A Guide to Choosing Healthy Oils

Originally published in 2008

If you're not sure how to choose healthy oils for cooking, it's worth studying the essential differences between saturated, monounsaturated, and polyunsaturated fatty acids. Once you understand the basic characteristics of these fatty acids, you'll know which commonly available oils are good for your health, and which ones are best limited or avoided altogether.

The fundamental differences between the three types of fatty acids that are found in all commonly available oils are as follows:

Saturated fatty acids pack together tightly, making oils that contain a large percentage of them extremely stable when exposed to heat and light. Oils that have a high percentage of saturated fatty acids are your best choice for cooking.

Monounsaturated fatty acids do not pack together as tightly as saturated fatty acids do. They are relatively stable when exposed to heat, so oils that contain a high percentage of monounsaturated fatty acids are decent choices for cooking.

Polyunsaturated fatty acids do not pack together very well. They are unstable when extracted out of whole foods, so oils that have a high percentage of polyunsaturated fatty acids tend to produce significant amounts of free radicals when exposed to heat. These oils should not be used for cooking.

So in evaluating plant oils for cooking, it should be clear that oils that contain a high percentage of saturated fatty acids are more stable than those that contain a high percentage of polyunsaturated fatty acids. When exposed to heat and light during processing, storage, and use, oils that contain a high percentage of polyunsaturated fatty acids tend to contain more free radicals than oils that contain mainly saturated and/or monounsaturated fatty acids.

To put this information to use, here's a look at the fatty acid composition of fourteen oils that are commonly available at regular grocery and health food stores:

Coconut Oil:

Coconut oil is by far the healthiest cooking oil. These days, you can find quality coconut oil at almost all grocery stores including Costco, Amazon, and Walmart.

Palm Oil:

Of all commonly available plant oils, palm oil is second only to coconut oil in its stability when exposed to heat. If you did not use palm oil when you were growing up, you might find its taste and odor to be objectionable.

Olive Oil:

Its high percentage of monounsaturated fatty acids makes olive oil relatively stable when exposed to heat. For cooking, it is the next best choice after coconut and palm oil.

Avocado Oil:

Like olive oil, it has a high percentage of monounsaturated fatty acids, which makes avocado oil relatively stable when exposed to heat. Avocado oil is best used for skin moisturizing purposes. Coconut oil is also an excellent skin moisturizer, and is less expensive per ounce than avocado oil.

Peanut Oil:

Because it has slightly more monounsaturated fatty acids than polyunsaturated fatty acids, peanut oil is relatively stable when exposed to heat. If you use peanut oil, I recommend that you limit use to just a few times per month.

Sesame Oil:

Sesame oil has almost equal percentages of monounsaturated and polyunsaturated fatty acids. It shouldn't be used for cooking on a regular basis; it is best used raw.

Canola Oil:

Although it contains a high percentage of relatively stable monounsaturated fatty acids, canola oil goes rancid quite easily, and relative to olive oil, forms high concentrations of trans fatty acids. Canola oil consumption has also been linked to vitamin E deficiency and heart disease, especially when a person is not getting enough saturated fatty acids in his or her diet. I recommend staying away from canola oil whenever possible.

Corn, Sunflower, Safflower, and Cottonseed Oils:

I recommend staying away from these oils completely. All of them contain large percentages of polyunsaturated fatty acids. They also have high concentrations of omega-6 fatty acids, which can cause a variety of health problems as described in my look at healthy vs. unhealthy fats and oils.

Hemp and Flaxseed Oil:

I don't recommend cooking with these oils because of their high concentrations of unstable polyunsaturated fatty acids. If their manufacturers have minimized exposure to heat and light with their processing and bottling techniques, a small amount of these oils in their raw forms can be a part of a healthy diet. But it's healthier to eat their seeds freshly ground.

Grape seed Oil:

Grape seed oil should also be avoided when cooking. As with most other vegetable oils, it contains a high percentage of polyunsaturated fatty acids which produce significant amounts of free radicals when exposed to heat.

Please Note: I calculated all of the fatty acid percentages listed above using the nutrient profiles for each oil as listed under the USDA nutrient database.

Based on the information above, I generally recommend using mainly coconut oil and/or olive oil for cooking. For those who do well with animal foods, grass-fed butter and beef tallow are also good choices for cooking.