The effect of olive leaf use on blood pressure; A systematic review and meta-analysis

Context: Hypertension has been identified as the world's third leading cause of death. Due to their cost-effectiveness and lack of adverse effects compared to antihypertensive medications, medicinal plants have gained popularity in most countries. The olive leaf is one of these plants. As a result, the purpose of the current systematic review and meta-analysis was to determine the effect of olive leaf consumption on systolic and diastolic blood pressure. Evidence acquisition: The following domestic and international databases were searched in order to retrieve relevant studies: PubMed, Scopus, Web of Science, Embase, Cochrane, ProQuest, and Google Scholar search engine, the ClinicalTrials.gov Protocol Registration and Results System (PRS), the ISRCTN registry administered by BioMed Central, and the World Health Organization's (WHO) International Clinical Trials Registry Platform. The data collected were analyzed using STATA software (version14) at a significance level of P<0.05. Results: Olive leaf consumption had a significant effect on systolic blood pressure [- 0.87 (95% CI: -1.09, -0.64)] and diastolic blood pressure [-0.39 (95% CI: -0.57, -0.21)] in five studies with a sample size of 145 people (mean age range of 33.30 +/- 5.25 years). Consumption of olive leaves also decreased cholesterol levels [-0.52 (95% CI: - 0.81, -0.22)], low-density lipoprotein (LDL-c) levels [-0.35 (95% CI: -0.58, - 0.12)], and triglycerides levels [-0.67 (95% CI: -1.19, -0.16)]. Nonetheless, the olive leaf had no statistically significant effect on reducing high-density lipoprotein levels. Conclusion: We observed that olive leaf consumption significantly reduced the levels of systolic and diastolic blood pressure, cholesterol, triglycerides, and LDL-c. Registration: The current protocol was also registered on PROSPERO (ID: 221277, Date: 16.04.2022).