Learn how Olive Leaf Extract could benefit your immune system.
Your immune system is a complex organisation of cells, hormones and organs that are highly influenced by your diet. A poor diet, particularly a diet low in antioxidants, could contribute to a compromised immune system, potentially increasing the occurrence and symptoms of the common cold and flu.(1, 2)
However, eating a healthy diet full of fruit, vegetables and healthy fats, and including natural supplements in your daily regime may help strengthen your immune system.(1-3)
What is Olive Leaf Extract? (And no, it’s not the same thing as Olive Oil)
Olive Leaf Extract is a natural supplement derived from the leaves of the olive tree. To make Olive Leaf Extract, these leaves are processed in a way to draw out the most beneficial compounds found in the olive leaf. Olive leaves are high in antioxidants or biophenols.
The most prominent biophenols found in olive leaves include Oleuropein and Hydroxytyrosol and its these two biophenols that research suggests are most likely elicit the potential actions and health benefits. For example, Olive Leaf Extract has been shown to elicit antimicrobial, antiviral and antioxidant actions. (4)
A study published in the International Journal of Molecular Sciences suggests the amount of biophenols found in the olive leaves exceeds those found in high quality olive oil. Results from this study showed the amount of oleuropein found in olive leaf products could reach 134mg/g whereas the amount of oleuropein found in virgin olive oil products could reach 11.2mg/kg. Variability in oleuropein levels in dependent of product analysis and type.(5)
Barbara Barbaro, co-author of the study ‘Effects of the Olive-Derived Polyphenol Oleuropein on Human Health’ states “In light of the unique combination properties of oleuropein it looks like we should go back to the future, and continue to exploit this key dietary component of the Mediterranean Diet to promote human health.”(5)
Olive Leaf Extract Research
Overall, olive leaf extract has not been significantly investigated under human clinical trial conditions and there is an absence of systematic literature reviews, so evidence is derived from limited human trials and traditional, invitro and animal studies.
One recent human study published in 2019 looked at the effect of olive leaf extract on upper respiratory illness (URI) in high school athletes. Thirty-two high school athletes took 20g of olive leaf extract (100mg oleuropein) or placebo daily for nine weeks. Results from this study showed no significant difference in the incidence of URI, however there was a significant 28% reduction in sick days in those athletes who took OLE compared to placebo. The average duration of each URI episode was 9.7 days in the OLE group and 12.3 days in the placebo group.(6)
What’s so good about Olive Leaf Extract?
Adults usually get between 2 and 4 common colds every year.(7) Over the counter supplements in conjunction with a healthy diet and lifestyle may have the potential to reduce the incidence of common colds. Olive leaf extract could impact how your immune system defends itself against infections.(4)
A review article published in Alternative Medicine Review in 2007 looked into the conventional, botanical, and nutritional considerations of the common cold and flu. From this review, in vitro and animal studies showed that olive leaf extract has some potential activity against the influenza virus and that olive leaf extract may reduce the infectivity and inhibit the replication of viruses that cause colds, influenza and lower respiratory tract infections. The body’s response to a viral infection may be enhanced with Olive leaf extract as it was suggested to stimulate phagocytosis – further clinical trials in humans are needed to validate these findings.(4)
Interestingly, gargling olive leaf tea may alleviate symptoms of a sore throat – potentially due to a reduction of inflammation and viral infectivity.(4)
How do biophenols help the immune system?
A study published in the Journal of Alternative & Complementary Medicine-New York showed that olive leaf extract had one of the highest antioxidant activities of 55 medicinal herbs tested, including green tea and milk thistle.(8)
These biophenols found in Olive Leaf Extract may have the potential to protect the body against potential infection by ‘scavenging up’ harmful compounds that we may consume though poor diet and environmental factors.(9, 10)
So, can olive leaf extract help improve your immune system?
By increasing dietary and supplemental antioxidants, such as those found in olive leaf extract, this in turn could increase your body’s total antioxidant capacity and furthermore protect your body from harmful compounds that may hinder immune system actions.
Olive leaf extract is a natural supplement, high in antioxidants, that research suggests could help support the immune system when taken correctly. People typically consume 15ml of a liquid Olive Leaf Extract daily or equivalent dose in capsules. Different brands will vary in antioxidant type and strength, make sure to read the label and follow directions for use.
Please speak to your healthcare professional to make sure olive leaf extract is suitable for you.
If you have any medical conditions or take any medications it is important to make sure they are all safe and compatible with olive leaf extract.
View article references
- Beck A, Lavander O. Host Nutritional Status and its Effect on a Viral Pathogen. The Journal of Infectious Diseases. 2000;182:S93-6.
- Khomich O, Kochetkov S, Bartosch B, Ivanov A. Redox Biology of Respiratory Viral Infections. Viruses. 2018;10(8):392.
- Wegar-Lucarelli J, Carrau L, Levi L, Rezelj V, Vallet T, Blanc H, et al. Host nutritional status affects alphavirus virulence, transmission, and evolution. PLOS Pathogens. 2019;15(11):e1008089.
- Roxas M, Jurenka J. Colds and influenza: a review of diagnosis and conventional, botanical, and nutritional considerations. Alternative medicine review : a journal of clinical therapeutic. 2007;12(1):25-48.
- Barbaro B, Toietta G, Maggio R, Arciello M, Tarocchi M, Galli A, et al. Effects of the olive-derived polyphenol oleuropein on human health. International journal of molecular sciences. 2014;15(10):18508-24.
- Somerville V, Moore R, Braakhuis A. The Effect of Olive Leaf Extract on Upper Respiratory Illness in High School Athletes: A Randomised Control Trial. Nutrients. 2019;11(2).
- Colds and flu statistics Health Direct Health Direct 2018 [Available from: https://www.healthdirect.gov.au/colds-and-flu-statistics.
- Wojcikowski K, Stevenson L, Leach D, Wohlmuth H, Gobe G. Antioxidant Capacity of 55 Medicinal Herbs Traditionally Used to Treat The Urinary System: A Comparison Using A Sequential Three-Solvent Extraction Process. Journal of Alternative & Complementary Medicine-New York. 2007;13(1):103-9.
- Lee O-H, Lee B-Y. Antioxidant and antimicrobial activities of individual and combined phenolics in Olea europaea leaf extract. Bioresource technology. 2010;101(10):3751-4.
- Umeno A, Takashima M, Murotomi K, Nakajima Y, Koike T, Matsuo T, et al. Radical-scavenging activity and antioxidative effects of olive leaf components oleuropein and hydroxytyrosol in comparison with homovanillic alcohol. Journal of oleo science. 2015;64(7):793-800.