Few foods have been the subject of more distortions than the oil from this hybrid plant 03/24/2008
Susan Allport is an award-winning science writer for The New York Times and other publications.
Susan wrote the acclaimed book The Queen of Fats: Why Omega-3s Were Removed From The Western Diet and What We Can Do To Replace Them (University of California Press, 2006), and has appeared on Oprah & Friends Radio and NPR's "Science Friday" and "The Splendid Table". For more, visit susanallport.com.
Most urban myths are pretty harmless. Think of the one about a certain coffee chain adding nicotine to its hot drinks. Or the sedative effects of eating turkey… or the origins of Santa Claus.
But the urban myth about canola oil: that it is a toxic food, unfit for human consumption, is anything but benign.
Americans consume too many omega-6 fats and too few omega-3s: an imbalance that has been linked—through well-defined, causal mechanisms — to many of our most common illnesses, including heart disease.
Canola oil, developed in Canada in the 1970s from a strain of rapeseed that is low in erucic acid, and introduced into the United States in 1985.
And its introduction has already made some inroads in correcting the great imbalance of omega-6s to omega-3s in American diets, according to an analysis by researchers at Pennsylvania State University.
These researchers reported a significant drop in the ratio of omega-6s to omega-3s in the American food supply in the years 1985 to 1994 (from 12.4:1 to 10.6:1). That's still far from an ideal, of about 4:1, but canola oil, with a ratio of just 2:1, makes that ideal possible.
Whether this healthy trend continues, though, and whether it benefits any single individual depends on that individual's acceptance of canola. Does he think of it as the great Con–ola, as one website describes canola, and avoid, therefore, every food with canola as one of its ingredients? Or does she trust the American Heart Association and the Mayo Clinic, who support the healthfulness of canola oil?
Canola canards proliferate on the Web
As someone who frequently encounters people who are virulently opposed to canola oil—whenever I speak or appear on a call-in radio show, I thought I would try to get to the bottom of canola's sinister reputation. I began by typing in “canola oil” and “negative effects” on my browser and up popped more than 200,000 web pages.
Many of these sites repeat the baseless, outlandish claims that canola oil is an ingredient of mustard gas … that the Canadian government paid fifty million dollars for GRAS (generally recognized as safe) status in the US ... and that canola oil causes emphysema, respiratory distress, anemia, constipation, irritability, blindness, as well as hair loss.
Others knock canola because it is usually sold as a refined oil or because it is a genetically modified (GM) plant.
Consumers worried about the effects of refining can always choose expeller pressed or cold-pressed canola oil.
And yes, there are GM forms of canola, as of many plants, but canola was originally developed by traditional plant breeding methods.
A few Web sites mention the fact that the large amounts of omega-3 ALA in canola oil are prone to isomerization, or becoming trans fats, during processing — which has indeed been a problem for canola-seed crushers in the past.
The heat of both “deodorization” (the final step in producing refined oils) and expeller pressing is great enough to cause isomerization of omega-3 ALA. The processors who crush the oil from canola seeds are well aware of this tendency now, and adjust the time and temperature of these procedures to keep trans-fat formation below 2 percent.
Isomerization and genetic modification are legitimate issues, but do they explain why canola has been singled out to become the stuff of urban legends?
I wasn't getting very far in my search, I realized. I certainly wasn't getting close to the kind of information that I as a science writer need in order to understand the reasons for such extreme views about a vegetable oil.
What, for instance, was the problem with erucic acid in the first place, such that it was bred out of rape seed plants by Canadian scientists? Had this fatty acid caused any problems in those populations in Northern Europe and Asia that had been using rape seed as a cooking oil for centuries? Is there anything to the claims by the Weston Price Foundation that canola oil is dangerous because of its low concentration of saturated fats (7 percent), a feature canola producers brag about?
And so I turned to someone who had practical experience with canola oil, someone who had actually raised animals on this fat in the 1960s and knew firsthand its long-term effects.
Dr. Joyce Beare-Rogers, a retired Canadian biochemist, was very surprised to hear about internet sites dedicated to disparaging canola oil, but there were problems, she explained, with using rape seed oil — and canola oil — as a sole source of dietary fat. The high levels of erucic acid in traditional rape seed oil caused experimental animals to develop lipidosis, an accumulation of triglycerides in their myocardium. Young animals aren't very good, it seems, at breaking down this unusual, 22-carbon, monounsaturated fat.
Erucic acid had never been a problem for populations in the past — because they had never had very much rape seed oil to use. But that would change with large scale cultivation in Canada.
Since scientists in Canada had already identified a low erucic acid strain of rape seed (one that was also low in glycosinolates, compounds that had prevented the use of the meal for animal feed), production was based on this new strain, and the oil given a new name—Canada + oil or “canola” — to signify its origin and new properties. That name, of course, also avoided the negative connotations of the word rape.
But even canola oil was found to cause health problems, Dr. Beare-Rogers continued—when it was made from seeds that had a very low percentage of saturated fats—3 percent. “Most people thought this was a good thing, but if you want to have normal cell membranes, you have to have sufficient saturates in the diet,” she went on. “Yes, animals are capable of making saturates,” she said in reply to my question. “But how well will they do it—especially if they are given large amounts of monounsaturates, as is the case with canola oil?”
At a meeting of the Canadian American Oil Chemists in 2002, Dr. Beare-Rogers did her utmost, she said, to persuade those oil producers who were trying to get the saturates in canola seeds as low as possible to aim instead for 7 percent — where canola is now.
We're still far from understanding what constitutes the perfect diet, my conversation with Dr. Beare-Rogers reminded me. And perhaps this is the reason for the online rumors about canola oil: people are suspicious, as they should be — as humans have always been — of a new food with which they have little experience. Researchers call this behavior neophobia, and it is evident in all omnivores, animals, like humans, that must eat a varied diet in order to get the many different nutrients they need to survive.
Canola oil is a Cinderella story, it is often said, with Canadian researchers turning the humble rape seed into a world wide commodity.
But for canola oil to have a happy ever after ending … for it to be the happy ending to the many medical problems that stem from our current imbalance of omega-6s and omega-3s, we need to see it as it is: an imperfect food all by itself (just like any other single food!).
And we should use canola oil as it should be used — as part of a balanced diet — balanced between omega-3s and omega-6s, as well as between saturates and unsaturates, where variety, as always, is the key.