Which oils are safe to cook with?

Published: 10 November 2015

Many of you will have seen the recent scary headlines about vegetable oils releasing cancer-causing chemicals when heated to high temperatures. As we read yet another story about food causing cancer, it’s no wonder members of the public are confused.

So, which oils should we use for cooking?

To start with, this latest news story is not actually news; it has been known for at least 30 years. The headlines have been sparked by new research that essentially tells us what we already knew, that the very high temperatures used in frying – especially deep frying – can result in oils breaking down and producing chemicals that are potentially harmful to our health. Oils that are rich in polyunsaturated fats (omega 3 and omega 6) are especially unstable at high temperatures.  

Deep frying

Our recommendation is to avoid deep-fried food altogether. Such foods are often high in saturated fat and salt which increase our risk of heart disease. However, if you do need to deep fry your food, our long-standing advice is that oils like corn and sunflower oils are not recommended for high temperatures. These oils are rich in polyunsaturated fats which can form undesirable compounds when heated at high temperatures. For deep frying in the home, better oils include refined olive oil (light olive oil) and rice bran oils.

Many takeaway operators (including some chains) have switched to using deep frying oils that are lower in saturated fat but stable at prolonged high temperatures. The list of oils that meet the industry standard for deep frying in fast food outlets can be found on the Chip Group website.

Shallow frying

For shallow frying, barbequing, stir-frying in the home, the Heart Foundation recommends using oils that are both lower in polyunsaturated fat and saturated fat. Unlike deep frying, these cooking methods don’t involve cooking at very high temperatures for a prolonged period of time, or reusing the oil. The best choices from a nutrition, affordability and availability perspective remain olive oil, canola and rice bran oils. 

You may also be confused about recommendations to start cooking with coconut oil, lard or butter. Despite various claims about their health benefits, coconut oil and lard are not recommended for wide culinary use because of their high saturated fat levels. Yes, they are relatively stable at high temperatures, but that is not good enough reason to use them regularly. The clear, unequivocal evidence remains that it is better for our hearts to replace highly saturated fats (such as butter, lard and coconut) with unsaturated fats.

Lard, butter and coconut are not back in when it comes to frying. Olive, canola and rice bran oil still reign supreme from a health and stability perspective.   

With all this said, let’s not lose sight of the big picture. We need to steer away from deep fried foods as part of a healthy dietary pattern. To get healthy fats into our diets, we should aim to choose foods like fish, avocado, nuts and seeds which are less processed, have the right types of fats, and also provide beneficial nutrients.

Take-home messages

• Choose olive, canola, or rice bran oil for shallow frying or barbequing
• Only use sunflower oil for salad dressing or in spreads (and don’t heat)
• Try to include healthy fats such as avocado, nuts, seeds and oily fish in your diet
• Products with high levels of saturated fat, such as coconut, butter and lard, should be used only very rarely
• Avoid deep frying foods but if you must do so, avoid oils that are rich in polyunsaturated fats because these are unstable at high temperatures

Still confused about what fats and oils are healthy? You can find out more in our guide to eating for a healthy heart

Eating for a healthy heart

Angela Berrill

National Nutrition Advisor

As a registered dietitian, I am passionate about educating people about the importance of health and nutrition. I believe in finding ways for people to enjoy food while also nurturing their bodies.