1. Antimicrobial and Antiviral Effects
From research and clinical experience to date, olive leaf is beneficial in the treatment for conditions caused by, or associated with, a virus, retrovirus, bacterium or protozoan. Potential applications may include:
- The common cold
- Candida infections
- Epstein-Barr virus (EBV)
- Herpes I and II
- Human herpes virus 6 and 7
- Shingles (Herpes Zoster)
- Chronic fatigue
- Hepatitis B
- Severe diarrhea
- Dental, ear, urinary tract, and surgical infections
Many people who live stressful lives or who may be particularly susceptible to colds and viruses may benefit from long-term use of olive leaf as a preventive agent. Some patients have expressed other unexpected benefits of olive leaf, including improved psoriasis, normalisation of heart beat irregularities, diminished cravings, less pain from hemorrhoids, toothaches and chronically achy joints.
The presence of oleuropein in several parts of the plant confers to Olea europaea natural resistance to microbial attack.
Oleuropein exerts its antimicrobial activity against both Gram negative and positive bacteria, including Lactobacillus plantarum, Bacillus cereus and Salmonella enteritidis. Moreover, in vitro studies revealed oleuropein antimycoplasmal activity, including mycoplasma strains resistant to common antibiotic treatments.
For its antimicrobial properties, oleuropein can be used as a food additive and for the treatment of human intestinal or respiratory tract infections. The molecular mechanisms underlying oleuropein antimicrobial activity are still unclear.
Oleuropein also possesses a well-documented antiviral activity. Its efficacy against hemorrhagic septicemia rhabdovirus (VHSV), hepatitis B virus (HBV), and human immunodeficiency virus (HIV) was demonstrated. The beneficial effect of oleuropein against VHSV is exerted through a virucidal effect, reducing virus infectivity and avoiding cell-to-cell fusion of uninfected cells, probably acting on the virus envelope.
Oleuropein treatment efficiently blocks the secretion of hepatitis B surface antigen from infected HepG2 and reduces the viremia in ducks infected with hepatitis B virus. Oleuropein’s action against HIV has been correlated to its ability to bind and inhibit in a dose-dependent manner HIV-1 integrase activity. Oleuropein, therefore, represents a suitable molecular template that should facilitate the identification and design of innovative HIV-1 integrase inhibitors.
Olive leaf extract has been shown to dispel protozoan-caused diseases. It’s not surprising its reputation as an anti-malarial dates back to the early 19th century. In the 1800s, physicians brewed olive leaves and administered the bitter tea to malaria patients. The doctors reported their patients improved after drinking this tea.
The Upjohn researchers determined that oleuopein inhibited at least 56 disease-causing bacteria, viruses and protozoa, including the malaria-causing Plasmodium falciparum. The researchers also found it was effective against Vaccinia, a contagious viral disease of cattle, produced in humans by inoculation with cowpox virus to confer immunity against smallpox.
2. High Blood Pressure:
One study assessing the efficacy of olive leaf in hypertensive persons noted that it was comparable to Captopril. Although it appears to be effective in reducing blood pressure, it does not appear to reduce blood pressure in normotensive persons.
Effects on blood pressure were first investigated in 1962, when an Italian scientist recorded lowered hypertension in animals. These results have been corroborated several times since, most notably in June 2015 in a study published by the British Journal of Nutrition.
Researchers gave 18 healthy participants an acute dose of Olive Leaf Extract, and tested their vascular function and inflammatory markers. They noted a ‘statistically significant improvement’ in both metrics.
The same researchers built on their findings with a ‘chronic blood pressure trial’, published in the European Journal of Nutrition in March 2016. This time, they administered olive leaf extract to 60 pre-hypertensive subjects over the course of six weeks. The results were positive: supplementation was associated with reductions in blood pressure levels, as well as improvements in cholesterol levels, triglycerides and the inflammatory marker interleukin-8.
Oleuropein is a bioactive compound found in the olive leaf. When oleuropein was tested on hypertension sufferers (high blood pressure) the blood pressure was reduced significantly and also provided other vascular benefits. Olive tree fruit has numerous beneficial compounds including hydroxytyrosol, oleacein, ursolic,and oleanic acids. However, it is oleuropein, found in the leaf of the olive tree that is largely responsible for the beneficial effect on high blood pressure.
A multitude of factors underlies uncontrolled blood pressure. Many cases of hypertension involve increased arterial stiffness. This stiffness, or lack of elasticity, usually begins in the arterioles—tiny peripheral arteries most distant from the heart—and eventually spreads to larger arteries. Oleuropein has been shown to specifically target arterial resistance and stiffness, improving endothelial function and bringing blood pressure under control. It accomplishes this in part by modulating calcium channel flow—with an excellent tolerability profile.
While tolerability has been excellent with oleuropein, the list of side effects associated with other blood pressure medications is long. This list includes swollen ankles and feet (edema), gastrointestinal bleeding, kidney impairment, excess potassium in the blood, negative interactions with other drugs, and, paradoxically, increased risk of heart attack.
3. Hypoglycaemic Action
The diabetic (and pre-diabetic) state of chronic blood sugar elevation imposes substantial oxidative stress throughout the body, triggering inflammation and tissue damage that rapidly accelerates aging.
Treatments for diabetes have two main goals: 1) lowering blood glucose to normal levels, and 2) limiting the damage done by the inevitable blood sugar spikes that still occur.
Oleuropein has been found to lower blood sugar through several mechanisms. They slow the digestion of starches into simple sugars, slow absorption of those sugars from the intestine, and increase the uptake of glucose into tissues from the blood. They protect tissues from the oxidant damage caused when glucose binds to proteins in the process called glycation. They also increase levels of other natural antioxidant systems in the body, broadening the degree of protection. Human studies reveal that taking olive leaf resulted in significant reductions in hemoglobin A1c levels, the standard marker of long-term exposure to elevated blood sugar in diabetic people. Supplementation also lowered fasting plasma insulin levels, an important point because chronic insulin elevations may contribute to diabetics’ higher cancer risks.
4. Anti-ageing & Antioxidant Effects
A liquid extract made directly from fresh olive leaves gained international attention when it was shown to have an antioxidant capacity almost double that of green tea extract and 400% higher than vitamin C.
Scientists have isolated the molecule that provides products from the olive tree with life extending benefits. This molecule, a polyphenol, that can help lower bad cholesterol and blood pressure, prevent cancer and protect against oxidative damage and help guard against cognitive decline. The olive leaf has antioxidant, anti-inflammatory, and disease fighting properties.
The primary active compounds in olive leaf are believed to be the antioxidants oleuropein and hydroxytyrosol, as well as several other polyphenols and flavonoids, including oleocanthal and elenolic acid.
Olive leaf harbours antioxidant properties that help protect the body from the continuous activity of free radicals. Free radicals are highly reactive chemical substances that can cause cellular damage if left unchecked. Some recent research on the olive leaf has shown its antioxidants to be effective in treating some tumors and cancers such as liver, prostate, colon, skin and breast cancer, although clinical studies are still lacking. Olive leaf is especially potent when used in combination with other antioxidants.
5. Arterial Endotheliail Health
Blood pressure is only one measure of cardiovascular health; arterial health is equally important. The endothelial cells that line arterial walls play a key role in maintaining blood flow and pressure. They also regulate the distribution of smooth muscle cells and sustain an even flow of blood through vessels. Endothelial dysfunction is one of the earliest stages in hardening of the arteries (atherosclerosis), which occurs when plaques build up in the arterial walls. These plaques eventually block blood flow and can trigger a heart attack or stroke.
Olive leaf fights endothelial dysfunction at multiple levels. It increases the production of nitric oxide, a signaling molecule that helps relax blood vessels. It reduces the production and activity of a class of molecules known as matrix metalloproteinases, or MMPs. Excessive MMP activity literally dissolves the gel-like matrix that holds cells together, making vessel linings increasingly vulnerable to plaque damage. It also helps to prevent the oxidation of LDL-cholesterol, which is one of the earliest events in developing atherosclerosis. Oxidised LDL triggers inflammation, further damaging arteries, and olive leaf extract has multi-targeted anti-inflammatory effects.
Polyphenol compounds found in olive leaves have been shown to help directly prevent the formation of arterial plaques (and thereby reduce the risk of heart attack and stroke) in two ways. First, they reduce the production and activity of a series of “adhesion molecules. These substances cause white blood cells and platelets to stick to arterial walls, resulting in early plaque formation. Second, they reduce platelet aggregation (clumping) by multiple mechanisms. This reduces the risk that tiny clots will form at sites of plaque to produce a stroke or heart attack.
6. Arthritis – Anti-inflammatory Effects
Olive leaf has long been used in the Mediterranean as a remedy for arthritis. Now, scientific evidence has proven that olive leaf can in fact interfere with the development of several different kinds of arthritis, including gout, rheumatoid arthritis, and osteoarthritis.
Gout is caused by the accumulation of uric acid crystals in joints, the byproducts of impaired recycling of DNA and RNA in cells. In a mechanism identical to that of allopurinol (the gold-standard drug therapy for gout), oleuropein prevents the buildup of uric acid by inhibiting xanthine oxidase, the enzyme responsible for converting DNA and RNA into uric acid. Oleuropein has also been found to help prevent and treat symptoms of rheumatoid arthritis. When administered at the earliest sign of arthritis in animal models, oleuropein prevented symptoms from developing and also produced marked improvement in the microscopic appearance of joint tissue from affected animals. When administered after arthritis was fully developed, there was significant improvement in inflammatory changes to joints, compared with untreated animals. Oleuropein had similar benefits on osteoarthritis. In animal models of this degenerative joint disease, olive leaf extract improved joint swelling, improved the microscopic appearance of joint tissue, and prevented the production of inflammatory cytokines.
(References available on request)