had a similar publication date, those with the greatest number of citations
    • Data were obtained for each paper on:
      • Study type
      • Diet or food investigated
      • Outcomes measured
      • Population studied
      • Key study results
      • Quality assessment
    • Upon assessment of the review, we provided:
      • A one-sentence summary
      • A list of its limitations
      • The bottom line of what the research means
    • The other review papers identified via the literature search are listed at the end of each health outcome section.

 

Results

Click on the below links to access a summary of each area investigated:

Blood Pressure

Cardiovascular Disease

Cholesterol and Blood Lipids

Cognitive Health and Impairment

Depression and Mental Health

Type 2 Diabetes (Prevention and Management)

Inflammation

Metabolic Syndrome

Rheumatoid Arthritis

Weight and Anthropometric Measures

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