The Truth About Fats & Oils

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Great news for all who love food that doesn’t taste like wood: Oil is not the Anti-Christ, and eating fat will not make you fat. Time to say “goodbye” (and good riddance) to that non-stick cooking spray, and “hello” to the wide world of cooking with actual oil. Vitamins A, D, E, and K are called “fat-soluble” because they need fat in order to be absorbed. “Oils are a critical piece of a healthy diet,” says Dr. Charles Carpenter, MD. They “contain nutrients in their own right, and help us utilize the nutrients in the rest of our food.” So, if you don’t have some fat in that lovely green juice you’re guzzling, you’re flushing key vitamins right down your own drain.
But, before you go throwing any old fat into the pan, you probably should know that all oils are not created equal. There are some you should cook with, some you shouldn’t, and some you should probably never eat again.

“Saturated” means “stable”

We now know that saturated fat is not the silent killer it was believed to be for the last half-century. In fact, saturation is not only not dangerous, it’s downright beneficial. Here comes the science: A fat is monounsaturated if it has one double bond within the fatty-acid chain. A fat is polyunsaturated if it has more than one. Saturated fats have no double bonds. What does that mean? The more double bonds, the more vulnerable the fat is to oxidation, which happens when the fat is exposed to light, air, and especially heat.

When it comes to cooking, “The first thing you need to know is degree of saturation,” says Dr. Cate Shanahan, MD, author of Food Rules: A Doctor’s Guide to Healthy Eating, and Nutrition Director for the Los Angeles Lakers. This is because when you cook, the more saturated a fat, the more stable and less likely to oxidize it is — making more saturated fats a better choice.
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When we eat oxidized oils, we’re essentially eating radiation, say Drs. Carpenter and Shanahan. “Oxidized oils are molecularly unrecognizable by our body,” says Dr. Shanahan. “Once inside, they react with oxygen and iron in our blood and spark free-radical cascades.” In her book, Deep Nutrition: Why Your Genes Need Traditional Food, Shanahan explains that these molecules can harm other cells they come in contact with once inside the body. This damage is otherwise known as inflammation, which has been linked to issues from arthritis to food allergies to IBS to cancer, heart disease, and stroke.
Furthermore, “You are what you eat,” says Dr. Carpenter. Not only can eating oxidized fats cause serious damage in the long run, as some of these fats are stored for energy, others are immediately incorporated into our cell membranes, which are made up of fat. If you eat bad, oxidized fats, your cell membranes could also contain these oxidized lipids. It's possible that these abnormal lipids could cause problems with cell function and cell-to-cell communication.
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If you’ve ever seen a cooking-oils list, you’ve probably seen the term “smoke point.” But, “smoke point is irrelevant,” says Dr. Shanahan. “It’s the protein that’s burning, but depending on the fatty-acid profile of the oil you’re cooking with, you will get degradation (oxidation) long before it starts to smoke.” Additionally, and perhaps more importantly, oils that are super-refined will have no smoke point — but that doesn’t change their fatty-acid profile. So, cooking with refined, polyunsaturated oil, such as canola, is even more dangerous due to the fact that you can expose it to heat for long periods of time (making it increasingly more oxidized) and it will never smoke to warn you of the danger.
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By “vegetable” oils we mean refined, polyunsaturated oils: corn oil, cottonseed oil, rapeseed (canola) oil, sunflower oil, safflower oil, and soybean oil. According to Drs. Carpenter and Shanahan, you might just want to never eat these oils again, ever. Not only are these varieties highly unstable, they oxidize easily, and the very process used to make them causes oxidation. Because it’s difficult to extract oil from a cottonseed or a rapeseed — as opposed to naturally oily things such as olives or avocados — the creation of these oils usually involves high heat and chemical solvents. (If you’re really interested, you can watch exactly how canola oil is made here). So, straight out of the bottle, you’re already getting oil that’s been oxidized to some degree — before it ever even hits the pan.
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The fact is, you can’t make a processed food without heat. Turn over just about any box or bag in your kitchen and chances are one of those vegetable oils (along with some level of oxidation) is in there. An inconvenient truth indeed.
Even less convenient is the fact that these refined, polyunsaturated oils are the most popular choice in most commercial kitchens because they’re cheap and have that high smoke point — so they can withstand high heats without making food taste burnt. But, there is hope! A growing number of packaged food brands and restaurants have started to make the switch, using more stable oils like avocado and animal fats for their house-made potato chips and French fries. And, rather than hiding from the world and only eating oil you’ve cold-pressed in your backyard, you can always ask that your meal be cooked in butter the next time you’re out to eat. Ain’t nothing wrong with that.
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It’s time to get down to brass tacks. According to the experts:
1. When frying anything, use animal fat: beef tallow, lard (from pigs), or duck fat.
2. When cooking with high heat (over 350 degrees in the oven or on a stovetop range), use coconut oil, sustainably sourced palm oil, avocado oil, or peanut oil.
3. For medium heat (250 degrees or below) or as a topping once the food has been cooked, use grass-fed butter or olive oil.
4. If you're using oil cold, try flax, walnut, sesame, macadamia, or any other polyunsaturated oil.
5. Steer clear of refined canola oil (a.k.a. rapeseed oil), cottonseed oil, corn oil, soybean oil, sunflower seed oil, safflower oil, light olive oil.

Expeller-pressed? Cold-pressed? Extra-virgin? What the...?

“The single thing to look for is refined (a.k.a. 'light') or unrefined,” says Dr. Shanahan. “This is the jackpot. You don’t need to refine something that has been extracted in a gentle way; you do need to refine something that’s been extracted in a harsh way, because the initial end-product is disgusting.” (Feel free to refer back to that canola oil video). Expeller-pressed is the same thing as cold-pressed, but when it comes to things like canola oil, which might say “cold-pressed” on the label, this is but the first in many, many steps of refinement. Extra-virgin means oil made from the first pressing — no refinement; you’re good to go.

Glass matters

When buying mono- and polyunsaturated oils like olive oil, walnut oil, and flaxseed oil, make sure you go for the dark, glass bottles. Unless you personally know your oil manufacturer, you have no idea how long those bottles have been sitting on shelves, exposed to light and heat — so the darker the glass, the better. The same goes for bringing your oils home. Keep your monos and polys in a cool, dark place away from your stove.

Perhaps all this is a little more info than you bargained for when looking for the best oil for cooking your taquitoes. But, there are as many facts to take into consideration as there are varieties of oil (we lost count, but it's quite a few).

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