Canola Oil

Is It Healthy?

What is canola oil?

Canola oil is a vegetable oil derived from the canola plant (Brassica napus L.) and is used to produce a myriad of foods, including margarine and shortening. Canola, the second-largest oil crop in the world, is produced via plant crossbreeding. Majority of canola crops are genetically modified (GMO) to increase oil quality and plant tolerance to herbicides. As canola becomes one of the most popular fat sources in the food industry, there are increasing concerns over its impact on health.

Types of canola oil

Most canola oils are refined, i.e. chemically extracted using hexane solvent and heat. The smoke point of refined cooking oil is around 204oC (399 oF). Cold-pressed canola oil does exist, but it is expensive and hard to find.

There are many steps involved in the manufacturing process of refined canola oil:

canola oil - seed cleaning

 

Canola seeds are separated and cleaned to remove plant stalks, dirt or other impurities. 

canola oil - seed conditioning and flaking

 

Seeds are pre-heated to around 35°C(95°F), then “flaked” by roller mills to break the seed’s cell wall.

seed cooking

 

The seed flakes are then cooked by a series of steam-heated cookers. Generally, this heating process is carried out at 80°–105°C (176–221°F) for 15–20 minutes.

canola oil - solvent extraction

 

The remaining seed flakes which contains 18–20% of oil is further extracted using hexane solvent. 

canola oil - pressing

 

Next, the cooked canola seed flakes are pressed in a series of screw presses or expellers. This process extracted 50–60% of the oil from the flakes, leaving the rest to be extracted by other methods.

solvent removal

 

The oil is heated at 95 – 115°C (203–239°F) via steam exposure to remove the hexane. 

oil processing

 

The extracted oil is refined by different methods, including steam distillation, exposure to phosphoric acid and filtration through acid-activated clays.

Nutrition facts

Fatty Acid Breakdown:

Saturated: 7%
Monounsaturated (e.g. omega-9): 64%
Polyunsaturated (e.g. omega-3, omega-6): 28%

Benefits

The health benefit of cold-pressed canola oil is:

  • High in good fats

Canola oil is rich in polyunsaturated fats (omega-3s and omega-6s), which are essential in the diet. Besides, it also contains high amounts of monounsaturated fats. Other than good fats, it also contains Vitamin E (an antioxidant) and vitamin K, which is needed for normal blood clotting. Nonetheless, it is important to note that the heating methods used during canola refining process could negatively impact polyunsaturated fats. 

The drawbacks

  • Unfavourable omega-3 to omega-6 ratio

The ideal omega-3 to omega-6 ratio should be between 2:1 and 4:1. In canola oil, the ratio is 1:2, which may not seem exceptionally disproportionate. Nonetheless, modern diets tend to be extremely high in omega-6s, which are present in most processed foods, and low in omega-3s. Yet, it is present in so many foods and its usage in foods continues to expand. It is a major source of dietary omega-6. The imbalance between omega-3s and omega-6s could lead to increased inflammation and a number of chronic conditions, such as heart disease1, obesity2 and dementia3. To maintain a more balanced ratio, it’s best to replace canola oil with cold-pressed oils such as camelina oil or flaxseed oil which are high in omega-3s. In addition, I would recommend you to replace processed foods which are rich in canola oil with natural, whole food sources of omega-3s like fatty fish. 

 

  • Declining memory, learning ability & weight gain

A recent study links consumption of canola oil with declining memory and learning ability and weight gain in mice, which modelled Alzheimer’s disease. This is the first study to suggest that canola oil is more harmful than helpful, particularly for the brain4.

 

  • High refined oil

Although unrefined, cold-pressed canola oils do exist, most canola oils on the market is highly refined. In the production of refined canola oil, canola goes through a series of stages, which involves high heat and exposure to chemicals, which remarkably reduces nutrients in the oil, including essential fatty acids, antioxidants and vitamins. These manufacturing processes also create high levels of oxidation and trans fat content, which are bad for health.

 

  • GMO and herbicides

More than 90% of the canola crops grown in the United States and Canada is GMO5,6, so that they are more resistant to herbicides. Although for decades,  many scientists deem GMO foods are safe and approved for human consumption, little data exists on their potential health risk and concerns over their potential impact on food safety and public health, which led to many consumers to avoid them.  Another issue with GMO canola crops is the liberal usage of herbicides by farmers to get rid of weeds without harming their crops. High levels of herbicides could increase health risks of hormone disruption, celiac disease and even cancer7.

References:

1. Food Nutr Sci. 2013 Sep; 4(9A): 94–97.

2. Nutrients. 2016 Mar; 8(3): 128.

3. J Nutr Gerontol Geriatr.2013;32(1):1-23. 

4. Sci Rep.2017 Dec 7;7(1):17134. 

5. PLoS One. 2011; 6(10): e25736.

6. GM Crops & Food. Biotechnology in Agriculture and the Food Chain. 2013. Vol 4 Issue 3: Special Issue on Consumer Affairs. 

7. Journal of Biological Physics and Chemistry. 2015. 15: 121-159.