It is one of the most hotly debated ingredients in Britain's kitchens.

Whether you're sautéing, deep-frying or drizzling over a salad, oil is a cooking staple – but choosing the right one has become increasingly confusing.

While some are hailed as heart-healthy superfoods said to boost brain power, others are blamed for fuelling inflammation in the body and heart disease. 

Some even turn rancid if left too long in the cupboard, while others should never be used for certain cooking methods, as heat can cause changes that make them a risk to health.

As a result, many health-conscious cooks are shunning traditional sunflower and rapeseed oils for trendier alternatives such as coconut oil.

But are these fashionable choices really any better for you – and how do they compare with kitchen classics like olive oil or butter?

Now experts have weighed in, revealing which oils you should be using – and which to avoid.

According to nutritionist Rob Hobson, author of Unprocess Your Family Life, one oil often criticised for its fat content isn't nearly as bad as you might think.

Olive Oil

Many people reach for olive oil believing it's the healthiest choice for cooking - but experts say that's not always the case.

Mr Hobson says that while extra virgin olive oil is packed with heart-friendly monounsaturated fats and antioxidants, it's not ideal for very high temperatures.

'It's rich in monounsaturated fats and antioxidants, which are great for heart health,' he said.

Extra virgin olive oil also contains relatively little saturated fat - about 2g per tablespoon - and is rich in polyphenols, plant-based compounds that support blood vessel and brain health.

The problem, he explains, is that extra virgin olive oil begins to break down when overheated. 

Its smoke point - the temperature at which it starts to burn and release smoke - can be as low as 160°C, rising to around 190°C for higher-quality oils. 

Beyond that, it starts to lose its beneficial compounds and produce harmful molecules called free radicals, which can damage cells and may raise the risk of heart disease.

That means while it's fine for gentle sautéing, the pricier 'extra virgin' varieties are best reserved for salad dressings, drizzling over cooked dishes or dipping bread.

For cooking at higher temperatures - such as roasting or frying - refined olive oil (often sold simply as 'olive oil' or 'light olive oil') is a better choice. 

It has a higher smoke point of around 220°C, making it more stable under heat. 

However, the refining process strips away many of the natural polyphenols and antioxidants that give extra virgin olive oil its unique health benefits.

Coconut Oil

Coconut oil is often touted as a 'healthier' oil to cook with - but experts are undecided. 

It is high in saturated fats with around 13g per tablespoon - almost half the recommended portion of 30g of saturated fat per day.

Rhiannon Lambert, Harley Street nutritionist and author of The Science of Nutrition, says: 'Approximately 90 per cent of its fat is saturated, which is a higher proportion than in butter.

'Diets high in saturated fat can increase blood cholesterol levels which can raise the risk of heart disease.'

Coconut oil advocates suggest the benefits are due to the fact it contains lauric acid, a saturated fat which some studies suggest may not be as harmful as other saturated fats.

Some research has suggested lauric acid raises HDL or 'good' cholesterol levels, which may lower overall heart disease risk.

But Mr Hobson stresses that the 'jury is still out on coconut oil's cardiovascular impacts'.

He adds: 'It can raise your total cholesterol level, which is bad news for heart health. So it's best used sparingly. Also you don't always want everything to taste if coconut.'

'While it's great in stir fries, baking and curries, it's not something I would fry my eggs in.'

Rapeseed Oil  

One contender to olive oil in terms of health benefits is rapeseed oil.

At around £3.50 a bottle, it costs roughly half as much as extra virgin olive oil and is also high in healthy monounsaturated fats, which may help reduce cardiovascular risk.

It's even lower in saturated fat - about 1.1g per serving - and contains alpha-linolenic acid (ALA), a type of omega-3 fatty acid found mainly in fish and essential for heart and brain health.

'Omega-3s are often lacking in our diets, so incorporating oils like this can help to improve overall fatty acid intake,' Mr Hobson said.

Rapeseed oil also has a relatively high smoke point of around 220°C, meaning it can withstand heat and is suitable for frying, roasting and baking.

Both rapeseed and other seed oils contain omega-3 and omega-6 fatty acids, but rapeseed has a more favourable omega-3 to omega-6 ratio than most others.

Omega-6 fats are essential for health, but some experts suggest excessive intake may promote inflammation. However, Mr Hobson says this concern is often exaggerated.

'Rapeseed oil sometimes gets a bad rap because of its association with omega-6 and the perception that it's a 'processed' oil,' he said. 'I think a lot of this criticism is overblown and fuelled by social media.'

Indeed, a 2019 study published in Circulation found no link between moderate omega-6 intake and an increased risk of cardiovascular disease.

Flaxseed Oil 

Flaxseed oil, also known as linseed oil, contains around 1.6g of saturated fat per serving and offers similar omega-3 benefits to rapeseed oil.

However, it is extremely delicate, with a smoke point of just around 110°C, meaning it breaks down easily and should never be used for cooking.

For this reason, Mr Hobson recommends using flaxseed oil only in salad dressings or for drizzling over cold or cooked foods to retain its nutritional benefits.

Sunflower Oil  

In recent years, seed oils have become the target of countless social media posts, with people claiming that they are 'toxic', 'poisonous' and, ultimately, are damaging our health. 

Critics have nicknamed some seed oils the 'hateful eight' - canola, corn, cottonseed, grapeseed, soy, rice bran, sunflower and safflower - and blame them for causing heart disease and type 2 diabetes.

Sunflower oil, in particular, has a bad reputation due to its particularly high levels of omega-6 fatty acids.

If this fatty acid is consumed in excess without sufficient omega-3, it can contribute to an imbalance that promotes inflammation.

But there is no need to throw out your sunflower oil just yet, according to Mr Hobson, as it's perfectly healthy to use in moderation.  

It is also lower in saturated fat than olive oil and coconut oil at around 1.5g per serving. 

And sunflower oil has a much higher smoke point at 232 degrees, making it ideal for frying, he says.