Understanding the idea of health benefits between the extra-virgin and the lighter types becomes apparent when you consider that the olive is the olive tree’s fruit. The oil is there to nurture the developing seed until it can begin to grow on its own. Rancid oil is less able to help the seed grow, and the olive has evolved to produce protective components. In the olive, we find some vitamin E and other antioxidant compounds known as polyphenols. These compounds help maintain the olive’s vitality while providing the distinct flavor characteristics detectable in premium oils.
Oil producers from around the Mediterranean, in addition to those in California, speak with understandable pride about the healthful attributes of their olive oil. They often tout that only the extra-virgin olive oil has the right stuff. Once you understand that it is the extra-virgin oil that contains the bulk of the beneficial phytochemicals, you can better appreciate the logic of their message.
Expect differences between, and within, brands of oils. Quality varies with the olive variety, the age of the tree, the geographical area, the method of cultivation, the weather and the length of the growing season. Some producers date the vintage of their oils, while others blend to achieve a consistent taste for their brand.
We find the same types of differences with fruits and vegetables, as well as with products such as wine.