Q: Will heating a "healthy" oil turn it "unhealthy"?

When heated above certain temperatures, "healthy" oils can become unhealthy. Polyunsaturated fats (walnuts, canola oil, corn, soybean, safflower) exposed to heat can generate high levels of toxic aldehydeproducts that promote heart disease and cardiovascular disease. The more omega-3 fatty acids in an oil, the more likely it is to be damaged by heating, thus changing the fatty acids into harmful substances. Oils high in monounsaturated fats, such as olive oil and peanut oil, remain stable when heated and will not produce these toxic results.