A key component in the Mediterranean diet is olive oil, along with a high consumption of plant-based foods and a low consumption of red meat. According to a recent study (Trichopoulou, et al., 2000), olive oil is more beneficial against cancer than other forms of added lipids.

This study also estimates that up to 25% of the incidence of colorectal cancer (also see Stoneham, et al., 2000), approximately 15% of the incidence of breast cancer, and approximately 10% of the incidence of prostate, pancreas and endometrial cancer could be prevented if the populations of highly developed Western countries could shift to the traditional healthy Mediterranean diet.

The health benefits and characteristics of olive oil are the topic of this article.

One of the main reasons to cook with olive oil is to benefit from the flavor it adds. Cooking with olive oil is like cooking with wine. Never use a wine or olive oil that does not taste good to you. An inferior one will leave an aftertaste.

You'll understand the difference if you do a taste test and compare the "pure" to the "extra-virgin" olive oil.

Fats should contribute no more than 30% of the calories in a diet. The majority of calories from fat should come from monounsaturated fats, as they have been shown to lower LDL ("bad") cholesterol (Kris-Etherton, et al., 1999; Williams, et al., 1999; Aro, et al., 1998).

Polyunsaturated fats should be used in moderation. Saturated fats should be avoided. They come from animal meats, dairy products and tropical oils such as coconut and palm oil. As noted throughout the literature, consumption of saturated fats has been shown to raise LDL cholesterol.

Extra virgin olive oil is a unique dietary lipid, according to Visioli and Galli (2000), in the sense that it is not extracted from seeds by means of solvents. Rather, it is obtained from the whole fruit (drupe), by using the cold-press technique, which does not alter the chemical nature of the drupe or that of the resulting oil. 

According to a study published in The Lancet in October 2000 (Owen, et al.), high consumption of extra-virgin olive oils, which are particularly rich in phenolic antioxidants (as well as squalene and oleic acid), should afford considerable protection against cancer (colon, breast, skin), coronary heart disease and aging by inhibiting oxidative stress. It is the unique profile of the phenolic fraction, along with high intakes of squalene and the monounsaturated fatty acid, oleic acid, which are believed to confer the extra-virgin oil's health-promoting properties. 

Extra virgin olive oil is graded by acidity. Lower acidity is associated with a higher quality product because acidity affects the taste and the aroma of the oil. Extra virgin olive oils are permitted to have a maximum acidity of 1%, but the top-quality oils tend to have less than 0.5% acidity. Virgin oil, by comparison, can have up to 3% acidity.

Olive oil or pure olive oil, in contrast to extra virgin oil, is chemically treated, heated and filtered to reduce its acidity. Ugo Erasmus, in his book Fats That Heal, Fats That Kill: The Complete Guide to Fats, Oils, Cholesterol and Human Health, notes that this manufacturing process alters an oil's characteristics. In fact, heating during processing or in cooking destroys the beneficial compounds in most oils, including olive oil. 

The color of extra virgin olive oil ranges from a pale yellow to bright green. Usually, the deeper the color, the more intense the flavor. It should taste sweet, with a little "edge" to it.