Long touted as a "heart healthy" fat, olive oil has now been shown to work its magic at the genetic level by turning off genes that are associated with heart disease and inflammation.

Researchers in Spain have shown that just because you inherited some "bad genes" from your parents and grandparents, you are not doomed to suffer the diseases to which you are predisposed. A healthy diet, they say, can modulate the effect of these genes.

At the Institut Municipal d'Investigacio Medica in Barcelona, scientists worked with three groups of healthy volunteers. One group followed a traditional Mediterranean diet with virgin olive oil which is rich in polyphenols, while the second group followed the same diet with a lower grade of olive oil low in polyphenols, and the third group followed their regular diet. Phenols are micronutrients in olive oil; the extra virgin oils have particularly high levels of them.

After just three months, the virgin olive oil group showed improvement in genes related to atherosclerosis or hardening of the arteries, as well as coronary heart disease.

Earlier researchers at the University of Cordoba in Spain concluded that eating a diet rich in virgin olive oil like the Mediterranean diet also represses pro-inflammatory genes through the action of olive oil's polyphenols. They suggested that this anti-inflammatory action explains in part the reduced risk of cardiovascular disease seen in people who eat a Mediterranean diet.

Researchers conducted a study of 20 patients with metabolic syndrome, a condition associated with increased risk of cardiovascular disease and type 2 diabetes.  They were able to identify 98 genes which behaved differently based on the amount of virgin olive oil consumed compared to lower quality olive oil.

Several genes that promote inflammation were repressed by the phenol-rich extra virgin olive oil which researchers believe suggests that diet can switch the activity of immune system cells to a less inflammatory state.

What does this mean for you? First, replace the vegetable fats in your diet, like corn oil, vegetable oil or sunflower oil, with olive oil.

Second, quality counts. Definitely buy the extra virgin olive oil and don't be fooled by the lower priced varieties.

What do olive oil labels mean?

Here's a quick guide to reading olive oil labels:

• Extra virgin - the best, least processed and unrefined, the oil from the first pressing of the olives has the highest levels of phenols and anti-oxidants and a delicate taste. To bear this label, the oil must also have a low acid content.
• Virgin – usually from the second pressing, but could also come from the first pressing that does not meet the acidity and quality levels of extra virgin. This has fewer phenols and anti-oxidants and a less delicate taste.
• Pure - undergoes some processing, such as filtering and refining, and although it says pure it can actually be a combination of refined and virgin oils.
• Extra light - undergoes considerable processing and only retains a very faint olive flavor. It is not a term regulated by law and in some instances is actually a mix of olive oil and other vegetable or canola oils.