By Lindsay Powers | Nutritional Therapist & Health Writer, Naturally Healthy News
Published: August 2023 | Last reviewed: August 2026
Olive leaf extract is a well-established botanical supplement, valued for its concentration of oleuropein, a polyphenol with well-documented antioxidant and anti-inflammatory properties. Derived from the leaves of the olive tree (Olea europaea) rather than the fruit or oil, it has been studied for its effects on blood pressure, immune function, inflammation and more.
This guide sets out what the current research shows for each benefit, how strong that evidence is, and how to use olive leaf extract safely.
Quick Summary
- Oleuropein, the extract’s main active compound, has solid antioxidant and anti-inflammatory evidence from lab and human cell studies
- Human trials support benefits for blood pressure and for reducing the frequency of upper respiratory infections
- Antimicrobial and cognitive benefits are currently supported by lab and animal research rather than large human trials
- Diet, activity, sleep and stress management have a greater impact on blood sugar regulation than any single supplement
- Speak to your GP before taking it if you’re on blood pressure medication or other prescription drugs
What Is Olive Leaf Extract?
Olive leaf extract is made by processing the leaves of the olive tree, typically into capsules, tinctures or teas. Unlike olive oil, which is valued mainly for its monounsaturated fats, the leaf contains a different and more concentrated set of polyphenols: chief among them oleuropein, along with hydroxytyrosol and luteolin. Mediterranean communities have used olive leaf preparations for generations, and modern clinical research has since examined these compounds directly.
Oleuropein: The Compound Behind the Claims
Most of the benefits attributed to olive leaf extract come from oleuropein, its primary active compound. Oleuropein is a strong antioxidant in laboratory settings, where it neutralises free radicals, and it has demonstrated anti-inflammatory activity [5]. The sections below set out the evidence for each benefit, organised by how well it is currently supported: from robust human trials through to early-stage laboratory and animal research.
Where the Evidence Is Strongest
Blood Pressure and Heart Health
Blood pressure support is the best-supported use of olive leaf extract. A double-blind, randomised, placebo-controlled trial in adults with mild-to-moderate hypertension found that olive leaf extract produced meaningful reductions in blood pressure [2]. Oleuropein is thought to help blood vessels relax, improving circulation. Anyone already taking blood pressure medication should discuss olive leaf extract with their GP first, as the effects can combine.
Fewer Upper Respiratory Infections
A randomised controlled trial in high school athletes, a group that trains hard and is often more susceptible to colds, found that those taking olive leaf extract experienced fewer upper respiratory illness episodes over the study period than those on placebo [1]. The trial was relatively small, but it is a genuine human RCT rather than a laboratory finding.
Antioxidant and Anti-Inflammatory Activity
Human cell studies have shown olive leaf extract protects red blood cells from oxidative damage [4], and a review attributes much of the extract’s anti-inflammatory action to oleuropein [5]. A systematic review and meta-analysis of oleuropein and olive leaf extract found consistent anti-inflammatory and metabolic effects across pooled trials [3]. This is one of the most consistently supported benefits of olive leaf extract, though optimal dosing for healthy adults is still being established.
Where the Evidence Is Still Developing
Antimicrobial Potential
Laboratory studies have found that oleuropein and olive leaf extract inhibit the growth of certain bacteria and fungi in test conditions [6]. This research is relevant given rising antibiotic resistance, though laboratory results do not necessarily predict what happens when the extract is taken orally and processed by the digestive system. Olive leaf extract is not a substitute for medical treatment of an infection.
Cognitive and Brain Health
Evidence for cognitive benefits currently comes from animal studies. In one study, mice given olive leaf extract showed improvements in markers of cognitive decline and depression-like behaviour [7]. Human trials confirming a cognitive benefit have not yet been conducted.
What About Blood Sugar?
A meta-analysis of oleuropein and olive leaf extract found supportive metabolic effects across pooled trials [3]. It is worth noting the regulatory context here: in 2014, the European Food Safety Authority assessed a specific claim linking olive leaf water extract to increased glucose tolerance and concluded the evidence submitted did not establish a cause-and-effect relationship [8]. That assessment does not rule out a benefit, but it means the claim is not currently an authorised health claim in the UK or EU. Diet, activity, sleep and stress management have a greater impact on blood sugar regulation than any single supplement. For a full approach, see our guide to blood sugar balance through diet and lifestyle. Olive leaf extract can be considered an addition to these foundations, not a substitute for them.
How to Take Olive Leaf Extract Safely
Olive leaf extract is typically available as capsules, liquid tinctures or dried leaf tea, with capsule doses in studies commonly ranging from around 500mg to 1,000mg of extract daily, standardised to a percentage of oleuropein. Product strengths vary considerably, so follow the manufacturer’s label rather than assuming one product matches another. Starting at the lower end and monitoring how you feel is a sensible approach.
Who Should Be Extra Careful
- If you take blood pressure medication, since effects may combine
- If you’re on any other prescription medication, particularly for blood sugar or blood clotting, given potential interactions
- If you’re pregnant or breastfeeding, as safety data is limited
- If you have a scheduled surgery, since some supplements can affect blood pressure or clotting around procedures
When in doubt, check with your GP or pharmacist before starting.
Frequently Asked Questions
Is olive leaf extract the same as olive oil?
No. Olive oil is pressed from the fruit and is valued mainly for its fat content, while olive leaf extract is made from the leaves and concentrated for polyphenols like oleuropein. They have different compositions and are used for different purposes.
How long does it take to notice an effect?
Clinical trials showing benefits, including the blood pressure study, used several weeks to a few months of consistent use [2]. Olive leaf extract is best regarded as a longer-term addition rather than a fast-acting remedy.
Are there side effects of olive leaf extract?
Olive leaf extract is generally well tolerated, though some people report mild digestive upset, headaches, or a feeling of light-headedness, particularly if blood pressure drops more than expected. Stop and check with a healthcare professional if you notice anything that concerns you.
Can I take olive leaf extract alongside other supplements?
In most cases, yes, though caution is needed when combining it with other blood-pressure-lowering supplements or medications for the reasons above. Anyone taking several supplements should review the full list with a pharmacist or GP periodically.
Final Thoughts
The evidence for olive leaf extract is strongest for blood pressure support and antioxidant activity, promising for immune support, and still developing for antimicrobial and cognitive benefits. Used alongside a balanced diet and any medication prescribed by your GP, it is a well-supported addition to a natural health routine.
References
- PubMed 30744092: The Effect of Olive Leaf Extract on Upper Respiratory Illness in High School Athletes: A Randomised Control Trial (Nutrients, 2019).
- PubMed 40990594: Efficacy of Olive Leaf Extracts in Controlling Blood Pressure in Hypertensive Patients: A Double-Blind Randomized Clinical Trial.
- PubMed 41848522: Metabolic and Inflammatory Effects of Oleuropein and Olive Leaf Extract: A Systematic Review and Meta-Analysis (Food & Function, 2026).
- PubMed 30255162: In Vitro Antioxidant Activity of Olive Leaf Extract and Its Protective Effect on Oxidative Damage in Human Erythrocytes.
- PubMed 29099642: Oleuropein Is Responsible for the Major Anti-Inflammatory Effects of Olive Leaf Extract.
- PubMed 39123180: Evaluation of the Antibacterial and Antifungal Properties of Oleuropein, Olive Leaf Extract, and Thymus Vulgaris Oil.
- PubMed 34127683: Olive Leaf Extract Prevents Obesity, Cognitive Decline, and Depression and Improves Exercise Capacity in Mice.
- EFSA Journal 2014;12(1):3655: Scientific Opinion on the Substantiation of a Health Claim Related to Olive Leaf Water Extract and Increase in Glucose Tolerance.
Our Recommendations
Naturally Healthy News is part of the Good Health Naturally family of brands.
If you’re looking to support healthy blood pressure and give your body extra antioxidant support, especially if your diet is light on polyphenol-rich foods, a high-quality olive leaf extract supplement can help fill that gap. Olive Leaf Extract with Zinc combines a standardised oleuropein extract with zinc to support normal immune function.
Disclaimer: The information in this article is intended for general informational purposes only and does not constitute medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your GP or a qualified healthcare provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay seeking it because of something you have read here.
