The oil debate seems to be perennial. Which oil really is healthiest to cook with? Is coconut oil good or bad? We did a deep dive on this to settle it once and for all.
A new study published in the ACTA scientific journal, showed we shouldn’t be relying on smoke points (what we've previously used as an indicator) to tell us which oils are healthiest to cook with.
“This study showed smoke point does not predict oil performance when heated. Oxidative stability and UV coefficients are better predictors,” says the study.
And here's the big news: “Of all the oils tested, extra virgin olive oil (EVOO) was shown to be the oil that produced the lowest level of polar compounds after being heated, closely followed by coconut oil.”
It also showed that vegetable, seed and nut oils, degraded more readily when heated, unlike extra virgin olive oil - despite their higher smoke point. And what do the experts say? Let’s break it down into groups.
Why are Vegetable and seed oils bad for you?
Despite what the Meadow Lea ad told us in the 80’s, vegetable and seed oils are not healthy.
“They were originally considered healthy because they contained polyunsaturated fats [omega 6 fats],” says Dr Nick Fuller from the University of Sydney and author of Interval Weight Loss, “We do need omega 6s, but our western diet is heavily unbalanced and the ratio of Omega 6 to Omega 3 is way off. Polyunsaturated fats cause inflammation. In Australia the ratio of poly fats to mono fats is 8:1, in America it’s 16:1.”
“Inflammation is linked to everything from cancer to autoimmune diseases which are dramatically on the rise,” says David Gillespie, author of Eat Real Food. “We need to decrease omega 6 fats and increase omega 3 fats.”
Oils to avoid are vegetable oil, grapeseed oil, sunflower oil, rice bran oil, safflower oil, peanut oil - essentially any seed or nut oils apart from macadamia oil which has a different fat composition.
“People cook with vegetable oil because it’s cheap and has a higher smoke point - that’s why it’s used in takeaway restaurants,” says Fuller, “but we eat way too much of it and it’s become a real problem.”
Olive oil: The best to cook with
Some people say we shouldn’t heat olive oil too much as it has a low smoke point, and that it should only be eaten cold in a salad dressing. But as the ACTA study proves, perhaps we shouldn’t have been relying on the smoke point. There are other factors which cause an oil to break down and extra virgin olive oil is the clear winner from every expert.
“Extra virgin olive oil has 70% monounsaturated fats, is low in polyunsaturated fats and is the best to eat and cook with,” says Fuller. “It’s not subjected to high temperatures during the extraction process, so has a higher level of antioxidants.”
“You can use any kind of olive oil for cooking,” says Fuller. “Light olive oil is lighter in flavour and good for cooking because it won’t flavour your food.”
Avocado oil has a similar fat content to olive oil, so is also recommended. Gillespie cooks with a number of refined oils “as they are cheaper,” he says. “I use refined versions of olive, avocado and macadamia oils, along with animal fats.”
Clearing the coconut oil myth
The argument here is the coconut oil is too high in saturated fat to consume. But Paleo advocates would have us cooking with coconut oil all day. Their argument is that saturated fat doesn't cause heart disease and cite numerous studies to back this up.
Plus, they say, coconut oil raises HDL, the “good” cholesterol in the body, while lowering LDL, the “bad” cholesterol. There are a few studies around to support this but also a few studies saying they don’t raise HDL enough to cancel out LDL.
“Olive oil is simply a much healthier option,” says Fuller while Gillespie says, "you can buy into the coconut oil hype if you want, but it’s too expensive to cook with anyway, especially when there are better, cheaper options.”
And if you need more convincing, not even Gwyneth Paltrow uses coconut oil in her recipes.
What about canola oil?
Canola oil is high in monounsaturated fats - which are the omega 3s we want to increase - so it’s okay to cook with. “It’s not as great as olive oil,” says Gillespie, “because it’s higher in polyunsaturated fat, but it doesn’t have as many polys as other vegetable, seed and nut oils."
Still, it's not ideal and the only real reason to cook with it is because it's cheap and flavourless - but you could just use a refined olive oil and it would still be healthier.
The bottom line
The biggest takeaway is that we should be reducing our polyunsaturated fat intake which is incredibly hard to do if you’ve ever looked at an ingredients list on any packet in the supermarket. Almost every processed food from seemingly healthy natural muesli, organic popcorn and even sultanas and gluten-free products to the more obvious cakes and biscuits contain either vegetable oil, nut oils or seed oils. This is why we shouldn’t then also be cooking with those oils, and aim to reduce our polyunsaturated fat intake.
Olive oil is the clear winner, whether it’s extra virgin or not doesn’t seem to matter too much - it’s the one oil that every expert can agree on and every study points to as the healthiest.
High in mono fats - EAT
Olive oil
Avocado oil
Macadamia oil
High in polyunsaturated fats - AVOID
Vegetable oil
Seed oils - grapeseed, safflower, sunflower,
Nut oils - apart from macadamia