Olive Leaf Extract: Benefits, Forms, Dosing, and Side Effects

Table of Contents

• Current evidence position
• Key safety points
• Brad's videos on this topic
• Overview
• Forms and Bioavailability
• Evidence for Health Benefits
• Recommended Dosing
• Safety and Side Effects
• Drug Interactions
• Dietary Sources
• References

Current evidence position

Brad has not made a video on this topic; this is a summary of the evidence, not his view. Small, short trials suggest olive leaf extract may modestly lower blood pressure: a 2021 meta-analysis of five trials in 325 adults with prehypertension or hypertension found that 500 mg a day lowered systolic blood pressure (MD -5.78 mmHg, 95% CI -10.27 to -1.30), while the comparisons at 1,000 mg a day showed no significant difference ^[12]. In a six-week crossover trial in 60 men with prehypertension, an extract providing 136 mg of oleuropein a day lowered 24-hour systolic blood pressure by 3.33 mmHg and LDL cholesterol by 0.19 mmol/L compared with control ^[17]. Diabetes results are mixed: in 79 adults with type 2 diabetes, 500 mg once daily for 14 weeks lowered HbA1c and fasting insulin ^[29], but a 24-week pilot trial in 31 adults with type 2 diabetes found no significant difference from placebo in HbA1c or insulin sensitivity ^[56]. A six-month trial in 124 people with knee pain or mobility problems found no overall benefit ^[33]. Because the extract may add to the effects of blood pressure and diabetes medicines, people who take them should talk to their doctor first ^{[25, 29, 53]}.

Brad's videos on this topic

None yet.

1. Overview

Olive leaf extract (OLE) is made from olive tree (Olea europaea) leaves. Their phenolic compounds include oleuropein, verbascoside and flavonoids including luteolin glucosides and rutin ^[35], and olive leaf extract holds a greater amount and variety of polyphenols than extra-virgin olive oil ^[4].

Oleuropein, a secoiridoid built from hydroxytyrosol, elenolic acid and a glucose molecule, is thought to account for much of olive's biological activity ^[13]. It and hydroxytyrosol give extra-virgin olive oil its bitter, pungent taste ^[6], and laboratory studies report antioxidant, anti-inflammatory and antimicrobial actions ^{[2, 6]}.

Olive preparations have a long history in traditional medicine in many parts of the world, and laboratory and animal studies report a wide range of effects, including on blood sugar and blood pressure ^[8].

Clinical research has focused on blood pressure, cholesterol and blood sugar, and any benefits appear modest. A 2021 meta-analysis of five small trials (325 adults) found that 500 mg a day lowered systolic blood pressure, but the authors cautioned that the small number of participants limits firm conclusions ^[12]. Trials in type 2 diabetes, bone health, menopause and knee pain are small, and most were short.

2. Forms and Bioavailability

Types of Olive Leaf Extract Products

Olive leaf extract is sold in several forms, which differ in strength and in how well they are standardized.

Capsules and Tablets: The form used in most of the trials described below. Trials used 250 mg ^{[27, 28]} to 1,000 mg ^[25] of extract a day.

Liquid Extracts and Tinctures: Liquid concentrates and alcohol-based tinctures are also sold.

Teas and Infusions: Dried olive leaves can be steeped in hot water.

Topical Preparations: A 2% olive leaf extract cream has been tested for cold sores (herpes simplex labialis) ^[18]. Creams act on the skin and are not meant for whole-body effects.

Oleuropein Standardization

Extracts are made to different strengths, so the milligrams of extract on a label say little on their own. Compare products by the milligrams of oleuropein per serving. Trials that reported oleuropein content gave from 51.1 mg ^[14] to 136 mg ^[17] of oleuropein a day.

Key Bioactive Compounds

Olive leaf extract contains several classes of bioactive compounds:

• Oleuropein (secoiridoid glycoside): The main phenolic compound, made of hydroxytyrosol, elenolic acid and glucose ^[13]. Laboratory studies report antioxidant, anti-inflammatory and antimicrobial effects ^[6].
• Hydroxytyrosol: Released from oleuropein, it is a potent scavenger of superoxide radicals in laboratory tests ^[7] and has antibacterial activity ^[34].
• Verbascoside and caffeic acid: Other phenolic compounds found in olive leaves ^[35].
• Flavonoids: Including luteolin 7-O-glucoside, luteolin 4'-O-glucoside, apigenin 7-O-glucoside and rutin ^[35].
• Triterpenes: Reported among the compounds isolated from the olive tree ^[8].

3. Evidence for Health Benefits

Blood Pressure

Olive leaf extract's possible blood pressure effect has been studied in several clinical trials. In isolated rabbit hearts and rat heart cells, an olive leaf extract blocked L-type calcium channels ^[24], the target of calcium channel blocker medicines.

Meta-analysis of 5 RCTs (n=325, 2021): A systematic review of five trials in adults aged 18 to 80 years with prehypertension or hypertension found that 500 mg a day of olive leaf extract, compared with placebo or no treatment, lowered systolic blood pressure over at least 8 weeks (MD -5.78 mmHg, 95% CI -10.27 to -1.30), with no significant change in diastolic pressure. A 1,000 mg a day combined formulation showed no significant change, and a third comparison at 1,000 mg a day showed no significant difference (systolic -11.5 mmHg vs -13.7 mmHg) ^[12]; the meta-analysis labels this comparison placebo, but its figures are those of the captopril trial ^[25]. The authors noted the small number of participants ^[12].

Olive leaf extract vs. captopril (2011): In a double-blind, eight-week trial in stage 1 hypertension (olive group mean baseline systolic 149.3 mmHg, diastolic 93.9 mmHg), the extract (500 mg twice daily) lowered systolic blood pressure by 11.5 mmHg and diastolic by 4.8 mmHg from baseline, compared with 13.7 and 6.4 mmHg with captopril (12.5 to 25 mg twice daily); the two groups did not differ significantly. The trial had no placebo arm ^[25].

Olive leaf extract and 24-hour ambulatory BP (n=60, 2017): In a crossover trial, 60 men with prehypertension (mean age 45) (systolic 121 to 140 mmHg, diastolic 81 to 90 mmHg) took an extract providing 136 mg of oleuropein and 6 mg of hydroxytyrosol a day for six weeks. It lowered 24-hour systolic blood pressure by 3.33 mmHg and diastolic by 2.42 mmHg compared with a polyphenol-free control ^[17].

Overweight men (n=46, 2013): In a 12-week crossover trial, olive leaf polyphenols did not change 24-hour ambulatory blood pressure ^[14].

Reviews: Reviews of oleuropein and olive leaf polyphenols list blood pressure-lowering effects among their reported actions, drawn largely from laboratory and animal work ^{[13, 26]}.

Overall assessment: Any fall in blood pressure appears modest, and results differ between trials. The trials were small and short, so how long any effect lasts is unknown.

Cholesterol and Lipids

Trials that measured blood lipids found mixed results.

Meta-analysis LDL findings (2021): In the 2021 meta-analysis, 1,000 mg a day of olive leaf extract lowered LDL cholesterol compared with captopril (MD -6.00 mg/dL, 95% CI -11.5 to -0.50) ^[12]. In the captopril trial itself, triglycerides fell in the olive leaf group but not in the captopril group ^[25].

Olive leaf extract (n=60, 2017): In the prehypertension crossover trial, total cholesterol fell by 0.32 mmol/L, LDL cholesterol by 0.19 mmol/L and triglycerides by 0.18 compared with control over six weeks ^[17].

Postmenopausal women with osteopenia (n=64, 2015): In a 12-month double-blind trial, women who took 250 mg a day of an olive polyphenol extract (Bonolive) with calcium saw total cholesterol and LDL fall significantly compared with calcium alone ^[27].

Healthy postmenopausal women (n=60, 2024): In a 12-week trial, 250 mg a day of olive leaf extract lowered triglycerides and the triglyceride to HDL cholesterol ratio slightly compared with placebo ^[28].

Overweight men (n=46, 2013): Olive leaf polyphenols had no effect on the lipid profile ^[14].

Overall assessment: Olive leaf extract may lower total cholesterol, LDL and triglycerides slightly, but not every trial found this. The effects are far smaller than those of statins. OLE should not be considered a substitute for established lipid-lowering medications in individuals with high cardiovascular risk.

Blood Sugar and Insulin Control

In rats, olive leaf extract reduced starch digestion and absorption in the gut ^[29], and reviews list hypoglycemic effects of oleuropein ^[6]. Clinical evidence in humans is limited and mixed.

Type 2 diabetes (n=79, 2012): In a 14-week trial in 79 adults with type 2 diabetes, a 500 mg tablet of olive leaf extract once daily lowered HbA1c and fasting plasma insulin compared with placebo, but did not change insulin levels after meals ^[29].

Type 2 diabetes pilot trial (n=31, 2025): In a 24-week placebo-controlled pilot trial (ESOLED) in adults with type 2 diabetes not taking insulin, olive leaf extract capsules did not change HbA1c significantly compared with placebo. Insulin sensitivity improved more with the extract, but the difference between groups was not significant. The extract was well tolerated, and the authors judged the trial inconclusive on glycaemic control ^[56].

Overweight men without diabetes (n=46, 2013): In a 12-week crossover trial, olive leaf polyphenols (51.1 mg oleuropein, 9.7 mg hydroxytyrosol per day) improved insulin sensitivity by 15% and pancreatic beta-cell responsiveness by 28% compared with placebo ^[14].

Men with prehypertension (n=60, 2017): In the six-week crossover trial, markers of glucose metabolism did not change ^[17].

Overall assessment: In type 2 diabetes, results are mixed: one 14-week trial found lower HbA1c and fasting insulin ^[29], while a smaller 24-week pilot trial found no significant difference from placebo ^[56]. In people without diabetes, one trial found better insulin sensitivity and another found no change in glucose markers. Results are inconsistent and need confirming in larger trials.

Bone Health

Two small trials in postmenopausal women have looked at bone.

Postmenopausal women with osteopenia (n=64, 2015): In a 12-month double-blind trial, 250 mg a day of an olive polyphenol extract plus calcium raised osteocalcin, a blood marker of bone building, compared with calcium alone. Bone mineral density fell in the calcium-only group and stayed stable in the extract group ^[27].

Healthy postmenopausal women (n=60, 2024): In a 12-week trial, 250 mg a day of olive leaf extract slightly improved bone mineral density in the right arm compared with placebo, and did not affect other body composition measures ^[28].

Overall assessment: One small trial suggests olive leaf extract may help keep bone mineral density stable in postmenopausal women with osteopenia, and a short trial in healthy women found only a small change in one arm. Neither trial measured fractures.

Knee Pain and Joint Function

Knee pain or mobility problems (n=124, 2022): In a six-month double-blind trial, one 125 mg capsule twice a day (Bonolive, 50 mg of oleuropein per capsule) did not improve the overall knee score or markers of inflammation and cartilage turnover compared with placebo. A post hoc analysis found a benefit in the subgroup with high walking pain at the start. The extract was well tolerated ^[33].

Overall assessment: The extract did not help knee pain or function across the whole trial group. Any benefit may be limited to people with the most pain at the start, a finding from a post hoc analysis that needs testing in a new trial.

Postmenopausal Symptoms

Evidence on olive leaf extract for menopausal symptoms is limited to one small trial.

Healthy postmenopausal women (n=60, 2024): In a 12-week double-blind trial in women aged 47 to 70 years, 250 mg a day of olive leaf extract improved the overall menopause-specific quality of life score compared with placebo (estimated mean difference -0.2, p = 0.027), and slightly lowered triglycerides ^[28].

Postmenopausal women with osteopenia (n=64, 2015): This 12-month trial measured bone turnover, bone density and blood lipids, not menopausal symptoms ^[27].

Overall assessment: One small trial found a small improvement in overall menopausal symptom scores. Whether a change of that size matters to women is unclear, and the finding needs repeating.

Immune Function and Respiratory Infections

Oleuropein and hydroxytyrosol have shown antibacterial and antifungal activity in laboratory research ^{[6, 34, 35]}. However, human evidence is extremely limited.

High school athletes and colds (n=32, 2019): In a nine-week trial during a competitive season, a daily extract (equivalent to 20 g of olive leaf, with 100 mg oleuropein) did not change how often students got sick (OR 1.02, 95% CI 0.21 to 4.44), but cut sick days by 28% (OR 0.72, 95% CI 0.56 to 0.93) compared with placebo ^[36].

Laboratory antiviral evidence: In cell culture, olive leaf extracts blocked herpes simplex virus type 1 (HSV-1), including at the step of viral entry into cells ^[37]. A commercial olive leaf extract and oleuropein also inhibited a fish virus (viral haemorrhagic septicaemia virus) in the lab ^[38]. Hydroxytyrosol inhibited a range of bacteria that cause intestinal and respiratory infections, while oleuropein was much weaker ^[34]. A commercial olive leaf extract was not broad-spectrum: it was active against Helicobacter pylori, Campylobacter jejuni and Staphylococcus aureus, including MRSA, but showed little activity against most other organisms tested ^[39].

Laboratory antifungal evidence: Olive leaf extracts showed combined antibacterial and antifungal action in the lab, with fungi tested including Candida albicans ^[35].

Overall assessment: Olive leaf extract shows some antimicrobial and antiviral activity in laboratory studies, but human evidence is limited to one small trial in which athletes had fewer sick days. Laboratory results cannot be extrapolated to clinical use without larger human trials.

Cold Sores and Herpes Simplex

Early evidence, mostly from creams, suggests olive leaf extract may help herpes simplex infections.

Topical cream for cold sores (n=66, 2022): In a double-blind trial in 66 people with HSV-1 cold sores, 2% olive leaf extract cream or 5% acyclovir cream was applied five times a day for six days. Both worked; the olive leaf group had less bleeding, itching and pain on day three and a shorter treatment course ^[18].

Genital herpes case report (2021): A case report described treating genital herpes with olive leaf extract ^[42].

Overall assessment: Preliminary evidence suggests topical olive leaf extract may help cold sores, with one small trial favouring it over acyclovir cream. Larger, independent trials are needed.

Antioxidant and Anti-inflammatory Activity

In vitro antioxidant effects: Oleuropein and hydroxytyrosol are potent scavengers of superoxide radicals and inhibit the respiratory burst of neutrophils in laboratory tests ^[7].

Anti-inflammatory mechanisms: In human blood cultures, oleuropein glycoside lowered the inflammatory signal interleukin-1 beta ^[43]. In activated human monocytes, hydroxytyrosol reduced COX-2 expression by blocking NF-kB ^[44].

Overall assessment: The antioxidant and anti-inflammatory properties of olive leaf compounds are well established in laboratory models. However, in vitro antioxidant activity does not automatically translate to meaningful clinical benefits in humans.

Weight Management

Animal evidence only: In mice on a high-fat diet, olive leaf extract ^[45] and oleuropein ^[46] reduced weight gain and visceral fat. No human clinical trials have demonstrated weight loss benefits.

Anticancer and Neuroprotective Effects

Laboratory and animal studies report anticancer effects of oleuropein and olive leaf polyphenols ^{[2, 4, 6]}. A 2016 review concluded that evidence for cancer protection in people remains anecdotal and that clinical trials are needed ^[4]. Neuroprotective effects remain theoretical.

4. Recommended Dosing

Dosing Based on Clinical Trials

Clinical trials of olive leaf extract have used a range of doses. Where reported, the amount of oleuropein is a better guide than the total milligrams of extract.

General Recommendations

Based on the available clinical evidence:

• Doses used in trials: 250 mg ^{[27, 28]} to 1,000 mg ^[25] of extract a day; trials that reported oleuropein content gave 51.1 mg ^[14] to 136 mg ^[17] of oleuropein a day.
• Dosing frequency: The captopril trial gave 500 mg twice daily ^[25] and the knee trial one 125 mg capsule twice a day ^[33]; the diabetes trial used one 500 mg tablet a day ^[29].
• Duration: Clinical trials have ranged from 6 weeks to 12 months. Longer-term safety data are limited.

How to Read a Supplement Label

Compare products by their oleuropein content. The milligrams of extract alone say little without the percentage of oleuropein. For example, 400 mg of an extract that is 25% oleuropein provides 100 mg of oleuropein.

5. Safety and Side Effects

General Safety Profile

In a six-month trial, olive leaf extract was well tolerated ^[33]. Most trials were small and short, so data on rare or long-term side effects are limited.

Common Side Effects

Reported side effects include:

• Gastrointestinal symptoms and joint pain: In the six-month knee trial, 47 adverse events were recorded with olive leaf extract and 67 with placebo. Joint and back pain were the most frequent (12 vs 22 events), followed by gastrointestinal complaints (abdominal pain, nausea, dyspepsia; 7 vs 6). The number of people with at least one adverse event did not differ between groups ^[33].
• Headaches: Headaches may occur, though how often is unknown.
• Allergic reactions: People with olive pollen allergy may also react to olives, and possibly to olive leaf extract; one man with olive pollen allergy developed itching of the palate and widespread hives after eating olives ^[52]. For trouble breathing or swelling of the face or throat, call your local emergency number (111 in NZ, 000 in Australia, 911 in the US, 999 in the UK).

Toxicology

In a 90-day study in rats, an olive leaf extract (Bonolive) caused no deaths or toxic effects, and the highest dose tested, 1,000 mg/kg body weight a day, was the no observed adverse effect level. Bacterial and cell tests found no mutagenicity, and a mouse test found no genotoxicity up to the limit dose of 2,000 mg/kg body weight a day ^[55]. Safety data in people come from short trials, the longest lasting 12 months ^[27].

Hypotension Risk

Olive leaf extract lowered blood pressure in trials ^{[17, 25]}. If you already have low blood pressure or take blood pressure medicines, watch for symptoms of low blood pressure (dizziness, light-headedness, fainting) and ask your doctor first.

Special Populations

Pregnancy and Lactation: There are not enough safety data for olive leaf extract during pregnancy and breastfeeding, so caution is advised.

Children: Safety data in children are lacking. Olive leaf extract supplements are not recommended for use in children without medical supervision.

Kidney or Liver Disease: People with significant kidney or liver disease should talk to a doctor before taking olive leaf extract.

6. Drug Interactions

Olive leaf extract may interact with several classes of medications:

Antihypertensive Medications

Olive leaf extract may add to the blood pressure-lowering effects of antihypertensive drugs, including:

• ACE inhibitors (e.g., captopril, enalapril, lisinopril)
• Angiotensin receptor blockers (ARBs)
• Calcium channel blockers (e.g., diltiazem, verapamil, amlodipine); an olive leaf extract blocked L-type calcium channels in animal heart cells ^[24]
• Beta-blockers
• Diuretics

In one trial, the drop in blood pressure with olive leaf extract was similar to captopril (12.5 to 25 mg twice daily) ^[25], so additive effects are plausible. Blood pressure should be monitored, particularly when starting olive leaf extract while already on blood pressure medicines.

Antidiabetic Medications

Olive leaf extract may add to the effects of insulin, sulfonylureas, metformin or other glucose-lowering medicines. In type 2 diabetes it lowered HbA1c and fasting insulin ^[29], and in diabetic rats it strengthened the glucose-lowering effect of the sulfonylurea glyburide ^[53]. If you take diabetes medicines, check your blood glucose more often when starting olive leaf extract and tell your doctor.

Blood Thinners and Antiplatelet Agents

In lab tests on human blood, olive leaf extract reduced platelet activity; whether it does so in people is unknown ^[54]. If you take a blood thinner or antiplatelet medicine, ask your doctor first. If you take prescription medicines, check with your doctor or pharmacist before starting.

Cytochrome P450 Interactions

Limited data exist on olive leaf extract's effects on cytochrome P450 enzymes, which break down many drugs. If you take a medicine with a narrow safety margin, ask your doctor or pharmacist first.

7. Dietary Sources

Olive Leaf Tea

Olive leaf tea is made by steeping dried olive leaves in hot water. In a 12-week trial in adults with prediabetes, 330 mL of olive leaf tea three times daily with meals lowered LDL cholesterol more than a low-concentration tea, and triglycerides also fell; body weight, waist size and insulin did not change ^[51].

Olive Oil

Extra-virgin olive oil contains some of the same phenolic compounds, including oleuropein and hydroxytyrosol, which give it its bitter, pungent taste ^[6]. Olive leaf extract contains a greater amount and variety of polyphenols than extra-virgin olive oil, and leaf and fruit polyphenols differ in structure ^[4]. Extra-virgin olive oil is a food fat with its own evidence, not a stand-in for olive leaf extract as a source of oleuropein.

Olives

Olive fruit is a main part of the Mediterranean diet ^[6], but its polyphenols differ in structure from those in olive leaf ^[4], so table olives are not a stand-in for olive leaf extract.