For one thing, researchers did not know how much oil the subjects actually consumed. In four out of five countries, high levels of oleic acid offered women no protection against breast cancer. More research will certainly be undertaken. If you limit your use, as we advise, almost any oil will do. Olive oil is a fine choice, as are canola, safflower, peanut, and sunflower oils.
Olive oil is rich in tradition and history compared with canola.
You can, of course, buy olive oil that's nearly flavorless. Taste is a personal issue. This is almost impossible to calculate, even for a nutritionist. All vegetable oils are pure fat, and all are combinations of saturated and unsaturated fatty acids. Fatty acids vary in their degree of saturation and in the length of their molecules.