Canola oil was developed from the rape see, a member of the mustard family. Rape seed is considered unsuited to human consumption because it contains a long-chain fatty acid called erucic acid, which under some circumstances is associated with fibrotic heart lesions. Canola oil has a high sulphur content and goes rancid easily. Baked goods made with canola oil develop mold very quickly.
During the deodorizing process, the omega-3 fatty acids of processed canola oil are transformed into trans fatty acids, similar to those in margarine and possibly more dangerous. A recent study indicates that “heart healthy” canola oil actually creates a deficiency of vitamin E, a vitamin required for a healthy cardiovascular system. Other studies indicate that even low-erucic-acid canola oil causes heart lesions particularly when the diet is also low in saturated fat.
Sally Fallon, Nourishing Traditions.