Impact of different types of olive oil on cardiovascular risk factors: A systematic review and network meta-analysis.

5 Repeated evidence

How much this weighs: several studies in people, combined — the strongest kind of evidence there is.

Type of study: meta-analysis or systematic review
Studied in: people
Participants: not stated in the abstract
Published: 2020 in Nutrition, metabolism, and cardiovascular diseases : NMCD
Cited: 42 times by other research
Who paid: Not declared. PubMed carries no conflict-of-interest statement for most articles; that is not the same as independent.
Source: PubMed 31378629 · doi 10.1016/j.numecd.2019.07.001

The plain-language write-up of this study is still being written. Below is the abstract exactly as the researchers published it.

Abstract by the researchers — original text

BACKGROUND AND AIM: This network meta-analysis (NMA) compares the effects of different types of olive oil (OO) on cardiovascular risk factors. METHODS AND RESULTS: Literature search was conducted on three electronic databases (Medline, Web of Science, and Cochrane Central). INCLUSION CRITERIA: Randomized controlled trials (RCTs) (≥3 weeks duration of intervention) comparing at least two of the following types of OO: refined OO (ROO), mixed OO (MOO), low phenolic (extra) virgin OO (LP(E)VOO), and high phenolic (extra) virgin OO (HP(E)VOO). Random-effects NMA was performed for seven outcomes; and surface under the cumulative ranking curve (SUCRA) was estimated, using an analytical approach (P-score). Thirteen RCTs (16 reports) with 611 mainly healthy participants (mean age: 26-70 years) were identified. No differences for total cholesterol, HDL-cholesterol, triacylglycerols, and diastolic blood pressure were observed comparing ROO, MOO, LP(E)VOO and HP(E)VOO. HP(E)VOO slightly reduce LDL-cholesterol (LDL-C) compared to LP(E)VOO (mean difference [MD]: -0.14 mmol/L, 95%-CI: -0.28, -0.01). Both, HP(E)VOO and LP(E)VOO reduces SBP compared to ROO (range of MD: -2.99 to -2.87 mmHg), and HP(E)VOO may improve oxidized LDL-cholesterol (oxLDL-C) compared to ROO (standardized MD: -0.68, 95%-CI: -1.31, -0.04). In secondary analyses, EVOO may reduce oxLDL-C compared to ROO, and a dose-response relationship between higher intakes of phenolic compounds from OO and lower SBP and oxLDL-C values was detected. HP(E)VOO was ranked as best treatment for LDL-C (P-score: 0.83), oxLDL-C (0.88), and SBP (0.75). CONCLUSIONS: HP(E)VOO may improve some cardiovascular risk factors, however, public health implications are limited by overall low or moderate certainty of evidence.