Vegetable Oils: The “Refining” of Our Health


Caveman Doctor recently read an article recommending vegetable oils for cancer patients to help them achieve “good health”. This website recommended safflower oil, soybean oil, and Canola oil, among several other vegetables oils. This confused Caveman Doctor for several reasons, as the only oil he has ever seen came from animal meat and when he crushed macadamia nuts and avocados over a rock with his club. He has never seen any oil come from vegetables or seeds and was really confused. Where do these oils come from and how are they even made?


Vegetable Oils 101

The history of vegetable oils can be traced back to several moments in history that stand out, and my favorite involves Rudolf Diesel. He designed his highly sophisticated diesel engine to run on peanut oil. Can we replace this diesel engine with the highly sophisticated human body and achieve the same results as Rudolf?
Oils are essentially fats that are liquid at room temperature, with few exceptions. Coconut oil, for example, is usually a mixture of liquid and solid at room temperature due to its high melting point (imagine if ice melted at 76 degrees instead of 32, it would often remain solid at room temperature). While many people assume that all oils are made of unsaturated fatty acids, coconut, palm oil, ghee, and several other are actually made of saturated fat. However, at room temperature, saturated fats are usually solid due to their more stable molecular structure (so stable that their melting point is higher than room temperature, whereas unsaturated fats are less stable molecularly and become liquid at room temperature). This is all due to the number of unbound carbons on the backbone of the fat (think more unbound carbons = more unsaturated = more often liquid at room temperature).

The Emergence of Vegetable Oils in Fast Food Restaurants

McDonald’s used to fry its french fries with tallow (beef fat), lard (pork fat), or palm oil, which are all saturated fats. While they are solid at room temperature, they melt quickly in a heated pan or fryer. You may be wondering why most fast food joints nowadays have replaced these cooking oils with peanut and canola oil, as well as a plethora of other vegetable oils that french fries soak and sizzle in.
These oils can be traced back to the 1980s, when the Center for Science in the Public Interest (CSPI) led an assault on McDonald’s for using lard and saturated fats to cook their fries, as it was apparently wreaking havoc on our health, similar to the reasons why your doctor has likely suggested a low-fat diet to you. There was of course no evidence to support this, but nowadays a smear campaign can often work much better than proof and the truth. Thus, fast food chains were forced to replace these “harmful” fats with “healthy” partially hydrogenated oil (like Crisco and margarine). At the time, CSPI even labeled Burger King’s switch to partially hydrogenated oil as “a great boon to American’s arteries.” It’s important to know that these partially hydrogenated oils are full of trans-fats and that these oils are a modern invention and rarely occur in nature. I like to think of them as “Frankenfats”, as they are a well-intentioned but disastrous invention.
So, by maligning saturated fats that fast food chains were using and ushering in the usage of partially hydrogenated oils, trans-fats increased throughout our society1. I think we all know how “healthy” trans-fats are as there has been a push to make them illegal in some cities. Studies (with actual data, not merely a smear campaign) show that replacing saturated fat with trans-fat decreases HDL (good cholesterol) and results in blood vessel damage2. This, of course, is rather ironic since the trans-fats were used to replace the “heart-damaging” effects of saturated fats and provide that “boon” to our arteries. To add insult to injury (literally), consumption of trans fats causes stress and inflammation on our bodies, elevating IL-6, CRP3 and the inflammatory pathways that we are consistently trying to keep low by limiting chronic stress, as previously discussed here and here. To summarize, CSPI and other groups waged a media campaign against naturally occurring fats and replaced them with Frankenfats that are worse for our bodies. Oh, the efforts and good intentions of you modern men…
Just as saturated fats were wrongly replaced with inflammatory trans-fats, leading to more health risks, this trend continues as we have ultimately gone from saturated fats to polyunsaturated vegetable oils. While many praise the health benefits of vegetables oils, few even know what vegetable oils are or how they are made. Consuming trans-fats can result in a slew of health issues as discussed above; however, replacing them with vegetable oil may even be worse! In fact, studies in mice have shown that switching to corn oil, a common vegetable oil, actually results in increased colon cancer in comparison to trans fats. In fact, corn and other vegetable oils high in linoleic acid are often used in animal studies to cause cancer4,5, which I briefly discussed when reviewing the benefits of CLA. When polyunsaturated fats replaced saturated fats in a randomized controlled trial in humans, the rate of cancer actually rose6. How can this be possible if so many health organizations are promoting their consumption? Before we can even answer this question, we need to take a look at how vegetable oils are made.

Is Olive Oil a Polyunsaturated Vegetable Oil?

No! Olive oil is a mostly monounsaturated fat, and as you will read below, is made by an entirely different process than vegetable oil. Like olive oil, there are some oils that contain mostly monounsaturated fatty acids (different from polyunsaturated fatty acids (PUFAs) in that they only have one carbon atom on their backbone that can be attacked by free radicals and oxidized as opposed to polyunsaturated fats, which have many). This gets a little complicated and organic chemistry heavy, but bear with me: a simple way to think about this is that all fats have a chain of carbon atoms as their backbone. Now imagine, like your spine, there is a whole chain of these carbon atoms that can be bound or unbound by a hydrogen atom. Each carbon atom is a vertebra and if the vertebra has a hydrogen atom attached, there is less room for a free-radical to come in and attack. As a result, the free-radical passes by, looking for an unprotected (and unbound) vertebra, or in this case.
Along these lines, saturated fats have no unexposed weak points for this roaming free-radical to attack:
Monounsaturated (mono=one) have a single double bond with exposed carbons on each side:
Finally, PUFAs (poly=many) have many sites that can be attacked by free radicals:


Some Common Sources of Monounsaturated Fat (percentages of monounsaturated fat in parentheses):

1. Macadamia oil: 85%
2. Olive Oil: 75%
3. Avocado Oil: 70%
4. Tallow (beef fat): 50%
5. Lard (pork fat): 40%
Another frequently used cooking oil by caveman eaters is coconut oil, which is mostly saturated fat. Its backbone is totally bound by hydrogens (saturated), and as a result it is very stable, solid at room temperature, and very resistant to free-radical damage during cooking.

The Industrial Process of Making Vegetable Oils: Chemical Refinement

Converting a vegetable or plant-based food into oil is a complicated chemical process, as the oil is not simply squeezed out of the vegetable as many would have you believe.
First and foremost, the process generally starts with a polyunsaturated fat source which, as describes above has many free carbons that are defenseless against heat damage and free radical attack. The final product is one of the many common vegetable oils, including:
1. Rapeseed oil (or based on the original process in Canada: Canola)
2. Peanut oil
3. Soybean oil
4. Sunflower oil
5. Corn oil
Intense chemical and mechanical manipulation of the vegetable source, removing many of the natural elements (including nutrients) is required to produce these unnatural oils. This also renders them damaged and defenseless against oxidation.

Step 1: Pressing

The first step in refinement involves extracting the small amount of oil from the plant-based source. This usually involves taking seeds (often genetically engineered to be immune to pesticides), crushing them, heating them to high temperatures, pressing them, and finally, bathing them in a hexane bath and other solvents made from crude petroleum. Petroleum! The oil is then separated from the seed residue and phosphate is added. The residue that is collected is often used as animal feed (hopefully no animals or animal products that we are consuming…).

Step 2: Neutralization, Bleaching, and Deodorization

After reading the title of this section, please be advised we are still discussing vegetable oil and have not switched to cleaning laundry. If you recall from the boring descriptions of the backbone of fats, PUFAs are somewhat defenseless against free-radical damage. Well, step 1, with all of its heating, pressing and chemicals, leaves the vegetable with significant oxidized damage that actually leaves the oil with a foul odor and unwanted color. This substance then undergoes a process called bleaching, which, just like when you bleach your socks, removes unwanted colors. The final process involves steaming the oils with extremely high temperatures, often over 500º F – much higher than the smoke point of nearly all of these oils – in order to remove residual substances that cause an unwanted taste or odor. This is appropriately called deodorization. Call me crazy, but anything that needs to be deodorized before eating doesn’t sound healthy to me.
While all the steps appear damaging and unhealthy for the oils (neutralization, bleaching, etc.), this last step of deodorization and heating in the process may be the most damaging of all as it severely weakness the fatty acids, leaving them less structurally sound as the high heat carries with it a hefty dose of free radicals. These free radicals wreak havoc on the structure of the fats and are very oxidizing.
However, the demise of your health doesn’t stop here, as many refined vegetable oil contain added butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA),7 both of which have been shown to cause bladder and thyroid cancer in animals.8

The Final Product

While the health implications are quite obvious just from the process of making vegetable oil, it actually gets worse. The destruction of the backbone of the oil leaves it oxidized and further weakened to defense against future oxidation and free-radical damage during storage and cooking. This is why the shelf life of vegetable oils is so short; they often go rancid after only 6 months of sitting in your cupboard. Of note, olive oil also goes rancid after 6 months as well, but coconut oil (with its very stable structure) can fight off free-radicals and oxidation and stay good for a year or two. Walnut and sesame oil (which I hope none of you use, or at least please don’t use it with heat but only drizzle it on foods if you MUST use it) can go rancid in as little as 2 months.
To add more insult to injury, most antioxidants that would help us fight possible free radical damage, like vitamin E, are destroyed by this extreme process. Oil that is produced the old fashioned way, such as coconut, olive, and macadamia oil avoid having their antioxidants and vitamin content destroyed. In fact when macadamia nuts, which contain an ample amount of antioxidants,9 are made into macadamia oil, it remain relatively full of the antioxidants.10
Note that virgin olive oil is produced through more physical means and not the chemical treatment described above. However, both refined olive oil and pomace oil (a type of olive oil) undergo chemical treatment. Unrefined, virgin, and organic coconut oil avoid chemical processing as well. However, you can still find some chemically altered coconut oil, which is known as RBD (refined, bleached, and deodorized). Stay away from these.
When applying simple caveman logic to the non-animal oils above, we can imagine it is possible to get oil from an olive, avocado, or macadamia nut by crushing it with a club over a rock. However, this is not possible with soybeans or corn. In fact, soybeans are not even edible unless they undergo processing so even if available, the caveman couldn’t have eaten them.

In Review:

1. Throw away your vegetable oils or donate them to your local lab where they run cancer experiments on animals.
2. Replace them with macadamia, avocado, olive, and coconut oil and grass-fed butter.
3. Never cook with unstable vegetable oils and PUFAs as they can become full of oxidative free radicals that damage your body.
4. Eat foods rich in antioxidants to help fight inflammation and avoid sources that actually introduce free radicals into our bodies, like vegetable oils.
5. Keep the bleaching to your gym socks and bottom of your bathtubs and avoid foods that need to be bleached and deodorized before they can be eaten.

Oils Caveman Doctor Never Uses:

1. Rapeseed oil
2. Canola oil
3. Peanut oil
4. Soybean oil
5. Sunflower oil
6. Corn oil
7. Safflower oil
8. Grape seed oil
9. Sesame Oil

Oils Caveman Doctor Uses:

1. Macadamia oil
2. Coconut oil
3. Avocado oil (his favorite!)
4. Olive oil (to garnish or only with low-heat)
5. Grass-fed butter
6. Tallow or lard (less frequently)
7. Palm oil

Parting Thoughts

The process of producing vegetable oils through neutralization, bleaching, and deodorizing clearly is not natural and likely not safe for your body. The final chemical product of vegetable oil quickly goes rancid with its short shelf-life, is defenseless against free-radical attack, is stripped of its healthy antioxidants, and often contains cancerous chemicals and compounds. These oils were never around in Caveman Doctor’s time and never stood in his way to optimal health. He hopes they don’t stand in your way, either.



1. Stender S, Dyerberg J, Astrup A. High Levels of Industrially Produced Trans Fat in Popular Fast Foods. New England Journal of Medicine. 2006;354(15):1650-1652.
2. de Roos NM, Schouten EG, Scheek LM, van Tol A, Katan MB. Replacement of dietary saturated fat with trans fat reduces serum paraoxonase activity in healthy men and women. Metabolism. 2002;51(12):1534-1537.
3. Lopez-Garcia E, Schulze MB, Meigs JB, et al. Consumption of Trans Fatty Acids Is Related to Plasma Biomarkers of Inflammation and Endothelial Dysfunction. J Nutr. March 1, 2005 2005;135(3):562-566.
4. Kritchevsky D. Diet and cancer. CA: A Cancer Journal for Clinicians. 1991;41(6):328-333.
5. Carroll K. Dietary fats and cancer. Am J Clin Nutr. April 1, 1991 1991;53(4):1064S-1067S.
6. Lee Pearce M, Dayton S. Incidence of Cancer in Men on a Diet High in Polyunsaturated Fat. . The Lancet. 1971;297(7697):464-467.
7. Wyatt D. Simultaneous analysis of BHA, TBHQ, BHT and propyl gallate by gas chromatography as extracted from refined vegetable oil. Journal of the American Oil Chemists’ Society. 1981;58(10):917-920.
8. Ito N, Fukushima S, Tsuda H. Carcinogenicity and Modification of the Carcinogenic Response by bha, Bht, and Other Antioxidants. Critical Reviews in Toxicology. 1985;15(2):109-150.
9. Quinn L, Tang H. Antioxidant properties of phenolic compounds in macadamia nuts. Journal of the American Oil Chemists’ Society. 1996;73(11):1585-1588.
10. Marisa M W. Functional lipid characteristics, oxidative stability, and antioxidant activity of macadamia nut (Macadamia integrifolia) cultivars. Food Chemistry. 2010;121(4):1103-1108.
© 2015 CDR Health and Nutrition, LLC. All Rights Reserved


  1. Diane and Tom

    Which oils do you cook with?

    1. cavemandoctor (Post author)

      You guys always read my mind. I will be doing a future post on why, but I mainly cook with pastured butter (grass-fed) and macadamia oil. Macadamia is amazing and make veggies taste great. I literally can’t get enough of it. I sometimes use avocado, but it leaves more of a distinct taste.

      Coconut oil is one of the most stable to cook with, but it can leave a taste as well. I use olive oil to garnish and sometimes when I microwave veggies.

      For searing of meat I generally do macadamia bc with meat it doesnt seem to affect flavor. For ground meats or meats that generally give off oil and fat, I often won’t use any. I just make sure it doesn’t get burnt.

      Pastured butter for shrimp and fish is amazing, and makes salmon skin nice and crispy (I literally only add salt and pepper).


    2. Lizette

      Helo, I was told to only use organic, cold pressed coconut oil, but the one I used untill now, seems to be beneficial to my health. Health shop person says, a cheaper cocnut oil, has hexane int? And are made from the outside of the coconut, that’s why it is less expensve. Is this true? On the label, mine says, made from Organic Coconuts. With a list of health benefits, but its deflavoured. Could you help?

  2. Diane and Tom

    Thanks! Very interesting! Great cooking tips! What about other nut oils?
    We’re surprised you eat shrimp? What about other shellfish?
    This is off of the cancer subject, but we’ve heard that since shellfish are bottom feeders, you really don’t want to consume them, due to what they’ve consumed!

    1. cavemandoctor (Post author)

      Thanks for the great questions,

      So, I have never fully bought into the whole “bottom feeder” theory, especially because I eat fish. I get the issues that people have with consuming them, though I eat fish that consume them as well, so I guess with shrimp I am streamlining the bottom food! Plus shrimp is full of selenium, iodine, some omega-3s and a couple other vitamins and nutrients, not to mention they are a delicious source of protein when cooked in pastured butter, salt, and pepper.

      My other issue is I have been slow to eat a lot of organ foods, so oysters and shrimp (a lame one albeit) are my organ foods.

      While there are no studies that I know of showing the risks of shrimp, there are surprisingly a bunch of studies showing their health benefits. I honestly see it more of as a personal preference.

      That being said, I only eat wild shrimp and never farmed.

      Hope this helps!

  3. Diane and Tom

    And thank-you for the “repair” of the polyunsaturated fat molecule.

  4. Pingback: Insulin, Carbohydrates, Obesity, and More Insulin - Caveman Doctor : Caveman Doctor

  5. reader

    can I cook eggs with macadamia oil?

    1. cavemandoctor (Post author)

      Absolutely! I do it all the time.

      1. JP

        Hi CD,
        I’ve been cooking with corn oil and I wanted to find out if corn oil the same as vegetable oil?
        you’re my hero 🙂

        1. cavemandoctor (Post author)


          Haha thanks for the comments. Though corn isn’t actually a vegetable, it goes through all the same processes to turn it into oil and is considered a vegetable oil. It has similar heath effect as well.


          1. reader

            Hi caveman doctor,
            My mother bought me grapeseed oil recently. Can I cook with grapeseed oil?

            1. cavemandoctor (Post author)


              So, while you can cook with grape seed oil, and it was a very nice gesture by your mother, I do not use grape seed oil. It has a high smoke point and it often used to cook under high heat, it is a vegetable oil. Like processed oils, it comes from a seed (grape seed). Remember, oils like macadamia, avocado, and olive oil (think of this foods as all producing oil from being crushed – with a caveman club if necessary), while oils from seeds need to undergo major processing to even form an oil.

              It is also 75% omega 6 fatty acids, which are inflammatory. There is a post on this coming up soon…

              My picks: Avocado oil, macadamia oil, olive oil (less so to cook with), grass-fed butter, or tropical oils like palm and coconut oil

              Sorry if you have to waste your mother’s gift!

  6. Pingback: Stop Taking Pills and Eat Your Vitamins and Nutrients - Caveman Doctor : Caveman Doctor

  7. Pingback: Inflammation: Which Foods Take the Blame? - Caveman Doctor : Caveman Doctor

  8. Pingback: The Modern Caveman Diet - Caveman Doctor : Caveman Doctor

  9. Pingback: Crisco, Trans-Fats, and Revisiting Vegetable Oils - Caveman Doctor : Caveman Doctor

  10. reader

    Thank you!

  11. Pingback: Omega-3 Fats and Your Health - Caveman Doctor : Caveman Doctor

  12. Pingback: Checking Your Oil: The Definitive Guide to Cooking with Fat - Caveman Doctor : Caveman Doctor

  13. Pingback: Anety

  14. Pingback: Sleeping Away Cancer - Caveman Doctor

  15. Pingback: Real Food Spotlight: Butter (is better) | Running Carrot

  16. Keli

    Fascinating analysis, Caveman Doctor – Two questions
    1. Do you have any idea when vegetable oils started to be introduced in bread ? ( Does that also coincide with time when McDonalds was required to start using them too ?)
    2. If you stop using vegetable oils, do you start automatically losing weight regardless of what else you are consuming ?

  17. Pingback: Triple C and sugar bitches | body yenta

  18. Pingback: triple C and sugar bitches | body yenta

  19. ..

    FYI, there’s a typo!

    “Along these lines, unsaturated fats have no unexposed weak points for this roaming free-radical to attack:” should be saturated.

    1. cavemandoctor (Post author)

      thanks! Fixed it

  20. Pingback: Do you know how oil is made? « Mint&Chilli

  21. Pingback: 3 Rules For Cooking With Fats | The Mindful Caveman

  22. Pingback: Butter is Better - Mindful Meals

  23. Jolie

    I love the smell of macadamia nut oil and I use the macadamia essential oil (from a health food store) for my hair. I have heard of a lot of people developing nut allergies so I have questions about using macadamia nut oil to cook with so much. A friend of mine developed a peanut allergy after eating too many peanuts, she said she ate them pretty much every day then one day developed a bad allergy to them. So, the question is, can you develope a nut allergy from cooking too much with the macadamia nut oil?

    1. cavemandoctor (Post author)

      Peanut are most common, but from my understanding tree nut allergies in general can occur.

  24. George

    I think coconut oil might be one of the healthiest oils and that the diet-heart hypothesis lies pretty much in ruins. That said there are certain things that are wrong or hard to reconcile in the anti-vegetable oil narrative. First of all coconut oil is a stable oil in general, but that doesn’t change the fact it still has a low smoke point, a fact a LOT of people promoting it are wrong on. Try looking for a high quality reference. Refined, bleached, and deodorized (RBD) oils undergo that process for a reason: to raise their smoke point and make them suitable for frying. Which brings me to those meta-analyses that show beneficial effects by substituting polyunsaturated fats for saturated fats. How do you explain those? Presumably they used RBD oils. Yes the process that made them might not be wonderful to contemplate (but neither is slaughtering livestock) but in the trials, their use and substitution for saturated fats keeps resulting in better results. I am aware of the argument put up by Bill Land’s research and Ramsden’s so I can see the wisdom in avoiding oils with lopsided omega 6 to omega 3 ratios, but that still leaves canola oil looking pretty good. Do you know of any studies that show canola oil is worse in comparison to saturated fats?

    1. cavemandoctor (Post author)

      Hey I agree. I think coconut oil is good but not the cure all like people make it. I like cooking with lard or butter. Any oil that is heated to extreme amounts and bleached is probably not healthy and oxidized.

      Many studies on issues with vegetable oils in general and as cancer-causers. Review my site and google scholar it. Many articles out there in general, not sure about canola oil specifically.

  25. Pingback: 3 Easy Steps To Getting Started With Paleo - Gen Y Paleo

  26. Pingback: 3 Easy Steps To Getting Started With Paleo | The Mindful Caveman

Leave a Comment

Your email address will not be published. Required fields are marked *

four × 5 =