Guest post: 7 Burning Questions About Cooking Oils

By Andy Bellatti MS, RD | 2014-10-20 01:40:54 | 5 Comments

istock_000017303961xsmallOils are an essential part of every home cook’s pantry. While their role in the kitchen is simple – oils add flavor, help impart creamy textures, and can aid in the browning process of some foods – their role in our diets is a source of confusion for many.

Are certain oils healthier than others? What about recommendations to avoid all oil altogether? How much oil is “too much”? Let’s answer some of these questions, once and for all.

1. What oils are healthiest?

Oils high in omega-3 fatty acids (i.e.: hempseed oil, flax oil, walnut oil) are very healthful. Since their fatty acids are very fragile, though, they are not suitable for cooking, as high temperatures will turn those healthful fats into unhealthy ones. Only use these oils to make dips, sauces, salad dressings, or to simply drizzle on food once it has been cooked and plated. To maintain the integrity of their vulnerable fatty acids, refrigerate these oils once opened (if possible, purchase them already refrigerated).

Oils high in monounsaturated fats (i.e: olive oil, avocado oil, almond oil, peanut oil) are also a good choice, since monounsaturated fats help increase HDL (“good”) cholesterol.

Unrefined coconut oil is another smart choice. Don’t put all saturated fats in the same bucket. Coconut oil is high in lauric acid, a saturated fat that has some cardiovascular benefits; it, too, can help increase HDL levels. And, 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).

Oils high in omega-6 fatty acids – including safflower and grapeseed – fall somewhere in the middle. 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).

These oils are often refined (for optimal health, these oils are better off consumed in an unrefined state, which, in most cases, isn’t available for purchase) and should therefore not be staples.

The refining process often entails deodorizing (to provide a neutral smell), bleaching, and anti-foaming agent treatment. 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.

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.

Partially hydrogenated oils (aka “trans fats”) are the epitome of cardiovascular atrocities and should be avoided at all costs.

2. What about canola oil?

Most canola oil is refined and undergoes a significant amount of high-heat processing, which is problematic since its omega-3 fatty acids are rather fragile.

3. Should I try to purchase organic oils?

Yes, whenever possible. Although we hear a lot about the importance of buying some produce organic, the same is true for oils. Many pesticides are fat-soluble, which means they accumulate in a plant’s fatty acids and oils.


4. I’ve been buying olive oil for years. From what I’m reading, you’re saying that’s a good choice, so I have nothing to worry about, right?

Wrong. Ready for a doozy? A lot of commercial olive oil is not 100% olive oil (I highly recommend the book “Extra Virginity: The Sublime and Scandalous World of Olive Oil;” until then, be sure to read this recent article from The New Yorker.). 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.

5. Fake olive oil? That’s insane! How can I make sure I’m buying the real thing? Are some brands better than others?

I try to stay away from brand names because brand availability varies by region. Instead, let me give you a few strategies you can use when purchasing olive oil, regardless of where you live. There are some precautions you can take to ensure you are getting legitimate olive oil:

  • Look for the California Olive Oil Council logo on a bottle. This guarantees you are getting 100% pure olive oil. You can also order directly from their certified producers (the list encompasses producers that have earned a certification over the past five years, so be sure to browse the archives).
  • For imported oils, look for the Protected Designation of Origin logo, which guarantees that the olive oil on the supermarket shelf was produced, processed, and prepared in a specific region of a country (as opposed to containing soybean from Northern Africa that was bottled in Italy and therefore technically “made in Italy”).  French olive oils will sport an “AOP” (Appelation d’origine protégée) logo, Italian ones a “DOP” (Denominazione di Origine Protetta) one, and Spanish olive oils should have a “DO” (Denominación de Origen)

6. Okay, so if I take those precautions when buying olive oil, I’ll be good to go?

Almost. You need to be familiar with oil’s three worst enemies: oxygen, light, and time.

Part of what makes olive oil so healthful (other than those monounsaturated fatty acids I mentioned earlier) are some unique antioxidants that susceptible to substantial damage from oxygen UV light, and time.

What does that mean for you? Some tips:

  • Only purchase extra virgin olive oil in tin cans or dark glass bottles (you don’t want to see the oil’s true color through the bottle).
  • Once you use olive oil, put the cork or cap back on immediately.
  • Purchase the smallest container of olive oil possible. Since time degrades fatty acid quality, the last thing you want is a three-year supply of olive oil sitting in your pantry.
  • The “Best By” date you see on extra virgin olive oil is roughly two years after manufacturing. For example, a bottle with a “Best By” date of July 2013 was most likely manufactured in July of 2011.  Since time degrades the healthful compounds in the oil, you want as ‘fresh’ a batch as possible. As an FYI, California olives are harvested in October, and Spanish and Italian ones in November.

olive-oils in jars

7. What about health experts who recommend avoiding oil altogether?

There is a movement that advocates for the elimination of plant oils, citing that oil is not a whole food and also not nutritious; they recommend sauteeing food in water instead.

In a way, they have a point. I definitely recommend that the majority of people’s 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 health-boosting phytonutrients, fiber, vitamins, and minerals. Adding sliced avocado to a salad is certainly more nutritious than dressing that salad with avocado oil.

The fact that some oils are better than others is not a green light to drown foods in “heart-healthy oils” or to think of potato chips cooked in peanut oil as “a healthy snack.” However, cold-pressed, healthful oils are rich in flavor, and a small amount added to dishes can add that extra culinary touch that takes foods dishes from “good” to “exquisite.”

Small amounts of high-quality oils certainly have a place in our diets. This is definitely one instance where quality undoubtedly trumps quantity.


andy-iconAndy Bellatti, MS, RD is a Las Vegas-based nutritionist with a plant-centric and whole-food focus who takes an interest in food politics, deceptive food marketing, sustainability, and social justice. His work has been published in Grist, The Huffington Post, Today’s Dietitian, Food Safety News, and Civil Eats, among others. He is also the Strategic Director of Dietitians for Professional Integrity, a group that advocates for ethical and socially responsible partnerships within the Academy of Nutrition and Dietetics. You can read more of his work on his Small Bites blog and can also follow him on Twitter and Facebook.

5 responses to “Guest post: 7 Burning Questions About Cooking Oils”

  1. Paulo Glikas says:

    Cooking with quality oils, and using only Estate bottled oils has always been on my shopping list. I greatly appreciate your article and found it quite informative. Thanks for such quality information.

  2. Michele says:

    Wow, an RD who recommends coconut oil? I’m impressed. So surprised not to see it bashed because it’s an evil saturated fat.

    • Claudia Zapata MS, RD says:

      Hi Michele, There’s definitely been a shift in thinking, and most RDs these days would agree coconut oil is a healthy fat, even though it’s saturated. Please check out Andy’s response below…

  3. Paulo: Thank you! Glad you found the article informative.

    Michele: It is important to remember that all saturated fatty acids are not created equal. Coconut oil is high in lauric acid, which has beneficial effects on HDL (“good”) cholesterol. It is time to move beyond old-school “all saturated fats are unhealthy” thinking!

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