Over the past few weeks, I have received an increasing number of questions about cooking oils. Given the apparent confusion and misinformation out there, I’ve constructed this list of facts, FYIs, and tidbits I consider absolutely crucial.
1. Oils with high omega-3 content (i.e.: hempseed oil, flax oil, walnut oil) are unsuitable for cooking. They should only be used to make raw dips and sauces, salad dressing, or to drizzle on food once it has been cooked and plated. Once opened, these oils should be refrigerated (if possible, purchase them already refrigerated).
2. Deprogram the “all unsaturated oils are healthful” slogan out of your head that has been drilled into the American public for decades. Some of these unsaturated plant oils offer large quantities of omega-6 fatty acids. Although omega-6 fatty acids are necessary (without them, our blood wouldn’t clot), the average American currently consumes too much of them, which is bad news from an inflammation standpoint (high cellular inflammation is theorized to be a main culprit behind several chronic diseases).
The worst omega-6 offenders? Corn and cottonseed oils. Not surprisingly, these oils are subsidized by our government, and ubiquitous in processed and fast food. Scary PS: Unless labeled ‘organic’, you can count on them also being genetically modified.
3. Make amends with coconut oil. It has been unfairly vilified for decades by government guidelines and federal health organizations, but there are significant amounts of clinical research which shows that its main fatty acid –=- lauric acid — helps maintain healthful cholesterol levels. Try it in savory recipes (like chili) or use it to make stovetop popcorn at home. Since coconut oil has a very high smoke point, its fatty acids can withstand high degrees of heat without oxidizing (once a fat oxidizes, its healthful benefits are gone).
4. Tread carefully with canola oil. The seed from which it is extracted — rapeseed — receives heavy pesticide treatment And, unless labeled ‘organic’, it is very likely genetically modified. Additionally, most canola oil is refined and undergoes a significant amount of high-heat processing, which worries me since its fatty acids are rather fragile. The occasional tablespoon of canola oil in a baking recipe that serves 12 is no cause for concern, but I do not recommend it as a staple cooking oil.
5. Although we hear a lot about the importance of buying some produce organic, the same is true for all oils. Many pesticides are fat-soluble, which means they accumulate in a plant’s fatty acids and oils.
6. Light and air can quickly deteriorate oils’ healthful properties, particularly olive oil (which contains a high level of antioxidants). Leaving an opened bottle of olive oil on a counter for just a few minutes can have a detrimental effect on its antioxidant content. To minimize UV light damage, purchase olive oil in tin cans whenever possible.
7. A lot of commercial plant-based oils (mainly corn, sunflower, and safflower) undergo a heavy amount of processing, including deodorizing (to provide a neutral smell), bleaching, and anti-foaming agent treatment. For optimal health, these oils are better off consumed in an unrefined state (which, in most cases, isn’t available for purchase). Keep in mind, too, that in an unrefined state, these oils can withstand much lower cooking temperatures, and should also ideally be stored in the refrigerator.
The deodorizing and bleaching processes are particularly worrisome as they expose these oils to temperatures well past their respective smoke points, thereby increasing the likelihood of their fatty acids undergoing oxidation and turning into harmful compounds. Although the deodorizing treatment does add antioxidants, these are not always the same ones originally found in the oil. Anti-foaming agents, meanwhile, are silicone-based compounds (one of the most common anti-foamers, polydimethysiloxane, is the main ingredient in Silly Putty).
My general rule for oil? Use ones extracted from foods which are naturally high in fat. Not coincidentally, nut, seed, olive, and avocado oils are far better choices than corn, vegetable, or cottonseed oils.
8. I reported on this over three years ago, but find that it continues to be worth repeating: a lot of commercial olive oil is not 100% olive oil (read this article from The New Yorker for all the details). This, of course, has huge implications from a health standpoint since these oils don’t provide the same heart-healthy fatty acid profile and antioxidant content of real olive oil.
To make sure you’re getting real olive oil, I suggest one of the following: purchase from these producers certified by the California Olive Oil Council, look for this International Olive Oil Council stamp of approval, or at the very least look for this Protected Destination of Origin symbol (which I learned about from my friend Robyn Webb), which guarantees that the olive oil you are buying was produced, processed, and bottled in the same estate (thereby eliminating the possibility of shady tampering).
One last important note: I recommend that the majority of your daily fat content come from whole foods that contain fats (i.e.: nuts, seeds, olives, fatty fish, coconut, unsweetened cocoa), as these foods deliver healthful oils along with bonus phytonutrients, fiber, vitamins, and minerals.
Congratulations – you are now a graduate of Cooking Oils 101… with honors!