Every diet should contain some form and a certain amount of fat. All fats and oils are not the same. Some are considered healthier than others.
Research has shown that a diet high in oleic acid, such as the famous olive oil-rich Mediterranean diet, is considered healthier than others. Traditionally the boundaries of edible oils were set as the more expensive olive oil on the one side and the cheaper palm oil on the other. South African sunflower oil lies somewhere in-between.