I have heard that olive oil is not as great as everyone says….

Willonda Thomas Cancer Dietitian Articles, Community Wellness


I have a new intern! Lora wrote up this q&a as a result of a question we received from a client. A great question and I’m thrilled to have Lora helping out on the Cancer Dietitian team!

Q: I have heard that olive oil is not as great as everyone says, if heated it turns to trans fat. True?

I will start by saying it isnot true that olive oil is turned to trans fat when cooked at high temperatures.

No doubt, you have heard that some fats are good for you while others are bad.  This is because there are different types of fatty acids that have different chemical structures. Think of the difference between olive oil, which is liquid when left out on the counter, and lard or butter, which remain solid when not refrigerated.

  • The “good” fats, mono- and polyunsaturated fatty acids, are found in plant products and are liquid at room temperature.
  • The “bad” fat, saturated fats, are found in animal products and are solid at room temperature.
  • See Julie’s article about fats here: Dietary Fat Recommendations: Have The Experts Been Lying?

What are Trans Fats?

Trans fats are actually vegetable oils that have been processed and their chemical structure changed in order to make vegetable oils more solid at room temperature.  This is a processing technique that food manufacturers use to extend the shelf life of some products, such as baked goods.

In addition to extending the shelf life, it is CHEAPER to manufacture solid fat, than to purchase solid fats like butter. However, although it increases the shelf life of the product, trans fats has been shown to  be harmful to the body, and result in an increased risk of heart disease.

Trans fats can be found naturally in small amounts in some dairy and meats.  However, these are not the harmful trans fatty acids you typically hear about.

Using Olive Oil for Cooking

Given that the production of trans fats requires a special hydrogenation process that does not occur naturally through cooking, it is impossible for olive oil to turn into trans fats while cooking, even at the highest of temperatures.

What is true though is that olive oil has a lower smoke point than other vegetable oils, meaning that it will start to degrade at lower temperatures.  This isn’t necessarily harmful, but it can produce an unpleasant taste.  For this reason, olive oil is not the best oil to use when cooking at high temperatures.

Is olive oil a healthy oil?

With a recent interest in the health benefits of the Mediterranean diet, olive oil is often promoted as a “healthier” vegetable oil, which isn’t necessarily the case.  Vegetable oils differ in their content of saturated and unsaturated fatty acids.

  • Olive oil is comprised of approximately 15-20% saturated fatty acids, while canola oil is only about 5% saturated fatty acids.
  • Other recently popular vegetable oils, like coconut and palm oils, can contain almost 50% saturated fatty acids, and are more solid at room temperature like meat fat and butter.
  • Vegetable oils, including olive oil, are a healthier choice than animal fats.

Want to know about Canola oil? Check out Julie’s article here: Quick Q&A: What is Canola Oil?

Should you cook with olive oil? 

If you’re cooking at a lower temperature, less than about 350˚F, then olive oil should be fine.  Olive oils also work well in recipes that do not require heat, such as in salad dressings and marinades.  When choosing which vegetable oil to cook with, consider not only the nutritional value of the oil, but which oil is best for the type of cooking you are doing.

– Lora