Olive Leaf

Purported Benefits, Side Effects & More

Olive Leaf

Purported Benefits, Side Effects & More
Olive Leaf

Common Names

  • Olive leaf extract

For Patients & Caregivers

Tell your healthcare providers about any dietary supplements you’re taking, such as herbs, vitamins, minerals, and natural or home remedies. This will help them manage your care and keep you safe.

What is it?

Olive leaf extract has not been shown to prevent or treat cancer in humans.

Olive leaves contain a substance called oleuropein, which is thought to help reduce cholesterol levels and inflammation. Olive leaf extracts (OLE) also reduce glucose levels in the blood. Laboratory studies found that OLE can kill a number of microorganisms including yeasts, bacteria, and fungi. It was also shown to have anticancer effects, but human studies are needed.

What are the potential uses and benefits?
  • To prevent or treat cancer

    Laboratory results show possible benefit, but human studies have not been conducted.
  • To lower cholesterol

    Animal studies have shown a possible effect. Human studies are lacking.
  • To reduce high blood pressure

    Animal and human studies show that olive leaf extract can lower blood pressure.
  • To fight infections

    Laboratory results show olive leaf extract to be effective against a variety of microorganisms.
  • To promote urination

    There is no evidence to support this claim.
What are the side effects?
  • Pollen from olive trees can cause severe respiratory allergy.
What else do I need to know?

Do Not Take if:

  • You are taking blood pressure medicine: In lab experiments, olive leaf extract increased the blood pressure lowering effect. Clinical relevance has yet to be determined.
  • You are taking insulin or other blood sugar medicine: In lab experiments, olive leaf extract lowered blood sugar levels. Clinical relevance has yet to be determined.

For Healthcare Professionals

Scientific Name
Olea europaea
Clinical Summary

Derived from the olive plant, both olive leaves and the extract have been used to treat infections, inflammation, diabetes, and hypertension. A major component of olive leaf, oleuropein, has been shown to have antioxidant (1) and anti-inflammatory activity (23). Because of its hypoglycemic effects, the leaf extract can induce insulin release and improve peripheral uptake of glucose (2). It also has antimicrobial (3) (22), anti-HIV (4), and anticancer (13) (14) (15) (18) (19) properties. Animal studies showed antiarrhythmic, spasmolytic, diuretic (5), antihypertensive (6), analgesic (20) (21), and cholesterol-lowering (7) effects.

Small studies suggest olive leaf extracts may reduce metabolic risk factors (25), gastrointestinal discomfort (26) and blood pressure (16) (17) (27). But data on its lipid-lowering effects are mixed (24) (28). Topical use of an olive leaf extract cream was shown to be superior to acyclovir cream in healing herpes simplex virus infection (29).

Purported Uses and Benefits
  • Cancer
  • High cholesterol
  • Hypertension
  • Infections
  • Promote urination
Mechanism of Action

The cholesterol-lowering effects of olive leaf extracts (OLE) are thought to be due to oleuropein, a compound present in the leaves. Studies on hypercholesterolemic rats suggest that OLE is more effective than pure oleuropein at lowering cholesterol. This implies that a synergistic effect occurs between oleuropein and another substance within the leaf (7).

Oleuropein is converted into elenoic acid in the body which may prevent viruses and bacteria from replicating (8). The antihypertensive and vasodilating effects of olive leaf occurred independently of the integrity of the vascular endothelium (9). Constituents of olive leaf have been shown to strongly inhibit the complement system, although it is unknown what effect this has on the body (10).

Hypoglycemic activities of olive leaf are attributed to two mechanisms: potentiation of glucose-induced insulin release and increased peripheral uptake of glucose. Hypoglycemic activity is greater in samples collected in the winter months (2). OLE may prevent diabetic neuropathy by reducing glucose-induced apoptosis through the inhibition of neural caspase 3 activation (20).

In vitro studies show that OLE has antimicrobial activities against E. coli, Pseudomonas aeruginosa, S. aureus, K. pneumoniae, Trichophyton mentagrophytes, Microsporum canis, T. rubrum, and Candida albicans (3) (22). Anti-HIV properties of OLE include upregulation of the expression of apoptosis inhibitor proteins as well as protein kinase signaling molecules (4). OLE promotes cell differentiation (18) and induces DNA fragmentation leading to apoptosis in leukemia cell line (19).

Adverse Reactions
  • Olive tree pollen may cause severe respiratory allergy (12).
Herb-Drug Interactions

Antihypertensive drugs: In rat models, olive leaf demonstrated antihypertensive activity (6). Clinical relevance has yet to be determined.
Insulin and antidiabetic drugs: In vitro and animal models suggest hypoglycemic effects (2) (6). Clinical relevance has yet to be determined.

Dosage (OneMSK Only)
  1. Montilla MP, Agil A, Navarro MC, Jimenez MI, Garcia-Granados A, Parra A et al. Antioxidant activity of maslinic acid, a triterpene derivative obtained from Olea europaea. Planta Med 2003;69:472-4.
  2. Gonzalez M, Zarzuelo A, Gamez MJ, Utrilla MP, Jimenez J, Osuna I. Hypoglycemic activity of olive leaf. Planta Med 1992;58:513-5.
  3. Markin D, Duek L, Berdicevsky I. In vitro antimicrobial activity of olive leaves. Mycoses 2003;46:132-6.
  4. Lee-Huang S, Zhang L, Huang PL, Chang YT, Huang PL. Anti-HIV activity of olive leaf extract (OLE) and modulation of host cell gene expression by HIV-1 infection and OLE treatment. Biochem Biophys Res Commun. 2003;307:1029-37.
  5. PDR for Herbal Medicines. Montvale, NJ: Medical Economics, 1998.
  6. Somova LI, Shode FO, Ramnanan P, Nadar A. Antihypertensive, antiatherosclerotic and antioxidant activity of triterpenoids isolated from Olea europaea, subspecies africana leaves. J Ethnopharmacol. 2003 Feb;84(2-3):299-305.
  7. Pasquale RD, Monforte A, Trozzi A, Raccuia S, Tommasini S, Ragusa S. Effects of leaves and shoot of Olea europaea L. and oleuropien on experimental hypercholesterolemia in rat. Plantes Med Phytother 1991;25:134-40.
  8. Horn C. Olive leaf to fight infection. Natural Health 2000;30:40.
  9. Zarzuelo A, Duarte J, Jimenez J, Gonzalez M, Utrilla MP. Vasodilator effect of olive leaf. Planta Med 1991;57:417-9.
  10. Pieroni A, Heimler D, Pieters L, van Poel B, Vlietinck AJ. In vitro anti-complementary activity of flavonoids from olive (Olea europaea L.) leaves. Pharmazie 1996;51:765-8.
  11. Brinker F. Herb Contraindications And Drug Interactions. Sandy, OR: Eclectic Medical Publications, 2001.
  12. Liccardi G, D’Amato M, D’Amato G. Oleaceae pollinosis: a review. Int Arch.Allergy Immunol. 1996;111:210-7.
  13. Kimura Y, Sumiyoshi M. Olive leaf extract and its main component oleuropein prevent chronic ultraviolet B radiation-induced skin damage and carcinogenesis in hairless mice. J Nutr. 2009 Nov;139(11):2079-86.
  14. Anter J, Fernández-Bedmar Z, Villatoro-Pulido M, et al. A pilot study on the DNA-protective, cytotoxic, and apoptosis-inducing properties of olive-leaf extracts. Mutat Res. 2011 Aug 16;723(2):165-70.
  15. Mijatovic SA, Timotijevic GS, Miljkovic DM, et al. Multiple antimelanoma potential of dry olive leaf extract. Int J Cancer. 2011 Apr 15;128(8):1955-65.
  16. Perrinjaquet-Moccetti T, Busjahn A, Schmidlin C, et al. Food supplementation with an olive (Olea europaea L.) leaf extract reduces blood pressure in borderline hypertensive monozygotic twins. Phytother Res. 2008 Sep;22(9):1239-42.
  17. Susalit E, Agus N, Effendi I, et al. Olive (Olea europaea) leaf extract effective in patients with stage-1 hypertension: comparison with Captopril. Phytomedicine. 2011 Feb 15;18(4):251-8.
  18. Abaza L, Talorete TP, Yamada P, et al. Induction of growth inhibition and differentiation of human leukemia HL-60 cells by a Tunisian gerboui olive leaf extract. Biosci Biotechnol Biochem. 2007 May;71(5):1306-12.
  19. Anter J, Fernández-Bedmar Z, Villatoro-Pulido M, et a. A pilot study on the DNA-protective, cytotoxic, and apoptosis-inducing properties of olive-leaf extracts. Mutat Res. 2011 Aug 16;723(2):165-70.
  20. Kaeidi A, Esmaeili-Mahani S, Sheibani V, et al. Olive (Olea europaea L.) leaf extract attenuates early diabetic neuropathic pain through prevention of high glucose-induced apoptosis: in vitro and in vivo studies. J Ethnopharmacol. 2011 Jun 14;136(1):188-96.
  21. Esmaeili-Mahani S, Rezaeezadeh-Roukerd M, Esmaeilpour K, et al. Olive (Olea europaea L.) leaf extract elicits antinociceptive activity, potentiates morphine analgesia and suppresses morphine hyperalgesia in rats. J Ethnopharmacol. 2010 Oct 28;132(1):200-5.
  22. Pereira AP, Ferreira IC, Marcelino F, et al. Phenolic compounds and antimicrobial activity of olive (Olea europaea L. Cv. Cobrançosa) leaves. Molecules. 2007 May 26;12(5):1153-62.
  23. Larussa T, Oliverio M, Suraci E, et al. Oleuropein Decreases Cyclooxygenase-2 and Interleukin-17 Expression and Attenuates Inflammatory Damage in Colonic Samples from Ulcerative Colitis Patients. Nutrients. Apr 15 2017;9(4).
  24. Lockyer S, Rowland I, Spencer JPE, et al. Impact of phenolic-rich olive leaf extract on blood pressure, plasma lipids and inflammatory markers: a randomised controlled trial. Eur J Nutr. Jun 2017;56(4):1421-1432.
  25. Haidari F, Shayesteh F, Mohammad-Shahi M, Jalali MT, Ahmadi-Angali K. Olive Leaf Extract Supplementation Combined with Calorie-Restricted Diet on Reducing Body Weight and Fat Mass in Obese Women: Result of a Randomized Control Trial. Clin Nutr Res. 2021 Oct 31;10(4):314-329.
  26. Malfa GA, Di Giacomo C, Cardia L, et al. A standardized extract of Opuntia ficus-indica (L.) Mill and Olea europaea L. improves gastrointestinal discomfort: A double-blinded randomized-controlled study. Phytother Res. 2021 Jul;35(7):3756-3768.
  27. Elkafrawy N, Younes K, Naguib A, et al. Antihypertensive efficacy and safety of a standardized herbal medicinal product of Hibiscus sabdariffa and Olea europaea extracts (NW Roselle): A phase-II, randomized, double-blind, captopril-controlled clinical trial. Phytother Res. 2020 Dec;34(12):3379-3387.
  28. Stevens Y, Winkens B, Jonkers D, Masclee A. The effect of olive leaf extract on cardiovascular health markers: a randomized placebo-controlled clinical trial. Eur J Nutr. 2021 Jun;60(4):2111-2120.
  29. Toulabi T, Delfan B, Rashidipour M, et al. The efficacy of olive leaf extract on healing herpes simplex virus labialis: A randomized double-blind study. Explore (NY). 2022 May-Jun;18(3):287-292.
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