3. Vegetable oils
Industrial produced vegetable oils (i.e. canola oil) are also a major health threat. Many of them are not suitable for frying because they are rich in polyunsaturated fatty acids. It is best to give them up at all and replace them with health oils. These include unrefined oils, rich in monounsaturated fats, like olive oil, grape seed oil or avocado oil.
It’s also much better to use cold oils (i.e. as a salad dressing) and reduce frying (whatever it may be). Steam or stewed dishes are definitely healthier.