Olive oil research. Researcher analysing samples of olive oils using an optical fibre spectrometer. The display screen shows how the spectrometer works (top diagram) and also shows a graph (bottom of screen). This graph shows the results of principal component analysis (PCA) for the olive oils. The amount of three principal components (PC1, PC2, PC3) are plotted against each other. The olive oils are clustered in three groups: extra virgin, non-extra virgin, and extra virgin from Tuscany. Olive oil is high in monounsaturated fats, which are healthier than polyunsaturated and saturated fats. Olive oil is thought to be one reason why the Mediterranean diet, in places like Tuscany, Italy, is a healthy one. Extra virgin olive oil is less acidic than ordinary olive oil.