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Dr. Cate Fats And Seed Oil Guide

List of Good Fats and Oils versus Bad

This page is YOUR resource list of all things pertaining to edible fats and oils, please bookmark if you are interested in this topic. 

Please read the FREQUENTLY ASKED QUESTION section for oils not addressed in the above graphic, and if not there either then please post a question for me in the comments section.

To be notified when your question is answered, please check the notifications box on your comment.

Bad Fats: NEVER eat these!

REFINED PUFA-Rich seed OILS a.k.a. “Vegetable oil”

Canola (also called “Rapeseed”), Corn, Cottonseed, Soy, Sunflower, Safflower, Grapeseed, Rice bran.

ALSO TOXIC: Refined Palm oil. (It’s not very high in PUFAs, but the refining is often more intense.)

PLUS: Anything that says hydrogenated because it’s going to start with refined oil and further process to create trans fats.

Vegetable oil is an industry term that sometimes includes olive oil, peanut, and coconut. However, when you see the word vegetable oil on the ingredients, it’s not going to be first press, unrefined olive, peanut, or coconut. It will be one of the cheap, refined PUFA-rich, seed oils listed above.

Good Fats: Eat THESE instead!

UNREFINED FATS and OILS, LOW in PUFA or high in Omega-3 and not heated

Avocado oil, Butter, Coconut Oil, Duck Fat, Ghee, Lard, Olive oil, Peanut oil, Tallow, Sesame oil, Flax oil, Walnut oil, Almond oil, Macadamia nut oil

Also: Anything that says cold-pressed and unrefined. It must say unrefined! If it says cold-pressed but is refined, it’s not good.


Almond oil, Avocado oil, Butter, Coconut, Duck Fat, Ghee, Lard, Macadamia nut oil,  Peanut oil, Tallow, Sesame/Toasted Sesame oil (Sesame is better if combined with peanut or other stabler fat, details below)


Flax oil, Walnut oil, Fish oil

Refined Oils: Limited Use

Refined high-PUFA seed oils are toxic. Refined high sat-fat/mufa oils are “ok but not great” because their fatty acids can handle the refining process without generating significant levels of mutated fatty acids and are therefore not going to be particularly toxic. However, the refining strips them of significant amounts of minerals and/or antioxidants so they are not as nutritious as their more expensive, higher-quality equivalents. You can think of them as the empty calories of the fat world. If you can afford to, get the better stuff. If you can’t, these are still far better than the high-PUFA oils. You’ll just need to be sure that the rest of your diet supplies plenty of antioxidants (lots of fresh greens and herbs, for example).

Knowledge Base:

Everything you need to know about dietary fats and oils, summarized in one place.


(The short version)

These oils contain a high percentage of polyunsaturated fatty acids (PUFAs). PUFAs are unstable, and break down rapidly when exposed to chemical stress. Ever heard of varnish? It’s what carpenters use to finish wood. Varnish is made from vegetable oils, including soy and linseed (which is rich in omega-3, like canola), because these oils are chiefly composed of PUFAs. PUFAs react with oxygen in the air to help polymerize the varnish into a nice hard coating that helps preserve the wood.

Varnish is good for your floors, but not so good for your brain, your arteries or mitochondria. I elaborate on that below, throughout this blog, and in Deep Nutrition chapters 7 and 8.

A little bit of PUFA is not a problem for us, we actually need some. And when we get PUFA from whole foods like sunflower, chia or flax seeds, it’s well protected by antioxidants nature builds into the seed. These protectants get stripped away during the industrial scale refining of sunflower and the other vegetable oils, and that’s just the beginning of the problems with vegetable oils.

The refining process not only strips away antioxidants, it makes PUFAs toxic by exposing them to heat, pressure, metals and bleaching agents. This chemically alters the molecules into a wide variety of potent toxins with long names like 4-hydroxynonanal and 4-hydroxyhexanol, aldehydes, and others. These molecules are toxic because they promote free-radical reactions that damage our cellular machinery including mitochondria, enzymes, hormone receptors, and DNA.

More information on the refining under “See How it’s Made” below.

Years of consuming these high-PUFA seed oils has a consequence that almost nobody is talking about just yet. Our body has no choice but to store the extra PUFA in our body fat, and that means that over decades the concentration of PUFA in our body fat gradually rises. Back in the early 1900s our body fat PUFA percentage was 2-4. Today it’s 10-30%. This makes our body fat prone to inflammation and has disastrous consequences for our overall health and ability to fuel our cells.

For more about how these oils affect our heart, brain and DNA, please read Chapters 7 and 8 of the 2017 edition of Deep Nutrition: Why Your Genes Need Traditional Food). For a deeper dive into the reason these oils promote diabetes, weight gain and most metabolic disease, see my latest book, The FATBURN Fix.


The google document above is a short, organized list. There are hundreds more yet to be compiled into the document. If anyone wants to volunteer to help out with this project, please let me know!


Supplement companies love extracting oils from whole foods and encapsulating them, and then promoting them as somehow superior to the whole food.  Common examples of supplement oils include:

  • Fish oil
  • Cod liver oil
  • Oregano
  • Cumin
  • Hemp seed
  • Flax
  • Udo’s oil
  • Borage oil

None of these are necessary on a whole foods diet with the possible exception of certain very high quality cod liver oils for those who cannot eat whole foods that are naturally high in PUFAs, such as raw or sprouted nuts and seeds, pasture-fed dairy and meats, liver (yum) and oily fish. If you are a vegan who cannot eat raw or sprouted nuts and seeds, then a flax oil supplement is a good way to go.


Our diets do contain too much omega-6, yes. But a common misperception is that vegetable oils are toxic because they contain omega-6, and omega-6 is pro-inflammatory. There are two points about this misperception I want to bring to your attention.

  1. Vegetable oils are toxic because the fats they contain are oxidized. And it’s the double bonds that make PUFAs susceptible to oxidation. But omega-3 fats have more double bonds than omega-6, generally speaking, and so seeds with a high omega-3 content, like canola, actually lead to more toxic degradation products than seeds with a high omega-6, like soy (all else being equal).
  2. Our brains need omega-6. Our brains are made out equal parts omega-6 and omega-3, so we need both in roughly equal amounts.

The fact that we get too much omega-6 now is a result of two major consequences of industrial food making:

  1. Soy is the most commonly used vegetable oil in processed foods and restaurants by a factor of nearly twice over Canola, the second most common.
  2. The animals we eat are fed soy and corn, which contain lots of omega-6, and the feed is often supplemented with other vegetable oils such as cottonseed that are also high in omega-6. The animals do not burn these fats for energy (neither do we), so they are stored in the adipose tissue. This means, for example, bacon from industrially produced pigs contains a lot of omega-6.

How much vegetable oil is too much?

That’s a little like asking how many cigarettes should a 4 year old smoke. More than none is too much. However because these oils are now added to spice mixes that are added to many otherwise healthy foods, it has become almost impossible to avoid entirely. Other than spice mixes, products with vegetable oil are best avoided whenever possible.


Fats are solid at room temperature and oils are liquid. Saturated fats are stiff, so highly saturated fat. (Figure below)

fat versus oil
Fats are solid at room temperature because their triglycerides are composed of relatively more straight, saturated fatty acids. Oils are liquid at room temperature because their triglycerides are composed of relatively more flexible unsaturated fatty acids, both mono-unsaturated (one double bond) and poly-unsaturated (two or more double bonds)


Fatty acid refers to a molecule composed of a several carbons linked together, generally anywhere from 4 to 26 carbon atoms, with a special group at the end called a carboxyl. The chain of carbon atoms may be linked together with single bonds, and be saturated, or contain one double bond, and be mono unsaturated, or contain two or more double bonds, and be polyunsaturated. Our bodies cell membranes are composed of all three types of fatty acids. We cannot make certain fatty acids, those have to come from food, these we call essential fatty acids and they come in two types: omega-3 and omega-6.

Fats Most fats and oils we eat are composed of three fatty acids bound to glycerol to form a structure called a triglyceride.  Triglycerides are very large molecules and the general idea is a little like three keys dangling off a keychain. When we eat any fat or oil, our digestive system breaks down the triglyceride into free fatty acids and glycerol so that the molecules can get into our intestinal cells, then the intestinal cell reassembles them back into triglyceride and ships them out in the bloodstream as chylomicrons, a kind of lipoprotein. When we eat too much, we store the extra as fat under our skin, all in the form of triglyceride.


If my oil says expeller pressed does that mean its okay?

No. Here’s why:

Bottles of organic oil often state “expeller pressed” as a selling point, to suggest that it has been gently treated, in an extra-virgin sort of way. But that couldn’t be farther from the truth. Firstly, expeller pressed simply means that the first step of the extraction was mechanical. The second step was probably the standard, solvent extraction using hexane.

But once the expeller-pressed oil has been extracted, it’s generally also refined, bleached and deodorized. These three additional treatments guarantee that the polyunsaturated fatty acid molecules will be oxidized in ways that generate toxins like 4-hydroxyhexanal, 4-hydroxynonanol, aldehydes and more. These compounds aren’t just hard to pronounce, they’re hard for our cells to tolerate and lead to mitochondrial uncoupling, DNA damage, free radical cascades and other cell-damaging events that accelerate the aging process and contribute to disabling disease. Don’t be fooled. (For more information, please read chapters 7 and 8 of the 2017 edition of Deep Nutrition: Why Your Genes Need Traditional Food)



The higher the heat, the more you need to be stirring unless you’re going for a specific effect, like char flavor or crispy skin.


BUTTER+OLIVE: Add a pat of butter to olive oil when cooking at high heat, the saturated fat in the butter protects the olive oil and the antioxidants in the olive oil protect the protein in the butter that might otherwise burn.

SESAME+PEANUT: Add sesame to peanut oil for Asian dishes. The ratio should be roughly 4-8:1 Peanut:Sesame. Sesame is high in PUFA, but it has powerful antioxidants that, when added to low PUFA peanut oil, protect all the PUFAs.


Should I make sure to use a high smoke point oil for pan frying, wok cooking or other high-heat applications?

No. Here’s why:

Smoke point is a sciencey sounding selling point that vegetable oil salesmen use to ooze their way into busy restaurants. If you’ve read about smoke points, you’ve probably read something like this “Refined oils have higher smoke points and typically a more neutral flavor than unrefined oils, which makes them better for sautéing, frying or even deep-frying.” I think the concept of smoke point is bunk. First of all, what chef is going to literally wait for food on the stove to start smoking before stirring it? Have you ever seen that on a cooking show? Secondly, and this is the more important point, the molecular degradation that occurs in these high smoke point oils both during their manufacture and then again when they’re exposed to high heat during cooking invisibly degrades the oil, generating molecules that are dangerous to our health.

If the food you order has black char on it, you’ll probably realize someone in the kitchen wasn’t paying attention to your dish, and send it back. The higher smoke point oils enable chefs to stir less often and in so doing to overheat your food without leaving any evidence.

I’m not saying theres no such thing as smoke point. Of course there is. But the myth is that the product is somehow superior because it has a high smoke point. You can increase the smoke point of any fat by removing proteins, antioxidants, and free fatty acids. For example, ghee has a higher smoke point than butter because the clarification process reduces the protein content.

I recommend using high-quality oils and fats like butter, lard or tallow, and yes, even EVOO, for stovetop frying. But be sure to stir! It should go without saying that overcooking your dishes not a healthy practice. Who needs high smoke points? Just eat properly cooked food.

HOW IT’S MADE: Refining steps that damage PUFAs


Manufactures produce a crude oil by extracting it in one of three ways:

  1. Mechanical extraction, either cold pressed (always below 120 degrees) or expeller pressed (the pressure is higher, which increases the temperature). This is the best. But it leaves a lot of oil behind in the seed or fruit, roughly half for expeller pressing, or more for cold pressing, so it’s typically done only by small batch, artisanal producers. Extra virgin olive oil is produced by mechanical extraction, as are other high-quality oils. The highest quality oils do not need to be refined and so the bottles may contain some cloudy-appearing material that’s actually very good for you. (The video below of Figone’s Olive Oil Pressing at Factory is a good example of what today’s mechanical, expeller pressing system looks like on a relatively small scale.)
  2. Double extraction. This is probably how most “expeller pressed” oil is actually produced. The manufacturer will mechanically press it first, obtaining about half of the oil they will ultimately be able to extract from the seed. This produces oil and an oil-rich seed cake. To remove the other half of the oil from the seed cake, they process with hexane, as below, making for a more “cost effective” product. Unfortunately, from a consumer choice standpoint, its not clear that oils produced this way won’t be called cold pressed or expeller pressed, even though that’s only part one of the process. It appears there’s simply no way to distinguish oils that have been only mechanically pressed from these “double extraction” oils, where half has been mechanically extracted and half has been processed by solvent extraction, as below.
  3. Solvent extraction, using hexane (also in your gasoline tank). This is the worst. They do remove as much of the hexane as they can, using bleaches or distillation, and it’s not quite as damaging to the polyunsaturated oil molecules as the refining process.

What is the best oil? See the heading in the FAQ section below: What is artisanal oil?


After the double extraction and solvent extraction, a sticky soapy sludge develops on top of the oil as a result of churning the phosphatides (when you work soap into a lather, your churning the phosphatides with water creating the foam). These phosphatides must be removed before refining, and so manufacturers use a “wash” of sodium hydroxide and water to accomplish this.

Cold pressed oils do not generally require degumming


Step one and, if it’s needed, step two produce what’s called a “crude oil.” Other than cold pressed oils,  the crude oils all contain numerous contaminants you would not want to eat. So the manufacturer cleans it up in three more very harsh steps that damage the PUFAs: refining, bleaching and deodorizing.

Refining: This is performed to remove the free fatty acids, which would contribute to a rancid taste. This is accomplished with either an acid or bleaching agent. In the latter case, the since bleaching has been performed the process skips ahead to deodorizing.

Bleaching: This is performed to remove chlorophyll, the chemical in plants that imparts the green color. Chlorophyll must be removed from these high PUFA seed oils because it promotes rapid oxidation of the PUFA fatty acids and would lead to a very sludgy, sticky oil that wouldn’t pour out of the bottle very well.  While bleaching improves its pour-ability, it also generates partially oxidized PUFAs compounds. These are the highly toxic compounds that promote oxidative stress in our bodies and can damage our DNA.

Deodorizing: This is performed to remove flavor components, which would come from chemicals originally present in the seed (such as antioxidant phytonutrients) as well as byproducts of the above steps. This is performed by heating the oil again to 510 F/ 265 c and forcing steam through it to try to capture the volatile materials.


The refined oil can be further treated to raise the melting point to create the desired, more solid texture. One method is hydrogenation, which creates a partially hydrogenated, solid fat. Another is inter-esterification, which rearrange the fatty acid locations on glycerol and also solidifies the fat. Both of these lead to generation of different forms of toxins than the above. Hydrogenation leads to the generation of fatty acids with a single trans bond, which block our body’s enzymes. Interesterification leads to the formation of triglycerides with unusual configurations and has been found to lead to elevated blood glucose levels.


Nature does not make bad fats, factories do. By mass producing oils, we can damage them in two different ways that can lead to rancid taste.

  1. ENZYMES.   When oils and fats are too old, they can break apart into free fatty acids, which taste bad and are one of the major causes of rancidity. Mishandling of the raw material before factory processing also promotes enzyme action. The enzymes that release free fatty acids are called lipases, and this kind of rancidity is called lipolytic rancidity. Rancid dairy is especially gross because it has a high portion of the short chain fatty acids that are powerfully bad tasting and are, in fact, partially responsible for the disgtuisting flavor and smell of vomit.
  2. OXIDATION. Another cause of rancidity occurs due to ultraviolet light or heat or metals and other chemicals contaminating the fat or oil. These cause oxidation reactions, and they affect the PUFA fatty acids first. The off flavor results from the fact that oxidation reactions can release free fatty acids from the triglyceride, just as enzymes can, however the freed fatty acids are also damaged chemically and can be very toxic. Rancidity resulting from oxidative release of fatty acids is called oxidative rancidity. Fish is very high in PUFA fats and both oxidative and lipolytic rancidity play a role in generating the rotten smells of old fish.

Is eating rancid food unhealthy?

Yes, in general.

If it were just enzymatic rancidity at play releasing otherwise normal fatty acids, the answer would be no. In fact, animal like vultures that seek out already killed prey seem to enjoy the released free fatty acids we find disgusting. But these animals are generally eating carcasses that are only a few days old at most and generally the parts they eat at this stage contain mostly oxidation resistant saturated fatty acids.

We don’t eat rotting meat, unless we’re living with a native Greenlander and enjoying Kiviaq (made of auks fermented in a seal skin). So when we are hungry enough to consider downing something rancid its generally going to old nuts or seeds that are high in polyunsaturated fats. Because these PUFA fats oxidize easily, if you’re getting an off flavor from nuts or seeds its unhealthy and best avoided.


Some of the most toxic fats have no flavor at all, and thus we can’t rely on taste to warn us that an oil contains toxic, oxidized fats. In fact, Canola, Soy and the other RBD oils are marketed to restaurants based on their lack of flavor, meaning the chef can use the same oil regardless of the spices and other flavor profiles.

Harvard Gets It Wrong

If you care about your health, ignore Harvard and Yale–at least for now. While many leading MDs are waking up to how wrong we were to insist that saturated fat was unhealthy, these two schools are digging their heels deep in the 1950s-era dogma.  Their recommendations is to avoid saturated fat as much as possible, and get roughly 25% of daily calories from polyunsaturated fat-rich foods like vegetable oils. The only evidence that supports this position is statistical (they do not offer a plausible physiologic mechanism), and their statistical work is seriously flawed by wrong assumptions and confounding variables.

In 2015, scientists at the NIH analyzed autopsy slides that were made as part of a study done in the 1970s. The study compared two diets, one rich in liquid vegetable oils (high polyunsaturated fats) and the other rich in hydrogenated vegetable oil (high in trans and saturated fats). Believe it or not, they found the folks on the hydrogenated vegetable oils had fewer heart attacks and strokes than the people on the liquid vegetable oils.

Walter Willet, the Dean of the School of Public Health, dismissed this finding as “a historical footnote.”

What Made Me Realize Harvard Gets it Wrong

I read a PhD dissertation that explained how polyunsaturated fatty acids (PUFAs) can ignite free radical reactions in our bodies. Free radical reactions are really bad. After reading more about oil processing and PUFA oxidation, I realized everything I’d learned about fats in medical school was wrong, and that it was necessary to reverse my earlier position on good fats and bad. As a practicing doctor, making this shift has not been easy, because it goes against what most of my colleagues still believe.

Technically Speaking:

This section defines some common scientific terms for those interested in more of the chemistry.

BEST METHOD OF DETERMINING OXIDATIVE STABILITY: Activated Oxygen Method or AOM, I think it’s heating to 100C with peroxide, and the longer it takes to get to a certain point, the more it resists oxidation.

RANCIDITY=any off flavor. Two reasons: free fatty acids released from trigylceride, producing an off flavor. And Partial oxidation of the fatty acids.

FREE FATTY ACID FLAVOR (from vegetable oil manual I downloaded):

The liberated free fatty acids have a distinct flavor and odor which are more disagreeable when the fatty acid chain length is shorter than 14 carbons

OXIDIZED FATTY ACID FLAVOR (From veg oil manual)

Hydroperoxides themselves have no flavor or odor but break down rapidly to form aldehydes, many of which have a strong, disagreeable flavor and odor.


“Hydrolytic rancidity, also called hydrolysis or enzymatic oxidation, occurs in the absence of air, but with moisture present. This normally is accomplished through enzymatic peroxidation, where enzymes found naturally in plant oils (i.e., lipoxygenase, cyclooxygenase) and animal fats (i.e., lipase) can catalyze reactions between water and oil.

Another degradation process is microbial rancidity, in which micro-organisms such as bacteria, molds and yeast use their enzymes to break down chemical structures in the oil, producing unwanted odors and flavors. Water needs to be present for microbial growth to occur.”

OXIDATION: Double bonds in the fatty acid reacting with oxygen.

OXIDIZED: Double bonds in the fatty acid that have reacted with oxygen to generate reaction products, usually with toxic e

IODINE VALUE: How many double bonds are present on average in the triglycerides in the oil. Does not distinguish between mono and poly. Higher value represents more double bonds.

PEROXIDE VALUE: Peroxide determination is the most widely accepted method for oil flavor quality determination. Peroxides are the major initial products of lipid oxidation and are measured by techniques based on their ability to liberate iodine from potassium iodide or to oxidize ferrous to ferric iron. Their content usually is expressed as milliequivalents of oxygen per kilogram of fat. Peroxide values of 0.5 meq/kg or less generally are necessary for a high flavor score. Because of the transitory nature or instability of peroxides, the level of peroxides may not serve as a true indicator of the actual state of oxidative rancidity of the fat or oil. During the course of oxidation, peroxide values reach a peak, then decline


What is artisanal oil and why is it the best?

Oil extracted using the highest quality mechanical (cold pressed) process that is tasty and wholesome enough to consume as is. Artesanal oils do not require any further steps and are sold unfiltered and unrefined. These are the most nutritious oils.

Can I eat seeds, nuts or fish that are high in PUFA?

Yes. Nature doesn’t make bad fats, factories do. For one thing, the seed oils are concentrated forms of PUFA, while the seeds, nuts and fish are not. Plus, when it comes to nuts and seeds, it’s the refining process that causes toxins, as described under How It’s Made: Edible Oils, above. When it comes to fish, consuming it raw, poached steamed or gently cooked will protect the PUFAs (so just don’t overcook it), and the fish tissue itself contains antioxidants so there will be far less PUFA breakdown.

I heard peanut oil was high in PUFA, why is it listed as good?

Peanut oil is higher in PUFA than olive oil, but still healthy when unrefined. This is because it has much less PUFA than the other seed oils, and the peanut seed protects its PUFA properly with plenty of antioxidants. These antioxidants would be removed during refining, but remain while unrefined.

Sesame oil is also high in PUFA, why do you list it as good?

Unlike the Hateful 8 seeds used to make industrially extracted and refined oils, sesame seeds are a traditional source of oil generally used for flavor. They are different for two more reasons as well. 1) Sesame seeds are relatively higher in fat (and antioxidants that protect PUFA) than most of the Hateful 8 seeds, which means the extraction process does not require harsh treatment. 2) The oil is not refined, and so the abundant antioxidants, minerals and vitamins are still present. I do recommend caution with heating, meaning don’t use for extended high heat cooking. Finally, I recommend combining it with peanut (see above) for stir fry.

Flax oil is high in PUFA, why is that good?

Flax is high in omega-3. It’s not used often as a culinary oil. Flax oil is sold as a supplement and is generally unrefined. Definitely don’t cook with flax because the omega-3 in flax is more unstable than the omega-6 in sesame.

Pumpkin oil, good or bad?

Pumpkin seed oil contains about 50% PUFA (mostly the omega-6 linoleic acid), 25% monounsaturated (oleic acid) and about 20% saturated. This high percentage of delicate PUFA means it must be unrefined to be edible and also that it’s not good to cook with.

What about high-oleic sunflower oil, is it better?

It is better, but not good, and the same applies to all high-oleic seed oils including soy, canola and safflower.

What about soy or sunflower lecithin?

This question came up so often I created a post, here:

What are your thoughts on Thrive Algae Oil?

Not a big fan. They say “Highest level of monounsaturated fats and 75% less saturated fat than olive oil and avocado oil* the fact they think less saturated fat is a good thing indicates they don’t really understand the chemistry. They also say “Light, neutral taste lets the flavor of your food shine through” neutral taste means its refined, as does the high smoke point. Refining strips away nutrients, but who knows if there ever were any since we’re talking about algae, pond scum Frankenfood. Ever see the movie Soilent Green?

What about skin products made with seed oils?

While PUFAs applied to your skin won’t build up in your body fat, damage mitochondrial or promote systemic inflammation, they won’t do as much good for your skin as products made with stable oils that are higher in mono and saturated fat. As far as refined versus unrefined when it comes to skin, there’s much less benefit from unrefined. While unrefined indicates a better product (and probably a higher pricetag) your skin can’t absorb a significant amount of the nutrients that refining would remove, so you’re not missing much.

PALM oil is showing up in more foods. How can I tell if it’s refined?

If it’s unrefined the ingredients usually say so because it’s much more costly and they want you to know. The tougher questions is HOW was it refined? High-heat refining can produce carcinogenic compounds. Right now, the best method is to go by cost. If the product containing palm is less expensive than similar products containing soy, canola etc, it’s probably best to avoid it. I know that’s not a very good answer, sorry!

Is Brain Octane Oil acceptable in bulletproof coffee? It is derived from coconut oil, but distilled with heat and pressure. Is it toxic?

It’s ok. Not toxic because the saturated fats are very stable to all the processing. Less nutritious than cream/butter, especially grass-fed.

How long does it take to get the excessive PUFA out of my body?

The half life is 18 months, so 4-5 years until you’re clear. That’s how long it takes to become ‘fully fat adapated.’ Fortunately you don’t need to wait years or even months before you start feeling results. You will start to experience improved energy the first day you swap out toxic fats for healthy ones in your breakfast.


Interesterification leads to elevated glucose:

Refining Steps:

Related Posts

From Carnivore Aurelius


Dr. Cate

With over two decades of clinical experience and expertise in genetic and biochemical research, Dr. Cate can help you to reverse metabolic disease and reshape your body.

This Post Has 59 Comments

  1. Dear Dr. Shanahan, I love this oatmilk that I drink, but it has rapeseed oil in it 🙁 Is that the same as Canola? Also, is it definitely bad for me or does it depend on how processed/refined the rapeseed oil is?

    They state “We think rapeseed oil is a good choice for our products since it contains both fatty acids and a high proportion of monounsaturated fat (compared to coconut oil, which is a saturated fat). We use only non-GMO rapeseed oil, processed as per other refined vegetable oils, but hexane is not involved in the processing of our oil. By the way, the rapeseed oil in our US Barista Edition is pressed and contains 0.0g/100g cholesterol and <0.1g/100g trans fat. Which means we can declare 0g on the package."

    Thank you! Nicola

  2. Dear Dr. Shanahan
    Thank you very much for all the information you provide. I’ve just finished your book and really enjoyed it.

    I do however have a few questions that so hope you can answer for me.

    I make stone age bread/crakers (from seeds, water and salt only) and I make toasted pumpkin seeds for my family (sometimes toasted in duck-fat or lard). My kids really enjoy both as a replacement for chips etc. Is this OK? Or would the PUFAs in the seeds be oxidized?

    Also – my husband has had lifelong problems with his sleep cycle and our Dr. tested him and found that his cortisol levels are out of wack. But since he started eating smoked cod liver (canned) twice a week the sleep problems have pretty much disappeared. We decided to supplement him w. cod liver after establishing that taking A, D and E-vitamins helped his sleep problems, but opting for a whole-food option instead of taking vitamin pills. But is the smoked cod-liver oxidized? And is it OK to eat the cod-liver oil from the can? The canning and smoking heats up the liver, but the oil does not smell bad at all (I sometimes use it on my salad).

    Hope you can help. Thank you for everything you do!

    Best Regards,
    Dawn Hoff

  3. Dear Dr. Shanahan,

    I love all that you do and I am learning so much from all of your interviews. ( The REal Skinny on Fat) When you get a chance to answer as I know you are busy, what do you think of fractionated coconut oil?


  4. I’m a co-owner of a pasture-based family farm (Weathertop Farm in VA). I just listened to your podcasts (actually 2 back-to-back) on Primal Blueprint. I listened twice to make sure I heard right. I have long known about Omega 6 to 3 ratios and vitamins etc…, but if I heard right, when pasture is a significant percentage of the hogs diet, you said the ratio of saturated to unsaturated fat changes. I assumed most animals were like beef where diets didn’t change the molecular structure (double vs. single bonds), just the health of that type of fat. I’m very interested in knowing more of what goes into the process of changing the percentages of saturated to unsaturated fat in pork. I know you’re very busy, but I would greatly appreciate a little direction as to where to find research on this and some explanation of what the grass in the diet is doing in a non-ruminant animal. Many thanks, Cedric

    1. HI Cedric! As is true with humans, the PUFA content of a pig’s diet is reflected in its body fat. There’s a decent amount of research in several species, look for “fatty acid profile essential dietary fats adipose” in google scholar. The exception to this trend seems to be cows, who’s complex gut flora may be why they’re more capable of preventing excessive PUFA concentration in their adipose. If I said pigs graze on grass I should have corrected myself, obviously that’s not the case.

    2. HI Cedric,
      The PUFA content in adipose reflects the PUFA content of an animals diet. Cows seem to be a bit of an exception. Lots of research can be found googline “fatty acid profile adipose dietary.” Sorry about the confusion around pigs eating grass, if I said that I misspoke–obviously they are not grazers. I may have been trying to say pasture raised, meaning access to outdoors.

      1. Thanks so much for getting back to me. I think I’m getting closer to my source of confusion. I was not under the impression that you were claiming pigs were solely grazers. (Although with good rotation practices, I think one can get their grass intake to be as high as 25% of their diet…to see our hogs “grazing” see: )

        And please believe me, I am not trying to play gotcha or anything…but in Primal Blueprint Podcast #216, starting around 21:30 you start advising against bacon if sourced from CAFO’s. You go on to say 100% grain fed, confined pork is “…extremely high in PUFA’s, higher than…properly fed pigs…Fatty acid profile of beef doesn’t change that much when the cow is fed grain…but of pigs it does. It just goes to that high PUFA…and unhealthily high…”

        I understood that to say grass intake could influence % of saturated fat to PUFA’s. I knew it changed the ratio of Omega-6 to O-3, but O-3 IS a PUFA. And simply changing the O-6 to O-3 ratio does not technically change the amount of total PUFA. Does that make sense? What am I missing? Can 20-25% intake of pasture change % of unsaturated fat to saturated fat?

        1. Sorry I did not explain very well The answer to the question: Can 20-25% intake of pasture change % of unsaturated fat to saturated fat? Is yes–at least if we’re talking about replacing corn and soy feed with grass.

  5. Hi Dr. Cate,
    Is it a bad idea to take a sunflower lecithin supplement for phosphotidylcholine? Is that just essentially taking sunflower oil (processed) ? Is there a better way to supplement PC? thanks!

  6. Hi, Dr Shanahan,
    I have been eating a lot of plantain chips, either from whole foods or trader joe’s over the last year because they are AIP compliant.
    WF Ingredient list: Plantains, Palm olein oil, and salt
    TJ’s Ingredient List: Plantains, Palm olein
    I realize the fatty acids in these chips, once fried, are likely of zero nutritional value, but I was always under the impression that palm oil or even palm olein oil (despite processing) was safe to eat because it was not an oxidizing oil. Is this an incorrect assumption, and should I stop eating these?


    1. I would very much like to know the answer to this as well! I have considered baking them from scratch but I can’t imagine they’d taste as good. I read somewhere that palm olein is toxic once oxidized, which I assume it is since the chips are fried?

  7. Hi Dr. Cate,

    Love your work! I saw that sunflower oil is listed as an oil to avoid. Should people also avoid sunflower butter and sunflower seeds?


    1. Sunflower oil is a problem because of the refining, and of course sunflower seeds are not refined. The answer on sunflower butter is determined by if you make yourself at home and don’t bake anything–good–or if you’re buying a processed product–not good.

    2. Sunflower oil is a problem because of the refining, and of course sunflower seeds are not refined. The answer on sunflower butter is determined by if you make yourself at home and don’t bake anything–good–or if you’re buying a processed product–not good.

      1. I currently buy the brand ‘Once Again’ organic unsweetened, unsalted sunflower seed butter because I don’t have time to make it myself. Is this a safe product to eat?? Thank you for your time.

  8. There are large numbers of companies making all kinds of snack crackers these days. Everthing with GMO’s to kale and real sugar and and and. But virtually all of them still use oils from the BAD list.

    Is there anything out there these days for chips and snacks from the supermarket we can buy that have good oils in them? Seems like there is a market out there for something that tastes great and is “better for you” because they have no “bad oils” they were processed with, or as ingredients.

    I keep looking…. Thanks.

  9. Dear Dr Cate,
    Still curious about Fish Oil and megatrans – in particular whether megatons are present in all omega 3 marine oils (krill oil, cod liver oil etc ). I note on pg.86 on Deep Nutrition you cite a study which showed that cod liver oil taken by pregnant mothers had protective and long lasting effects on the baby’s intelligence. So cod liver oil is not all bad. But does it, at the same time as offering these benefits, also put megatrans into our bodies? If so, what should we do?

    1. Correct it’s not all bad. There is the potential for all of these marine oils and indeed all omega-3 supplements to have the degraded, Megatrans bad fats. But there is a lot of variability in the processing that can make a huge difference in the shelf life.

      The higher quality supplemental oils generally use words like cold pressed and unrefined on the label.

      It would be nicer if these companies could explain how they avoid oxidation during their processing.

      1. This feels like a deeply significant piece of information. I’m just an ‘ordinary consumer’ – somewhat more informed after reading Deep Nutrition, but not an expert on fish oil processing methods, avoidance of oxidation etc. When buying fish oil, cod liver oil, krill oil etc it sounds like it is something of a lottery – there is no realistic way for me to know whether the oil I am buying contains Megatrans or not. (And it is is probably the case that most fish oils do contain it, but I will never know for certain which ones do or don’t.). So it would seem reasonable to conclude that our health would be better served by avoiding the stuff altogether?

        1. Yes, we can be fooled into believing that because something’s in a capsule it’s all honkey dorey. You can sometimes tell by flavor but you would have to know what’s normal. If there’s an alternative you can use that would be better but you simply may not need it if you are not eating veg oils and your diet contains grass fed fats or a lot of PUFA rich nuts. Or oily cold water fish.

      2. I just warned about this. Hopefully they will do some private testing of fish oil supplement oxidation.

  10. A quick question about Fish Oil .On page 168 of Deep Nutrition you mention that fish oil contains megatans and should be avoided. Does this apply to all omega 3 oils? For example are cod liver oil, fermented cod liver oil (e.g. by Green Pastures) and krill oil (as recommended by Dr Mercola) all equally suspect in this regard (that they contain megatrans)? Grateful for your advice as I am perplexed about this!

  11. fatty fish and printing out the list.
    1) why do you say that it´s important to be cautious with heat when preparing fatty fish? I don´t eat raw fish…

    2) is it ok to print out the above list of good fats and oils versus bad?

    regards, b.i.g,

  12. I’d really like to know why Sunflowe and Safflower oils, specifically, are considered bad vegetable oils. Sunflowers themsleves are touted as having seversl health benefits. I am actually not quite sure what a Safflower is ?. Anyway, is it the refining process that makes these oils toxic? Is a small amount (as in the amount in some health foods sauces/dressings ok? Specifically I am vegetarian and recently fell in love with Beyond meats Beyond burgers. I see no major red flags except Sunflower oil, and refined coconut oil. But is this harmful if I were to eat these once or twice a week? Or is it just better to flag those ingredients like HF corn syrup and gluten and completely avoid. I do realize this is something processed, but the ingredients are not terrible and they are delish and a solid source of plant protein.

  13. Thank you for this info and research! I am wondering about nut butters, specifically my favorites: cashew and almond?

    1. If you make them yourself, absolutely so. If its processed and you’re buying it, might be less good than yours depending on how its made, specifically how high its heated, but at least you won’t have the oil refining steps which are the worst, most chemically damaging.

  14. I’m really enjoying Deep Nutrition audiobook Dr. Cate! I’m already recommending it to friends and family.

    I do have two questions on specifics. My prepackaged, moist ready rice contains canola and/or sunflower oil. As far as I can tell, it amounts to 1-2g of fat. Is this amount (of oils) enough to worry about? I do enjoy the convenience of the packages.

    On Endurance Planet podcast (if I heard correctly) you mentioned not eating sugars or carbs before a workout. For convenience, many of us take 1 gel 20 minutes before a race starts. Could you let me know if you think that is a bad idea in terms of performance? Thank you!

  15. Hi Dr. Cate, I am reading Deep Nutrition and it has been life changing in terms of my perspective! Can you please comment on whether fish oil is safe to take? I have been taking the brand SFH (Stronger, Faster, Healthier) for years.
    Also — can you please direct me to the best “restaurant survival guide” you have? Thank you!

  16. Hi Dr. Cate-
    I’m a Family Practice NP and I’m SO with you on the vegetable oils! I steer my patients and my family away from processed foods. Once in a while I will come across store- bought chips or crackers cooked in avocado or coconut oil (no PUFA on label, but doesn’t say refined or not).. are those OK for “occasional use”?

    and what about heating up seeds at low heat? I make an “overnight” chia pudding in almond milk with berries which I stove-top heat in the AM for 5-7 min at very low heat. Is that fine? or risky? What about baking them (like cookies with flax or hemp seed?)
    By the way, most of my patients are really on board with increasing their healthy fats- they can’t believe they can leave the skin on the chicken! So we are making progress!

    1. Once in a while I will come across store- bought chips or crackers cooked in avocado or coconut oil (no PUFA on label, but doesn’t say refined or not).. are those OK for “occasional use”? Yes
      On the “chia pudding in almond milk with berries which I stove-top heat in the AM for 5-7 min at very low heat. Is that fine?” Yes low, moist heat and being still in the seed protects the PUFA, same applies for baking since relatively moist.

  17. Just read Tufts University Health & Nutrition Letter: Unsaturated Fat Best for Heart in their May 2017 isdue
    New study published in The BMJ November 2016
    Unbelievable instead of butter or lard choose corn canola soybeans instead of coconut milk Soy milk
    How do you answer them Dr.Cate? How do we fight back?

    1. They can’t admit they were wrong. It’s up to the next generation of dietitians and MDs (and anyone else who wants to join us) to form new organizations that get it right. The only way to fight it to not be snobby about ‘brand name’ institutions like Harvard Tufts and so on and recognize that we need to wash out the old guard and make way for the new. I’m teaching medical students and they’re eager to hear the truth so they can do right by their patients.

  18. As a massage therapist I have spent years with my hands immersed in lotions containing canola oil. Is this as dangerous as ingesting? Or is it not as damaging when only contacted externally?

  19. I use KTC refined coconut oil, because the coconut smell and taste swamps with unrefined (It’s also more affordable)

    According to their FAQ, “it is a refined oil where any impurities in the raw material have been removed and it is not hydrogenated. The refining process for coconut oil is a physical process. The purpose of refining is to remove any impurities present in the raw material to produce 100% oil. The oil itself is not affected by the refining process.”

    Elsewhere they describe their refining process:
    ————- quote ————–

    Coconut oil is physically stripped from the husk and extracted by pressing (not chemical extraction). The oil is then refined. During processing the oil is filtered number of times as well as at the end of process before loading or packing. End product has very low moisture content and high temperatures during deodorisation can guarantee that it is microbiologically safe.

    Temperatures used in process of crush and refining are lower than the normal cooking temperatures – below 80-110C.

    Where processes require to use higher temperature 180-220C vacuum is used to reduce temperature impact.

    All process aids are food grade and fully removed from the oil.

    For bleaching refineries use natural absorbent (bleaching earth or bleaching clay) and active carbon similar to what is used to purify water. Name “bleaching” came from the fact that the same time oil become lighter in colour because of pigments are also absorbed by clay.
    ——————— unquote ————-

    Does this process conform to your expectations, or is it better at all?

    1. That’s pretty standard refining process, yes. The reason refined coconut oil is ‘limited use’ and not ‘avoid’ has to do with the fact that the fatty acids are very stable and not much damaged during the refining. What’s lost is many antioxidants, vitamins and minerals.

    1. Limited use only. (I added it to the graphic, thank you for bringing it up!)
      The mostly saturated fatty acids in coconut are not going to be damaged by the harsh RBD processing the way the PUFA fats are damaged in vegetable oil.

    2. Yes it is ‘OK’ not good and not bad, but in the middle there. The reason ? Because the sat fat in coconut oil is ‘sturdy’ and won’t be damaged. The refining in this case primarily removes antioxidants and some minerals, but honestly coconut oil doesn’t have that much of either to remove. It’s almost the junk food of healthy fats.

  20. How do you determine avocado oil from refined avocado oil? Same for peanut oil. What to look for on the label. I use avocado oil from Chosen Foods.

        1. OK then that’s refined and it’s in the limited use category. Meaning it’s not expected to contain toxic fatty acids to any significant degree, but its also stripped of significant levels of nutrients (minerals, antioxidants) so it won’t be particularly healthy.

          1. I have been using this exact same avocado oil for cooking, is it bad to use it with high heat then? What if i find virgin avocado oil then it would be ok to cook it with? or which one would be the best to cook it with? Peanut oil? Thank you so much for your amazing book it changed my life! <3

          2. Avo, peanut and olive can be used for high heat, you just have to stir and watch more carefully than you would with lower heat cooking.

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