Perhaps because we offer organic cooking oils – extra virgin olive and macadamia nut – we regularly get questions about our stance on canola oil.
Accordingly, we asked Vital Choices contributor Susan Allport to address canola oil's history and attributes, and dig into some of the alarming anti-canola assertions that have proliferated on the Internet.
She is an experienced science writer who contributes to The New York Times among other publications.
More to the point, Susan is well versed in the subject of nutritional fats, having authored The Queen of Fats, which we consider among the best books on the topic of omega-3s.
To read her enlightening account, see “Canola Oil: Poisonous Poseur or Positive Health Partner?”
Shifting reasons for Canola's healthy reputation
When it was first introduced, canola oil was touted for its unusual and supposedly superior fatty acid profile, which makes it low in saturated fats and high in monounsaturated fats.
At the time, saturated fat was being demonized as bad for heart health, while olive oil was being lionized for its alleged heart-health benefits, which were attributed to its high percentage of monounsaturated fats.
But both of those nutritional tides seem to be turning.
Evidence is showing that saturated fat is not the villain that Professor Ancel Keys' famous but unscientific “Seven Countries Study” made it appear. The distortions that stemmed from Keys' selective use of epidemiological evidence prompted US authorities to mount a woefully misguided campaign against animal fats (see “Comic Critique of the Heart Disease Consensus”).
And monounsaturated fats—which population studies have linked to reduced heart risks—are losing some of their cardiovascular luster.
New research indicates that the associations seen between olive oil and reduced heart risks probably stem more from the arterial effects of the potent antioxidants in extra-virgin and virgin grade olive oils, rather than their abundant monounsaturated fats (See “Mediterranean Myths” and “EVOO Confirmed as Best Cardiac Choice”).
So why does canola oil retain a heart-healthy reputation?
Canola and omega-3s
Nowadays, canola is praised for its unusually high proportion of omega-3 fatty acids. The omega-3s in canola oil are not the same omega-3s found in our cell membranes and in fish and fish oil, called EPA and DHA.
Instead, the omega-3s in canola oil and all other land-based plant foods come in the form of a shorter-chain molecule called alpha-linolenic acid (ALA), only 5 to 10 percent of which gets converted to essential EPA and DHA. (The remainder is burned as cellular fuel.)
But—absent an overload of competing omega-6 fats from seeds—modest intake of leafy greens and grass-fed livestock provides enough omega-3 ALA to allow humans to survive and thrive.
Some scientists hypothesize that “marine” omega-3s from fish, shellfish, and aquatic plants enabled and accelerated the evolution of early hominids that dwelled near the rivers, lakes, and coastal regions of East Africa. Regardless of whether that proves true, omega-3 ALA from leafy greens—and from prey animals that graze on ALA-rich grasses—has clearly been the main source of omega-3s for most peoples around the world.
Because American's diets are so low in omega-3s—and so high in the pro-inflammatory omega-6 fats that compete with omega-3s for space in our cell membranes—any dietary omega-3s, no matter how metabolically inefficient they may be, enhance health.
At about 11 percent, the omega-3 (ALA) content of canola oil far exceeds that of all other common cooking oils except soybean oil, which contains about 8 percent omega-3 ALA.
Flax oil contains a whopping 57 percent omega-3 ALA, which makes it a great choice for salad dressings or to drizzle over foods. But because flax oil has a very strong nutty flavor, and because ALA is vulnerable to heat damage, flax oil is unsuitable for cooking applications. (University tests commissioned by the Canola Council of Canada indicate that the ALA in canola oil is not significantly damaged or converted to trans fat by normal cooking temperatures.)
And when it comes to redressing the omega-6 overload in American diets, canola is far preferable to soy oil. Canola oil contains only about 21 percent omega-6 fatty acids, while soy oil contains about 54 percent omega-6 fatty acids, and corn and sunflower oil contain 57 and 71 percent omega-6s respectively.
Instead of being high in omega-6 fats, canola is high in monounsaturated fats. About 61 percent of canola oil is monounsaturated oleic acid, versus only about 23 percent of soy oil.
By comparison, olive oil contains about 75 percent monounsaturated fat, while macadamia nut oil contains about 78 percent monounsaturated fat.
(Note: these aren't the only oils dominated by monounsaturated fat. Most safflower oil now comes from a hybrid, “high-oleic” version of the plant, so it contains about 77 percent monounsaturated fat and only about 14 percent omega-6 fats. The same is true of high-oleic sunflower oils, which can be found in natural food markets.)
In the past, we've argued that because American diets are so overloaded with omega-6s, it makes sense to use cooking oils that are very low in these fats. And this is why we've chosen to offer only olive oil and macadamia nut oil, not canola oil.
But canola oil is here to stay, and we agree with Susan Allport that it can play a healthful role in Americans' diets.