Fats in the diet are extremely important.
Without the right ones, our bodies can not function properly.
However... there is a lot of confusion out there about the health effects of different fats and oils.
One cooking fat that is heavily marketed as a healthy choice is canola oil.
It is low in saturated fat and high in unsaturated fats, including omega-3 fatty acids.
The manufacturers call it the "world's healthiest cooking oil" - although some experts disagree.
This article takes an in-depth look at canola oil and how it can affect your health.
Back in the day, an oil called rapeseed oil was often used for industrial purposes.
It was cheap to produce, but people couldn't eat it because it contained some unfavorable substances:
- Erucic acid: a fatty acid that caused heart damage in some rat studies ().
- Glucosinolates: bitter compounds that made the oil taste bad ().
A bunch of Canadian scientists wanted to turn rapeseed oil into an edible oil, so they used selective breeding techniques to "create" seeds that contained less of these harmful, bitter substances.
This is how canola was born... but "Canola" is a marketing term. It stands for Canadian Oil (some believe it stands for Canada Oil, Low Acid).
Canola is actually not a unique plant. It's just a name for rapeseeds that have been bred to be low in these undesirable compounds.
Since the year 1995, biotech giant Monsanto has manufactured rapeseeds that are genetically engineered to be resistant to the herbicide RoundUp.
Today, about 90% of the world's canola crop is genetically modified.
Bottom Line: Canola oil is extracted from rapeseeds that have been bred to contain less of some unfavorable substances. Most of the world's canola crop is genetically modified.
If a picture speaks a thousand words, a video can speak a million.
This short shows how canola oil is made. I recommend you watch it:
I don't know about you... but this certainly doesn't look "natural" to me.
It's certainly nothing like the simple processes used to make other popular fats/oils, like butter, olive oil or coconut oil.
The mere fact that it is exposed to high heat should turn you away from this oil. It is high in polyunsaturated fats, which are very sensitive to high heat and easily become oxidized (rancid).
A toxic solvent called hexane is used to extract the oil from the seeds. Trace amounts of hexane have sometimes been found in cooking oils.
During this highly unnatural manufacturing process, some of the oil becomes damaged. You just can't tell because the oil is also deodorized, which removes the smell.
One study analyzed canola and soybean oils found on store shelves in the U.S. They found that 0.56% to 4.2% of the fatty acids in them were toxic trans fats ().
This is not listed on the label, unfortunately.
Artificial trans fats are incredibly harmful and associated with many serious diseases, especially heart disease... the biggest killer in the world (, ).
However, keep in mind that cold-pressed and organic canola oil has not gone through the same process and won't contain so many oxidized fats or trans fats.
Unfortunately, the great majority of rapeseed/canola oils are made with the industrial processing method.
Bottom Line: Canola oil is made with a highly unnatural processing method that involves high heat, deodorization and the toxic solvent hexane. Significant amounts of trans fats are formed during this process.
Like most highly refined oils, canola oil is low in essential nutrients.
However, it does contain a little bit of the fat soluble vitamins E and K.
A typical fatty acid composition of canola oil is ():
- Saturated: 7%.
- Monounsaturated: 63%.
- Polyunsaturated: 28% (with omega-6 and omega-3 in a 2:1 ratio).
Keep in mind that the exact figures and ratios can vary between different batches. According to conventional wisdom, saturated fat is bad and unsaturated fats are good, so according to that, the fatty acid composition is pretty much perfect.
However... there are a few things that need to be mentioned here.
Therefore, the low saturated fat content of canola oil is completely irrelevant, although it does allow for some excellent marketing slogans.
Canola oil is also high in monounsaturated fats, which are healthy. These are the fats found in large amounts in olive oil.
Now to the polyunsaturated fats... which is where the story gets interesting.
It is true that canola oil contains a balanced ratio of omega-6 and omega-3 fats.
However, keep in mind that although we need some amount of polyunsaturated fats, we absolutely .
Eating a lot of canola oil would raise your intake of polyunsaturated fats to unnatural levels, much higher than we were exposed to throughout evolution.
These fatty acids do get incorporated into cell membranes and are prone to oxidation, which can cause free radical chain reactions and damage important molecules like proteins and DNA (, ).
Also, the omega-3s in canola oil are ALA (Alpha Linolenic Acid).
ALA is the plant form of omega-3s, which is useless until it is converted into the animal forms - EPA and DHA.
Several studies suggest that humans are ALA to EPA and DHA, so the high omega-3 content of canola oil may not even be worth bragging about (, ).
Also keep in mind that during the nasty manufacturing process, much of these "heart healthy" polyunsaturated fats have already gone rancid and a large portion turned into trans fats!
Really... if you want a good source of omega-3s, then eat some fatty fish once or twice a week, or supplement with fish oil.
Bottom Line: Although canola is high in polyunsaturated fats, a large part of them have already gone rancid or turned into trans fats. It is low in saturated fat, which doesn't really matter because saturated fat is harmless.
We have several controlled trials where researchers feed people with canola oil, then observe what happens to blood markers like cholesterol.
In these studies, canola oil lowers total cholesterol, LDL cholesterol and triglyceride levels by up to 25%. It has very little effects on HDL levels (, , , , , ).
However, these studies are very short in duration (longest is 4 months, but most are 3-4 weeks), which is too short to determine anything about heart disease itself.
It's important to realize that cholesterol levels are a risk factor, not necessarily a cause of disease.
To know if something really prevents heart disease, then we need to measure heart disease itself, not just a blood marker that is associated with it.
Other studies that spanned a number of years have shown that even though vegetable oils lower cholesterol in the short term, they can increase heart disease risk in the long term (, ).
Therefore, I would take the cholesterol lowering effects of canola oil with a grain of salt. It is likely that consuming it has some other detrimental effect that outweighs the benefits of lowered cholesterol.
Seed- and vegetable oils are generally unhealthy. Conventionally produced rapeseed/canola oil is no exception.
If you can get your hands on organic, cold-pressed canola oil, then it won't be as high in oxidized fats and trans fats, so I suppose it is fine to consume.
But I definitely wouldn't make it a large percentage of calories and I would definitely NOT cook with it, as it is still too high in polyunsaturated fats.
Conventional canola oil (which is what most people are consuming) is low in nutrients, high in oxidized omega-6 fats, high in trans fats and the omega-3s happen to be in an inefficient form.
Overall, canola oil is not as bad as other vegetable oils (like soybean oil), but it is still far from being healthy. You would do much better eating olive oil or coconut oil instead.
When in doubt, keep this golden rule in mind: "Nature doesn't make bad fats, factories do!" - Dr. Cate Shanahan, MD.
If you want to learn more about which cooking oils to eat and which to avoid, then read this article here: Healthy Cooking Oils - The Ultimate Guide.