Cooking Oils Causing Cancer?

Last Modified: May 29, 2008

Dear OncoLink "Ask The Experts,"

I was diagnosed with an early-stage hormone-positive, pre-menopausal breast cancer. I have been increasing my intake of veggies, fruits, omega 3's. Recently, I heard that olive oil loses its nutritional content at high heats and can actually be a carcinogen. Is this true? What are the best oils to use for high heat and for my health. Thanks!

Karen Wagner MS, RD, LDN, Clinical dietitian specialist for the Abramson Cancer Center, responds:

Thank you for the great questions, and I wanted to commend you on making important dietary changes. Increasing your fruit, vegetable and omega-3 consumption is a great way to improve your overall diet.

To try to clear up the confusion about olive oil, we need to start with the “smoke point” of oils. The “smoke point” of an oil is the temperature at which the oil starts to break down or smoke. Delicate oils, such as extra virgin olive oil, walnut oil, and flax seed oil, have relatively low smoke points, around 300 degrees F or less. The broken-down parts of the oil are said to have been oxidized, and these may cause some damage to cells, but this has not ever been linked to any increased risk of cancer in any population. Furthermore, your body can use anti-oxidants from your diet to stop this damage. If you are eating a wide variety of fruits and vegetables, chances are that you are getting plenty of antioxidants. It is a good idea, though, to cook with fats with a higher “smoke point”. Refined oils have higher smoke points. If you would like to use olive oil to cook with, you could look for an olive oil that is NOT labeled “extra virgin”. A good rule of thumb is that if a particular oil is very fragrant, for example if the extra-virgin olive oil has a strong olive flavor, then don’t use it for cooking. Oils with higher smoke points are refined canola oils, refined peanut oils, refined corn oil, and refined safflower oil. The smoke point of these oils is closer to about 450 degrees F. Keep in mind, too, that eating vegetables and enjoying them is such an important part of a healthy diet, that what ever oil you use, it is much healthier to eat the vegetables than to not eat them. I hope this answers your questions.