Cooking oils are used in all kinds of food, either as a direct ingredient or perhaps more commonly as a cooking agent. Whether as part of a sauce or dressing or as a key ingredient when baking, there is a massive demand for oils in both homemade and mass-produced food. But when it comes to picking which oil you choose to consume (or avoid), how do we know which cooking oil is the healthiest?
As we discuss in our Vegan Cooking Oils article, most oils that are described as such are naturally vegan friendly as they derive from plants. Other oils and fats that come from animal sources tend to be described as such, with lard, goose fat, butter (from dairy milk) all being non-vegan.
But when we look at just the vegan-friendly oils, there are loads to choose from. The problem is, figuring out which cooking oil is the healthiest is not simply a case of assessing how much of the oil is made up of saturated fat. There are various factors that affect how healthy a cooking oil is, not least what you are using it for (for example, to drizzle over a salad or to roast potatoes).
Types of Vegan Cooking Oil
We’ll get onto the factors that affect how healthy oils are shortly, but first, let’s briefly go through the main vegan-friendly cooking oils that are available in most UK supermarkets or that are found as ingredients in common food products.
A very common cooking oil that has relatively low saturated fat content (around 10%) and relatively high smoke point (around 230°C) making it a very good contender as an all-rounder in many people’s eyes. Problems can sometimes occur, however, if it is over-refined, more of which later.
Another very popular oil for both cooking and for dips or dressings, olive oil comes in various grades and levels of quality from refined to virgin to extra virgin. Extra virgin olive oil is the highest grade and uses cold mechanical extraction methods and no solvents or extra refining methods. It must contain less than 0.8% of free fatty acids. Virgin olive oil, meanwhile, can have up to 2% free fatty acids.
Vegetable oil is the generic name given to oils that are a blend of two or more plant-based oil with rapeseed oil, corn oil and sunflower oil often used.
Commonly known as Canola Oil in the USA and some other countries, rapeseed oil comes from the yellow-flowering Brassica napus plant that is a common sight in UK fields. It can appear in various forms as it can be highly refined, unrefined or cold-pressed/expeller pressed.
It tends to have a very low saturated fat content at around 7-8% and a high smoke point of above 200°C when it is refined, though the unrefined version has a low smoke point of just over 100°C.
Derived from sesame seeds, this is no good for anyone who has a sesame seed allergy. There are several varieties including the dark brown oil that is derived from roasted or toasted seeds (commonly used in the cuisine in many parts of Asia) and cold-pressed sesame oil that is a lot lighter in colour.
Also known as maize oil, this is extracted from maize (corn) germs. It has one of the higher smoke points among cooking oils (of around 232°C, even for refined corn oil) making it particularly useful for high-temperature cooking and deep fat frying (see below for more info on this). It is also quite low in saturated fat content at around 12-14%.
A by-product of the winemaking industry, grapeseed oil (or grape seed oil or just grape oil) is produced from the seeds of grapes, as the name would suggest. It has a low saturated fat content at around the 10% mark and a relatively high smoke point of over 215°C.
One of the lower smoke points of the oils at around 160°C, walnut oil is likely to break down if used for cooking at higher temperatures. Its delicate, nutty flavour can be used to good effect in dressings. Renaissance painters also used it as a thinner for oil paints and as a brush cleaner.
One of the highest smoke points of all the plant-based oils (typically 250°C for unrefined and 271°C for refined), avocado oil is high in vitamin E and low in saturated fats and given its similar monounsaturated fat profile as olive oil is thus seen as one of the healthier oil options.
Also called linseed oil, it is produced from the dried and ripened seeds of the flax plant. Unrefined flaxseed oil has a very low smoke point of just over 100°C, making it far from perfect for frying or high-temperature cooking.
It also tends to go rancid more quickly than most other oils and is therefore usually kept refrigerated to prolong its edible period. It is a very good source of α-Linolenic acid (ALA), which is an essential omega-3 fatty acid. In fact, it is made up of over 50% ALA, making it one of the primary sources of omega-3 in a vegan diet.
There is some controversy over the use of palm oil, but we’ll leave that to our article that asks and answers the question Is Palm Oil Vegan?. If you accept that it is vegan (on the basis it comes from a plant), it is worth noting that many health organisations like the World Health Organisation suggest people should restrict their consumption of palm oil on the basis of its relatively high saturated fat content (around 50%).
Safflower oil comes from the seeds of the safflower (or Carthamus tinctorius if you prefer). The flowers are sometimes called “bastard saffron” as they are occasionally used in cuisine as a cheaper alternative to saffron. Safflower oil has a very lower saturated fat content compared to most oils (at around 7.5%) and a smoke point of around 212°C, depending on how refined it is.
Rice Bran Oil
One of the vegetable oils with a particularly high smoke point (around 232°C), rice bran oil is often favoured for high-temperature cooking like stir-frying and is popular in many Asian countries including India, Japan and Indonesia.
Also known as groundnut oil, peanut oil veers towards the higher end of oils when it comes to saturated fat content (around 20%), and it also has a high smoke point (around 232°C). This combination makes it very stable at high-temperature cooking, as we shall explore later in the article.
Hempseed oil (or hemp oil or hemp seed oil) has a low saturated fat content (around 7-9%) and a low smoke point (around 160-170°C) so it tends to be used as an addition to a dressing or similar sauce that doesn’t require it to be heated. It is also a good source of α-Linolenic acid (ALA), an omega-3 fatty acid, at around 20%, but it contains more (over 50%) linoleic acid (an omega-6 fatty acid).
Coconut oil is a solid fat at room temperature and it is very high in saturated fats (often upwards of 80%). As such, many health authorities, including the World Health Organisation and the NHS, strongly suggest people should restrict their consumption of coconut oil. This is partly because it contains a high amount of lauric acid which can raise cholesterol levels in the blood and thus increase the risk of developing heart disease.
No prizes for guessing that soybean oil comes from that vegan staple, the soybean. It is one of the most used vegetable oils, and its relatively low saturated fat content (around 15%) and reasonably high smoke point (240-250°C) means it’s fairly versatile.
Made from seeds of the cotton plant, this has a relatively high saturated fat content which becomes very high (upwards of 90%) when the oil is hydrogenated. It has been used as a cheap alternative to other vegetable oils in things like potato crisp production and in fast food restaurants, but it is one of the less healthy options.
Factors Affecting Healthiness of Cooking Oils
There are many factors that can affect how healthy a particular cooking oil is and indeed even the exact meaning of “healthy” can change depending on the circumstances of the individual consuming the oil in question. But without delving too much into the science at hand, here are the main factors that affect how healthy – or unhealthy – a cooking oil can be.
One of the most obvious and simple factors that can affect how healthy an oil is, is what the oil is made up of in terms of saturated and unsaturated fats. According to Heart UK, a charity focussing on the damaging effects of cholesterol, “Cutting down on foods that contain a lot of saturated fat and replacing them with foods that contain more unsaturated fat can improve your cholesterol levels.”
There are those who debate the relevancy of the saturated v unsaturated dichotomy and say the notion that saturated fats are bad per se is outdated. However, despite such claims, virtually all mainstream public health bodies, including the NHS, maintain that as a general rule we should limit our intake of saturated fats.
Based on this advice, the likes of coconut oil (which is usually at least 80% saturated fat) and palm oil (usually more than 50% saturated fat) would be very bad. Conversely, safflower oil, rapeseed oil, almond oil and hemp seed oil (all of which contain around 10% or less saturated fat) would be very good. The problem is, things are not necessarily that simple. The reason is that the composition of oils can change quite dramatically when heated, and so it very much depends on what you using the oil for (see below).
Having said that, although monounsaturated and polyunsaturated fats are generally considered to be healthier than saturated fats because they contain carbon-carbon double bonds, they are actually a lot less stable than saturated fats when heated. This is because saturated fats contain four single bonds and no carbon-carbon double bonds. The upshot of this is that, when heated, unsaturated oils are more likely to produce toxic products.
Omega-3 Fatty Acids
The amount of omega-3 fatty acids and omega-6 fatty acids also plays a part in whether an oil can be considered healthy or not. Both the quantities of these fatty acids and the ratio between the two can have an influence on the health impacts (positive or negative) of the oil in question. For instance, too much omega-6 has been shown to cause inflammation, although the evidence can sometimes contradict that suggestion and it could actually reduce inflammation in some circumstances.
In addition, whether an oil is likely to increase levels of cholesterol in the blood should be taken into account. The complication is that there is so-called “good” cholesterol (called high-density lipoprotein or HDL) and “bad” cholesterol (called low-density lipoprotein or LDL). Different fatty acids – whether saturated, monounsaturated or polyunsaturated – can affect the HDL and LDL levels in the blood in different ways and it is sometimes difficult to ascertain whether the overall cholesterol make-up in a person’s blood is improved or made worse by the consumption of certain oils.
It is not just the fat composition of oils that affects their healthiness. Some oils, such as extra virgin olive oil, are also high in antioxidants and vitamin E that can also bestow health benefits. These factors should also be taken into account when assessing how healthy an oil is. Note that oils that have been heavily refined often have their vitamin and nutrient content reduced or eradicated.
What It’s Being Used For
As mentioned, what you are using the oil for can have a big impact on whether it is healthy or unhealthy. For instance, an oil that is low in saturated fats might be good to drizzle over a salad, but – particularly if it has a low smoke point – it could oxidise very easily when used in cooking, particularly high-temperature cooking, which could render it extremely unhealthy.
This is because various toxic or potentially toxic substances could be formed as the oil is broken down and combined with oxygen in the air, water or compounds from the food that is being cooked.
The smoke point of an oil is the lowest temperature at which it begins to burn. At this point, it will start to produce smoke which is a sign that the oil is oxidising. This can mean that new and potentially harmful compounds (such as aldehydes) form in the oil and thus will be consumed when you eat whatever food you’ve cooked in it. There is research suggesting that even inhaling the fumes from burning oil can have harmful effects and raise the risk of developing heart disease or cancer.
Generally speaking, the more refined an oil is, the higher its smoke point will be. But if oils are not stored properly, for instance, if they are exposed to direct sunlight or heat, they can degrade and their smoke points can be reduced. The volume of oil used, the type of pan and the type of food that is being cooked can also affect the smoke point of a particular oil.
Not to Be Confused with Flash Point
Note that the smoke point of an oil should not be confused with its flash point. While the smoke point is the temperature at which the oil starts to burn (and degrade and form new potentially harmful compounds), the flash point is the lowest temperature at which the vapours of that oil (or other volatile substance) will ignite if there is an ignition source.
Given that a lit gas hob is obviously a potential source of ignition, it is essential that you never cook at a temperature that is above the flash point of an oil. Thankfully, the likelihood of doing so is low given the flash point of most cooking oils is over 300°C. But it is something to bear in mind if cooking over an open fire or at particularly high temperatures on a roaring barbecue.
Smoke Points of Common Cooking Oils
Here we’ll list the smoke points of some of the more common cooking oils based on various scientific sources including a study published in the Food Chemistry journal about the emissions of aldehydes from heated cooking oils.
Note that smoke points can be altered by various factors including how an oil has been stored and how refined it is so these figures are meant as a guide only and cover only an approximate average range for the oil in question.
|Cooking Oil||Smoke Point (°C)|
|Hemp Seed Oil||160-170|
|Rice Bran Oil||225-235|
Based on the smoke points alone, the likes of flaxseed oil and hemp seed oil shouldn’t be used for cooking if the temperature is likely to get near or above their respective smoke points. Coconut oil has a similar smoke point to hemp seed oil, but because of its higher saturated fat content, it is a lot more stable when heated than oil from hemp seed, which is extremely low in saturated fats.
Based on the smoke points, rapeseed oil, rice bran oil and especially avocado oil are the best for higher-temperature cooking such as stir-frying. Note that some refined versions of other oils have smoke points of 220°C too, but it is rarely something that is listed on a label.
Similarly, the least refined oils, such as cold-pressed rapeseed oil, might be very good compared to highly refined oils when they are fresh. But less refined oils have a tendency to spoil a lot quicker than refined oils and oxidisation can take place if they are not stored correctly, again rendering them less healthy than might be assumed. Oils, particularly unrefined oils, should be stored away from light, heat and oxygen.
Given that refinement processes can increase the smoke point, a greater level of refinement can indeed be a good thing when using an oil for cooking and particularly for high-temperature cooking. But on the other hand, the refinement process tends to hydrogenate some of the fat, leading to quantities of trans fat, which is associated with a greater risk of developing coronary heart disease. The refinement process can also expose the oil in question to heat, various chemicals and other things that can strip out some of the more useful nutrients (for example, vitamin E).
Healthiest Vegan Oil for Cooking: Avocado Oil
As mentioned, the smoke point is of critical importance when it comes to cooking, especially at high temperatures. Cooking at a temperature above (or even near to) the smoke point of an oil is a recipe to produce a host of potentially cancer-causing compounds. So, when cooking at 200°C or higher, we’d recommend choosing avocado oil.
It is low in saturated fats, which would usually make it unstable at high temperatures, but because its smoke point is so high, this should not usually be an issue. And, because it is significantly higher in monounsaturates than polyunsaturates, this gives greater stability than some other polyunsaturated fat-rich oils that have similar smoke points such as soybean oil.
The downside of avocado oil is that it is not always readily available in supermarkets and it can be quite expensive if it is of good quality. As a fallback, a good quality sunflower oil would generally suffice and if cooking at a slightly lower temperature, olive oil – which is also high in monounsaturates – is also a solid option.
Healthiest Raw Vegan Oil: Flaxseed Oil
Clearly, those people who follow a raw vegan diet will not have to worry too much about the smoke point of cooking oils. Instead, the composition of the oil is of greater import. Given the strong association between saturated fat intake and coronary heart disease mortality, opting for an oil that is low in saturated fats makes sense.
Also, something that is important for vegans in particular, an oil that contains good quantities of α-Linolenic acid (ALA), an omega-3 fatty acid, could be very beneficial (as vegans will not be consuming oily fish which is one of the best sources of omega-3 fatty acids.
As such, our top oil to use when not cooking (so for things like drizzling on salad on vegetables) is flaxseed oil. Although it can go rancid very quickly and needs to be refrigerated, and ideally in a container that does not let in light, we think the benefits outweigh such minor inconveniences. If you don’t want to mess about with the storage requirements of flaxseed oil, however, other solid contenders would be extra virgin olive oil and cold-pressed rapeseed oil.
Of course, when using an oil in dressings the flavour is likely to be a key factor in your choice. Rapeseed and flaxseed oil are both fairly mild and neutral, whilst olive oils tend to have far greater complexity. The former may be best when you simply want an oil with which to emulsify a sauce or dressing, whilst olive oil may have more to offer if you are looking to add real grassiness, spice or fruitiness to a dish (depending on which olive oil you use)
Healthiest Vegan Cooking Oils: Conclusions
In summary, the healthiest vegan-friendly cooking oil depends on what you are using it for.
Best for High Temperature Cooking: Avocado Oil
One of the highest smoke points of any cooking oil, this oil should do the trick even at very high temperature such as those reached when stir-frying. It is low in saturated fats and is rich in monounsaturates and though it can be a little on the pricey side, it is becoming more available than it once was. In addition, some may have ethical queries about avocados in general.
Best Raw Oil: Flaxseed Oil
Although it can spoil very easily and need to be stored in the fridge (ideally in container that stops it being exposed to light), the fact that flaxseed oil is so rich in omega-3 ALA makes it an excellent choice for vegans (who might struggle to get enough omega-3 fatty acids, depending on their other dietary choices). The light, nutty flavour makes it great to drizzle on salads or other raw foods.
Best All-Rounder: Cold-Pressed Rapeseed Oil
As well as having a very low saturated fat content, rapeseed oil (or canola) is brilliant when eaten raw, for example on salads. It has also been found to compare well to other oils when used in cooking in terms of toxic compound emissions. As such, with a relatively high smoke point (of over 200°C and approaching 240°C for more refined oil), it can be used for most cooking.
In addition, for those concerned with food miles, local (UK) rapeseed oils are common, whereas olives, avocados and certain other base products will have been sourced from much further afield.
Other strong contenders include extra virgin olive oil, which has long been associated with the healthy so-called Mediterranean diet, and hempseed oil, which is particularly low in saturated fats and contains a decent dose of α-Linolenic acid (ALA).