Clinical Study Conducted by Our Team in the USA Highlights the Importance of High-Quality Greek Olive Oil for Health

The results of a clinical study on the beneficial effects of olive oil on human health were presented at a special event held on November 3, 2015. The study was conducted at the Department of Nutrition of the University of California, Davis*, and at the USDA Western Human Nutrition Research Center in California.

As part of the study, olive oils were selected following the analysis of hundreds of samples by the Faculty of Pharmacy of the University of Athens. Their composition was subsequently confirmed by the Olive Center of the University of California, Davis. The human trial, conducted for the first time, demonstrated that high-quality Greek extra virgin olive oil rich in oleocanthal may help protect the cardiovascular system.

Extra virgin olive oils contain a wide range of natural compounds, the concentration of which varies significantly among different olive varieties. Many of these compounds have been shown to possess antioxidant and anti-inflammatory properties. While the term "total phenols" is commonly used as an indicator of an olive oil's antioxidant capacity, its biological activity may be attributed to specific compounds.

One such compound is oleocanthal, which is responsible for the characteristic peppery sensation felt in the throat when consuming certain fresh, high-quality olive oils. Oleocanthal has been shown to inhibit the same enzyme targeted by aspirin, ibuprofen, and other non-steroidal anti-inflammatory drugs (NSAIDs). This mechanism is also the basis for the use of low-dose aspirin in reducing cardiovascular risk.

In fact, oleocanthal is often considered a natural anti-inflammatory compound. However, until this study, its activity had only been demonstrated in laboratory experiments and not in humans.

Platelet aggregation, a highly sensitive indicator of the effects of low-dose aspirin, was used as a model to evaluate oleocanthal's potential role in helping protect against blood clot formation and, consequently, reducing the risk of heart attacks and strokes.

* University of California, Davis (UC Davis)
* USDA Western Human Nutrition Research Center, California, USA

The Power of Olive Oil: The Role of Oleocanthal and Oleacein

In this study, researchers investigated whether the consumption of 40 ml (approximately 3 tablespoons) of olive oil with different phenolic compositions could inhibit platelet aggregation in healthy men.

Nine normal-weight male participants were enrolled in the study and consumed three different olive oils in a randomized sequence, with a one-week washout period between each oil. The impact on platelet function was evaluated two hours after consumption.

Olive oils rich in oleocanthal and the related compound oleacein were found to significantly inhibit platelet aggregation. In contrast, an olive oil that did not contain these compounds, despite having an equivalent total phenolic content (primarily in the form of free tyrosol), failed to produce the same effect.

Interestingly, among the nine participants, four exhibited a strong response at the two-hour time point, comparable to the effect observed with a pharmaceutical dose of ibuprofen, while the remaining five participants showed little or no response.

Research Team

This study was conducted in collaboration with Dan Flynn, Executive Director of the UC Davis Olive Center, and was carried out by:

• Roberta R. Holt
• Karan Agrawal
• Selina Wang
• Theresa Pedersen
• Eleni Melliou
• Prokopios Magiatis
• John W. Newman

The findings highlight the importance of specific olive oil phenolic compounds, particularly oleocanthal and oleacein, and their potential contribution to the biological activity of high-quality extra virgin olive oil.

There is a EFSA approved health claim on olive oil polyphenols (Commission Regulation (EU) 432/2012):

• Olive oil polyphenols contribute to the protection of blood lipids from oxidative stress. The claim may be used only for olive oil, containing at least 5 mg of hydroxytyrosol and its derivatives (e.g. oleuropein complex and tyrosol) per 20 g of olive oil. In order to bear the claim information shall be given to the consumer that the beneficial effect is obtained with a daily intake of 20 g of olive oil.

Olive oil comprises mainly of the monounsaturated fatty acid oleic acid (C18:1). There is also a EFSA approved health claim on the unsaturated fatty acids (Commission Regulation (EU) 432/2012):

• Replacing saturated fats in the diet with unsaturated fats contributes to the maintenance of normal blood cholesterol levels. The claim may be used only for food which is high in unsaturated fatty acids, as referred to in the claim HIGH UNSATURATED FAT as listed in the Annex to Regulation (EC) No 1924/2006.

ANNEX

Pharmacological and biological properties of the measured compounds

A summary of the available scientific data for the measured compounds is following:

In total, oleocanthal, oleacein, oleuropein aglycon, ligstroside aglycon present important biological activity and they have been related with anti-inflammatory, antioxidant, cardioprotective and neuroprotective activity.

Biological properties of Oleocanthal

Oleocanthal is the dialdehydic form of the ligstroside aglycon without the carboxymethyl group (Mateos R. et al., 2004) which has been related with the "bitter and burning" sensation on the throat, mainly on the base of the tongue that occurs when tasting extra-virgin olive oil.

The pharmacological actions of oleocanthal are the following:

• Action against Alzheimer's disease

According to scientific research, it has been proved that the soluble oligomers of amyloid-b1-42 peptide act as the basic neurotoxin in the Alzheimer's disease. As a result, compounds that can modify the formation of these oligomers, referred to as ADDLs, are possible to have therapeutic effects on the AD.

Oleocanthal is of particular interest because of its ability to perturb this particular oligomerisation and reduce the pathogenesis of AD by protecting, at the same time, the neurones from ADDLs΄ effects on the synapse pathology. (Pitt J. et. al., 2009). Oleocanthal is also able to inhibit the tau-fibrils formation by modifing covalently the PHF-6 peptide which is of vital importance to their formation. This leads to neurofibrillary tangles which are inherently linked to neurodegenerative diseases as the AD.

The two aldehyde groups of oleocanthal react with the structural unit of lysine to form a complex through the Schiff base formation reaction on the PHF6 peptide, affecting significantly the accumulation of T (tau) proteins in neurofibrils. (Li W. et al., 2009).

It has also been found that oleocanthal interacts with the tau-441 protein causing the stabilization of its secondary structure conformation, thus no further conformation can take place. (Monti M.C et al., 2012)

By examining the oleocanthal action on cell culture, but also on guinea pigs' brain, it has been discovered that oleocanthal is possible to successfully remove amyloid-β (Αβ) from the brain, through an increase in the expression and the activity of P-glycoproteins (P-gp) and LDL lipoproteins receptors. LDL lipoproteins bind with proteins-1 (LRP1), which are big Αβ transfer proteins to the blood-brain barrier.

So, it has been discovered that oleocanthal increases the P-gp and LRP1 activity and consequently the Αβ removal increases.

As a result, the following conclusion is extracted: potential decrease in the risk of developing AD, which is linked to the extra-virgin oil consumption, could be due to the Αβ removal reinforcement from the brain. (Abuznait A.H., 2013)

• Action against osteoarthritis

Osteoarthritis is a disease whose progression is characterized by increased nitrogen monoxide (NO) production which involves degradation of articulate cartilage.

Recently, oleocanthal isolated from extra-virgin olive oil was found to present anti-inflammatory action similar to that of ibuprofen, a non-steroid anti-inflammatory drug used widely in the therapeutic treatment of common inflammatory diseases.

Oleocanthal and its derivatives reduce the lipopolysaccharides-induced synthesis of NO in cartilage cells without significant effect on the cell viability.

Moreover, oleocanthal intervenes in prostaglandin synthesis through the inhibiting action it exerts on the cyclooxygenase enzymes. (Cicerale S. et al., 2012)

Therefore, oleocanthal can potentially be used as a therapeutic weapon in the treatment of inflammatory degenerative diseases, both in the cure of rheumatoid arthritis and in that of osteoarthritis. (Iacono et al., 2010)

• Inhibition of cyclooxygenase enzymes COX-1 και COX-2

Oleocanthal inhibits cyclooxygenase enzymes in the biosynthetic path of prostaglandins; the latter being inflammatory factors. (Iacono A., 2010)

Oleocanthal has been proved to inhibit cyclooxygenase enzymes in a dose-related manner, imitating the anti-inflammatory action of ibuprofen. (Beauchamp G.K. et al., 2005)

The cyclooxygenase enzymes 1 and 2 (COX 1 and COX 2) are responsible for the transformation of arachidonic acid into prostaglandins and thromboxanes, which are produced as a response to inflammatory or toxic stimuli.

Cyclooxygenase 1 and 2 can be harmful to the human body.

Especially, research made both on humans and on animals, has showed that COX 2 is involved in the pathogenesis of different types of cancer (Harris R.E. et al., 2003, Boland G. et al., 2004, Subbaramaiah K. et al., 2002) and may also play a role in atherosclerosis. (Chenevard R. et al., 2003).

Findings presented by Beauchamp G.K. et al., prove that oleocanthal not only imitates the mechanism of action of ibuprofen, but also presents higher activity compared to the latter, in inhibiting the action of COX 1 and COX 2 in equimolar concentrations.

For example, a concentration of 25 μM of oleocanthal inhibited the activity of COX up to 41-57%, whereas, a concentration of 25 μM of ibuprofen inhibited only 13-18% of the COX activity.

Furthermore, it has been suggested that long-term intake of small quantities of oleocanthal from extra-virgin olive oil consumption, are in part responsible for the low incidence of diseases associated with a Mediterranean diet.

It is known that low long-term doses of ibuprofen and of other COX inhibitors, like aspirin, have significant benefits on human health as far as the prevention from developing cancer (e.g. rectum and breast cancer) (Garcia-Rodriguez L. A. & Huerta-Alvarez C., 2001, Harris R. E. et al., 2006) and cardiovascular disease (Hennekens C.H., 2002) is concerned.

As a result, long-term consumption of extra-virgin olive oil rich in oleocanthal may contribute to reduction in the incidence of the above diseases. (Cicerale S. et al., 2012)

• Anti-tumor action / Action against cancer

Oleocanthal is able to inhibit the proliferation and metastasis of tumor cell lines of human mammary and prostate epithelial cells, and has shown anti-angiogenic activity.

It blocks the phosphorylation of c-Met kinase in vitro with IC50 4,8 μM, and may, therefore, have a therapeutic use in the control of malignancies.

It also inhibits proliferation, metastasis and invasion of MCF7, MDA-MB231 and PC-3 tumor cell lines of the breast and the prostate, respectively.

• Controls skin ageing

It prevents excessive proliferation of keratinocytes in stress situations due to environmental reasons, by stimulating the synthesis of skin lipids, and genes that are directly related to the differentiation among cells. (Estanove C. et al., 2009).

· Antimicrobial activity

Oleocanthal, as proven, cannot be hydrolyzed in the stomach and thanks to this helps inhibit the bacterium Helicobacterpylori growth, which is responsible for developing peptic ulcer and certain types of cancer. (Romero C. et al., 2007)

Biological properties of Oleacin

Oleacin is a substance with pharmacological actions similar to those of oleocanthal.

• Anti-oxidant activity

Oleacin, unlike oleocanthal, has a significant action in that it protects human cells from oxidative stress to a greater extent, even when compared to hydroxytyrosol. (Pavia-Martins F. P. et al., 2009).

• Angiotensin Converting Enzyme (ACE) inhibitor

ACE inhibition induces vasodilation; thus, oleacin could potentially be used in the treatment of hypertension and heart failure. (Hansen K. et al., 1996, Somova L.I. et al., 2003)

• Anti-ageing action

Oleacin is a strong anti-oxidant and so it can prevent LDL oxidation, oxidative stress and oxidative damage on DNA.

Hematopoietic endothelial progenitor cells (EPC) are the basic mechanism through which damaged blood vessels are repaired.

These cells are also particularly sensitive to oxidative stress.

Oleacin reduces cell ageing induced by angiotensin II and inhibits the formation of reactive oxygen species (ROS).

This results in a decrease in nitrotyrosine and in oxidative damage on DNA.

Oleacin augments the angiogenic potential of the hematopoietic endothelial progenitor cells in vitro.

Oleacin can, therefore, protect the EPCs from oxidative stress caused by angiotensin II. (Parzonko A. et al., 2012)

• Heart-protective activity

Oleacin inhibits myeloperoxidase release from neutrophils, which can explain the important role of olive oil in the prevention of cardiovascular diseases. (Czerwińska M. et al., 2012−a)

• Anti-inflammatory action

Oleacin is strong lipooxigenase (LOX) enzyme inhibitor taking part in the inflammation procedure.

Biological properties of the monaldehydic form of the oleuropein aglycon

Chemically, it is classified under ortho-diphenols categoty, which are a bioactive part in the mechanism of protection of the olive tree fruit from insect attacks and pathogenic bacteria. (Bianco A.D. et al., 1999).

It is also known for its antioxidant action which is comparable to oleuropein.

Moreover, there is evidence that it can prevent further cell proliferation in breast cancer. (Pérez-Trujillo M. et al., 2010).

• Protection from diebetes

Amylin (hIAPP) was discovered in 1987, when isolated from amyloid deposits, taken post mortem from pancreas of patients with type II diabetes.

It is a peptide hormone consisting of 37 amino acids, which is located along with insulin in the secretory granules of the pancreas beta-cells and is secreted in response to trophic stimuli and other secretagogues.

Tests on humans have demonstrated that concentrations of insulin and amylin in plasma raised and lowered parallel, following meals.

The pancreatic amylin deposition is a hallmark of diabetes mellitus type II and there is ample evidence that amylin oligomers exhibit cytotoxic action to the pancreas beta-cells.

The oleuropein aglycon prevents increasing the concentration of amylin in the human body.

It has also been shown that amylin aggregates, grown in the presence of oleuropein aglycon, cannot interact with the cell membrane and destabilize it.

As a result, there is no cytotoxicity in beta-cells. (Rigaccia S. et al., 2010)

• Protection from the Alzheimer's disease

The oleuropein aglycon has been found to be one of the substances responsible for being involved in the protection of the central nervous system from degeneration caused by Alzheimer's disease, by reducing the levels of beta-amyloid, as it has been demonstrated in guinea pigs. (PLOSone 2013, DOI: 10.1371/journal.pone.0071702). 

An International Society for Oleocanthal

Experts from the worlds of science, academia, gastronomy, and media established the Oleocanthal International Society (OIS) to foster research on one of the most important phenolic compounds found in extra virgin olive oil.

On May 30–31, 2015, on the island of Zakynthos, Greece, an international group of olive oil experts, scientists, physicians, researchers, journalists, and gastronomic professionals gathered to establish the non-profit Oleocanthal International Society (OIS).

OIS was founded through the vision of retired Spanish physician Jose Antonio Amerigo, who dedicated his efforts to promoting preventive medicine through nutrition and the health benefits of high-quality olive oil.

Among the founding members and contributors were internationally recognized olive oil researchers Prokopios Magiatis and Eleni Melliou, whose pioneering work in the measurement and identification of olive oil phenolic compounds has contributed significantly to modern olive oil research.

Zakynthos was selected as the venue for the Society's inaugural meeting due to its rich olive-growing tradition, its connection to ancient Hellenic and Mediterranean culture, and the discovery of exceptional high-phenolic olive oils in the Ionian Islands.

The establishment of OIS in Zakynthos was further supported through the collaboration of Prokopios Magiatis, Eleni Melliou, and Dimitris Therianos, founder of the Therianos Family Estate. The organization and hosting of the conference were made possible through the cooperation of the Regional Unit of Zakynthos, the ECO Zakynthos Network, the Union of Agricultural Cooperatives of Zakynthos, and numerous local supporters who shared a common vision of promoting olive oil research and the island's agricultural heritage.

The conference brought together leading international experts, including Gary Beauchamp, discoverer of the anti-inflammatory properties of oleocanthal, Paul Breslin of Rutgers University and the Monell Chemical Senses Center, Li Li Ji of the University of Minnesota, and renowned Spanish chef Danny Garcia Peinado, among many others.

As part of the conference activities, participants experienced the hospitality and olive oil culture of Zakynthos firsthand. A special lunch, organized through the ECO Zakynthos Network and prepared by Dimitris Therianos and his family, showcased local products and authentic Zakynthian gastronomy. The event concluded with a memorable dinner among the olive trees, highlighting the close relationship between science, culture, gastronomy, and the Mediterranean way of life.

The founding of the Oleocanthal International Society in Zakynthos marked an important milestone in international olive oil research and recognized the contribution of the island, its producers, and its scientific collaborators to the global dialogue on olive oil, health, nutrition, and Mediterranean culture.

Today, OIS continues to promote scientific research, international collaboration, and public awareness regarding the health-promoting properties of olive oil phenolic compounds, helping to advance knowledge in one of the most important fields of Mediterranean nutrition.