Olives and olive oil have been a staple part of the Mediterranean diet for thousands of years. In ancient Greece, Homer, referred to olive oil as liquid gold, due to the health giving properties associated with its consumption. Scientists have since discovered that it is the polyphenols in olive fruit that are the main active ingredients, particularly hydroxytyrosol. Consumption of olive oil polyphenols contributes to the protection of blood lipids from oxidative damage. Olive oils can vary in the quantity of polyphenols they provide due to many factors including ripeness, exposure to sunlight during the growing season and general yield.