我只是说canola oil好，没泛指所有的植物油都好。美国市场上的vegetable oil就是豆油。Canola oil是从加拿大开发的底芥酸油菜籽榨的油（=Canadian oil, low acid），与旧时国内的菜油不一样。
Canola oil的饱和脂肪酸比橄榄油要低，monounsaturated fat与你用来炒菜的大妈级橄榄油（light and extra-light olive oil）不相上下。你要想要得到更多橄榄油的benefit要用超级处女橄榄油，其monounsaturated fat更高一点，但其主要好处来自溶解在里面的别的物质，受热就破坏了。用它来炒菜是暴殓天物，应该用来拌菜。
超级处女橄榄油比canola oil贵得多。Canola oil比橄榄油耐高温。所以最好使用canola oil炒菜，用超级处女橄榄油来拌菜，蘸面包，或直接用小酒杯喝。这样可以确保你的倌长久健康。
我也引用一下Wiki
Canola oil is low in saturated fat, is high in monounsaturated fat, and has a beneficial omega-3 fatty acid profile; it has well established heart health benefits[21] and is recognized by many health professional organizations including the American Dietetic Association, and American Heart Association, among others.[22][23][24][25] Canola oil has been authorized a qualified health claim from the U.S. Food and Drug Administration[26] based on the theory that the absence of saturated fats in the oil content makes it a healthy food, consumption of which cannot cause coronary heart disease.
http://en.wikipedia.org/wiki/Canola_oil