Mention the words ‘canola oil,’ and you often get two extreme reactions. Some believe it is heart-healthy as it is low in saturated fats and rich in omega-3 fatty acids.
For others, canola oil is toxic and can lead to heart problems and liver disease.
So, what’s the truth about canola oil? Read on to find out.
What is canola oil?
Canola is an oilseed crop developed in Canada through plant cross-breeding. Keith Downey and Baldur R, Stefansson from the University of Manitoba, Canada, bred canola from rapeseed in the early 1970s.
The word ‘canola’ comes from the combination of ‘Canda’ and ‘ola,’ which means oil.
While canola and rapeseed plant look quite similar, they contain different nutrients. Rapeseed oil contains erucic acid, which can cause heart problems if consumed. Canola plant was developed through cross-breeding to lower its erucic acid levels.
Over the years scientists have developed many varieties of canola through genetic modification to make them disease and drought resistant (1).
Most canola crops grown in the US today are genetically modified (GMO).
How is canola oil manufactured?
According to the Canola Council of Canada, canola oil is manufactured using the pre-press solvent extraction method (2):
- Seed cleaning – The weed seeds, pods, and stems are removed from the canola seeds.
- Seed pre-conditioning and flaking – Canola seeds are preheated to 35°C and then flaked by roller mills.
- Seed cooking – Flakes are cooked by passing them through a series of steam-heated drum or stack type cookers. The cooking cycle lasts 15 to 20 minutes.
- Pressing – The cooked canola seeds flakes are then pressed in a series of screw pressers and expellers. This process removes around 50 to 60 percent oil.
- Solvent extraction – The press cake from the expellers, which contains 18 to 20 percent oil, is broken into small pieces before solvent extraction with n-hexane.
- Meal desolventizing and toasting – The solvent is removed and recaptured from the marc in a desolventizing toaster.
- Oil refining – The oil is processed with water precipitation and organic acids to remove phospholipids, mucilaginous gums, free fatty acids, color pigments, and fine meal particles. These processes ensure stability and shelf life. This oil then goes through bleaching and deodorization.
Further processing – Canola oil is made into margarine and shortening through a process called hydrogenation, which solidifies the oil.
Why is canola oil bad?
1. It is mostly GMO
Canola has been genetically engineered to be resistant to pests and herbicides. GMO foods can lead to many kidney, liver and neurological health issues.
2. Highly refined
The processing of canola oil involves exposure to heat and chemicals. The process involves mixing canola seeds with hexane, which is derived from petroleum.
Canola oil processing also includes bleaching and deodorizing, which requires chemicals.
Refining decrease the levels of nutrients like fatty acids, antioxidants, and vitamins in oils.
3. High in omega-6 fats
Canola oil is rich in omega-6 fatty acids. While omega-6 fatty acids perform an essential function in the body, having too much of these fats can cause an imbalance in the body.
While the ideal ratio of omega-3 and omega-6 fatty acids in the body should be 1:1, it is estimated to be around 1:15 in a typical western diet. This imbalance can lead to obesity, heart disease and Alzheimer’s disease (5).
Health risks of canola oil
1. Heart disease
Canola oil is promoted as oil that is beneficial for heart health, but many studies dispute this claim.
During 2004 to 2006, 2071 participants aged between 24 and 36 participated in a study.
The study showed that among participants who were overweight or obese, higher consumption of canola was associated with a higher risk of having metabolic syndrome (6).
Metabolic syndrome refers to a cluster of conditions like high blood sugar, high blood pressure, high cholesterol and excess belly fat, which can increase your risk of heart disease.
Partially hydrogenated vegetable oils like canola oil can cause inflammation and calcification of arterial walls, which increases the risk of coronary heart disease (7).
2. Increased inflammation
Many studies have shown that canola oil can lead to inflammation and oxidative stress.
During a 2011 study, researchers gave a diet containing 10% canola oil to rats. The results showed that canola oil reduces antioxidant status and increases plasma lipids, which are risk factors for cardiovascular disease (8).
Another recent study showed that when rats were fed canola oil, it increased their levels of markers for oxidative stress (9).
3. Kidney and liver issues
Most of the canola oil produced in the US and Canada is genetically modified. Studies have shown that genetically modified food can cause liver and kidney damage.
In a review on 19 studies animals were fed GMA food. The results showed that a GMO diet could lead to liver and kidney problems (10).
4. Affects memory
Canola oil can also negatively impact memory. During a 2017 study, mice were given a canola oil supplemented diet for six months.
The results showed that chronic exposure to canola oil leads to a significant increase in body weight and impairments in their working memory (11).
When these mice were on a high canola diet, it caused a breakdown in their neuron communication hubs.
During another study, researchers gave180 older individuals a diet rich in vegetable oils including canola oil or a diet in which vegetable oils were replaced with extra virgin olive oil.
The results showed that the individuals that took olive oil instead of vegetable oils had improvement in cognitive function (12).
Consuming canola oil has been linked to an increased risk of stroke. According to a 2000 study from Canada, stroke-prone spontaneously hypersensitive rats had a shorter lifespan when they were fed canola oil as their sole source of fat. The rats that consumed non-canola based diet lived longer (13).
Another study from Food and Drug Safety Center, Kanagawa, Japan, showed that canola oil induced shortening of blood coagulation time and increased fragility in erythrocyte membranes, which may promote strokes in stroke-prone spontaneously hypersensitive rats (14).
6. Retards growth
The FDA did not allow the use of canola oil in infant formula for many years. Canola oil contains euroric acid, which infants can not break down properly. The unhealthy fats in canola oil may retard the growth of infants.
Unfortunately, now FDA regards canola oil as safe for use. In 2013 when a multinational company applied to the FDA to use canola as its source of fat in infant formula in the US, the FDA had no objections (15).
Canola oil is processed at high heat and is extracted with the neurotoxin hexane.
7. Increase trans fat intake
According to a study published in the Journal of Food Lipids, canola and soyabean oil purchased in the US has trans fat contents between .56 % to 4.2% (16).
When canola oil undergoes hydrogenation, its levels of trans fats increases. These trans fats are known to increase LDL cholesterol and decrease HDL cholesterol. So avoid canola oil since it is often labeled partially hydrogenated oil.
8. Triggers insulin resistance
Canola oil can trigger insulin resistance in the body. Insulin resistance is the precursor to diabetes. According to a 2014 study on the anti-diabetic activity of different oils, canola oil contributes to the onset of type 2 diabetes by increasing insulin resistance.
The study showed that the group that consumed canola oil developed the highest insulin levels in just four weeks (17).
Healthier options for cooking oils
There are several healthier alternatives to canola oil for cooking. These include –
1. Olive oil
Olive oil is rich in monounsaturated fatty acids, which help prevent heart disease, cholesterol, and blood sugar. It is also rich in anti-inflammatory compounds including polyphenol antioxidants (18).
2. Coconut oil
Cold-pressed, virgin coconut oil has a high heat threshold, so it is one of the best oils for high heat cooking. Coconut oil raises the levels of HDL cholesterol in your blood, and this helps reduce the risk of heart disease (19).
3. Avocado oil
Avocado oil contains oleic acid, a monounsaturated omega-9 fatty acid. This fatty acid is responsible for its numerous health benefits (20).
4. Ghee or pasture-raised butter
Both butter and ghee (clarified butter) contain alpha lipoic acid and conjugated linoleic acid, which helps in promoting weight loss.
5. Flaxseed oil
Canola oil is extracted from the seeds of the canola plant. Because it is cheap, the food industry uses it much more than other oils.
It may be marketed as a healthy food choice, but many studies suggest it causes inflammation and can cause heart disease, liver, and kidney issues.
So, avoid using canola oil and opt for healthier oils like olive oil, coconut oil, ghee, flaxseed oil, and avocado oil.