Cooking oils: the good, the bad and the ugly

Supermarket shelves are filled with cooking oils. With so many choices, and so many trends in the health food community, it’s hard to know which is the healthiest cooking oil to put in your shopping trolley.

“There are ‘health halos’ associated with some cooking oils and opposite perceptions about others, not all of which are warranted,” says Kris Sollid from the International Food Information Council (IFIC). A health halo is the impression that a specific food is really good for you despite a lack of factual information to back up the idea. Where these beliefs stem from is anyone’s guess,” Sollid says.

With this in mind, which cooking oil should you reach for when prepping a meal? There are several things to keep in mind for your health: the oil’s smoking point (the temperature at which the oil starts to break down, making it unhealthy), the type of fat it contains, and its flavour.

And just to be clear, all cooking oils are 100 per cent fat. “Just like with any food that contains fat, all cooking oils contain a blend of different types of saturated and unsaturated fats,” he says. “While some cooking oils are higher in certain types of fat, no oil contains only one type. A cooking oil is considered healthy if it’s high in mono- and polyunsaturated fats.”

Our food experts weigh in with multiple options.

Canola oil as one of the healthiest cooking oils because it offers blends of heart-healthy fats (as do olive and soybean oils).

“Canola oil is also a great source of monounsaturated fatty acids (MUFAs),” says Sollid. “Compared to olive oil, canola oil contains less MUFA but less saturated fat and more alpha-linolenic acid (ALA) omega-3 fat. Canola oil has the least saturated fat and the most ALA omega-3 fat of the common cooking oils.”

According to the National Institutes of Health’s Office of Dietary Supplements, ALA is an essential fatty acid. This means that your body can’t produce it and it must be consumed through what you eat and drink.

The smoke point of canola is 200°C, which makes it ideal to use when cooking something at a high temperature.

When you’d like your oil to add a little flavour to your food, olive oil is one of the most recommended options. But it’s important to keep in mind that its smoke point is lower than canola oil, so consider how you’ll be using it.

“Olive oil varieties have a lower smoke point but provide bigger flavour, so they are best suited for direct consumption in things like salad dressings and in lower temperature cooking techniques like sautéing, pan frying and baking,” says Sollid.

He also notes that olive oil is known for its high MUFA content, but also provides a small amount of ALA, the plant form of an especially beneficial type of polyunsaturated (PUFA) omega-3 fat.

One thing to remember, just because an oil is deemed ‘healthy’ doesn’t make it a health food. “Cooking oils are calorie dense – one tablespoon contains about 500 kilojoules,” says Sollid. Therefore, even the healthiest oils should be used in moderation.

Avocado oil is one of the newer cooking oils in terms of consumer popularity, although a 2019 study published in the journal Molecules admits that more research needs to be done to confirm its potential health benefits. Still, chefs and knowledgeable home cooks like it for a few very important reasons.

“For me, the benefit of avocado oil is primarily its high smoke point and neutral flavour,” says Abbie Gellman, chef at the New York Institute of Culinary Education. “Extra virgin olive oil has a lower smoke point, which means it breaks down at a lower heat level compared to avocado oil.

When an oil breaks down during cooking, the flavour will be off and carcinogens form. Because of this, avocado oil is better suited for high-heat cooking like stir frying.”

Peanut oil has a neutral taste and high smoke point of 230°C, making it a good oil to use for frying and stir fries. However, it may not be healthier than other cooking oil options because it’s chemically processed, which diminishes its mineral value.

You’re probably seeing a recurring theme here – our experts put a lot of emphasis on the smoke point of a particular oil, and with good reason.

“Chemistry of oil does change,” says Professor Britt Burton-Freeman. “Some of these compounds give a distinctive ‘fried’ taste and aroma people like. Others can give off-putting aromas.”

Kelly Springer, a registered dietitian,  chooses safflower oil when cooking vegetables on high heat or searing meats because of its very high smoke point, of 260°C.

“It won’t break down when cooked at high temperatures,” says Springer. “This is critical since oils that are cooked at high heat with a low smoke point, such as walnut oil, will degrade and turn into trans-fat. Safflower oil is high in omega 6 and has a neutral flavour.”

For a while it seemed like coconut oil was promoted as a must-use for everything – from cooking to skin care. But dietitians say that not everything is as it seems with this popular oil.

“Coconut oil is thought to be somewhat more beneficial to heart health than animal fats like butter, but not as heart-healthy as cooking oils that are made from plants like olive, canola, or soybean oil,” says Sollid.

He explains that coconut oil is mostly saturated fat, more so than other cooking oils from plants. With that being said, not all types of saturated fats impact health in the same way.

“Coconut oil has been shown to raise LDL cholesterol (the ‘bad’ kind of cholesterol), while also raising HDL (the ‘good’ kind) more than other types of saturated fat, particularly when it replaces carbohydrates,” says Sollid.

His advice? Coconut oil shouldn’t replace a significant amount of other plant oils in your diet. “If you enjoy the flavour of coconut oil, consider using it in place of butter or shortening, or paired with other cooking oils, keeping in mind that only small amounts should be used,” he says.

The health benefits of flaxseed have drawn a lot of attention from the wellness community. For example, a 2020 review of clinical trials involving flaxseed, published in Combinatorial Chemistry and High Throughput Screening, finds it has potential in the fight against heart disease, diabetes, hypertension, and more.

But what about flaxseed oil? According to Gelman, flaxseed oil is extremely delicate and should be stored in the fridge and never, ever heated.

So how can you include this oil in your culinary adventures? “It can be used as a drizzling finisher over roasted or cooked vegetables and salads,” she says.

When you’re looking for an oil that goes big on flavour, it’s hard to beat sesame oil. Springer lauds its bold nuttiness, noting that it pairs well with rice vinegar making it a staple in Asian-inspired cooking. However, it’s best to use it in small amounts to get that flavour for your dish.

“Keep in mind, sesame oil needs to be refrigerated,” she says. “With a smoke point of 170°C, sesame oil is considered to have a medium smoke point, making it preferred for low-heat baking or light sautéing. If using high heat, opt for another oil such as safflower or avocado oil.”

Another fine choice of oil is derived from soybeans, says Sollid. If you don’t think you’ve ever used soybean oil before, think again. It is another oil labelled simply as ‘vegetable oil’.

“It contains less MUFA than olive oil, but more polyunsaturated fatty acids  and more ALA omega-3,” he says. “Of these three cooking oils, only canola oil contains more ALA than soybean oil.”

It has a high smoke point at 230°C, making it good option when frying food.