About 40% of the calories in the typical Greek diet come from olive oil. To some eyes, that looks like a lot of fat, yet this traditional Mediterranean style of eating -- which emphasizes fish, olive oil, whole grains, and fruits and vegetables -- seems to contribute to the favorably low rates of heart disease among people who live in the countries that ring the Mediterranean Sea. What is it about olive oil that makes it such a key part of this healthful way of eating? Two Israeli scientists took a look at this question in a recent issue of Nutrition Reviews.

Oil with a healthy touch

Foods that have ingredients that offer specific health benefits are called "functional foods," and olive oil fits this bill in several ways. Much of the fat in olive oil is in the form of monounsaturated fatty acids (MUFA), a type of fat that, unlike saturated fat, does not raise blood cholesterol levels. In fact, some scientists think that compared with polyunsaturated fats like corn or safflower oil, olive oil can more effectively lower both total and LDL (bad) cholesterol levels.

As a plant-based food, olive oil is also a rich source of vitamin E and polyphenols, the same compounds that give red wine and tea their "heart healthy" edge. (Other vegetable oils contain some of the same nutrients, but because olive oil is produced by mechanical pressing rather than by chemical extraction, it's possible that more of these nutrients survive intact in the finished product.)

Both vitamin E and polyphenols act as antioxidants, inhibiting the development of heart disease by reducing the oxygen-related damage along artery walls. An ingredient in olive oil also seem to make the blood less likely to clot, reducing the chance that an errant blood clot will block an artery and lead to a heart attack or stroke.

The authors of this report say that there is some evidence that the "healthy fats" and antioxidants in olive oil can help control blood pressure and reduce the risk of some types of cancers.

Olive oil is only part of the answer

Remember, though, that the health benefits of a Mediterranean style of eating extend beyond olive oil, and those who simple dribble olive oil on top of what they usually eat -- thinking that it will make them healthier -- are missing the point. This type of diet tends to be low in animal fat. It contains generous amounts of whole grains, fruits, and vegetables. In nutrient terms, that makes it high in fiber, vitamins, minerals, and a host of disease-fighting phytochemicals. All of these factors probably contribute to the health profile attributed to a Mediterranean-type diet.