Effects of high phenolic olive oil on cardiovascular risk factors: A systematic review and meta-analysis.

BACKGROUND: Cardiovascular diseases are the world's leading cause of death. Prevention by nutrition is an easy and effective approach especially by advising foods with nutraceutic properties like high phenolic olive oil (HPOO).

AIM: The aim of this review was to systematically access and meta-analyse the effects of HPOO on risk factors of the cardiovascular system and thusly to evaluate its use as a nutraceutical in prevention.

DATA SYNTHESIS: Medline/PubMed, EMBase, the Cochrane Library, CAMbase and CAM-QUEST were searched through July 2013. Randomized controlled trials (RCTs) comparing high vs. low (resp. non) phenolic olive oils in either healthy participants or patients with cardiovascular diseases were included. For study appraisal the Cochrane Collaboration's risk of bias tool was used. Main outcomes were blood pressure, serum lipoproteins and oxidation markers. Standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated and analysed by the generic inverse variance methods using a random effects model. Eight cross over RCTs comparing ingestion (21-90 d) of high vs. low (resp. non) phenolic olive oils with a total of 355 subjects were included.

RESULTS: There were medium effects for lowering systolic blood pressure (n = 69; SMD -0.52; CI -0.77/-0.27; p < 0.01) and small effects for lowering oxLDL (n = 300; SMD -0.25; CI [-0.50/0.00]; p = 0.05). No effects were found for diastolic blood pressure (n = 69; SMD -0.20; CI -1.01/0.62; p = 0.64); malondialdehyde (n = 71; SMD -0.02; CI [-0.20/0.15]; p = 0.79), total cholesterol (n = 400; SMD -0.05; CI [-0.16/0.05]; p = 0.33); HDL (n = 400; SMD -0.03; CI [-0.14/0.08]; p = 0.62); LDL (n = 400; SMD -0.03; CI [-0.15/0.09]; p = 0.61); and triglycerides (n = 360; SMD 0.02; CI [-0.22/0.25]; p = 0.90).

LIMITATIONS: The small number of studies/participants limits this review.

CONCLUSIONS: HPOO provides small beneficial effects on systolic blood pressure and serum oxidative status (oxLDL). HPOO should be considered as a nutraceutical in cardiovascular prevention.