Jane Reside, ND

Can you imagine one plant that is an antioxidant, anti-inflammatory, is able to lower high blood pressure, can reduce the risk of dementia and other types of cognitive decline, is antibacterial and antiviral, reduces LDL cholesterol and thereby decreases the formation of plaque in our arteries, helps to control diabetes, and can help to treat depression & anxiety?

Olive leaves – from the olive tree, Olea europaea, first cultivated in the Mediterranean basin over 3000 years ago – show activity in all of these health applications. It has a rich traditional history, and now present-day research and science back up its medicinal uses. Let’s see what’s behind the many amazing properties of this unassuming little leaf.


Many plants that grow in unforgiving conditions contain phyto-compounds that help them survive and thrive, and to ward off infection and other disease; this happens to make the plant useful as medicine to humans. One such class of these compounds is grouped in a family known as polyphenols. In general, polyphenols are strongly antioxidant in action; in the olive leaf, the most predominant polyphenol is oleuropein, an especially potent antioxidant which is at the heart of many of the leaf’s therapeutic actions. Many plants from the Mediterranean region are rich in antioxidants, which may explain that region’s good health statistics. Olea europaea  is a major part of that, and we’re going to have a closer look at the benefits of its leaves.


First up is colds & flus. Olive leaf has potent antiviral action – studies show activity against influenza viruses, as well as herpes, rotavirus, and the family of respiratory syncytial viruses, commonly acquired by our kids 1. Botanica makes one of my favourite products for fighting viruses: Botanica’s Olive Leaf Throat Spray. The nose and mouth are the first point of contact for respiratory infections — 1-2 pumps of the spray, a few times a day, can catch a virus on contact, before it has a chance to colonize. And it tastes awesome. Olive leaf has also been shown to exhibit antibacterial activity, specifically against Escherichia coli which is the leading cause of bladder infections and gut infections; Helicobacter pylori, responsible for stomach ulcers; and Staphylococcus aureus, specifically MRSA which is the antibiotic-resistant form of this pathogenic bacteria. Very exciting, as we are all starting to come to terms with antibiotic overuse.


Olive leaf may be best known for its ability to lower blood pressure, particularly in mild-to-moderate hypertension. Its antioxidant activity specifically protects the hypothalamus from oxidative stress 2; this tiny gland in the centre of the brain acts as a control center for many of the body’s metabolic functions, including blood pressure regulation. Oleuropein also has antilipidemic activity – a fancy way of saying that it reduces lipids, including triglycerides and LDL cholesterol 3. Antioxidant activity further benefits the heart by protecting cell membranes in our blood vessels from free radical damage 4; this is a major mechanism of preventing atherosclerosis – or plaque – especially in the coronary and cerebral arteries, helping to lower the risk of heart attack and ischemic stroke.


Oleuropein, and its metabolite hydroxytyrosol (another potent antioxidant produced via gut microbes) are at the heart of its anti-inflammatory activity. Both oleuropein and hydroxytyrosol are able to inhibit several inflammatory enzymes, such as lipoxygenases, without affecting the cyclo-oxygenase pathways 1 — in plain language, they seem to act very much like ibuprofen, but without the digestive side effects. This could mean an effective treatment for arthritis and other causes of joint pain, and an effective adjunct to protecting the cardiovascular system, the gut, and possibly the brain.


Depression and anxiety are complex mental health disorders which can be attributed to many factors; current research suggests one of those may be inflammatory processes affecting neurotransmitters and neurons. We also know that chronic high stress is often at the root of developing depression or anxiety, seen, for example, in PTSD. One animal study showed a significant decrease in PTSD-induced anxiety behaviour, and an increase in serotonin after just 14 days of an extract of oleuropein and hydroxytyrosol 5. Another study looked at depression caused by high prednisone dosages, and saw a complete reversal of depressive behaviour when olive leaf extract was given just before the steroid 6. Interesting what a simple, yet strong, antioxidant is able to do.


Olive leaf is known to have a hypoglycemic effect, through two suggested mechanisms: a moderation of glucose-induced insulin release, and an increased uptake of glucose at the cellular level 7. Type 2 diabetes, also referred to as insulin-resistance diabetes, develops when our cells stop allowing insulin to bind — if insulin can’t bind to a cell, the cell won’t allow glucose across the membrane, and we end up with chronically high blood glucose, known as hyperglycemia. In one randomized control trial of human subjects, the oral olive leaf extract significantly lowered Hemoglobin A1C, the current marker for Type 2 Diabetes 8. And in regards to the oxidative damage we see in diabetes-related consequences, such as tissue damage to the retina and to blood vessels, olive leaf works well here too.


Both oleuropein and  hydroxytyrosol extracts — again through their potent antioxidant activity — are shown to reduce oxidative damage in the realm of age-related accumulation of free radicals in the brain. This is particularly relevant in cognitive decline and different forms of dementia, including Alzheimer’s. We also see this in other neurological disorders: one study showed significant decrease in oxidative damage to the substantia nigra, an area of the brain involved in the process of developing Parkinson’s Disease 2.


Recall that oleuropein and other phenols in olive leaf are able to reduce oxidative damage at the hypothalamus. This not only affects blood pressure mechanisms but our entire endocrine system — the array of hormones in your body that control energy levels, blood sugar, the metabolic burning of food calories, weight control, resilience to stress, reproduction, water balance, and many other functions. I call it ‘command central’. Antioxidant protection of endocrine tissue — like the thyroid gland for example, results in better overall metabolic balance. Oleuropein and hydroxytyrosol also show the ability to protect mitochondria 3, at the heart of metabolic energy production.


There are very few cautions with using olive leaf – however, one to keep in mind is for those who are taking blood pressure medications: Olive leaf extract is so effective for lowering blood pressure, you may find an additive effect with your medications, lowering it too much, so use some caution here. When in doubt, check with your naturopathic physician or herbalist. And of course, always make sure you inform your medical doctor of any natural therapeutics that you are taking.


Whether you prefer to take a liquid herb or a capsule, Botanica has both options available for you. Botanica Olive Leaf Complex is free of herbicides and pesticides. It is non-GMO, dairy free, soy free, gluten free and vegan. Each dose contains 82.5 mg Oleuropein, and it may be taken straight in the mouth or with water or juice. We have also created highly concentrated Olive Leaf Liquid Capsule, for those who prefer to swallow a capsule over a liquid.


  1. Omar, S.H. 2010. Oleuropein in olive and its pharmacological effects. Scientia Pharmaceutica 78(2), 133-154. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3002804/
  2. 2. Sun, W., Frost, B., and Liu, J. 2017. Oleuropein, unexpected benefits! Oncotarget, 8(11), 17409. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5392257/
  3. Bulotta, S., Celano, M., Lepore, S.M., Montalcini, T., Pujia, A., and Russo, D. 2014. Beneficial effects of the olive oil phenolic components oleuropein and hydroxytyrosol: Focus on protection against cardiovascular and metabolic diseases. Journal of Translational Medicine, 12(219). https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-014-0219-9
  4. Burja, B., Kuret, T., Janko, T and Frank-Bertoncelj, M. 2019. Olive leaf extract attenuates inflammatory activation and DNA damage in human arterial endothelial cells. Frontiers in Cardiovascular Medicine, 6, 56. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531989/
  5. 5. Lee, B., Shim, I., Lee, H., and Hahm, D.H. 2018. Oleuropein reduces anxiety-like responses by activating serotonergic and neuropeptide Y (NPY)-ergic systems in a rat model of post-traumatic stress disorder. Animal Cells and Systems, 22(2), 109-117. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6138302/
  6.  Badr, A.M., Attia, H.A., and Al-Rasheed, A & N. 2020. Oleuropein reverses repeated corticosterone-induced depressive-like behaviour in mice: Evidence of modulating effect on biogenic amines. Scientific Reports, 10(3336). https://www.nature.com/articles/s41598-020-60026-1
  7. El, S.N., and Karakaya, S. 2009. Olive tree (Olea europaea) leaves: Potential beneficial effects on human health.  Nutrition Reviews 76(11). 632-638. https://academic.oup.com/nutritionreviews/article/67/11/632/1851027
  8. Ahmadvand, H., Noori, A., Dehnoo, M.G., Bagheri, S., and Cheraghi, R.A. 2014. Hypoglycemic, hypolipidemic and antiatherogenic effects of oleuropein in alloxan- induced Type 1 diabetic rats. Asican Pacific Journal of Tropical Disease. 4(1), S421-S425. https://doi.org/10.1016/S2222-1808(14)60481-3

About the Author

Jane Reside, ND

Jane Reside, ND

Jane has been a practicing ND in Victoria and on Pender Island, BC for 20 years. With a degree in biochemistry & microbiology from the...

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