Does olive oil lose its health benefits when heated?

Contrary to what you may have heard, olive oil does not lose its health benefits or become unhealthy when heated.

Olive oil has been used for cooking for thousands of years. It is a cornerstone of the Mediterranean diet. So why do some people believe that olive oil should not be used for cooking? One persistent rumor is that olive oil will lose its health benefits when heated. This rumor is false. Here's why:

First, olive oil's main health benefit is its fat composition. Olive oil is mostly monounsaturated fat. Cooking with an oil will not change its fat composition. Olive oil's percentage of monounsaturated fat remains the same after heating, even to high temperatures.

According to the American Heart Association, monounsaturated fats can help reduce bad cholesterol levels in your blood which can lower your risk of heart disease and stroke. They also provide nutrients to help develop and maintain your body’s cells.  The Food and Drug Administration (FDA), in 2004, approved a health claim for olive oil on the basis that the monounsaturated fat in olive oil may reduce the risk of coronary heart disease when used in place of saturated fat. 

All olive oils, whether extra virgin or refined, heated or raw, contain a comparable amount of monounsaturated fat.

What about trans fats?

Cooking oils, when heated, may form small amounts of trans fats. However, the concentration is minuscule – less than 1% - even with lengthy heating.

The smoke point myth 

All olive oil has relatively high smoke point (between 365 and 410 F) that is generally not impacted by household cooking.  But smoke point is not the most important factor when evaluating a cooking oils suitability for cooking. The key issue in comparing oils is oxidative stability--the extent to which a cooking oil resists breaking down under heat, which may result in the formation of potentially harmful compounds. Research has found that extra virgin olive oil is the most stable cooking oil under heat when it comes to the production of polar compounds, outperforming cooking oils that have a higher smoke point.  One reason for this is that olive oil contains phenols and antioxidants that protect it from breaking down when heated.

Another important factor is the fatty acid composition of the oil (monounsaturated fats like olive oil resist oxidation better than polyunsaturated fats like soy and corn). Read more 

And another important factor appears to be the extent to which the oil has already been subjected to high heat by refining (most other commercially available cooking oils like canola, soy, corn, sunflower, etc.) have been refined in the production process, unlike EVOO which has not been refined.

This new research is consistent with a 2004 study in which measured potentially harmful aldehydes produced when extra virgin olive oil, olive oil and canola oil were heated to 464°F.  The study found that both extra virgin and regular olive oil performed better than canola oil, even though canola oil ha a higher smoke point. Read more

Furthermore, it is not likely that you will exceed the smoke point of olive oil when cooking. Stovetop cooking does not usually 350ºF, even if you turn the burners to high and even if you turn your oven up to 450ºF, the food and oil does not reach that temperature.  

Watch this demonstration to learn more and learn more about the research here. 

Antioxidants and Polyphenols

You may have also heard that you should not cook with olive oil because the phenols will be destroyed by the heat--this is also not true.  It is true that phenols in olive oil are sensitive to heat. However, a 2015 study made a remarkable discovery. When cooking with extra virgin olive oil, the phenols move into the food. Potatoes fried in EVOO contained more phenols and antioxidants than potatoes boiled in water. Read more.

Furthermore, a 2020 study by the University of Barcelona in the Journal Antioxidants  confirmed that extra virgin olive oil retains significant amounts of these healthy compounds during cooking. Read more.

What about the taste?

The flavor compounds in olive oil are delicate and will evaporate when heated. Heating olive oil does not damage the health benefits but it will make the olive oil lose some flavor.  Some people consider this to be a good thing as they do not want their foods to taste like olive oil. However, if you have an expensive olive oil with complex flavors, you may want to save it for finishing and cold uses.

In conclusion, olive oil is safe to cook with. Heating olive oil will not destroy the health benefits or turn olive oil unhealthy. You can feel confident using olive oil in all of your recipes. 

Further Reading: 

• Smoke Point Is Not a Reliable Indicator of Cooking Oil Stability
• Why Olive Oil is the Best Oil for Frying
• The Culinary Institute of America Clarifies Guidance on Cooking With Olive Oil
• Olive Oil Retains Health Benefits During Cooking
• USDA Recommends Olive Oil for Deep Frying 
• US News reports on olive oil smoke points