Question: "I've heard that parts of olive oil turn into trans fats when heated. Is this true?"—Sheila Nazarro, via e-mailAnswer: I'm not sure how that rumor got started, but I can emphatically tell you this: Olive oil does not develop harmful artificial trans fats when heated to higher temperatures, like those used for sautéing or pan-frying. You need a chemistry lab—not a sauté pan—to alter the formation of a chain of fatty acids like those in oil. (To turn a fatty acid trans, extra hydrogen atoms must be added, which causes molecules on the chain of fatty acids to flip from one side to the other.) Olive oil—or any pure, nonhydrogenated vegetable oil—is an ideal, healthy medium for sautéing aromatics, roasting vegetables, or using in a spice rub for meats.
Watch: Nutrition Essentials on Healthy Fats