<p>The article seems sloppy. Corn oil is predominantly polyunsaturated (the kind of fat that is being criticized), but canola oil is predominantly monounsaturated. (Note that the leaves of the plant whose seeds produce canola oil are edible.)</p>
<p>“Vegetable oil” can be of various types, some of which are predominantly polyunsaturated (corn, cottonseed, high linoleic safflower), some monounsaturated (olive, canola, high oleic safflower), and some saturated (coconut, palm).</p>
<p>Trans-fats from hydrogenated oils are generally considered unhealthy and should be avoided.</p>