It’s pressed from the seeds of a special variety of Brassica napus, a plant in the mustard family closely related to bok choi and turnips. Brassica napus’s unfortunate common name is rapeseed (from rapum, Latin for “turnip”). But that’s not its only problem. Rapeseed typically contains high levels of erucic acid (which makes oils go rancid quickly, is toxic in large doses, and may cause cancer) and glucosinolate (which tastes so bitter and unpleasant that it’s undesirable even in animal feed). But in the 1950s and 1960s, Canadian scientists began developing strains of it with lower levels of the problematic chemicals. In 1974, a University of Manitoba professor named Baldur Steffanson introduced a rapeseed variety with extremely low erucic acid and glucosinolate content that was dubbed canola, for CANadian Oil, Low Acid.

Thanks to the name (in Europe the oil is still called rapeseed oil, or even—take this, marketers—rape oil), canola growers have spoken carefully when describing their product. “Canola is genetically totally different from rapeseed,” says Sheri Coleman, director of marketing for the Northern Canola Growers Association, despite the fact that the plants are the same species. A particularly vicious e-mail rumor that falsely blamed canola for mad cow disease and claimed it was the source of mustard gas made the rounds a few years back, and public misconceptions still plague producers. In reality, canola oil was granted a qualified health claim by the FDA that its low saturated-fat content reduces the risk of heart disease.

There is some legitimate controversy, however. More than 60 percent of the canola crop in Canada (where most of it is grown) comes from genetically modified seed, making it illegal in Europe and opposed by activists throughout the world.