Cooking Oil Smoke Points

I was reading your article about ‘Butter Versus Oil‘ and was wondering if you could answer a question about cooking oils. I agree that ghee and coconut oil are best to use for high-temperature cooking. It’s just that you mentioned grapeseed oil should not be used. From what I’ve read on other sites, it has a pretty high heat tolerance, some sites say up to 485F. Why is it not good to use these oils for cooking? I also thought avocado oil could be used due to its high heat tolerance. Is this not the case?

A Healthy Foodie’s Answer

I’m glad you bring up this question, because it’s something I’ve been meaning to address.

In order to answer your question, we need to clarify one point — smoke point is not a reliable indicator of when an oil is becoming damaged. (The smoke point generally refers to the temperature at which a cooking fat or oil begins to break down and become rancid.) By the time you see smoke, the oil is likely already damaged.

While food sellers and processors do various things to improve their oil’s smoke points — including refining them in various ways — the composition of the oil remains the same. Since grapeseed oil is mostly omega-6 fats, and omega-6 fats are not heat stable, grapeseed oil should not be cooked with, regardless of when it starts to smoke.

Avocado oil is going to be a little more heat stable because it has a high monounsaturated fat content (like olive oil). It’s good for light cooking, but nothing too extreme — light sauteing, yes; deep-frying or high-temperature searing, no.

I know this can be confusing because often the packaging will tell you an oil is “ideal for cooking,” even though it’s not. A good example is all of the cooking oils sold in plastic bottles in grocery stores — these oils are just about the worst thing you can use, even though that’s what they’re marketed for. Applying heat to these delicate oils causes them to break down and become rancid, leading to free radical formation in the body, which can damage cells.

The best way to tell if an oil is good for cooking is by looking at the fat breakdown on the nutritional information label. If the oil is mostly polyunsaturated fat (anything higher than 40 per cent, I’d say), don’t cook with it. Polyunsaturated fats, your omega-3s and omega-6s, are delicate and easily break down and become rancid when heated. If the label doesn’t give the fat breakdown, you can always look it up on nutritiondata.com.

I went into a little more detail in this post about which oils are best for cooking and why. But it’s important to remember damaged oils can lead to cell damage, something we should all avoid. Cooking with the right oil, oil that will stand up to the heat you’re using, is vital.

The Healthy Foodie is Doug DiPasquale, a Holistic Nutritionist and trained chef who lives in Toronto.