Can Olive Leaf Extract Move 24-Hour Blood Pressure in People Already Treated for Hypertension?

Study Overview

The study, “Efficacy of olive leaf extracts in controlling blood pressure in hypertensive patients: a double-blind randomized clinical trial,” was published in the Journal of Hypertension in 2025 by Feten Lamti and colleagues. It was a multicenter, randomized, double-blind, placebo-controlled trial — exactly the design we want when testing a nutraceutical claim.

The investigators randomized 621 participants who were being treated for hypertension: 307 to oral olive leaf extract (OLE) and 314 to placebo. The primary endpoint was change in 24-hour systolic and diastolic blood pressure from baseline to week 12. That endpoint matters because ambulatory 24-hour monitoring is harder to game than office blood pressure and better reflects the pressure load arteries experience during ordinary life.

Secondary endpoints included blood-pressure load, blood-pressure variability, metabolic parameters, C-reactive protein (CRP), and body weight. In other words, the trial did not only ask whether a cuff reading moved; it asked whether olive leaf extract changed the broader cardiometabolic pattern that often travels with hypertension.

Key Findings: The Actual Numbers

The headline is the 24-hour systolic result. Olive leaf extract reduced 24-hour SBP by 6.4 mmHg from baseline, with a 95% confidence interval from -10 to -2.1. Placebo moved by only -1.5 mmHg, with a confidence interval crossing zero (-3.9 to 0.51), and the comparison was reported as statistically significant at P < 0.01.

The secondary blood-pressure metrics point in the same direction. Systolic blood-pressure load fell from 53.9% to 42.2% in the OLE group (P = 0.03), while placebo did not change significantly (P = 0.55). Diastolic load fell from 30.7% to 21.2% with OLE (P = 0.03), while placebo again did not significantly change (P = 0.12). Systolic variability did not improve meaningfully (+2%; P = 0.23), but diastolic variability dropped by 13.3% (P = 0.04). The authors also report improved lipid profile and significant reductions in blood glucose, triglycerides, CRP, and body weight, with no significant adverse events.

Mechanism: Why Olive Leaf Might Affect Blood Pressure

Olive leaf extract is not the same intervention as extra virgin olive oil. EVOO delivers oleic acid plus phenolics such as hydroxytyrosol, tyrosol, oleocanthal, oleacein, and secoiridoid derivatives. Olive leaf extract is more strongly associated with oleuropein, a phenolic secoiridoid that can be metabolized into hydroxytyrosol-like compounds and has been studied for antioxidant, endothelial, and metabolic effects.

The biological case is plausible. Hypertension is not just “too much pressure”; it is often tied to endothelial dysfunction, oxidative stress, vascular stiffness, renal sodium handling, insulin resistance, and low-grade inflammation. Oleuropein and related olive phenolics may preserve nitric-oxide signaling by reducing oxidative quenching, lower lipid oxidation, and blunt inflammatory signaling. If nitric oxide lasts longer, vascular smooth muscle relaxes more easily, and pressure can fall.

The CRP and metabolic findings matter because they make the result look less like a random cuff fluctuation. Lower triglycerides, glucose, CRP, body weight, and improved lipid profile suggest that OLE may be nudging the hypertension phenotype rather than acting as a single-channel vasodilator. That said, the abstract does not report all secondary effect sizes, so the strongest evidence remains the ambulatory blood-pressure data.

Context: How This Compares With Previous Research

This trial lands in an evidence base that has been promising but uneven. Smaller olive leaf and olive-polyphenol trials have reported improvements in office blood pressure, oxidized LDL, endothelial function, and insulin-related markers. Extra virgin olive oil trials also tend to show better oxidative and vascular biomarkers when the oil is phenolic-rich rather than refined.

What makes this paper stand out is scale. A 621-person randomized trial is unusually large for the olive-polyphenol supplement category. It also used 24-hour blood-pressure monitoring, which is more clinically convincing than one-off office readings. Compared with the 2026 Phytomedicine trial of olive leaf extract plus potassium in 70 adults with untreated mildly-to-moderately elevated blood pressure, this study is broader and more pragmatic: it tests olive leaf extract in people already living with treated hypertension.

It does not contradict the EVOO literature; it sharpens it. The consistent theme is that olive-derived phenolics appear most interesting when outcomes involve vascular oxidation, endothelial function, inflammation, and blood-pressure dynamics. The mistake would be to collapse all olive products into one category. Olive leaf extract, high-polyphenol EVOO, refined olive oil, and generic “olive oil” are not biologically identical interventions.

Limitations

• • Adjunctive setting: participants were treated hypertensive patients, so the result does not prove olive leaf extract works the same in untreated hypertension.
• • Dose detail is not visible in the PubMed abstract: readers need the full paper for the extract standardization, dosing schedule, and product composition.
• • Secondary outcomes are under-reported publicly: the abstract says glucose, triglycerides, CRP, lipids, and weight improved, but it does not provide all effect sizes.
• • Short follow-up: 12 weeks can show blood-pressure movement, not fewer strokes or heart attacks.
• • Product specificity: “olive leaf extract” is not one uniform substance; oleuropein content and extraction methods vary widely.

Our Take

This is one of the stronger olive-polyphenol blood-pressure papers because it combines sample size, randomization, blinding, placebo control, and ambulatory monitoring. A -6.4 mmHg 24-hour systolic reduction is clinically meaningful if it is durable. Even after subtracting the placebo movement, the signal is large enough to matter.

But the right interpretation is “credible adjunct,” not “natural antihypertensive replacement.” The study strengthens the vascular case for olive phenolics and deserves a place in the evidence map. It also raises the bar: future olive leaf trials should report extract chemistry clearly, publish full secondary endpoint tables, and test whether blood-pressure reductions persist beyond 12 weeks. For now, this is bookmark-worthy evidence — especially for clinicians and consumers who want olive-polyphenol claims grounded in actual ambulatory BP data.

Reference

Lamti F, Trabelsi I, Dhaoui R, Hajji E, Ben Amor B, Sekma A, et al. Efficacy of olive leaf extracts in controlling blood pressure in hypertensive patients: a double-blind randomized clinical trial. Journal of Hypertension. 2025;43(11):1878-1884. doi: 10.1097/HJH.0000000000004141. PMID: 40990594.