Efficacy of Olive Leaf Extract in Improving Blood Pressure in Pre-Hypertensive and Hypertensive Individuals: A Systematic Review and Meta-Analysis.

Annually, approximately 10 million deaths are attributed to hypertension, highlighting the critical need for effective treatments beyond conventional medications due to their limitations. Therefore, the aim of this study was to evaluate the impact of Olea europaea L. on blood pressure in adults with prehypertension and hypertension. The search, conducted from November/2022-October/2024 was performed on EBSCO, CABI, CNKI, Cochrane Library, DOAJ, PUBMED, SCOPUS, and WEB OF SCIENCE databases using Hypertension AND Olea europaea L. Eligible studies included those evaluating the effect of Olea europaea L. on systolic/diastolic blood pressure in hypertensive or pre-hypertensive adults. Exclusion criteria were multi-preparation interventions. Data on reference, country, sample, intervention/control details, duration, and differences in systolic and diastolic blood pressure, adverse effects, and medication use were extracted manually. The mean differences, heterogeneity (I²) and quality of the studies were assessed using Review Manager (version 5.4). From 211 found studies, 3 met the eligibility criteria, considering 248 participants analysed. An antihypertensive effect was observed on systolic and diastolic blood pressure in the pre- vs. post-intervention in the global analysis (systolic -6.03 mmHg, 95% CI: [-11.60, -0.46], I² = 82%, p = 0.03; diastolic -2.38 mmHg, 95% CI: [-4.96, 0.20], I² = 50%, p = 0.07) and in the sub-analysis that included the studies with the highest dose (1000 mg/day) (systolic -11.45 mmHg, 95% CI:[-13.99, -8.91], I² = 0%, p ≤ 0.001; diastolic -4.65 mmHg, 95% CI: [-6.56, -2.74], I² = 0%, p ≤ 0.001). Olive leaf extract (1000 mg/day) may reduce systolic and diastolic blood pressure by -11.45 and -4.65 mmHg, respectively. However, limitations include variable trial quality and exclusion of studies not written in English. Additional comprehensive clinical studies are essential to confirm its efficacy and safety.