Dr. Elisa Minaldi 'll tell us the beneficial effects of olive oil and olive leaf extract were already known in the ancient world and have been scientifically studied and proven over the past two centuries.  

Most of the interesting properties of EVO oil, from a medical standpoint, can be attributed precisely to polyphenols, thanks to their anti-oxidant effect. The growing interest regarding the nature of polyphenols has produced a multitude of studies in order to investigate their medical efficacy. This has led the groundwork for the development of new therapies against chronic inflammatory states, such as atherosclerosis, cancer, and age-related neurodegeneration. Nowadays almost 80 percent of the extracts from the olive tree are included in the European Pharmacopoeia, including several polyphenols such as oleuropein, hydroxytyrosol, tyrosol, apigenin, caffeic acid, and verbascoside.

The first two, are the most abundant polyphenols in EVO oil, and considered to have nutraceutical effects.  These substances activate the same circuits involved in calorie restriction, particularly in muscles, adipose tissue, and kidney. The benefits of a low-calorie diet, including extension of life expectancy and reduction of aging-related diseases, are well described and recognized in the scientific literature. However, a calorie restriction regimen can be difficult to sustain on the long term. Dietary intake of nutraceuticals that can mimic its effect, such as EVO oil, might be an excellent alternative. Polyphenols, but especially oleuropein and hydroxytyrosol, lead to increased levels of sirtuins, the same family of proteins activated by caloric restriction. The result is counterregulation of inflammation and cellular oxidative damage, reduction of cholesterol and triglyceride synthesis, and inhibition of adipogenesis through the PPAR-gamma cellular pathway.

A WAY TO REDUCE INSULIN RESISTANCE AND TYPE DIABETES MELLITUS

Several studies have shown that subjects who reduced their consumption of saturated fatty acids and increased their consumption of dietary unsaturated fatty acids (n-6 PUFAs and MUFAs contained in EVO) had a significant reduction in insulin resistance and risk of type 2 diabetes mellitus (DM2). Insulin resistance, defined as a defect in insulin's ability to make glucose act on peripheral tissues, may precede the development of DM2. This condition can be associated with hyperglycemia due to insufficient insulin secretion by pancreatic beta cells.
The effect on insulin resistance partly explains the beneficial effects of the Mediterranean diet, characterized by low intakes of saturated fatty acids and high intakes of MUFAs (oleic acid especially) on obesity and DM2.

THE BENEFICIAL PROPERTIES AGAINST THE DEVELOPMENT OF ALZHEIMER'S DISEASE, CANCER AND CARDIOVASCULAR DISEASE

Some scientific studies have also suggested that oleuropein and oleocanthal, responsible for the stinging taste of EVO oil, could prevent the development of Alzheimer's disease by reducing the deposition of Beta-amyloid plaques responsible for neuronal damage. In addition, the signaling pathways activated by these two polyphenols and involved in the inhibition of cellular aging have been identified.
A similar protection mechanism against cellular aging and oxidative stress also seems to underlie the anti-tumor effect of polyphenols, especially oleuropein and hydroxytyrosol. Studies on breast, colon and prostate cancer cell cultures have also observed an anti-proliferative and anti-angiogenic action of these substances.
EVO oil also appears to have beneficial properties against atherosclerosis and cardiovascular disease. The reason has to be searched on the powerful anti-oxidant effect of polyphenols, but are also involved mechanisms of protection against ischemia/reperfusion injury with possible reduction in the extent of infarct tissue, reduced lipid synthesis at the plaque level, reduced platelet aggregation, and decreased blood concentrations of cholesterol and triglycerides are also implicated.

References:

-       Rigacci S, Stefani M. Nutraceutical Properties of Olive Oil Polyphenols. An Itinerary from Cultured Cells through Animal Models to Humans. Int J Mol Sci. 2016 May 31;17(6):843.

-       Visioli, F.; Galli, C. The effect of minor constituents of olive oil on cardiovascular disease: new findings. Biochem. Biophys. Res. Commun. 1998, 56, 142–147.