Larry King talked recently with Sheryl Crow about her breast cancer diagnosis and during that conversation she issued several warning about cancer causing habits. One that stuck in our minds was cooking with olive oil. Many people use olive oil at high heat to stir fry. Apparently bringing olive oil to a smoking point creates a health risk as it increases the amounts of polycyclic aromatic hydrocarbons PAHs.
Polycyclic aromatic hydrocarbons are a group of chemicals which are formed when petroleum, petroleum products, coal, wood, cellulose, corn, or oil are burned. There are over 100 PAHs which have been studied. During oxidation and detoxification in the liver they are thought to form substances which damage DNA, starting a chain of events which could lead to cancer. A few of them have been classified by the EPA and The Department of Health and Human Services as carcinogenic.
Be careful when you eat out
Burning any cooking oil can increase the amounts of PAHs. Oil of any kind which has been repeatedly heated to its smoking point will lose it’s natural antioxidants and begin to accumulate free radicals and other cancer causing substances. Commercial industrial kitchens which fry foods would be where this sort of thing might happen. It is unlikely that you would repeatedly fry at continuous high temperatures with the same oil at home. In commercial operations the oil is examined regularly with a rancidity test and discarded before it gets to a dangerous stage. Olive oil is typically not used in commercial kitchens as it is much too expensive. Cheaper oils like canola, corn or peanut oil are used instead. Extra virgin olive oil has fewer free fatty acids and more antioxidants which soak up free radicals. So heating it would produce fewer free radicals than a lower grade olive oil.