The effects of olive leaf extract on cardiovascular risk factors in the general adult population: a systematic review and meta-analysis of randomized controlled trials

Elham Razmpoosh, Shima Abdollahi, Mahdieh Mousavirad, Cain C. T. Clark, Sepideh Soltani

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    Abstract

    Abstract: Background: The aim of this systematic review and meta-analysis was to determine the effect of olive leaf extract (OLE) supplementation on cardiovascular-related variables, including lipid, glycemic, inflammatory, liver and renal-related factors, as well as blood pressure. Methods: PubMed, ISI Web of Science, Scopus, and Cochrane library were searched, up to October 2021, for relevant controlled trials. Mean differences and standard deviations were pooled for all outcomes, using a random-effects model. The methodological quality, as well as quality of evidence were assessed using standard tools. Results: Twelve studies (n = 819 participants) were included in our analyses. Overall analyses showed that OLE supplementation significantly decreased triglyceride (TG) levels (WMD = − 9.51 mg/dl, 95% CI − 17.83, − 1.18; P = 0.025; I2 = 68.7%; P-heterogeneity = 0.004), and systolic blood pressure (SBP) (WMD = − 3.86 mmHg, 95% CI − 6.44, − 1.28 mmHg; P = 0.003; I2 = 19.9%; P-heterogeneity = 0.28). Subgroup analyses also revealed a significant improvement in SBP (− 4.81 mmHg) and diastolic blood pressure (− 2.45 mmHg), TG (− 14.42 mg/dl), total cholesterol (TC) (− 9.14 mg/dl), and low-density lipoprotein-C (LDL-C) (− 4.6 mg/dl) measurements, in patients with hypertension. Significant reductions were also observed in TC (− 6.69 mg/dl), TG (− 9.21 mg/dl), and SBP (− 7.05 mmHg) in normal-weight individuals. However, no meaningful changes were seen in glucose hemostasis, liver and kidney, or inflammatory markers. Conclusion: The present study revealed that supplementation with OLE yielded beneficial effects for blood pressure and lipid profile in adults, especially in patients with hypertension. As the quality of evidence for glucose hemostasis variables, liver, kidney, and inflammatory markers, were low-to-very low, higher quality RCTs may impact the overarching results. This study was registered at PROSPERO with the code CRD42022302395.
    Original languageEnglish
    Article number151
    Number of pages15
    JournalDiabetology & Metabolic Syndrome
    Volume14
    Issue number1
    Early online date21 Oct 2022
    DOIs
    Publication statusPublished - Dec 2022

    Bibliographical note

    Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.

    Keywords

    • Olive leaf extract
    • Cardiovascular diseases
    • Blood pressure
    • Meta-analysis
    • Systematic review

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