aturated fats are not affected much by oxidation because they are very stable and have a high degree of resistance to oxidation. Monounsaturated fats, since they have a pair of missing hydrogen atoms are somewhat vulnerable to oxidation. Polyunsaturated oils, which are missing several pairs of hydrogen atoms, are very unstable and highly reactive to oxidation.

Polyunsaturated oils are so vulnerable that even at room temperature and in subdued light oxidation occurs inside the bottle. All polyunsaturated vegetable oils sold at grocery stores have become rancid to some degree before you even bring them home. Because the oils have been highly refined and deodorized you can't smell or taste anything, but the free radicals are there, waiting to attack your body.

If you store the oil in the cupboard at room temperature, the oxidation process continues. When you open the bottle and expose the oil to oxygen in the air, oxidation is accelerated. If you leave it out on the counter where it is exposed to light, oxidation progresses even faster. To make matters worse, if you use the oil in cooking you greatly accelerate the rate of oxidation and free radical formation. For this reason, you should never use polyunsaturated oils in cooking. Most people do this all the time. They buy a bottle of soybean oil and keep it in the cupboard for months and use it along with margarine for all their cooking. It's no wonder why cancer, diabetes, Alzheimer's and other diseases associated with free radicals are becoming more and more prevalent nowadays.One of the best ways to prevent these diseases is to not use polyunsaturated oils. Because of this, I don't eat polyunsaturated vegetable oils at all or anything made with them. I know too much about the damage they can do to the body. I recommend that if you have any polyunsaturated vegetable oils (corn oil, soybean oil, safflower oil, etc.) in your home that you throw them out. Don't even consider using them; get rid of them now. Throw away salad dressings made with these oils as well.

Olive oil is all right to use because it is primarily a monounsaturated fat and, therefore, much more stable than polyunsaturated oils. I recommend you use it mostly for salads. You may also use it for low temperate cooking. Store it in the refrigerator and use it up within a month or so.

The only fats you should use for moderate to high temperature cooking are saturated fats like lard, butter, and coconut oil. Lard has a high smoking point so it makes a good high temperature cooking oil. Coconut oil is highest in saturated fat so it makes an excellent all-purpose cooking oil. It is very stable under heat, but has a relatively low smoking point, so keep frying temperatures below 350 degrees F.