COOKING oil is a definite kitchen staple used for frying, baking, roasting, grilling, and plenty more.

But with so many different types on offer, it can be hard to know which one’s best to use – particularly when it comes to benefiting our health.

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While some oils have a more pronounced flavour, others are kinder to your heart and better for high-heat cooking.

And some experts warn certain cooking oils and the way they’re used can increase the risk of cancer due to the formation of harmful compounds when overheated or reused.

Aleks Jagiello, a Doctify-rated Registered Dietitian, explained the health risks attached to some of the nation’s favourite oils.

“When oils are heated past their smoke point, they can break down and produce aldehydes, acrolein, and polycyclic aromatic hydrocarbons (PAHs), all of which have been linked to cell damage and increased cancer risk,” she said.

“This is especially concerning with oils high in polyunsaturated fats (PUFAs), such as sunflower, soybean, and corn oil, which are more prone to oxidation at high temperatures.

“Reusing cooking oils, particularly for deep frying, leads to the production of trans fats and oxidised fats, which studies suggest may contribute to chronic inflammation and cancer development. 

“Additionally, consuming too much omega-6 from refined vegetable oils without balancing it with omega-3 has been associated with long-term inflammation, a factor in various cancers.”

A meta-analysis of 70 articles found that high blood levels of n-6 PUFAs were associated with a lower risk of cancer. 

But studies on PUFAs and cancer risk have produced conflicting results. 

Another type of cooking oil Aleks warns against are partially and fully hydrogenated plant oils as they can be “particularly harmful”.

These are commonly made from rapeseed, palm, or sunflower oil and are often added to processed foods.

“These oils contain trans fats, which are linked to increased risk of heart disease, inflammation, and other health issues,” said Aleks.

“It’s best to avoid products that list ‘hydrogenated’ or ‘partially hydrogenated’ oils in their ingredients.”

Many studies have linked hydrogenated vegetable oils to a number of health risks.

Some research suggests that hydrogenated vegetable oils harm blood sugar control.

One 16-year study in nearly 85,000 women found that those who consumed the highest amount of trans fats, which are a byproduct of hydrogenation, had a significantly higher risk of type 2 diabetes.

And studies have revealed trans fats can increase levels of LDL (bad) cholesterol while decreasing good HDL (good) cholesterol, both of which are risk factors for heart disease.

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What oils are best to drizzle over food?

How you use certain oils can impact their health benefits

Aleks recommnds the best oils for drizzling over food are extra virgin olive oil, flaxseed oil, walnut oil, pumpkin seed oil, and unrefined sesame oil, as they’re rich in healthy fats, antioxidants, and unique flavours.

“Extra virgin olive oil is the most versatile choice,” she said, “Adding a smooth, slightly peppery taste to salads, vegetables and soups, while providing heart-healthy monounsaturated fats.

“Flaxseed oil is an excellent source of omega-3 fatty acids but should never be heated, making it ideal for dressings or drizzling over roasted vegetables.

“Walnut and pumpkin seed oils bring a nutty depth to dishes, while hemp seed oil offers a balanced omega-3 to omega-6 ratio, perfect for grains and salads.

“Unrefined sesame oil enhances Asian dishes with its distinct aroma. These oils retain their beneficial properties when used raw.”

What oils are best for frying?

When it comes to frying and high temperature cooking, Aleks recommends oils with a higher smoke point and less prone to oxidation.

These include refined avocado oil, refined olive oil and both refined and unrefined coconut oil.

“Unrefined, cold-pressed oils should never be heated, as they degrade quickly and lose their beneficial properties,” said Aleks.

“It’s also important to note that refined oil does not automatically mean heat-stable – refining simply removes non-fat compounds, but it doesn’t necessarily make an oil suitable for frying.

“Oils high in polyunsaturated fats (PUFAs), such as flaxseed and walnut oil, are more prone to oxidation at high temperatures, leading to the formation of harmful compounds.

“For the safest and healthiest frying options, stick to oils that are naturally more stable under heat.”

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Is it ok to cook with butter?

Cooking with butter, especially clarified butter (ghee), offers several benefits beyond enhancing flavour.

Butter is a natural source of fat-soluble vitamins A, D, E, and K, which support immune function, bone health, and skin health.

Grass-fed butter (made from the milk of cows that eat fresh grass) also contains higher levels of conjugated linoleic acid (CLA), which has potential anti-inflammatory and metabolic benefits.

But its low smoke point can lead to the release of highly harmful compounds, warns Aleks.

“The smoke point of butter is low (135°C/275°F), and heating it beyond this temperature causes it to burn – turning brown, emitting a burnt smell, and releasing highly harmful compounds, such as acrolein, which is classified as a free radical.

“Free radicals are known to increase the risk of cancer and accelerate cellular ageing, contributing to overall health deterioration.

“It’s safer to fry with clarified butter (ghee), which has a higher smoke point (252°C/486°F), making it more stable at high temperatures.”

A 2016 study published in PLOS One suggests that butter has little or no link to heart disease and may actually protect people from diabetes.

But other studies have shown butter consumption is linked to higher risk of death and cardiovascular disease.

And how about low calorie cooking sprays?

Cooking oil sprays offer a convenient way to control portions and reduce fat intake, making them popular for low-calorie cooking.

But Aleks says they can often contain additives, emulsifiers, and propellants, which may not be ideal for long-term health.

“Many sprays use oils high in polyunsaturated fats (like sunflower or canola oil), which can become unstable at high temperatures and form harmful compounds,” she said.

“Additionally, while marketed as ‘1 kcal per spray’, this is based on an extremely short burst – longer sprays can add a noticeable amount of fat and calories without consumers realising it. 

“While these sprays can be useful for greasing pans with minimal oil, a healthier alternative is using a refillable spray bottle with high-quality oils like extra virgin, ensuring better nutrition without unnecessary additives.”

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So what’s the best choice when it comes to picking a cooking oil to use at home?

There are two cooking oils Aleks tends to use at home.

One of them is extra virgin olive oil, due to its well-researched benefits, including heart-protective monounsaturated fats and natural polyphenols.

Monounsaturated fats help lower levels of LDL (bad) cholesterol in your blood and raise levels of HDL (good) cholesterol, while polyphenols can help lower blood pressure and improve blood vessel function.

A 2024 study in the Journal of the American Heart Association found that both high and low amounts of extra virgin olive oil can lower LDL cholesterol levels. 

A 2022 study in the Journal of the American College of Cardiology found that consuming more than 1.5 teaspoons of olive oil daily reduced the risk of dying early from any cause by 19 per cent. 

And a 2023 study of 60,582 women and 31,801 men found that higher olive oil intake was associated with lower risks of cardiovascular disease, cancer, neurodegenerative disease, and respiratory disease. 

The second is coconut oil, which Aleks uses occasionally when preparing Asian dishes.

“Mainly for its flavour rather than any particularly health advantages,” she explained.

“While coconut oil is stable at high temperatures, I use it in moderation due to its high saturated fat content.”