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Olive leaf extract is a concentrated supplement made from the leaves of the olive tree (Olea europaea), and its most studied compound is a polyphenol called oleuropein. A handful of small, short trials suggest it may modestly lower blood pressure readings and nudge some blood sugar markers, but other trials found no effect, several were funded by extract makers, and it is not a replacement for prescribed medicine. Here is what the research actually tested, who should be careful, which medicines it may interact with and what to look for on a label.
Peptide Labs does not sell a standalone olive leaf extract supplement; one product we carry lists it inside a blend, described below. This article is general information, not medical advice.
Key Takeaways
- Olive leaf extract comes from the leaves, not the fruit, and is usually standardized to its oleuropein content.
- Small trials report modest drops in blood pressure readings, but one 8-week trial found no change and evidence is limited.
- Several of the positive trials were partly funded by, or supplied by, the companies that make the extracts.
- People taking blood pressure or blood sugar medicines should talk with a clinician first because effects could add up.
- High blood pressure readings belong with a clinician; a supplement is not a substitute for diagnosis or care.
What is olive leaf extract?
Olive leaves have long been brewed as a tea in Mediterranean folk use. Supplements concentrate the leaves into a powder or liquid extract. The main compounds studied are oleuropein and its breakdown product hydroxytyrosol, both polyphenols. Olive oil contains related compounds, but leaves and oil are different products, so research on olive oil does not automatically apply to leaf extracts. Most labels state the share of oleuropein in the extract, which is one of the few ways to compare products, because the amount of active compounds varies with the olive variety, the season the leaves were picked and the extraction method.
In the European Union, olive leaf is also registered as a traditional herbal medicine. The European Medicines Agency (EMA) concluded, on the basis of long-standing use rather than strong trial evidence, that olive leaf preparations can be used to promote water elimination in mild water retention after a doctor has ruled out serious causes. That is the same idea behind other herbal “water pills”, which we cover in our guide to water pills.
Olive leaf extract benefits: what the research shows
The claims you will see most often are about blood pressure, blood sugar, cholesterol and immunity. The human evidence is strongest, though still limited, for blood pressure readings. Everything below is a research summary, not a promise of any effect.
Blood pressure research
A 2011 trial in Indonesia compared a proprietary olive leaf extract with captopril, a prescription blood pressure drug, in adults with stage 1 hypertension. After 8 weeks both groups had lower readings and the difference between groups was not statistically significant. A 2017 crossover trial in 60 men with prehypertension found 24-hour systolic readings about 3 mmHg lower after 6 weeks of extract compared with a control drink; half of that study’s funding came from the extract’s manufacturer. A larger 2025 trial in Tunisia gave an extract or placebo for 12 weeks to 621 people whose hypertension was already being managed with medicine, and found a larger drop in 24-hour systolic readings with the extract.
Not every trial agrees. A 2021 Dutch trial in 77 adults with overweight and mildly high cholesterol found no significant change in blood pressure, blood lipids, glucose or insulin after 8 weeks, and its lead author worked for an ingredient company. A 2025 meta-analysis could include only three studies with 248 participants, noted variable quality and called for more research. If your readings are high, a clinician can confirm them and discuss options; foods and herbs studied in the same area include hibiscus tea, beetroot and hawthorn berry, with similar limits.
Blood sugar and insulin research
A 2013 New Zealand crossover trial in 46 middle-aged men with overweight found 15% better insulin sensitivity after 12 weeks of olive leaf polyphenols compared with placebo, with no change in cholesterol, blood pressure or body composition. The extract and placebo were supplied by the manufacturer, which also co-funded the grant. A 2024 meta-analysis of 12 randomized trials with 703 adults found mixed results; in its pooled analysis of studies using smaller amounts, fasting glucose actually favored the control groups. The authors asked for larger, more consistent studies.
Cholesterol, immunity and antimicrobial claims
Memorial Sloan Kettering Cancer Center (MSKCC) notes that olive leaf extract kills yeasts, bacteria and fungi in laboratory tests, but that does not show it fights infections in people. Human data on cholesterol are mixed, and the anticancer findings come only from lab and animal studies. Claims that olive leaf extract “boosts immunity” or works like an antibiotic are not supported by human trials.
| Study | Who took part | Length | What it found | Caveat |
|---|---|---|---|---|
| Indonesia, 2011 | Adults with stage 1 hypertension | 8 weeks | Similar drop to captopril | Proprietary extract; no placebo group |
| UK, 2017 | 60 men with prehypertension | 6 weeks per arm | 24-hour systolic about 3 mmHg lower | Half funded by the extract maker |
| Tunisia, 2025 | 621 people already on medicine | 12 weeks | Larger systolic drop than placebo | Single trial; one author from a drug lab |
| Netherlands, 2021 | 77 adults with overweight | 8 weeks | No change in lipids or blood pressure | Lead author from an ingredient firm |
| New Zealand, 2013 | 46 men with overweight | 12 weeks | Better insulin sensitivity | Maker supplied the capsules |
Olive leaf extract side effects and safety
Trials lasting up to 12 weeks reported few side effects, and the 2025 Tunisian trial reported no significant adverse events. Long-term safety has not been studied. The main cautions come from how the extract may act on the body:
- Blood pressure medicines: MSKCC advises against combining olive leaf extract with blood pressure drugs without medical advice, because the effects could add up and readings could drop too far.
- Insulin and other blood sugar medicines: lab and animal studies show glucose-lowering effects, so combining them could raise the risk of low blood sugar.
- Fluid restriction: the EMA says olive leaf medicines must not be used by people told to limit fluids, such as those with severe heart or kidney disease, and are meant for adults only.
- Allergy: olive tree pollen can cause severe respiratory allergy, so people with that allergy should ask a clinician before using leaf products.
- Pregnancy and breastfeeding: there is little safety research, so ask your prenatal provider first.
See a clinician promptly for blood pressure readings that are consistently high, headaches with high readings, dizziness or fainting, or low blood sugar symptoms such as shakiness and sweating.
How to read an olive leaf extract label
- Confirm the plant part is the leaf (Olea europaea leaf), not olive fruit or oil.
- Look for the oleuropein percentage; without it you cannot tell how concentrated the extract is.
- Check whether olive leaf sits inside a proprietary blend, which shows only the total blend weight.
- Scan for stimulants such as caffeine, which can raise heart rate and blood pressure.
- Look for an independent quality seal, explained in our guide to third-party tested supplements.
- Read “supports healthy circulation” as a marketing statement the FDA has not evaluated.
The one product we carry that lists olive leaf is Animal Cuts, a pill-pack formula in which a labeled complex lists olive leaf extract with L-tyrosine and sage leaf. The label does not disclose how much olive leaf each pack contains, and the packs also contain several caffeine sources. Its label says it is not for anyone under 18 or pregnant or nursing, and to consult a physician first if you have high blood pressure, heart, thyroid, liver or kidney conditions or take any medication. It is not a way to get olive leaf extract on its own.
Frequently Asked Questions
What is olive leaf extract good for?
Small trials have studied blood pressure readings, blood sugar markers and cholesterol, with mixed results. Evidence is limited, and it is not a substitute for medical care.
What is oleuropein?
Oleuropein is the main polyphenol in olive leaves. Labels often list its percentage so you can compare how concentrated an extract is.
What are the side effects of olive leaf extract?
Short trials reported few side effects. The main concerns are adding to the effect of blood pressure or blood sugar medicines and allergy in people sensitive to olive pollen.
Can I take olive leaf extract with blood pressure medication?
Only after talking with your clinician, because the combined effect could lower your readings too far.
Is olive leaf extract the same as olive oil?
No. Both contain related polyphenols, but they are different products and the research does not transfer from one to the other.
Is olive leaf tea the same as an extract?
Tea is a milder, unstandardized preparation. Most trials used concentrated extracts, so their results may not apply to tea.
Questions about a label? Contact us or read our Buyer’s Guide. Follow the label and ask a healthcare provider before starting any supplement, especially if you take medicines. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Last reviewed October 2026.
Related guides: Hibiscus Tea Benefits, Side Effects and Blood Pressure Research, Garlic Supplement Guide: Forms, Research, Side Effects and Interactions, Third Party Tested Supplements: What USP, NSF and Other Seals Mean, Olive Oil Benefits: Research, Nutrition and Types of Olive Oil.