Harm of PUFA

They tell us to use more vegetable oil… Is their motivation pure?

Who is “they?” Hmmm, good question.

The American Heart Association gives a long list of oils they claim are “better-for-you.” They are all highly polyunsaturated fats made in a factory – like sunflower, corn, and soybean oils. Then they go on to say:

American Heart Association tells us to eat more polyunsaturated fats

Blends or combinations of these oils, often sold under the name ‘vegetable oil,’ and cooking sprays made from these oils are also good choices.”[1]

Phew! At least we have the AHA by our side to show us right from wrong. All we have to do is listen to them and our heart will be fine, right?

WRONG! If they were doing it right, then people would not be dropping dead of unexpected sudden cardiac death. (We have a whole page on this topic if you would like to check it out.) Clearly they got something wrong. And, indeed, they did. They have the whole “fat thing” wrong – which debunks most of their philosophy…

The Chemistry

This one topic has given us a lot of trouble. Not because we don’t understand it – and not because there is no clear answer to the issue. Nope. Indeed, the chemistry is pretty straightforward. It all makes perfect sense.

That is not the troubling part. The problem lies within the powers at be. They keep spewing junk science our way to tell us that vegetable and cooking oils are good for us when they are not. Not even close. Common sense chemistry is the answer, yet no one seems to look at it!

[And an even more troubling thing to wrap your head around? Think about all the money being made in the sale of vegetable oils. We are not talking chump change here. While we will never know an exact amount, it is somewhere in the billions – if not more. There is a huge and vested interest in making sure people buy cooking oil. Just sayin’..]

Vegetable oils are made of mono- and poly- unsaturated fats. That means the long carbon chains have one or more double bonds. That is why they are liquids at room temperature. The double bonds cause kinks in the molecules and prevent them from packing well. But these bonds serve a much more important role.


Polyunsaturated fats have multiple double bonds - more reactivity

One of the first concepts of basic organic chemistry is that a double bond is much more reactive than a single bond. Being highly “reactive” is not a good thing. It means it changes form and function easily. It does not stay the same “well behaving” molecule when put in certain environments.

So what happens when you heat them up? Oh, they oxidize and form other chemical compounds, like volatile aldehydes.[2] That means they react with the oxygen around it to form different (and harmful) compounds. They are chalk full of mutagenic and carcinogenic properties, which affect DNA. Excellent…

And what happens when you eat them? They also oxidize when they become part of your cell and mitochondrial membranes.[3] These membrane lipid peroxidation products are also very harmful. They may even be the centerfold piece on our aging.

That’s it. Really straightforward. More double bonds means more reactivity. More reactivity means more oxidation. Oxidation is bad. This is all the common sense chemistry coming out. However, that is not enough to fully “prove” the harm of polyunsaturated fats. We need to substantially back this up with the observable / testable science.

What does the research have to say about this topic?

The Scientific Literature

It turns out that common sense chemistry lines up really well with the scientific research.

So first of all, we see that dietary fats correlate with the types of fatty acids composing your cell membranes.[4][5][6] The more unsaturated fat you eat, the more unsaturated your membranes will be. That is not a good thing – to have a high degree of unsaturation and all. That is because they are more susceptible to oxidative stress. They break down easier if they have more double bonds, just like what were talking about above.

Having a high degree of unsaturation (lots of double bonds) is also linked to shorter lives. The more saturated your cell and mitochondrial membranes are, the longer the life you will have.[3][7] We suspect this is precisely due to the higher stability of your membranes when you have have more saturation. The advanced lipoxidation end-products are pretty nasty.


Fats in your membranes

Omega-6 to Omega-3 Ratio

Having a lot of the omega-6 fats around in your membranes will lead to certain peroxidation products that are especially bad: malondialdehyde & 4-hydroxy-2-nonenal.[8] They inhibit gene expression and promote cell death. They will also interfere with proteins and DNA. Having said this, the oxidation products can also be protective – that is what they are there for. It is a regulation system – a balance.[8] But having such a high ratio of omega-6 to omega-3 fats (15:1 as we have in our standard American diet) is where things go south.

This high ratio is not “normal” for human beings. We have evolved to eat a ratio around 1:1.[8] But do you know what changed? Yep, the introduction of vegetable and cooking oils. They are almost entirely made up of omega-6 fats.[9] They range anywhere from 80% to 20% omega-6 composition, with only about 1% omega-3. That is certainly not a 1:1 ratio…

Having such a high ratio correlates with tons of inflammatory diseases: heart disease, diabetes, arthritis, metabolic syndrome, etc.[10] Correlation is not causation, but the trend is clear. Omega-6 fats are pro-inflammatory. They damage the cells (from their oxidation products), and then other substrates come in to try to help the problem, which is the “inflammation” part. This is problematic when the damage is frequent and you are always in a state of inflammation – chronic inflammation.

The Really Frustrating Part

Okay, so we can see all the ways having these polyunsaturated fats in our diet is bad for us. They are reactive and produce nasty things when they are heated up or when they breakdown from oxidative stress in the body. Then how can people get away with promoting vegetable oils as a “healthier alternative” to using saturated fats? That’s the real question.

Them telling us to use vegetable oils is ridiculous

From our research, it is only due to one simple fact about polyunsaturated fat: it lowers your cholesterol levels. It lowers both total and LDL cholesterol.

We won’t even want to go through the trouble of citing references for this because it is everywhere. It is true, and you can easily find it for yourself to be true. Just Google it. What we care about is the idea of cholesterol being “bad.” That is a lot more fun to deal with. Yes, polyunsaturated fats lower cholesterol.. The real question lies with cholesterol. Is it really as much of a problem as people claim it to be?

It is not true. Absolutely. We have a whole page that talks about the vital role cholesterol plays in your body – check it out here. Cholesterol is not a problem – especially not LDL, like people love to shout about. Having high cholesterol may signify a problem, but it, itself, is not the problem. So lowering your cholesterol via cooking oils is not helping anything.

Not only are you not helping anything, you are actually hurting everything. Instigating chronic inflammation is one of the worst things you can do to your body, and that is exactly what you get with using cooking oils.

Bottom Line

Never ever use vegetable oils!! Simple.

Maybe use extra virgin olive oil (low omega-6 composition) for cooking, but try to stick with saturated fats like butter and coconut oil. They will not form nearly as many of the nasty products during the cooking, and they will also keep your cell membranes strong through its resilience to oxidative stress.

Go back to what mother nature had intended for us – using fats from animals, not fats processed in a factory.


[1] “Healthy Cooking Oils”. American Heart Association. (2018). [Online]. Available: https://recipes.heart.org/Articles/1013/Healthy-Cooking-Oils. Accessed: 29 May 2018. 

[2] Grootveld M, Rodado VR, Silwood CJ. (2014). Detection, monitoring, and deleterious health effects of lipid oxidation products generated in culinary oils during thermal stressing episodes. Inform 25(10): 614-624.

[3] Barja G, et. al. (2017). The Cell Aging Regulation System (CARS)Reactive Oxygen Species 3(9):148–183.

[4] Sheehy PJ, Morrissey PA, Flynn A. (2007). Influence of heated vegetable oils and α‐tocopheryl acetate supplementation on α‐tocopherol, fatty acids and lipid peroxidation in chicken muscle. British Poultry Science 34(2): 367-381.

[5] Mcmurchie, E. J., Gibson, R. A., Charnock, J. S. & Mcintosh, G. H. (1986). Mitochondrial membrane fatty acid composition in the marmoset monkey following dietary lipid supplementationLipids. 21(5): 315–323.

[6] Geiser, F. (1990). Influence of polyunsaturated and saturated dietary lipids on adipose tissue, brain and mitochondrial membrane fatty acid composition of a mammalian hibernatorBiochimica et Biophysica Acta (BBA) – Lipids and Lipid Metabolism 1046: 159–166.

[7] Pamplona R. (2008). Membrane phospholipids, lipoxidative damage and molecular integrity: A causal role in aging and longevity. Biochimica et Biophysica Acta – Bioenenergetics 1777(10): 1249-1262.

[8] Ayala A, Munoz MF, Arguelles S. (2014). Lipid Peroxidation: Production, Metabolism, and Signaling Mechanisms of Malondialdehyde and 4-Hydroxy-2-Nonenal. Oxidative Medicine and Cellular Longevity 2014: 1-31.

[9] Orsavova J, Misurcova L, Ambrozova JV, Vicha R, Mlcek J. (2015). Fatty Acids Composition of Vegetable Oils and Its Contribution to Dietary Energy Intake and Dependence of Cardiovascular Mortality on Dietary Intake of Fatty Acids. International Journal of Molecular Sciences 16: 12871-12890.

[10] Bhardwaj K, Verma N, Trivedi RK, Bhardwaj S, Shukla N. (2016). Significance of Ratio of Ometga-3 and Omega-6 in Human Health with Special Reference to Flaxseed Oil. International Journal of Biological Chemistry 10(1-4): 1-6.

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