Olive leaf
A polyphenol-rich leaf extract, best known for blood pressure and cholesterol.
- Blood pressure
- Cholesterol
- Blood sugar
- Antioxidant markers
- Weight and body fat
A plain-English overview, not advice. Written from published reviews and trials and from what people say in public forums.
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On this page
What is olive leaf?
Olive leaf extract comes from the leaves of the olive tree, Olea europaea, native to the Mediterranean and grown widely for its fruit and oil. The leaves carry their own concentration of polyphenols, chiefly oleuropein and the compound it breaks down into, hydroxytyrosol. It is sold as a capsule or tablet extract, standardised to a stated percentage of oleuropein, which is how the dose is measured. This is a different part of the plant from olive oil or the whole fruit, which are not standardised for oleuropein and are not what the research on this page is about.
Why do people take olive leaf?
Blood pressure
The thinking. Blood pressure is the most common reason people buy olive leaf extract, often after a raised reading at a check-up. The thinking rests on its polyphenol content: reviews describe oleuropein and hydroxytyrosol as acting on the lining of blood vessels and as antioxidants, and link that activity to blood pressure.
What research has found. A pooled analysis of thirty trials and around 1,700 people found olive leaf lowered systolic and diastolic blood pressure, alongside blood fats, body weight and a marker of inflammation. A smaller trial in men with borderline-high readings found a similar pattern: the top number fell by roughly 3 to 4 mmHg, the bottom by 2 to 3, against a polyphenol-free control. A fair body of trials has looked at this, and most point the same way.
Cholesterol
The thinking. Cholesterol is another common reason people reach for olive leaf, often flagged at the same check-up as blood pressure. The same polyphenol content is behind the thinking: reviews describe oleuropein and hydroxytyrosol as acting on blood fats in a similar way to how they act on blood vessels.
What research has found. A pooled analysis of fourteen studies and around 600 people found a small average fall in total cholesterol, alongside triglycerides and a measure of insulin. A smaller eight-week trial in adults with mildly raised cholesterol, testing the leaf extract on its own, found no clear change in blood fats over that shorter period. A reasonable number of trials have measured this, and most of them agree.
Blood sugar
The thinking. Blood sugar is a further reason some people take olive leaf, particularly where a fasting reading has started to creep up. Reviews describe oleuropein as acting on how sugar is absorbed from food in the gut, and on how the body responds to insulin afterwards.
What research has found. Trials here point in different directions. Small trials found short-term improvements: one in overweight men found a 15% improvement in insulin sensitivity over twelve weeks, and another found a smaller rise in blood sugar after a sugary drink, though only at a lower dose. But the two largest pooled analyses, covering the trials together, found no clear change in fasting blood sugar, and one found it slightly higher than placebo at a low dose. Studies here point in different directions, so this one is still being worked out; the dose, how long people took it and who took part all seem to matter.
Antioxidant markers
The thinking. Olive leaf is marketed heavily on its polyphenol content, and some people take it specifically with antioxidant activity in mind, apart from blood pressure or cholesterol. The thinking follows the same chemistry: reviews describe hydroxytyrosol as one of the more studied plant antioxidants, acting on the reactive molecules produced by ordinary cell activity.
What research has found. A four-month trial in adults with overweight and prediabetes found lower levels of oxidised cholesterol and other markers of oxidative damage, alongside improved measures of the body’s own antioxidant defences. A smaller one-week trial in healthy adults, testing hydroxytyrosol on its own, found no clear change in similar markers, so the two trials do not fully agree. The studies disagree, so this is unsettled: dose, duration and who took part all seem to shift the result.
Weight and body fat
The thinking. A smaller number of people take olive leaf with their weight in mind, usually alongside one of the other reasons rather than instead of it. Reviews describe hydroxytyrosol as acting on how the body handles fat and energy, which is the thinking behind testing it for weight and body composition.
What research has found. A six-month trial in women with overweight found a drop in weight and visceral fat at the highest dose after four weeks, though the difference had faded by twelve and twenty-four weeks. A separate three-week trial in healthy adults found a small reduction in body fat and weight at a lower dose. The two trials do not fully agree on how lasting any change is. Results here go both ways, which usually means the dose, the length of a trial or the group taking part makes the difference.
What does olive leaf do in the body?
Oleuropein is the main polyphenol in olive leaves, one of a family of plant compounds called secoiridoids. Reviews describe it and the compound it breaks down into, hydroxytyrosol, as acting largely as antioxidants: they are thought to mop up the reactive molecules produced by ordinary cell activity, in the way many plant polyphenols do.
Beyond that antioxidant activity, reviews describe hydroxytyrosol as acting on the lining of blood vessels and as having an anti-inflammatory effect alongside it. Together, these are the two mechanisms researchers most often point to when explaining why the leaf’s polyphenols might touch blood pressure, blood fats and blood sugar, though reviews describe the underlying pathways as still being worked out, and say more research is needed to confirm them in people.
What do people say about taking olive leaf?
These are anecdotes people have shared, not evidence.
What people like
- Several people take it through autumn and winter, hoping to catch fewer colds or pass fewer to their children; a few feel it has helped.
- A small number describe a specific complaint easing soon after starting it, among them thrush and a herpes flare, though each is a single account.
- A few combine it with other herbs or vitamins, such as oregano oil, echinacea or a multivitamin, rather than taking it alone.
- One parent says it works well for their children, though their partner dislikes the taste; another gives it to the family each winter.
Common complaints
- Several of the strongest reports of side effects come from one forum for a long-term chronic illness, whose members often react more sensitively to supplements.
- Within that group, several describe an upset stomach, dizziness or a short-term drop in blood pressure with palpitations soon after starting it.
- A few say they felt nothing at all even after several days at a high dose, and gave up on it for that reason.
- One person kept taking it for longer and described feeling overstimulated, low in mood and unable to sleep properly, and eventually stopped.
How people take it
- Capsules are the usual form people describe; a couple mention a liquid, taken as drops added to water, instead.
- One person switched to a different brand and a lower dose after an early reaction, and found that easier to tolerate.
- Several combine it with other herbs or vitamins, rather than taking it alone, most often around the same time as a cold or a trip abroad.
- A few parents give it to their children as well as taking it themselves, especially through the winter months when colds are more common.
Read from these public discussions:
- anyone here using olive leaf extract? (Mumsnet, 2019)
- Thrush/vulval itching and olive leaf extract (Mumsnet, 2014)
- Best 'freshers flu' remedies (Mumsnet, 2014)
- Olive leaf extract (Phoenix Rising ME/CFS Forums, 2015)
- Experiences with Olive Leaf Extract? (Mouths of Mums, 2014)
What forms of olive leaf are there?
| Form | What’s different | Per serving, on products we list |
|---|---|---|
| Olive leaf (by oleuropein) | The leaves are dried and extracted, then standardised to a stated percentage of oleuropein. | not in our price tables yet |
What else is worth knowing about olive leaf?
- Labels state the oleuropein percentage the extract is standardised to. Trials tested oleuropein doses from about 20 mg to 136 mg, or, where hydroxytyrosol was given on its own rather than whole leaf extract, from about 5 mg to 25 mg a day.
- Trials describe it as well tolerated: several report no adverse events, and none of the trials here recorded a notable side effect.
- Most trials recruited people who already had something to shift, such as a raised blood pressure reading, cholesterol already high, or existing overweight and prediabetes, rather than people with results in the typical range.
- Research on hydroxytyrosol taken as part of extra virgin olive oil, or from whole olives, is a separate body of work from research on the leaf extract itself, and is not what this page draws on.
If you take medication, are pregnant, or have a health condition, check with a pharmacist or GP first.
The research behind this page (19 studies)
- A GRADE-assessed systematic review and meta-analysis of randomized controlled trials evaluating the effects of olive leaf or olive pomace supplementation on cardiometabolic and anthropometric health markers. (2026, meta-analysis)
- Impact of phenolic-rich olive leaf extract on blood pressure, plasma lipids and inflammatory markers: a randomised controlled trial. (2017, randomised trial)
- The impact of oleuropein, hydroxytyrosol, and tyrosol on cardiometabolic risk factors: a meta-analysis of randomized controlled trials. (2025, meta-analysis)
- The effect of olive leaf extract on cardiovascular health markers: a randomized placebo-controlled clinical trial. (2021, randomised trial)
- Metabolic and inflammatory effects of oleuropein and olive leaf extract: a systematic review and meta-analysis. (2026, meta-analysis)
- Olive leaf extract effect on cardiometabolic risk factors: a systematic review and meta-analysis of randomized clinical trials. (2024, meta-analysis)
- Nutritional implications of olives and sugar: attenuation of post-prandial glucose spikes in healthy volunteers by inhibition of sucrose hydrolysis and glucose transport by oleuropein. (2019, randomised trial)
- Oleuropein, a component of extra virgin olive oil, lowers postprandial glycaemia in healthy subjects. (2018, randomised trial)
- Olive (Olea europaea L.) leaf polyphenols improve insulin sensitivity in middle-aged overweight men: a randomized, placebo-controlled, crossover trial. (2013, randomised trial)
- Hydroxytyrosol supplementation improves antioxidant and anti-inflammatory status in individuals with overweight and prediabetes: A randomized, double-blind, placebo-controlled parallel trial. (2025, randomised trial)
- One-week administration of hydroxytyrosol to humans does not activate Phase II enzymes. (2015, randomised trial)
- Effect of Long-Term Hydroxytyrosol Administration on Body Weight, Fat Mass and Urine Metabolomics: A Randomized Double-Blind Prospective Human Study. (2022, randomised trial)
- Antioxidant Effects of a Hydroxytyrosol-Based Pharmaceutical Formulation on Body Composition, Metabolic State, and Gene Expression: A Randomized Double-Blinded, Placebo-Controlled Crossover Trial. (2017, randomised trial)
- Hydroxytyrosol, Tyrosol and Derivatives and Their Potential Effects on Human Health. (2019, review)
- Health Effects of Phenolic Compounds Found in Extra-Virgin Olive Oil, By-Products, and Leaf of Olea europaea L. (2019, review)
- Hydroxytyrosol: A natural compound with promising pharmacological activities. (2020, review)
- Hydroxytyrosol: Bioavailability, toxicity, and clinical applications. (2018, review)
- Valuable nutrients and functional bioactives in different parts of olive (Olea europaea L.)-a review. (2012, review)
- Beneficial effects of the olive oil phenolic components oleuropein and hydroxytyrosol: focus on protection against cardiovascular and metabolic diseases. (2014, review)
How much does olive leaf cost?
That depends on the form and the pack, so we work out the price of the same dose of every olive leaf product we can find and rank them.