Why it's best NOT to cook with Extra Virgin Olive Oil

This wonderful article is written by George Mateljan, creator of whfoods.org and the World's Healthiest Foods Cookbook. The George Mateljan Foundation, a not-for-profit foundation with no commercial interests, is a new force for change to help make a healthier you and a healthier world.

Why it's best not to cook with extra virgin olive oil

Protecting the nutrient richness of the World's Healthiest Foods is high up on my list of goals for each and every one of our health-supporting foods. But when it comes to extra virgin olive oil, I take an especially careful approach with respect to exposing it to excessive amounts of heat. All vegetable oils are susceptible to heat damage-much more so than the whole foods from which they were pressed or extracted. But in the case of extra virgin olive oil, the susceptibility is especially great.

Here are some of the reasons that extra virgin olive oil requires special attention. The effect of heat on its monounsaturated fats All types of olive oil (including extra virgin) contain a large amount of monounsaturated fat. In fact, 70-80% of the total fat found in olive oil is monounsaturated. This monounsaturated fat comes from the monounsaturated fatty acid (MUFA) called oleic acid. In comparison to all commonly used vegetable oils, olive oil is fairly unique in its high MUFA content. Canola oil comes close (60-70% MUFA), but many of the other commonly used vegetable oils, including sunflower, safflower, corn, and soybean oils naturally contain less than half as much MUFA as olive oil.

It's worth noting here that cooking oil manufacturers sometimes create high-oleic version of these other oils, so that it is now possible to purchase high-oleic sunflower or safflower oil in many food stores. In general, monounsaturated fat increases the stability of a vegetable oil in comparison to polyunsaturated fat. This increased stability is related to the chemical structure of monounsaturated fat. MUFAs have fewer "reactive spots" than PUFAs (polyunsaturated fatty acids) and it is more difficult for oxygen radicals to interact with these kinds of fat. However, despite this lower reactivity, olive oil and other vegetable oils containing a high amount of MUFAs (like canola oil) still have relatively low smoke points and cannot withstand a large amount of heat. Unless these high-MUFA oils have been refined or conditioned in a way that increases their smoke point, they typically cannot withstand heats of much greater than 200-250˚F (93-121˚C) without incurring damage (the temperature of stove-top frying is 375-525˚F, or 191-274˚C). So even though the high-MUFA composition of extra virgin olive oil increases its chemical stability, it does not protect this wonderful oil from most stovetop or oven cooking temperatures.

Recent studies have made it clear that oleic acid can directly alter the activity of certain cancer genes and appears to have anti-cancer effects that may be part of the Mediterranean diet's health benefits. Yet, to get these benefits it's important to enjoy extra virgin olive oil when its MUFAs are best protected, which means at heats below 250˚F (121˚C). Heat damages extra virgin olive oil Research studies on the heat susceptibility of extra virgin olive oil tend to focus on higher heat ranges than we typically recommend at the World's Healthiest Foods. Heats between 320-374˚F (160-190˚C) are most often used to determine the changes that occur in extra virgin olive oil due to heating. Studies on this subject repeatedly show that heats as low as 320˚F (160˚C) can substantially damage the phenols in olive oil. There are also, of course, delicious salad dressings and recipes containing extra virgin olive oil that do not call for any heating whatsoever. In all of these circumstances, you'll get to enjoy the great flavor of extra virgin olive oil along with the full benefits of its amazing health-protective phenols.