It’s a fair bet if you do any cooking at home you will have at least one bottle of oil in your cupboard. It may be olive oil or canola, or perhaps sesame, sunflower or even macadamia, and it’s probably a regular ingredient in your household. Yet is the oil you use the best oil for you and do you use it in the best way? Some of the information out there can be quite sensational and shocking, so let’s cut through the misinformation to discover the oils you need in your kitchen.

The benefits of oils

Fat can be heated to a higher temperature than water. While water turns to a gas at 100°C, fats remain in liquid form at temperatures above 200°C. The significance of this to cooking is that fat will give food a crisper texture and more intense flavour.

Fat is also an important part of a healthy diet. Together with protein and carbohydrates, fat is one of the three macronutrients which make up the bulk of the food we eat. These are the nutrients we need every day, and in the largest quantities, to be healthy.

However, the quantity and type of fats you use have a fundamental impact on your health and there are three “fat factors” to consider:

• The type of the fat
• How the fat reacts to heat
• How much of the fat you use

Fat type

We tend to talk of ‘fats’ as one substance. However, in nutrition there are three distinct groups of fatty acids: saturated, poly-unsaturated and mono-unsaturated. These are all present in animal and plant foods, so all the fats we consume contain a combination of these three.

However, each fat we use tends to be dominated by one group. For example, butter is 80 per cent fat and, while it contains both mono- and poly-unsaturated fatty acids, it’s mostly saturated. In contrast, sesame oil also contains all three groups but is largely made up of poly-unsaturates. Broadly speaking, animal fats tend to be higher in saturates while plant fats are higher in the mono- and poly-unsaturated fatty acid groups.

On average, Australians eat more than 40g of saturated fatty acids per day, which is twice the recommended daily intake.

While we need fats from each of these groups, many people eat too many of the saturated fatty acids. On average, Australians eat more than 40g of saturated fatty acids per day, which is twice the recommended daily intake. In New Zealand it is estimated that 15 per cent of daily energy comes from saturated fat.

Diets high in saturates are linked to an increased risk of cardiovascular disease, cancer and diabetes. In Australia, for instance, the Dietary Guidelines released by the National Health & Medical Research Council include limiting saturated fatty acids as a core dietary change necessary for optimum health.

In contrast, mono- and poly-unsaturated fatty acids are associated with health benefits including reduced cardiovascular risk and improved mental health, reducing the risk of depression and cognitive decline in old age.

Fat on heat

The suitability of a fat for a particular cooking task is also dependant on its reaction to heat. Structural differences between the fats and the relative amounts of saturated versus un-saturated fatty acids all affect the stability of a fat and the way it reacts at different temperatures. Heat can change the structure, composition and flavour of a fat, with some burning and smoking at relatively low temperatures, while others are able to be kept at high temperatures for much longer without their flavour or chemical composition being affected.

Butter is structurally quite different from sesame oil. One is solid at room temperature while the other is a liquid. Butter is full of saturated fatty acids, which are highly stable. These fatty acids can be heated to high temperatures, with few changes occurring to their chemical structure. In contrast, sesame oil is high in poly-unsaturated fatty acids, which are more unstable. This means sesame oil is better suited for use at medium to lower temperatures, because when heated too high it undergoes fundamental chemical changes. At the oil’s ‘smoke point’ there is a deterioration in flavour; it starts to break down into a gas and the remaining liquid gains a burnt flavour. This not only ruins your dinner; it’s also believed the remaining liquid contains larger quantities of free radicals.

When choosing an oil it is therefore important to pick one which can be heated to a high enough temperature for the cooking method you are using.

Quantity

Watch any TV cooking program and you’ll see the host adding lots of olive oil: standing there talking while pouring cupfuls of oil into their cooking. While this may work for celebrity chefs, it is not a good strategy for home cooking. Even the healthiest of oils can be overconsumed. They are energy dense, high in kilojoules and too much will contribute to weight gain.

Moreover, excess fat intake also places you at risk of some cancers and heart disease, so how much fat you use in cooking is a significant part of the health equation. Adding more than you need to your diet will harm your health, regardless of whether the fat is dominated by saturated, mono- or poly-unsaturated fatty acids. Quantity counts.

Olive oil

Over the last few years, supermarkets have set aside more and more shelves for olive oil and there’s a large range of different types available:

Extra virgin olive oilis the first pressing of the olives. This has to be a cold pressing and the resultant oil has no more than 0.8 per cent acidity. It is a premium-grade oil extraction.

Virgin olive oil is the second pressing. No heat or chemicals are used and the resultant oil has an acidity of no more than 2 per cent. It’s the second-best grade of olive oil.

Pure olive oil and olive oil are usually a blend of virgin and light oil.

Light olive oil is refined olive oil. It is a later extraction from the olives and has been chemically treated to reduce strong flavours and aromas. The term ‘light’ refers to the taste and colour. It has the same fat and kilojoule content as the other oils.

Health effects: Olive oil is about 70 per cent mono-unsaturated fatty acids, 16 per cent saturated and 10 per cent poly-unsaturated. Mono-unsaturated fatty acids have been found to reduce total and LDL cholesterol levels and are associated with a reduced risk of heart disease.

What to use: Extra virgin olive oil is the least processed choice. It is the first pressing and likely to contain the most antioxidants and other phytonutrients.

How to use: The relatively low smoking point (190°C) means extra virgin olive oil should only be used at lower temperatures. It is best used for gently sauteing foods on a lower heat or adding at the end of cooking, to flavour the final dish. It’s also beautiful in salad dressings.

Canola oil

There seems to be a lot of scare mongering about canola oil on the internet. I’ve read it’s poisonous, toxic, used to make mustard gas, the product of genetic engineering and can affect your nervous system. There is little evidence that any of this is true.

Canola comes from rape seed. It’s from the mustard family of plants, but is not the source of mustard gas. Canola is the result of natural plant breeding techniques, called hybridisation, and not genetic engineering. Rape seed is high in erucic acid (30-60 per cent), which can damage the heart, but canola has been specifically bred to be low in erucic acid (on average, 0.6 per cent).

Health effects: Canola oil is high in mono-unsaturated fatty acids. Moreover, it has the lowest saturated-fat content of all the common oils. Canola is 60 per cent mono-unsaturated, 7 per cent saturates and 29 per cent poly-unsaturated fatty acids. Canola oil is associated with a reduced risk of heart disease.

What to use: While canola itself was not produced by the result of genetic engineering, genetically modified canola is present in some products. This will be listed on the ingredients list, so check the labels of the products you’re buying. Cold-pressed canola oil is available, which means it has been extracted without the use of chemicals or solvents.

How to use: Canola oil has a higher smoke point than olive oil (240°C). It can therefore be used for higher-temperature cooking without affecting flavour and antioxidants or increasing free radical damage. It also has a blander flavour than olive oil, making it a good multi-purpose oil. Canola is useful in baked goods and can also be used in stir-frying or where a medium-to-high temperature is required.

Coconut oil

Together with palm oil, coconut oil is one of the few plant-based oils dominated by saturated fatty acids. Despite this, it has been argued that coconut oil has a beneficial effect on health.

The saturated fatty acids in coconut oil are different from those present in meat and butter. Researchers have suggested these medium chain fatty acids can boost metabolism, improve satiety after eating and promote weight loss. Two of these medium chain fatty acids, caprylic acid and lauric acid, are being studied for potential immune-boosting effects.

The saturated fatty acids in coconut oil are different from those present in meat and butter.

Whatever the benefits or otherwise of coconut oil, it is important to advise against substituting all the un-saturated fats you consume with coconut oil. Coconut oil still contains also contains mystiric and palmitic acid, two saturated fatty acids which have been linked to raising cholesterol levels. Lauric acid, while being investigated for its effect on the immune system, has also been associated with elevated cholesterol. Plus the potential benefits from consuming coconut oil will only occur if it is used in moderation, in conjunction with un-saturated oils.

Health effects: The jury is out on the health effects of coconut oil. It contains over 85 per cent saturated fats, although many of these are medium chain fatty acids, which has led some researchers to suggest potential health benefits. To maximise the potential benefit it is important to consume in moderation only and to still use un-saturated fats in your diet.

What to use: Food-grade, organic coconut oil is available. Most health-food shops will stock or be able to order coconut oil for you.
How to use: Being high in saturated fatty acids, coconut oil can be used where higher temperature cooking is required. It is also possible to replace butter with coconut oil in baking, although you need to be aware of the changes to flavour that will occur.

Sesame, peanut and sunflower seed oils

Sesame, peanut and sunflower seed oil are all commonly available. They are high in poly-unsaturated fatty acids and contain the Omega 6 essential fatty acids. It is important to be careful with peanut oil as it can cause reactions in people with peanut allergies.

Health effects: These three oils are high in poly-unsaturated fatty acids and also have distinct amounts of mono-unsaturates. They are beneficial oils to include on a regular basis.

What to use: Choose cold-pressed extra-virgin oils where available and, given they are sensitive to light, store these oils in a dark cupboard or the fridge.

How to use: These oils have a higher smoking point (232°C) than olive oil and are in a similar range to canola oil. They are excellent for stir-frying or frying, although it is important not to exceed the smoking point, to prevent oxidation, flavour degeneration and the accumulation of free radicals.

Macadamia oil

Macadamia oil is different from the other nut and seed oils as it primarily contains mono-unsaturated fatty acids (85 per cent). It also contains saturated fatty acids (14 per cent) but virtually no poly-unsaturates (1 per cent).

Health effects: Macadamia is high in mono-unsaturated fatty acids, which are associated with a reduced cardiovascular risk. Its fatty acid profile also makes it a highly stable oil.

What to use: Cold-pressed extra virgin macadamia oil is available from health-food shops and some supermarkets.

How to use: Macadamia nut oil has a distinctive flavour which makes it excellent for salad dressings and vinaigrettes. It has a medium smoke point of 210°C which, in combination with its flavour, makes macadamia oil excellent for stir-fries. It is also great for roasting vegetables, in combination with herbs and spices, where it imparts a gentle nutty flavour.

The best oil is …

The answer to the question of which is the healthiest fat to use in cooking is it depends. There is no one perfect fat that will suit all your cooking needs. In fact there is considerable evidence that varying the fats you eat is beneficial to your health. Using olive oil some nights and mixing that up with canola, sesame, macadamia and so on varies the fatty-acid profile of your diet. It increases the likelihood you’ll be eating the fats you need.

It also comes down to how much of each fat you’re eating. Too much of any of the fats, no matter what their fatty acid profile, will increase your potential to gain weight while also increasing your risk of heart disease and other health problems.

Craig Hassel from the University of Minnesota writes, ‘Whether coconut oil is ‘good’ or ‘bad’ for you is a function of your genetics, your current diet, your current health, how extensively you might choose to use coconut oil, and how you are living. Science has a very difficult time dealing with all of these factors, so don’t look for nutrition science to resolve the good-versus-bad debate any time soon. Stay away from the false dichotomy; we are dealing with shades of grey, not black and white.

This applies to all the oils discussed above. All the oils have health benefits which are negated if you eat too much. The suitability of an oil depends on what you are cooking and what else you are eating.

Five steps to choosing your oil

1. Wherever possible buy cold-pressed and extra virgin oils; these are the first pressings and are extracted without heat or chemical solvents. This yields a purer oil, with a full flavour.
2. Rather than adding mono- and poly-unsaturated fatty acids to your diet, use them to replace some of the existing saturates you use. Add canola oil to baking and dip your bread in olive oil rather than using butter.
3. Use the right oil for the cooking job. While olive oil is great for lower temperatures, it’s unsuitable for medium- to high-temperature frying. Watching the smoke point of the oil you are using is one of the best guides.
4. Find ways to reduce the overall amount of fat you use. While most recipes talk about tablespoons and cupfuls of oil, it is usually possible to reduce this down to teaspoons and dessertspoons.
5. Vary the oils you use to ensure you are getting all the different fatty acids you need to be healthy and enjoy your diet.