Parts Used & Where Grown
Olive is a small evergreen tree native to Mediterranean regions. The characteristic green to blue-black fruit of this tree yields a useful, edible oil. Both the oil and the dried green-grayish colored leaves are used medicinally.1, 2
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3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
This supplement has been used in connection with the following health conditions:
1,000 to 1,600 mg of whole olive leaf extract per day
Olive leaf has been found to reduce high blood pressure, and one clinical trial showed it may be as effective as a blood pressure-lowering medication.
Olive leaf contains a number of active constituents, including flavonoids and other phenolic compounds, that have positive health effects, and has been used traditionally to support respiratory, digestive, immune, and cardiovascular health. Among its many positive metabolic effects, olive leaf has been shown to lower high blood pressure. An uncontrolled pilot trial with 663 pre-hypertensive subjects found taking a supplement providing 240 mg of compounds found in olive leaves and fruit (200 mg of oleuropein and 40 mg of hydroxytyrosol) daily for two months was associated with a 13 mmHg drop in systolic blood pressure and 7.1 mmHg drop in diastolic blood pressure. Another uncontrolled trial that enrolled ten volunteers with hypertension or pre-hypertension found treatment with 1,600 mg of olive leaf extract (providing 240 mg of oleuropein and 16 mg of hydroxytyrosol) daily for 28 days lowered systolic and diastolic pressures, and the effect was stronger in those with higher baseline blood pressure. In a randomized, double-blind, placebo-controlled, crossover trial (in which all participants receive placebo during one phase and treatment during another phase, in random order) that included 60 participants with borderline high blood pressure, six weeks of treatment with olive leaf extract providing 136 mg of oleuropein and 6 mg of hydroxytyrosol per day resulted in small (approximately 3 mmHg) reductions in systolic and diastolic pressures. In a double-blind trial, the blood pressure-lowering effect of 500 mg of olive leaf extract twice daily for eight weeks was nearly as great as that of captopril, a drug used to treat hypertension: systolic pressure was 11.5 mmHg lower and diastolic pressure was 4.8 mmHg lower in those who received olive leaf extract, versus drops of 13.7mmHg and 6.4 mmHg in those who received captopril.
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In a double-blind trial, people with osteoarthritis of the knee had a significant improvement in their pain after taking olive leaf extract.
Hydroxytyrosol, a phenolic compound present in olive leaf and extra-virgin olive oil, has anti-inflammatory activity. In a double-blind trial, treatment with 50 mg per day of olive leaf extract (providing 10 mg per day of hydroxytyrosol) for 4 weeks significantly improved pain, compared with a placebo, in people with osteoarthritis of the knee.
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Olive leaf is an herb that directly attack microbes.
Type 1 Diabetes
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Olive leaf extracts have been shown to improve blood sugar control in animals with diabetes.
Olive leaf extract has been shown to reduce oxidative stress, inflammatory signaling, and autoimmune activity, and to improve glucose metabolism and protect pancreatic cells in animal models of type 1 diabetes. These results have not yet been reproduced in human clinical trials.
Type 2 Diabetes
500 mg of olive leaf extract or three cups of olive leaf tea daily
Preliminary research suggests olive leaf may improve glucose metabolism and have benefits for people with type 2 diabetes.
In a placebo-controlled trial, 79 subjects with type 2 diabetes received 500 mg per day of olive leaf extract or placebo. After 14 weeks, those who received the olive leaf extract had lower fasting blood insulin levels and HbA1c, but no difference in post-meal insulin levels was seen. The same researchers also reported finding olive leaf extract inhibited starch digestion and glucose absorption in animals with experimental diabetes. On the other hand, 100 mg per day of olive leaf extract, in combination with fenugreek and bergamot extracts, was no better than placebo at restoring healthy glucose metabolism in a trial with 100 participants with prediabetes. Another trial included people with prediabetes who received either olive leaf tea of a control tea three times per day for 12 weeks. Olive leaf tea reduced fasting blood glucose levels and improved lipid levels. In overweight men at risk for developing type 2 diabetes, a high-polyphenol olive leaf extract (providing 51.1 mg of oleuropein and 9.7 mg of hydroxytyrosol per day) improved insulin sensitivity and pancreatic function after 12 weeks. More research in subjects with type 2 diabetes is needed.
Traditional Use (May Not Be Supported by Scientific Studies)
The olive tree has been held in high esteem throughout history. Moses reportedly decreed that men who cultivated the leaf be exempt from serving in the army. The oil is symbolic of purity and goodness, while the olive branch represents peace and prosperity. Winners in the Greek Olympic games were crowned with a wreath of olive leaves.3 Historically, medicinal use of olive leaf has been for treatment of fevers and for the topical treatment of wounds or infection. As a poultice, it was also used by herbalists to treat skin rashes and boils.4
How It Works
How It Works
Olive leaf has a wide number of constituents, including oleuropein and several types of flavonoids (e.g., rutin, apigenin, luteolin).5 While olive leaf is traditionally associated with a wide number of medicinal claims, few of these have been verified by experimental study. In an animal study oleuropein (when given by injection or in intravenous form) was found to decrease blood pressure (e.g., systolic and diastolic) and dilate the coronary arteries surrounding the heart.6 This ability to lower blood pressure may justify the traditional use of olive leaf in the treatment of mild to moderate hypertension.7 However, human studies are needed to clearly establish olive leaf as a potential treatment for high blood pressure.
In addition, a test tube study has revealed that oleuropein inhibits the oxidation of LDL (“bad”) cholesterol. LDL oxidation is one part in a series of damaging events that, if left unchecked, can lead to the development of atherosclerosis.8 This action may provide one clue as to why those consuming a Mediterranean-based diet may lower their risk of developing atherosclerosis.
Oleuropein from olives may also have antibacterial properties. When unheated olives are brined to preserve them, oleuropein is converted into another chemical called elenolic acid. Elenolic acid has shown antibacterial actions against several species of Lactobacilli and Staphylococcus aureus and Bacillus subtilus in a test tube study.9 Whether or not the oleuropein in the leaf undergoes such a transformation is open to question at this point, raising some question as to its antibacterial effects and potential use for this purpose in humans.
Olive leaf extracts have been employed experimentally to lower elevated blood-sugar levels in animals with diabetes.10 These results have not been reproduced in human clinical trials and as such, no clear conclusions can be made from this animal study in the treatment of diabetes.
How to Use It
The effective amount of olive leaf for human use is not established. To make a tea, steep 1 teaspoon (5 grams) of dried leaves in 1 cup (250 ml) of hot water for 10–15 minutes.11 Dried leaf extracts containing 6–15% oleuropein are available commercially, but no standard amount has been established.
Interactions with Supplements, Foods, & Other Compounds
Interactions with Medicines
The safety of olive leaf has not been established in pregnancy. Olive leaf can be irritating to the stomach lining and should be taken with meals.12
1. Wren RC. Potter's New Cyclopedia of Botanical Drugs and Preparations. Essex, England: CW Daniel Co., 1985, 204.
2. Bruneton J. Pharmacognosy, Phytochemistry, Medicinal Plants. Paris, France: Technique & Documentation-Lavoisier, 1995, 487-9.
3. Grieve M. A Modern Herbal, vol II. New York: Dover Publications, 1982, 598.
4. Foster S. 101 Medicinal Herbs. Loveland, CO: Interweave Press, 1998, 148-9.
5. Bruneton J. Pharmacognosy, Phytochemistry, Medicinal Plants. Paris, France: Technique & Documentation-Lavoisier, 1995, 487-9.
6. Petkov V, Manolov P. Pharmacological analysis of the iridoid oleuropein. Arzneimittelforschung 1972;22:1476-86.
7. Weiss RF. Herbal Medicine. Gothenburg, Sweden: AB Arcancum, 1988, 160-1.
8. Visioli F, Galli C. Oleuropein protects low density lipoprotein from oxidation. Life Sciences 1994;55:1965-71.
9. Fleming HP, Walter WM, Etchells JL. Antimicrobial properties of oleuropein and products of its hydrolysis from green olives. Applied Microbiol 1973;26:777-82.
10. Peirce A. Practical Guide to Natural Medicines. New York: William Morrow and Co., 1999, 469-71.
11. Foster S. 101 Medicinal Herbs. Loveland, CO: Interweave Press, 1998, 148-9.
12. Petkov V, Manolov P. Pharmacological analysis of the iridoid oleuropein. Arzneimittelforschung 1972;22:1476-86.
Last Review: 05-24-2015
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The information presented by TraceGains is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2023.