It is cultivated in northern climates (primarily in Canada, Germany, France, and the Netherlands) for the production of animal feed, vegetable oil for human consumption, and biodiesel. Rapeseed is a major crop in India, grown on 13% of cropped land there. According to the USDA, rapeseed was the third leading source of vegetable oil in the world in 2000, after soy and palm. The same source calls rapeseed the world's second leading source of protein meal, although only one-fifth of the production of the leading soy meal. In Europe, rapeseed is primarily cultivated for animal feed (due to its very high lipidic and medium proteinic content), and is the leading option for Europeans to avoid dependence from the American soya, as well as to avoid importation of GMO soya beans.
Natural rapeseed oil contains erucic acid, which is mildly toxic to humans in large doses but is used as a food additive in smaller doses. Canola is a specific variety of rapeseed bred to have a low erucic acid content. Canola was developed in Canada and its name is a combination of "Canada" and "Oil". The name was also chosen partly for obvious marketing reasons.
The rapeseed is the valuable, harvested component of the crop. The crop is also grown as a winter-cover crop. It provides good coverage of the soil in winter, and limit nitrogen run-off. The plant is ploughed back in the soil or used as bedding.
Processing of rape seed for oil production provides a rapeseed animal meal as a by-product. The by-product is a high-protein animal feed, competitive with soya. The feed is mostly employed for cattle feeding, but also for pigs and chicken (though less valuable for these). The animal by-product has a low content in glucosinolates (responsible for metabolism disruption in cattle and pigs).
Rapeseed has been linked with adverse effects in asthma and hayfever sufferers. Some suggest that oilseed pollen is the cause of increased breathing difficulties. Others suggest that it is the inhalation of oilseed rape dust that causes this, and that allergies to the pollen are relatively rare. There is also some recent evidence that the extensive use of this and similar vegetable oils in food is leading to a significant increase in cases of macular degeneration of the eye.
Some varieties of rapeseed are sold as greens in asian groceries.
See also: biosafety