Olive oil is the keystone of the Mediterranean diet, and is its most characteristic food. More than 80% of the visible fat of this diet is consumed in the form of olive oil, which is almost the only source of fat, employed both in cooking (stir-frying, deep frying) and as a dressing. In spite of the great importance of olive oil in the Mediterranean diet, many of the properties of some of its components remain unclear. It has already been shown that olive oil has a wide range of healthy properties, including the reduction of LDL cholesterol in comparison with diets high in saturated fatty acids (SAFA), control of blood pressure, the lowering of inflammation markers, as well as beneficial effects on certain types of cancer and cardiovascular disease and age-related cognitive decline [1-4].