By Dr. Mercola
Anytime you cook food, you run the risk of creating heat-induced damage. The oils you choose to cook with must be stable enough to resist chemical changes when heated to high temperatures, or you run the risk of damaging your health. One of the ways vegetable oils can inflict damage is by converting your good cholesterol into bad cholesterol—by oxidizing it.
When you cook with polyunsaturated vegetable oils (such as canola, corn, and soy oils), oxidized cholesterol is introduced into your system. As the oil is heated and mixed with oxygen, it goes rancid. Rancid oil is oxidized oil and should NOT be consumed—it leads directly to vascular disease.
Trans fats are introduced when these oils are hydrogenated, which increases your risk of chronic diseases like breast cancer and heart disease. But the problems don't end there.
The majority of these vegetable oils (at least in the U.S.) are made from genetically engineered crops, and they're heavily processed on top of that. So not only are the polyunsaturated fats being oxidized, but these oils also contain other toxins, such as glyphosate and Bt toxin found in genetically engineered corn and soy.
Glyphosate is the active ingredient in the broad-spectrum herbicide Roundup, which is used in very large amounts on all of these crops. So there are a number of reasons for avoiding vegetable oils, but the fact that they're oxidized is clearly a high-priority one.
Another important factor is that most vegetable oils are high in omega-6 fats and it is the ratio of omega-3 to omega-6 fats that plays a powerful role in determining many illnesses. So if you are consuming large amounts of vegetable oils you will seriously distort this vital ratio and increase your risk of many degenerative diseases.
The One Cooking Oil That Takes the Heat: Coconut Oil
Of all the available oils, coconut oil is the oil of choice for cooking because it is nearly a completely saturated fat, which means it is much less susceptible to heat damage. And coconut oil is one of the most unique and beneficial fats for your body.
Although mainstream media portrays olive oil as the "healthiest oil," this title does not extend to cooking. Olive oil is primarily a monounsaturated fat, which means it has one double bond in its fatty acid structure. Although a monounsaturated fat is inherently more stable than a polyunsaturated fat, the overabundance of oleic acid in olive oil creates an imbalance that has been associated with increased risk for breast cancer and heart disease.
However, olive oil is a smart fat to include in your diet in a non-heated form, such as in a salad dressing. By heating virgin olive oil to over 200 to 250o F,1 you are running the risk of creating oxidized oil that can do your body more harm than good. One way to help prevent your olive oil from becoming rancid is add one drop of astaxanthin to it, according to industry expert Rudi Moerck.
As you can see in the chart below, coconut oil contains the most saturated fat of all edible oils—but don't let the term "saturated fat" scare you away. Saturated fats are not the cause of heart disease, in spite of what you may have heard. Whenever you need a cooking oil, a good-quality coconut oil can be used in place of any other oil type, for any kind of recipes.
Just realize, coconut oil can vary widely in terms of the variety of coconuts used and the type of processing, and these factors will greatly impact the health benefits of the oil. Most commercial coconut oils are refined, bleached, and deodorized (RBD) and contain chemicals used in processing.
Make sure that your coconut oil is certified organic, which means it contains no genetically engineered ingredients, and that it's free of bleaching, deodorizing, refining, or hydrogenation.
For more in-depth information on this topic, see this special report on benefits of coconut oil.
Type of Oil