Canola is a type of edible oil derived from plants initially bred in Canada by Keith Downey and Baldur Stefansson in the 1970s. The oil is extracted from a group of cultivars of rapeseed variants from which low erucic acid rapeseed oil and low glucosinolate meal are obtained. The word "canola" was derived from "Canadian oil, low acid" in 1978. The oil is also known as "LEAR" oil (for Low Erucic Acid Rapeseed).
Canola was developed through conventional plant breeding from rapeseed, an oilseed plant with roots in ancient civilization. The word "rape" in rapeseed comes from the Latin word "rapum," meaning turnip. Turnip, rutabaga, cabbage, Brussels sprouts, mustard and many other vegetables are related to the two canola species commonly grown: Brassica napus and Brassica rapa. The negative associations with the word "rape" resulted in the more marketing-friendly name "Canola". The change in name also serves to distinguish it from regular rapeseed oil, which has much higher erucic acid content.
Canola oil has been claimed to promote good health due to its very low saturated fat and high monounsaturated fat content, and beneficial omega-3 fatty acid profile. The Canola Council of Canada states that it is completely safe and is the "healthiest" of all commonly used cooking oils. It has well established heart health benefits and is recognized by many health professional organizations including the American Dietetics Association, and American Heart Association, among others. Canola oil has been authorized a qualified health claim from the US Food and Drug Administration based on its ability to reduce the risk of coronary heart disease due to its unsaturated fat content.
Genetically modified canola which is resistant to herbicide was first introduced to Canada in 1995. Today 80% of the area of canola is sown with genetically modified canola.
In the UK
You can buy excellent cold-pressed extra virgin rapeseed oil in the UK and the one I use is called R-Oil, which is produced in Lower Swell in the Cotswolds. You can search for your nearest stockists by typing in your postcode.
Although the classic Mazola oil product is produced from corn (maize), Mazola also produce an organic and a non-organic rapeseed oil labelled as vegetable oil. You need to study the small-print to discover that it's a rapeseed product, though there is a clue in the flower picture on the bottle.