Clinical study on the beneficial properties of olive oil on health
The study was carried out at UC Davis’ Department of Nutrition* and the Human Nutrition Research Center of the USDA, and was funded by the “Captain Vassilis and Carmen Constantakopoulos” Foundation and the company Gaea. Part of the study comprised the tasting of olive oil varieties that were selected after the analysis of hundreds of samples by the Faculty of Pharmacy of the University of Athens; the varieties’ composition was verified by the UC Davies Olive Center. Trials on people, which took place for the first time, showed that quality Greek extra virgin olive oil, rich in oleocanthal, can protect the cardiovascular system.

Extra virgin olive oil contains a wide array of natural ingredients, whose concentration varies greatly between each olive variety. It has been proven that many of those chemical compounds have antioxidant and anti-inflammatory properties. While the term “total phenols” is generally used to denote a variety’s antioxidant capacity, its “medicinal” properties may be a result of specific chemical compounds. One example is the substance called oleocanthal, which is associated with the spicy aftertaste of some fresh and high-quality olive oil varieties. It is known that this compound inhibits the effect of the enzyme that is also inhibited by aspirin, ibuprofen, and other nonsteroidal anti-inflammatory drugs (NSAID), and this is the reason behind the daily use of “children’s” aspirin to lower the risk of cardiovascular disease. In reality, oleocanthal is considered to be a natural NSAID, its effect, however, had only been proven in the laboratory, and not on people, until now. Platelet aggregation is a sensitive means of gauging the effect of a low aspirine dosage, and was used as a model in the study of oleocanthal regarding its capacity to prevent the formation of blood clots, which lead to heart attacks and strokes.

The olive oils that were tasted were selected on the criterion of having the same concentration of total phenols, but a different ratio of active oleocanthal and oleacein. More specifically, the olive oils selected were the following: one high in oleocanthal, from a variety of Koroni from the area of Kalamata PDO, one from an Arbequina variety high in oleacein, and a tester olive oil that was extra virgin, with an equal content in total phenols, but containing no oleocanthal or oleacein.

The study focused on whether the consumption of 40 ml (three spoonfuls) of each olive oil – of a different composition – can inhibit platelet aggregation in healthy men. The nine men who took part in the study – who were of normal weight – consumed the three olive oils in a random order, leaving a week between each trial; the effect on platelet function was assessed 2 hours after olive oil consumption. The oils that were rich in oleocanthal and oleacein were found to significantly inhibit platelet aggregation, while the olive oil that didn’t include the substances, but had an equivalent total phenol content (mainly in the form of free tyrosol), failed to produce the same effect. It is interesting to note that of the nine people studied, four had a strong reaction within the 2-hour framework, similar to the medicinal properties of ibuprofen; the other five showed little or no reaction.

Comparatively, the best results came from the Greek extra virgin olive oil of the Koroneiki variety. This study clearly proves that the varieties rich in natural anti-inflammatory substances may have an effect on people that is equivalent to that of the NSAID, and that there is a wide array of reactions from person to person, which requires further investigation. Therefore, as with people, all extra virgin olive oils aren’t the same, and the “total phenols” criterion is no longer enough to prove their differentiation; moreover, a parallel relationship arises between olive oil quality and its effect on health.

* The research was organized in collaboration with the Executive Director of the UC Davies Olive Center, Dan Flynn, and was carried out by Roberta R. Holt, Karan Agrawal, Selina Wang, Theresa Pedersen, Eleni Melliou, Prokopios Magiatis, and John W. Newman.