“Poisonous.” “Toxic.” “Avoid like the plague.”
Is canola oil healthy? For some reason, people love to hate it. Really hate it.
That’s partly because the canola plant is derived from rapeseed, which contains a toxic compound called erucic acid and bitter-tasting compounds called glucosinolates.
But in the 1970s, Canadian scientists—using conventional breeding—developed a type of rapeseed that has very low levels of erucic acid and glucosinolates. Since then, canola has become the second most popular oil in the United States. (It’s a distant second to soybean oil.) But, at least on some websites, the idea that canola is “toxic” has stuck.
Chefs prize canola for its neutral taste. And health experts recommend it because it’s very low in saturated fat and high in mono- and polyunsaturated fats. That means it helps lower LDL (“bad”) cholesterol.
So why all the vitriol? Some critics worry that most canola plants are now genetically engineered. So are most soybean plants, but that’s a subject for a different article.
Is canola oil healthy? Here’s the lowdown on the other main charges.
Charge: Canola oil is unfit to eat.
The Facts: “Are you cooking with motor oil?” asks Al Sears, one of the Internet’s most vocal opponents of canola oil (alsearsmd.com).
Sears, a Florida physician who specializes in what he calls “integrative, anti-aging medicine,” warns that canola oil has been used as an engine lubricant and in synthetic rubber and ink.
But people have been using edible fats and oils for soap, lubrication, and fuel for thousands of years. Even coconut oil, which Sears touts, is used to make soap and shampoo. So is Sears cooking with shampoo?
Charge: Canola oil damages the heart.
The Facts: Critics are confusing canola with rapeseed. The high level of erucic acid in rapeseed did cause lesions in the hearts of a rare breed of laboratory rat, says Sean O’Keefe, a professor of food science at Virginia Tech.
“But there was no damage to the hearts of other strains of rats or other animals,” he adds. “After many studies, the researchers realized that their data was accurate only for that inbred rat and certainly not for humans. And, anyway, canola oil doesn’t have enough erucic acid to matter.”
Charge: Canola oil stiffens cell membranes, causes kidney damage, and leads to premature death.
The Facts: All of that did happen when researchers fed canola oil—as the only fat in the diet—to a special strain of rat that easily develops high blood pressure and suffers strokes.
But that doesn’t mean anything about what happens in people, points out physiologist Paul Lewandowski, an assistant professor and researcher at Deakin University in Australia.
“Unlike humans, this strain of rat absorbs toxic amounts of phytosterols from canola oil, which may account for some of the oil’s toxicity to it,” he explains.
Researchers haven’t had reason to do long-term trials on toxicity in humans. But “based on several human intervention trials we have conducted, there is no evidence to suggest that the typical consumption of canola oil is unhealthy,” notes Peter Jones, Canada Research Chair in Nutrition and Functional Foods at the University of Manitoba.
Charge: Canola is one of the most chemically altered oils.
The Facts: Not true, says Jennifer Marchand, who supervises oil processing at Cargill, the largest oil processor in the United States.
“We don’t process canola oil any differently than other seed oils,” she says. Cargill uses essentially the same machinery and methods to produce canola, soy, corn, and sunflower oil, notes Marchand.
Charge: Canola oil contains LDL-raising trans fat.
The Facts: “The use of heat during the processing of vegetable oils can create trans fats,” explains O’Keefe, whose 1994 study at the University of Florida has fueled some of the fears about trans in canola. “But these particular trans fats haven’t been tested to see if they raise LDL,” he adds. “And the amounts in canola are usually quite small.”
In fact, a 2002 survey by the Food and Drug Administration found trivial amounts of trans fat—0.02 grams and 0.07 grams per tablespoon—in two major brands of canola oil. The soybean oils the FDA tested had about the same tiny amounts.
Sources: Am. J. Clin. Nutr. 100: 88, 2014; J. Food Lipids 1: 165, 1994; Lipids 39: 11, 2004.
This article was originally published in 2014 and has been updated.