Q. I heard that the heat from cooking makes oil dangerous. Is oil safe to cook with?
A. “Oil is safe to cook with under usual conditions,” says Alice H. Lichtenstein, DSc, senior scientist at Tufts’ HNRCA and executive editor of Tufts Health & Nutrition Letter. “The primary concern I suspect your source was referring to is oxidation, a natural process that occurs when one molecule gives up an electron to another as part of a chemical reaction. The process creates free radicals, which can cause damage that could increase risk for problems such as heart attack, stroke, and cancer. Oils and oily foods (like nuts and whole grains) can oxidize over time, even without cooking. Exposure to light, heat, and air speed up this process. Keep oils in a cool, dark place, and store nuts, whole-grain flours, and fish-, nut-, and seed oils in the refrigerator to keep them fresh longer. Repeatedly-heated cooking oil has been found to have more signs of oxidation, so it’s best not to reuse cooking oil.”
“To counteract free radicals, whether they are formed by normal metabolism in the body or in oils, eat plenty of plant foods. Fruits, vegetables, and other plants have antioxidants that can counteract free radicals in the body.”