High blood pressure: a clinical study evaluates olive leaf extract

Why are researchers interested in olive leaves?

Olive leaves contain various polyphenols, notably oleuropein, an active compound found in particularly high concentrations in this plant.

Researchers are investigating their potential effects on vascular function, particularly the contraction and dilation of blood vessels, as well as on oxidative stress and inflammation (1–4).

This research, carried out mainly on cells and in animals, explores possible biological mechanisms. However, it is not sufficient on its own to demonstrate a benefit in humans, which must be assessed in clinical trials.

Today, olive leaf is available in extract form in certain dietary supplements, with oleuropein content varying depending on the product.

Discover Olive Leaf Extract, a dietary supplement providing 250mg of Olecol® daily, an Olea europaea leaf extract standardised to 32% oleuropein.

What does this new study on olive leaf extract show?

A recent study published in 2025 in the Journal of Hypertension investigated the effects of olive leaf extract on blood pressure in patients being treated for hypertension (5).

A study involving 621 patients

Here are the main characteristics of this trial:

• It was a multicentre trial, conducted across several centres.
• It was a randomised, double-blind, placebo-controlled trial, in which participants and investigators were unaware of the group to which participants had been assigned.
• It included 621 patients already being treated for high blood pressure: 307 received olive leaf extract and 314 received a placebo.
• The follow-up period lasted 12 weeks.
• Changes in blood pressure were assessed using 24-hour ambulatory monitoring.

This method records blood pressure at regular intervals throughout the day and night. It therefore provides a more comprehensive picture than a single measurement taken in the doctor’s surgery.

A reduction in 24-hour systolic blood pressure

After 12 weeks, the average 24-hour systolic blood pressure had fallen by 6.4 mmHg in the supplement group, compared with 1.5 mmHg in the placebo group.

Systolic pressure is the pressure exerted by the blood on the walls of the arteries when the heart contracts.

Fewer readings exceeding the set thresholds

Blood pressure burden refers to the proportion of readings exceeding the specified thresholds during the 24-hour recording. It therefore provides information on the frequency of excessively high readings.

In the group receiving the supplement:

• the proportion of systolic readings exceeding these thresholds fell from 53.9% to 42.2%;
• the proportion of diastolic readings fell from 30.7% to 21.2%.

Diastolic pressure corresponds to the pressure in the arteries when the heart relaxes between two contractions.

The study also found, in this group, a 13.3% reduction in diastolic blood pressure variability, i.e. the fluctuations between readings. No significant change was observed in systolic blood pressure variability.

Secondary results to be confirmed

The researchers also report favourable changes in certain metabolic parameters, notably blood glucose and blood lipids, including triglycerides. A reduction in CRP, a marker of inflammation, and in body weight was also observed.

These secondary findings need to be confirmed by further studies. All these observations relate to the specific conditions of this trial, which was conducted in patients already being treated for high blood pressure.

A randomised, double-blind, placebo-controlled trial conducted in patients already being treated for hypertension.

A study that adds to our knowledge, albeit with limitations

Previous trials focusing on olive leaf generally involved smaller sample sizes, using different extracts, doses and protocols.

A meta-analysis published in 2025 included three trials totalling 248 participants. It noted favourable findings, particularly regarding systolic blood pressure, but the results varied across the studies.

The authors highlighted the uneven quality of the trials and the need for further research (6).

With 621 participants, the new trial alone involves more patients than the three studies included in that meta-analysis.

Its randomised, double-blind, placebo-controlled design, combined with 24-hour blood pressure monitoring, provides additional data on the effects of the extract under investigation (5).

Several limitations must nevertheless be taken into account. The 12-week follow-up period does not allow for an assessment of the persistence of long-term effects. Differences in composition between the extracts also limit the comparability of the results and their generalisation to all olive leaf-based supplements.

Finally, this trial does not allow us to conclude that there is a reduction in the risk of heart attack or stroke.

The results observed regarding blood pressure still need to be confirmed and supplemented by further research.

Are all olive leaf extracts equally effective?

The composition of an olive leaf extract depends on several factors, including the variety of olive tree, the harvest period and the extraction process.

Two extracts may therefore have different levels of oleuropein and other polyphenols.

Standardisation ensures a defined and controlled content of a compound of interest – in this case, oleuropein – from one batch to the next. It provides information on the extract’s composition.

Discover Olive Leaf Extract, a dietary supplement providing 250 mg of Olecol® daily, an Olea europaea leaf extract standardised to 32% oleuropein.

Depending on their composition and the research protocols used, olive leaf extracts may be studied for their potential effects on various parameters.

Olecol® is currently the subject of research into cholesterol and other blood lipids. The study presented in this article, however, evaluated a different olive leaf extract.

Cardiovascular health: what other nutrients and formulations are there?

Olive leaves are not the only ingredient being studied in the field of cardiovascular health. Other nutrients and compounds are also the subject of research.

Nutrients and compounds studied individually

Magnesium is the subject of extensive research into its links with cardiovascular health, particularly the regulation of blood pressure.

Discover OptiMag®, a formula providing several forms of magnesium.

Omega-3 fatty acids EPA and DHA, for their part, contribute to the normal functioning of the heart and have been extensively studied for their effects on cardiovascular health.

Discover Super Omega 3, a supplement providing omega-3 fatty acids EPA and DHA in concentrated form.

Coenzyme Q10 is a compound naturally present in the body. It is particularly concentrated in tissues with high energy demands, such as the heart muscle.

Discover Coenzyme Q10, a supplement providing CoQ10 in oil-based capsules, with tocopherols.

Formulas combining several ingredients

Some formulas combine olive leaf extract, nutrients and other plant extracts.

Discover Tensix®, a formula combining a standardised olive leaf extract with hawthorn, arginine alpha-ketoglutarate, magnesium, potassium and celery extract.

A dietary supplement is not a substitute for medical treatment of high blood pressure. The participants in the study discussed in this article were, in fact, already being treated for high blood pressure.

Treatment should never be stopped or altered without medical advice. Before taking any supplements, seek advice from your doctor or pharmacist, particularly if you are taking an antihypertensive, a blood sugar-controlling medication or an anticoagulant, or if you have kidney disease.