Selecting a Healthy Cooking Oil and Reusing it Safely

by Sarah TheHealthyHomeEconomist

healthy cooking oil is not used as biofuelIf you talk with anyone who has ever worked at a fast food joint, chances are that one of the things they will tell you is how gross the frying oil gets as it is repeatedly reused.

Even if procedures are supposedly in place to prevent the continual reuse of disgustingly rancid cooking oil, restaurant managers frequently ignore them and push the envelope as much as possible to keep cooking oil costs down.

While this vegetable oil is great for fueling automobiles, it’s not at all good for your health, certainly not as a healthy cooking oil!

The scary truth is that restaurant cooking oil is rancid before it is even used and this is because the oils of choice are factory processed and high in polyunsaturates – oils that were never designed to be heated at all much less fried in.

The cheap oils of choice for restaurant frying are canola or soy oils – both already rancid from factory processing even if marketed as transfat free.  In addition, both canola and soy oil are most likely genetically modified unless organic and what restaurant uses organic cooking oil?  Not even Chipotle last time I called and checked.

You see, it doesn’t really matter if a restaurant serves a meal of sustainable organic fare sourced locally.  If it’s cooked in soy or canola oil, which is what Chipotle uses for everything except the chips (which are fried in sunflower oil which a no-no polyunsaturate for cooking too), then the meal is going to make you feel terrible later anyway – at least it makes me feel terrible which is why I don’t value eating at Chipotle over any other standard restaurant.

But Wait!  Isn’t Canola Monounsaturated Like Olive Oil?

While it might be argued that canola has a high amount of monounsaturated fats which are more stable for frying than a predominantly polyunsaturated oil like soy, canola also has a large percentage of delicate omega 3 and omega 6 polyunsaturated fats which are almost certainly rancid upon leaving the factory (there are other ways to destroy oils besides hydrogenating them!) and denatured to an even greater degree by the time something is inappropriately fried in them at a restaurant!

If a restaurant claims to be using olive oil (which is low in polyunsaturates) for cooking, be on the alert.  It is most likely not 100% olive oil.   Restaurant grade olive oil is cut with GM canola oil or a cheap polyunsaturated oil.

Healthy Frying at Home

Even though fried foods at restaurants have a bad rap and for very good reason, do not despair – frying at home can be a much healthier experience!

All that is required to safely cook and fry in oils at home is selecting the correct type of fat and keeping the heat below the smokepoint.

Traditional cultures seemed to know instinctively which fats were best for cooking and these fats are almost without exception animal fats.

If you are uncertain about whether a fat is safe to cook in or not, just google it and note the percentages of saturated, monounsaturated, and polyunsaturated fats (all fats and oils are a mixture of the three).

If the percentage of polyunsaturates is very low as is the case with animal fats, then it is a good bet that the oil is fine to cook or even fry in.

Example:  I am asked frequently whether grapeseed oil is a good cooking oil.  It is certainly marketed as a heart healthy oil, but what is the truth?

The answer is that grapeseed oil is not a good oil to cook in and certainly not to fry in.  It is very high in polyunsaturates (nearly 75%) which most Americans are already overdoing with their predilection for processed foods which are loaded with rancid polyunsaturates.

A better choice would the be a traditional fat like tallow which is the usual fat I use for frying.

Tallow is less than 5% polyunsaturated.

In a nutshell, as a general rule of thumb if you are not sure about a particular cooking oil, let your fingers do the walking and make sure it is very low in polyunsaturates before you select it for cooking or frying.


Can You Reuse a Healthy Cooking Oil?

While you may remember Grandma reusing bacon grease or leaving a dish of used cooking oil by the side of the stove for later use, be aware that even healthy oils can have plenty of free radicals in them after cooking that can harm your health.

Here are the two things to keep in mind before reusing any cooking fat – even if traditional:

  1. Did you exceed the smokepoint for the particular fat you selected for frying?  Be sure to know what the smokepoint of your cooking oil is and even test it with a frying thermometer before starting to cook the food with it.  Exceeding the smokepoint ensures that free radicals will be in your food even if you cooked with a very healthy, traditional fat.    If you did exceed the smokepoint, it’s definitely best to not reuse the oil!  Even high smokepoint oils can be damaged when the heat gets too high.
  2. Are there a lot of bits of food in the oil after you finished cooking?  Even if you stayed below the smokepoint for the particular oil you used, having food particles left in the oil will reduce the smokepoint of the oil if it is used again.   If you want to be super safe, it is best to not reuse the oil at that point.  If budget reasons require the use of the oil again, be sure to filter out the food particles as best you can. This way, it won’t contain food residue which will cause a significant drop in the temperature of the smoke point and increase free radical production.

Want to Know More About What Fats to Eat and What Fats to Avoid?

Check out my eBook Get Your Fats Straight to get the skinny on fats in an easily understandable, comprehensive format.


Sarah, The Healthy Home Economist

Sources and More Information

Cooking with Olive Oil: Yay or Nay?

Traditional and Unusual Uses for Olive Oil

Is Rice Bran Oil a Healthy Fat?

Why Pumpkin Seed Oil is Not Good for Cooking

Caution When Using Chicken Fat for Cooking

How Argan Oil Benefits Health

Red Palm Oil Benefits Rival Coconut Oil

Walnut Oil: Healthy Sub for Flax Oil

The Many Shades of Palm Oil

Picture Credit


Comments (64)

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  2. This is all very interesting, fascinating and, a little scary. It makes sense though. I was always told that safflower oil, canola oil, and olive oil were good for you. The this whole frying thing?I’m going to have to reconsider my eating habits. Thanks for the informative post.

    • It’s all so confusing. Another alternative health site says olive oil and safflower oil are fine, and a friend of mine who is a whole foods guru uses olive oil. I have heard canola is not ideal across the board. I use olive oil for cooking, but still use canola for baking recipes. It tastes funny when I use olive oil for baking. I have had difficulty finding a lot of these other oils at stores and have found them online only. Then they priced themselves right on out of my budget :(

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  4. When I fry pastured bacon I save the bacon fat to cook in later – there are usually little bits of bacon in there so should I be straining those out or does it not matter with the animal fats?

  5. Sarah, about testing the smoke point, I’m confused: Can I use a regular cooking thermometer instead of a frying/oil/candy thermometer to take the temperature of my oil? You said to test it before frying, but this is confusing because don’t you take the temperature while it is frying? Do I just keep the thermometer in the oil the whole time I am cooking to make sure it doesn’t go above the smoke point? This is all new to me. Please clarify the whole process. Thanks.

  6. Pingback: Selecting a Healthy Cooking Oil and Reusing it Safely | CookingPlanet

  7. Thanks Sarah for sharing! That makes a lot of sense about reusing the oil. I am sensitive to gluten and to vegetable and canola oils. I get a more severe digestive reaction from consuming vegetable oil than gluten. My guess is the rancidity of the oil that makes me so sick. My biggest frustration with eating out is I have to ask every time I order if they cook with vegatable oil, if it is in the sauce, dressing or mayo. It really limits my food selection unfortunately :( . I hope that more people step up and start cooking with only healthy animal fats. Most restaurants, even good, local organic ones, use some form of vegetable oil in their cooking.

  8. I use rice bran oil and just googled it and found it’s 33% polyunsaturated fat! Seems high! However the blurb under the table of data said “Rice Bran Oil: The most balanced and versatile oil on the market and closest to the AHA recommendations. Rice bran oil is a superior salad, cooking, and frying oil which leaves no lingering after taste. The high smoke point prevents fatty acid breakdown at high temperatures. Its light viscosity, allows less oil to be absorbed in cooking, reducing overall calories. It mixes better in salad dressings and improves the taste of baked goods, providing cholesterol reduction, nutritional and anti-oxidant value.”
    Now I’m a little confused.

  9. Adrianne Severson via Facebook April 9, 2013 at 2:17 pm

    mmmm Chipotle is sooooo good! I wish it were closer. I choose not to be THIS picky about my occasional eating out.

  10. This is good to know. My son and I just ate there the other day and I was thinking I found a healthy alternative to some of the other popular places. But it did leave us feeling heavy for a day after. I’ll need to question our local place to see what oil they use. Thanks for the info!

  11. Amanda Brown via Facebook April 9, 2013 at 1:40 pm

    Agreed! They deserve some credit for trying to be a better option. Unless you choose to never eat out; for those of us to enjoy an occasional dinner out I think it’s important to support a business that sources local, organic, and grass-fed options.

  12. Chipotle was the last eatery we hadn’t given up on until I learned about the soy oil. Until these places abandon their cheap GMO junk oils or at least LABEL THEM…I’m not eating there, and especially not feeding it to my children. I love to cook, so it’s no big deal!

    Also, while I was pregnant with each of my two children, whenever we would eat at Chipotle I would get terrible indigestion and feel awful for a couple days afterwards. It was the onion/pepper fajitas for one…I cut those out and felt a little better. Our family has cut out modern wheat (we eat sprouted Einkorn), all soy and all corn products. We decided to “reminisce” and get corn chips a few weeks back…let’s just say it didn’t smell very good in our house for about 24 hours! The only one not “cutting the Limburger” was our 16 month old….he didn’t eat the Chipotle at all. It’s just not worth it…

  13. I have a friend that use Wildtree products. They tout their grapeseed oil. I shared your post with her along with 2 others that I just found supporting your information. ( I didn’t doubt you, just wanted to add to my discussion ) Her response was “moderation in all things.” So I wonder, is it okay to use moderation for something like frying with grapeseed oil? My instinct tells me no, but what what do I know?

  14. Caitlin Reed via Facebook April 9, 2013 at 11:31 am

    Crystal Stewart I know!!! But I at least appreciate that Chipotle puts forth the effort they do to use organic, local, sustainable foods… I don’t want to never go out. I’m sure tons of other places use bad cooking oils too, but unless you never ever eat out, I feel like there’s no way to avoid them entirely. I do what I can to avoid them (cooking probably 90% of meals at home) and I am miles away from the Standard American Diet! I have cut down my Chipotle consumption considerably too 😀 baby steps. Cutting it all out at once would overwhelm me and lead to worse decisions, so I’m taking it slow and sensual.

  15. Michelle Goldstein April 9, 2013 at 11:07 am

    Good reminder to be more assertive when eating out regarding asking about oil used, especially for vegetarian stir fries…Because I also keep kosher, I often use refined coconut oil for frying at home. It is parve so can be used for meat or dairy meals. Thanks for your excellent website and articles!

  16. Joe Robinson via Facebook April 9, 2013 at 11:00 am

    I cannot believe there isn’t more loud concern about canola oil. I know a biochemist who swears it causes what he calls liquid brain. It is in so many so called healthy foods in health food stores and Whole Foods uses it a lot in items in their fresh food bar. Good grief!

  17. It’s really just not safe eating fried foods out at restaurants. You just don’t know what you are getting. Personally at home we use lard.

  18. Nathan Audrey Dennis Westich via Facebook April 9, 2013 at 10:49 am

    Say you don’t have access to tallow…is coconut oil good for deep frying? Saute-Extra virgin olive oil?

  19. I usually go meatless at any restaurant, anyway. It’s hard enough to source good quality meat to eat at home, so I know restaurants don’t do it (unless they are advertising it loudly, which a few do). So if going vegetarian at Chipotle, which I do sometimes (salad), there isn’t anything that would need to be cooked in oil. I know the pinto beans are cooked with bacon; the black beans might have something harmful in them. Almost any restaurant can offer something acceptable on the menu; you just have to stay away from the other stuff.

  20. This topic is so perfect for us this morning. My son who is vegetarian loves to make french fries and onion rings at home and is wondering if there is a healthy vegetarian oil…? We’d love suggestions.

  21. can someone recommend a good deep fryer? i see a glass one that one blogger said she wished she had, but i can only find 3 reviews on it and they were not too good. thanks!

  22. Mary MacDonald via Facebook April 9, 2013 at 10:37 am

    I’ve emailed Chipotle about their use of soy and was told they’re experimenting with rice bran oil, which I know I know very little about.

  23. I will say in Chipotle’s favor is that their food is better than McDonalds or Wendy’s or other fast food. If nothing else it is WHOLE food rather than hyper processed. I don’t think it is GOOD food but it a better choice. With my life, there are times where I need to pick the lesser evil, Chipotle is a lesser evil…. :/

  24. Sandy Trob Francisco via Facebook April 9, 2013 at 10:22 am

    My daughter is allergic to soy, and my eldest son used to work there. He said they have soy in just about everything, so we stay away from it.

  25. Sahnya Greenfield via Facebook April 9, 2013 at 10:17 am

    I’ve been in contact with then quite a bit regarding soy, for awhile my son was reacting to any amount of it. The carnitas are cooked without soy, all other meats and veggies do have the soy. I’ve heard mixed info on the rice, being told there was no soy oil in it and others saying there is soy oil. Despite the oil controversy it is the ONLY fast food restaurant we can go to and feel good enough about. While I find their use of soy oil a huge disappointment I can feel better about going there on a rare occasion that other quick stops.

  26. My understanding was that Chipotle used lard for their carnitas so that has been my usual go – to while there (on top of salad with salsa and guac). No pepper/onions as those are in the soybean oil. Has anyone else researched this?

  27. I was wondering about the quality of US Wellness meats. I have a great local farm but haven’t been able to source grass-fed sheep. Would love to order some in the meantime. I’m so partial to local foods but would be happy to know a trusted source online as rendering sheep tallow interests me!

  28. Larry Underwood via Facebook April 8, 2013 at 8:42 pm

    My local Captain D’s franchise fries with lard. Love getting fish and chips there on the odd (rare) occasion.

  29. I’ve been using tallow for frying but have noticed it leaves a very slight film in the throat when eating. I don’t particularly enjoy the feeling but I will eat it. However, I’m not the only one cooking, and the other cook in the kitchen does not like it and does not use it.

    Does anyone have a recommendation about this? The source of the tallow was US Wellness Meats, so I think it is good quality. Would it be better if I rendered some myself? Or would someone suggest an alternative that doesn’t leave this film?

    Thanks so much.

  30. Sheep’s tallow is my cooking fat of choice (I much prefer the flavour to beef tallow). I also like expeller-pressed coconut oil, if I need a flavourless oil. I wish that restaurants would go back to using traditional fats! The strange thing is, I find tallow to actually be cheaper, measure-for-measure, than vegetable oil (as long as I render it myself).


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