Welcome to article one of our series on canola oil, the most sold cooking oil around the world.
A typical consumer will recognize the name from the back of their chip bag. Few know the side effects of this refined, bleached, and deodorized oil.
What is canola oil?
In response to anti-saturated fat propaganda, the packaged food industry began pushing “healthier” alternatives to traditional saturated fats like butter and lard. In place of these naturally occurring fats, government agencies and oil refiners began pushing polyunsaturated fats from soybeans and corn.
As data came in about the inflammatory effects of these polyunsaturated fats, the same agencies and refiners began promoting new fats in their stead. Coinciding with this shift, the movement behind the Mediterranean diet began taking hold. When researchers discovered lower mortality in certain regions of Greece, Italy, and Spain, assumptions began flying.
Out of these hypotheses, increased use of the monounsaturated fats from olive oil gained traction.
Due to the relatively high processing costs of olive oil, manufacturers turned to other cheap vegetable oil sources instead.
At the time, rapeseed oil was cheaply produced in Canada. Due to a few heart-damaging side effects, however, the FDA banned rapeseed oil for human consumption earlier in the century. In response, refiners recruited a group of scientists to genetically modify the oil-producing seed. If successful in removing the known deadly fatty acids from rapeseed oil, refiners could market a new “health-conscious” product.
As a result of their success, low erucic acid rapeseed (LEAR) oil was born. Prior to hitting the market, manufacturers slapped a sexier name on the engineered fat. As an ode to its national origins, Canadian oil became “canola”.
How is it processed?
Canola oil is commercially known as a refined, bleached, and deodorized (RBD) oil. This acronym describes its processing.
Canola seeds are first crushed to expel oil. After crushing, seeds are treated with the chemical solvent hexane. Hexane extracts the maximum volume of oil from the seeds to minimize processor waste.
Not all hexane is removed from this process. In every bottle of RBD canola oil, residual hexane remains.
Following hexane treatment, the oil is bleached to remove its unfriendly dark color. Finally, canola oil is treated with high heat to boil off its unpleasant odors. In this final step the oil reaches temperatures as high as 455 degrees F. When exposed to this high heat, unsaturated fat converts to trans-fat isomers.
Interestingly, these trans fats are not reported on food labels. In independent studies, researchers have found these trans-fats account for nearly 4% of fat in canola oil. The recommended intake of unnatural trans-fats is 0 g.
Side Effect #1, Canola and the Brain
The Alzheimer’s Center at Temple University’s Katz School of Medicine performed an animal study on canola oil and brain function.
These researchers compared the effect of canola oil on otherwise identically fed mice.
Initial findings were quite obvious: the canola mice got fat. Surprisingly, these researchers disproved earlier studies suggesting canola oil had no effect on weight gain.
Subsequent findings were significantly more alarming. In the brain of canola-fed mice, researchers discovered negative effects on memory, synaptic integrity, and ratios of certain protein markers in Alzheimer’s mouse models.
In other words, when mice ate a canola-enriched diet, their brain began deteriorating.
Now that we’ve introduced our series topic, we’ll return next Monday with more side effects of canola oil consumption.
Until then, start looking through your pantry. If anything uses canola, soybean, or another seed oil, throw it out.
In its place, use virgin, unrefined, or cold-extracted oils. Grass-fed ghee, butter, and lard are great animal-based cooking oils. If you’re looking for non-animal based oil, we recommend unrefined coconut oil.
Lauretti et al. Effect of canola oil consumption on memory, synapse and neuropathology in the triple transgenic mouse model of Alzheimer’s disease. Nature Scientific Reports. 2017.
Crosby, Guy. Ask the Expert: Concerns about canola oil. Harvard School of Public Health, The Nutrition Source.