Are unsaturated oils bad for your skin?

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How to cite: Wong M. Are unsaturated oils bad for your skin?. Lab Muffin Beauty Science. July 17, 2017. Accessed July 24, 2024.

An article by Beautyeditor (now rebranded as The Skincare Edit) recently came to my attention, thanks to some readers who pointed me in its direction. In it, she blames polyunsaturated oils for aging, tells you to avoid them in your skincare AND diet, and tells you to use saturated fatty acids (in particular squalane) instead.

Are unsaturated oils bad for your skin?

As a big fan of oils containing unsaturated fatty acids (in particular rosehip oil which is my SOS skin saviour), I had to dig into this. Here’s a closer look at the science behind oils…

The facts about unsaturated oils

Let’s start with what Beautyeditor/The Skincare Edit got right. Unsaturated fatty acids are indeed less stable than saturated fatty acids, which means they’ll have a shorter shelf life.

Fats and oils are collectively known as triglycerides. Unsaturated triglycerides oxidise more easily than saturated triglycerides because they contain more double bonds, which are more reactive than single bonds. You’ll know an oil’s been oxidised when it goes rancid and smells a bit gross. The oils will react when exposed to air, light, heat and free radicals (though adding antioxidants like vitamin E to the oil will slow this down).

Triglyceride molecules consist of 3 fatty acids (blue) linked to a glycerin molecule (purple):


It’s the fatty acids that can vary and contain double bonds. Fatty acids are divided into saturated (no double bonds), monounsaturated (1 double bond) and polyunsaturated (2 or more) fatty acids.


Here are some common fatty acids in each category:

  • Saturated: lauric, myristic, palmitic, stearic
  • Monounsaturated: oleic (omega-9), palmitoleic
  • Polyunsaturated: linolenic, eicosapentaenoic, and docosahexaenoic (omega-3), linoleic (omega-6)

The fatty acids can vary, so you can get a triglyceride that contains, say, 2 saturated fatty acids and 1 polyunsaturated fatty acid. Most natural fats and oils aren’t entirely saturated or monounsaturated or polyunsaturated, but very few have an even balance of all three.

  • Mostly saturated fats and oils include coconut oil, butter, palm oil, beef fat
  • Mostly monounsaturated fats and oils include avocado oil and olive oil
  • Mostly polyunsaturated fats and oils include fish oil and most of the common skincare oils: safflower, sunflower, rosehip, almond, hemp, and grapeseed oils

Why might unsaturated oils be bad?

So far so good, but does this instability have an effect on your skin? Here’s where her argument gets dicey.

It turns out that Beautyeditor/The Skincare Edit is a follower of Ray Peat, who believes that polyunsaturated fatty acids (PUFAs) are a big cause of aging. He advocates avoiding them in the diet because he thinks they cause oxidative stress, which builds up to cause aging. This goes against the advice of pretty much all recognised medical bodies. PUFAs include the essential omega-3 and omega-6 fatty acids, which are called “essential” because we can only obtain them from our diets. They’re required for all sorts of things in our bodies including healthy heart and brain function, and more importantly making cell membranes which all cells need, hence why there are recommended intake guidelines.

Other things Ray Peat recommends: avoiding exercise, increasing white sugar consumption, increasing dairy consumption, eating more ice cream (I’m serious).

(A really detailed breakdown of PUFA pseudoscience can be found here.)

The case for unsaturated oils

OK, so Ray Peat is clearly a quack (see here for why cranks who opposite “mainstream experts” are usually full of BS). But his argument for rancid PUFAs causing negative health effects is theoretically plausible.

However, studies where unsaturated fatty acids and oils been used on skin have usually found beneficial effects. The oils in those studies would have been susceptible to oxidation, much like an oil you’d use in your skincare routine.

Not all of these studies are high quality, but they give you an idea of the overwhelming consensus: that polyunsaturated oils are probably more good than bad, and the scaremongering is unnecessary. It’s also worth noting that I couldn’t find any studies that found that unsaturated oils increased the signs of aging. This isn’t surprising, since we have plenty of unsaturated fatty acids and lipids in our skin naturally. Unsaturated fatty acids are required for making skin, in particular for making ceramides.

Applying them to skin can be beneficial:


Essential fatty acid supplements are potentially helpful for treating skin conditions like eczema, acne and psoriasis, and is potentially beneficial in preventing skin cancer.



Some skin conditions are associated with PUFA deficiencies:


There’s no evidence behind the claim that polyunsaturated oils are detrimental and cause aging. There’s also no evidence behind a lot of the other dodgy claims in her unsaturated oil posts. A selection:

  • Squalane is an antioxidant: Bad news, squalENE works as an antioxidant because it has double bonds. SqualANE can’t work in the same way.
  • The sun isn’t the main cause of skin aging, it’s diet: There are no reliable sources for this, it seems to just be Ray Peat’s gut feeling. This study on 300 women found that “UV exposure seems to be responsible for 80% of visible facial aging signs [in Caucasian women]”, and is a bit more reliable since it’s actually a study and aligns with what every other study on the topic has found.
  • Age spots aren’t from the sun but from PUFAs: Except linoleic acid treats hyperpigmentation.
  • 20-60% of stuff applied on your skin get absorbed into your bloodstream: This is complete poppycock, luckily. You’d gain a lot of weight from moisturiser…and you’d have eaten all your clothes.
  • It takes four years to detox PUFAs from your tissues: You probably don’t want to do that, unless you really hate having cells.

Use oils to your heart’s content!

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79 thoughts on “Are unsaturated oils bad for your skin?”

  1. I respect both you and Michelle of Beautyeditor. I have been reading both your and her posts for years. I feel your article is a tad insulting towards her, as she does provide very valuable and well researched content. I am no chemist but I feel some of the points made can be elaborated on for us ‘lay people’ to understand, as I often read articles where people do not substantiate their comments. Can you perhaps provide some references that support your comments? I say this because I have read Ray Peat’s articles many years ago, I read everything Beautyeditor writes, and also what you write, and I personally chose years ago to only use olive oil, coconut oil and butter for cooking. This is long before I read Beautyeditor, and I did my own research. My cousin (who is a food technologist) makes face creams for beauty salons and private sale and she refuses to use PUFA’s in her creams or her diet, many years ago already. This is because she emphatically believes they are not very beneficial. I say this not to criticize you, my goal is for me to be able to do further research to increase knowledge. I personally believe that a fair percentage of what is applied to skin DOES get absorbed, depending on the molecular structure/size -as I said I am not a chemist, but from what I have read in the past, a lot can be absorbed through skin. For instance, essential oils can be measured in the blood stream about 20 minutes after application. The same goes for hormone gels applied to skin, medications, anti- inflammatory creams etc. So one would have to be specific when commenting. I think some of what Dr Pete says is taken out of context. Obviously one does not have to agree with everything he says but he is a biologist, not a quack. When reading criticisms of someone’s work, I would love to have references beneath your article to substantiate the criticism. From what I recall, Dr Pete did not say sunflower oil etc is that bad for you, he basically says to eat them infrequently. His comments about sugar I think are also taken out of context, as he implies sugar isn’t the big ogre people make it out to be. We obviously need sugar in our cells, balance is everything, as with most things. I hope you do not take my comment as undue criticism as I enjoy reading your posts, but I feel it would have been more factual to make your points without being disparaging towards Beautyeditor, by simply providing your info with references and without sarcasm. My aim with this comment is to question in order to have an open mind and not just accept what someone says. Thank you for an interesting read!

    • I’ve included a lot of references as in-text links (in pink) but I didn’t list them out at the end. They’re mostly peer-reviewed papers. Beautyeditor didn’t link to any that I saw.

      Here’s another review of peer-reviewed studies on fish oil:

      Very few things absorb transdermally, hence why only a few drugs are administered that way. From this paper:

      “The limited permeability of molecules is due to the outermost layer of the skin, the stratum corneum. This “dead” layer of tissue has the ability to prevent the permeation of foreign compounds including drug molecules and therefore acts as a very effective barrier.”

      • Thank you so much Michelle, I did try to check out some of the pink links but they would not go through i.e. the one from as well as one or two of the others do not seem available. I will try them again later. I did read the one on supplements, thank you for the link. I don’t use soy as am allergic to it, as well as the fact that it is the most GMO produced ‘food’ and I don’t trust Canola oil. I generally try to get what I need from fish and other foods where omega’s are concerned. The only reason I mentioned the skin absorption is because I use medications and products that are absorbed topically, but I understand that not everyone has experience with this and also that not all things are absorbed, obviously. Thank you for your prompt response, I appreciate it.

    • Michelle you are so rad, for doing this article. Keep the info on the net honest. I totally disagree With this poster Vivella, is she the beauty editor trolling perhaps ? All you are doing is dispelling misinformation with scientific evidence. Boom, can’t argue that too much.

      Keep up your amazing work.

    • You use the word ‘believe’ a lot and appear to think that doing so is persuasive — as though the subject at hand is subjective, based on faith, and involves choosing one’s special choice rather than precision of method and the accumulation and analysis of data — along with appeals to authority and ancedata about what you and people you know eat (no one asked). You are inordinately preoccupied with Michelle’s tone and lecture her about an open mind, again, as though facts ought to be massaged to accommodate your worldview. Not all perspectives are equal; it is not unseemly to correct trendy ignorance based on misapprehensions, fears, and a strong distaste for research.

      • Saurs, I used the word believe twice, within context. You do not know me, my background, age, or anything about me but find it necessary to insult me/jump to conclusions about me. I am not preoccupied with anything actually, except doing my own research for many years. I don’t care what others do or use. My only reason for commenting at all was that I felt the tone of the article was insulting towards Beautyeditor, instead of being merely factual, it was a slight put down. One of the other reasons I responded is that I do not just ‘believe’ articles I read, and there are many blogs that wax lyrical about products without even reading the ingredient list. It seems these days one cannot just give one’s view, because everyone wants others to agree with them. The whole point being that one should question things, keep an open mind, learn – but there is no need for lack of etiquette. When I question something, I always maintain polite respect for others’ views, but it seems there is no room for educational interaction, so there is no point in my commenting further.

        • It seems these days one cannot just give one’s view, because everyone wants others to agree with them.

          My concern is not winning you over or persuading you to ‘believe’ anything. You appear to think that Michelle has done Beautyeditor a disservice by disagreeing with her and citing peer-reviewed studies that contradict her thesis; this is quite literally how a normal back-and-forth argument over evidence works, and if viewing it in its native habitat makes you uncomfortable, that is your problem, it belongs to you, and what it is, too. I don’t know what “educational interaction” means, but facts seem to disquiet you and you think people are being rude when they use them without hesitation or hedging. I can’t help you there. I agree than an open mind is a wonderful thing, which is why your behavior here seems perplexing. You are literally angry that Michelle wrote a blogpost that put forth a dissenting view based on the available data, while critiquing Beautyeditor for drudging up long-debunked paranoia about fats. That’s Michelle’s job here. That’s what she does. It’s okay if you don’t like it, but you’re not going to argue her out of her own existence because disagreement troubles you.

          Reality exists whether or not you, personally, confront it. I addressed the substance of your comment, which was mostly various kinds of fallacy (naturalistic, appeals to authority), along with tone-trolling and failing to demonstrate the etiquette you are now preaching.

          • Saurs, I do find your comments highly intelligent and particularly coherent and also find that your language seems to me confrontational toward Vivella’s comments which had politely and moderately expressed her opinion. I found all of your opinions [Michelle/Saurs/Vivella] to be of value and perhaps your expressed opinions [Saurs] might triumph in a debate [scientific and/or personal] but i felt uncomfortable as the overall vibe came across as confrontational and a bit attacking which brings me back to Vivella’s comments which i think were expressing the need for dialogue without attack. Trusting my comment is fair though not contributing directly to the knowledge base of the original post “are unsaturated oils bad…”

    • It sounded condescending because you have a party that bases her arguments on a new age bullshitter and then you have a reasonable party providing science based arguments. That happens and it’s unfortunately inevitable sometimes, it may not be (probably wasn’t) intentional, but when someone makes such obscure, almost silly claims, and then actual science hits you exposing the nonsense you just said, what can you expect?

  2. Great post! There is no substitute for scientific, evidence-based information. Like you said, Ray Peat is a quack.

  3. Thank you for answering my question, Michelle!
    But it means The Ordinary 100% plant-based squalane does nothing to my skin? Should I convert to rosehip oil? Thank you in advance!!

    • I wouldn’t say it does nothing – it’s a nice lightweight oil that will soften your skin and thus help it hold onto moisture – but it wouldn’t act as an antioxidant.

      • Hi Michelle, all the beauty industry “experts” such as Paula from Paula’s Choice say squalAne oil is antioxidant. I’m confused…

        • Unfortunately they often get the details wrong – squalene is only antioxidant because it contains double bonds, while squalane has no double bonds and can’t soak up free radicals. See e.g. this paper which says:

          >The already well-known antioxidant activity of squalene seems to be due to its chemical structure: a highly unsaturated isoprenoid hydrocarbon, containing 6 double bonds. Due to this double bond structure, this isoprenoid hydrocarbon acts as a strong antioxidant and a natural antibiotic.

  4. Thank you, Michelle. This really is a wonderful post.
    i am quite shocked, that this could came up as a topic of fear mongering. Even outside the scientific papers, I thought the polyunsaturated oils are known as ‘health oils’. Omega here, Omega there.

    I can imagine, someone got the trans-fats mixed up, as they are unsaturated fats too. To make the mistake of throwing these oils together can seriously play with the health of people in the long term. 🙁

  5. A refreshing and entertaining read, and once more proof that doing your own research beats believing in self-proclaimed experts any day.
    Of course everyone is entitled to their own opinion and can follow his or her own dietary advice, but too many people simply believe what they read without question.

  6. Thanks for this! I’ve read some of the information you are critiquing and found it very unconvincing (and the responses to people’s questioning it not accepted very graciously). You’ve broken it down in a very clear and objective way.

      • Haha this was actually really difficult – the importance of omega fatty acids was established decades ago and no one really researches it anymore because it’s so uncontroversial (except perhaps to Ray Peat and his followers).

  7. Thank you for calmly and concisely deconstructing the logorrhea of quacks who employ scarequotes when discussing ‘food’ — in invariably classist ways — and seem proud of their ignorance and fear-mongering of non-specific ‘chemicals.’ This is the worst kind of counter-productive laziness, just regurgitating junk science that Feels Good to them.

    • Thank you! You’ve summed up a lot of my feelings about the topic here: “regurgitating junk science that Feels Good to them” is exactly what Goop etc. do!

  8. Michelle, thank you for this post and many others before it. Right on! Intelligent, factual, persuasive and simple enough to understand. Keep doing the great job of educating us!

  9. Michelle, have you ever done a post on how to determine what is a good source? I think that could be helpful for people to understand why the evidence you cite may contradict what they have found in their own research. You always cite peer reviewed sources, but what other criteria is helpful in evaluating sources? Lyn mentioned the year they were published, which is a great point. Consensus in the scientific community is another one that comes to mind (or at least the number of peer reviewed, recent studies that have the same conclusion). I think it could be helpful for some readers to have almost a checklist of qualities of a good source, so they can rely on more than just confirmation bias 🙂

    • I’ve been working on one but it’s turning into a book rather than a post! I might release it as a download at some point…

      • “Bad Science” by Dr Ben Goldacre is a very good book on this topic, he covers peer review, double-blind etc.
        He’s also one of the people involved in, the campaign to make pharmaceutical companies release all trial results, not just favourable ones.
        Thanks for all the work you do Michelle 🙂

  10. Fantastic post, thank you. It’s so helpful to understand the science behind what you read online – there is so much contradictory information, it’s very difficult to know what to believe. If you could write a similar article on Advanced Glycation End Products, supplements which claim to prevent glycation, and on whether glycation is intensified through the topical application of products containing honey (I’ve heard such confusing things and have no idea whether I can go back to masking with raw honey, which was cost-effective and always made my skin glow) that would be amazing.

  11. I cannot agree more with you. Finished medical university and learning about biochemistry, nutrition, diabetes, dermatology, etc. I can strongly say that u are right. I hope people who read the beautyeditor articles have more sense on them to doubt and think after such an disinformation article. If my teacher read that article she will take the airplane and go by herself to slap her.

    • I just happened upon Beautyeditor’s post “Why Squalane Is the Best Face Oil” and as soon as I started reading it I couldn’t believe what I was reading. From all my research and my creating face oils for my own use (with good results) I didn’t agree with what I was reading. How strange that with just a bit more surfing the web I landed upon your site discussing Beautyeditor’s take on unsaturated/polyunsaturated fats. I had actually googled “which plant oils have squalene?” I was hoping for a LIST of oils that have squalene.

      I do a lot of reading as I’m making all kinds of bath and beauty products for myself and family & friends. So far all have loved what I’ve gifted to them and I love controlling what’s in my stuff. I enjoyed reading your info here and it goes hand-in-hand with all the knowledge I’ve gained on what I call ‘delicate’ oils, due to their propensity to go rancid quickly. I’ll know more when I get feedback from those family members who received a face oil mix that was developed to help them with their oily skin (over production of oleic acid but deficit in linoleic acid production), they also have constant acne. From all my research–hundreds of hours of reading–I’m thinking it will help.

      Thank you for all the hard work you put into this information, again, couldn’t believe what I read on Beautyeditor’s blog; it went against all of my research–it was the only place that I found such worry concerning polysaturated fats.

  12. Slightly off topic, but your link to your rosehip oil experience reminded me. I recently tried rosehip oil (very oily skin – oil within 1 hour of washing with gently pH balanced cleanser). It does not absorb into my skin. Apply at night just put it into my pillowcase, applying during the day, one my skin started oozing it’s oil, I was so greasy that I had to remove it. I used 2-3 drops.

    I just started using a retinoid serum and noticed it has oils, doing the same to my skin, not absorbing.

    Do oils stay on the skin like this or should they absorb? Just interested in your thoughts since you understand skin structure so well.

    • Is your skin oily? Mine is, I usually just let ooze at night (kind of like an overnight mask), and I don’t use oils at all during the day.

      • Thank you! Yes, very oily skin; sorry for typo’s on my orig post, was trying to say that when I apply it at night it doesn’t soak into my skin – just sits on the surface and I hate to even put my face on my pillowcase.

        • i have an extremely oily skin too. from what i understand, oils with high linoleic acid content should be good for oily skin e.g. rosehip, tamanu, prickly pear(?), watermelon seed(?). maybe other oils would fare well for you? since their linoleic acid makeup and content differs, as well as oleic acid. please correct me if i am wrong!

  13. Thanks once again for another fantastic and hugely informative post, Michelle. You’re a born educator, it’s a rare skill having the ability to impart knowledge in such an easily understandable way. I do love a good debunking article 🙂
    For anyone interested in learning more about how to distinguish between solid science and flaky pseudoscience I highly recommend checking out the James Randi Educational Foundation’s website and Youtube Chanel, and this wonderful video from Last Week Tonight – never fails to bring a smile to my face!

  14. I think there’s something to be said about the oils oxidizing on our skin during the day, in the heat, in the sun. You didn’t mention that. One small study that oils are probably good for our skin is not really convincing to me. This new fad to slather our faces in 30 different kinds of unstable oils on a daily basis and then go out in the sun is a bit of an expirement. I think if you really care about skincare and anti aging one would be cautious. At least only using oils at night before bed and keeping them refrigerated. And definitely out of the bathroom. After Michelle’s post I stopped using face oils. I will say that my sun spots have almost completely gone away and I’m not fighting their reappearance every day anymore. Maybe bc I use so much sunscreen. But it’s just like Paula.. I won’t take a chance with essential oils. What if she’s right? And frankly, I think Paula has much better skin than Caroline who seems to love oils and Essential oils. Same with Michelle.. her skin looks flawless. And I believe she’s 40..? Look at people’s skin.. they have to be over 35 for it to really matter… that’s just the truth. And then you’ll have an idea who is doing it right. IMO.

    • One small study that oils are probably good for our skin is not really convincing to me.

      I linked 5 studies, actually. She’s linked none.

      This new fad to slather our faces in 30 different kinds of unstable oils on a daily basis and then go out in the sun is a bit of an expirement. I think if you really care about skincare and anti aging one would be cautious. At least only using oils at night before bed and keeping them refrigerated. And definitely out of the bathroom.

      I wouldn’t say that it’s a new fad – ancient civilisations used a ton of plant oils.

      And frankly, I think Paula has much better skin than Caroline who seems to love oils and Essential oils. Same with Michelle.. her skin looks flawless. And I believe she’s 40..? Look at people’s skin.. they have to be over 35 for it to really matter… that’s just the truth. And then you’ll have an idea who is doing it right.

      I’m sure it’s easy to find people who do use plant oils and have flawless skin – that’s the issue with anecdotal evidence. You also need to take into account sun exposure, natural skin pigmentation, genetics… all of which have been found to influence skin aging, certainly far more than unsaturated lipids which already exist in your skin.

      • Hi, I might be late for the game but anyway
        You are confused between oxidizing and antioxidizing substances.
        And yes, plant oil got oxidized on your skin all day as they are supposed to sacrified themselves to provent your skin from being oxidized.
        Squalance on the other hand – it is not oxidant nor antioxidant either, so yeah, pretty inert.

        About Paula Choice, she def ages better than Caroline since she uses squalance and BOTOX – she admited it somehwere here and there
        Carolin on the other hand didn’t get any type of agressive intervention and if you zoom up closely on her skin, you can see her texture is suprizingly fine but what the structure underneath is damn bad – it got something to do more with her gens rather than what she put on her face.

        • Oxidization does not occur over the course of one day. I’m 44 and still get ID’d (confused for 19). I use PUFAs every day and will give them ALL the credit for my firm wrinkle-free skin. The “beauty editor” is completely confused about this and misleading people away from the anti-aging gems of the plant world.

  15. Well, I totally believe anyone who tells me to eat more sugar and ice cream 🙂 I’m all over that. And since I like hearing that kind of advice so much, everything else they say must be true!

  16. I read that olive oil vs sunflower oil study. Olive oil definitely seems problematic in term of skin thinning & irritation. Is this hormetic irritation & good exfoliation or do I need to stop removing my eye makeup with olive oil? My husband love sunflower oil on his oily skin tho.

  17. That Beauty Editor article sounded hokey, so I did a little more digging AKA 2 more minutes of googling, and found this. Thank you! How refreshing it is to find logic and science around skin care advice instead of “hope and dreams”!

  18. Thank you for writing this article, real science being sued to explain skincare always makes me feel warm and fuzzy inside. One thing I was curious about was wether PUFAs are more suceptile to free radicals breaking their double bonds? One argument from that quack that beautyeditor quoted was
    “Free radicals are reactive molecular fragments that occur even in healthy cells, and can damage the cell. When unsaturated oils are exposed to free radicals, they can create chain reactions of free radicals that spread the damage in the cell, and contribute to the cell’s aging.”
    Now the first sentence is true, but would unsaturated fats be more than saturated fats because they have more double bonds? Now I’m trying to remember my organic chemistry,

    • Double bonds are more susceptible to attack, yes – but the free radicals would create the chain reactions with or without the unsaturated oils, and the oils applied to skin don’t really end up in cells to any large degree. It’s more relevant to unsaturated oils going off in storage faster than saturated oils.

  19. I’ve long stopped reading Beautyeditor because most of the theories make no sense and can only work on normal skin if at all (not acne-prone skin), which in my opinion can take pretty much any product and isn’t very discerning. There were too many articles that just made no sense whatsoever…

    Isn’t it true that squalane oxidises into squalane peroxide that is super comedogenic?

    Why would one want that on their skin? Unless in the tiniest of quantities, but then you might as well opt for something with a little more substance like rosehip oil if you’re opting for a natural emollient.

    But I’m not a fan of straightup oils for anything except maybe a body moisturiser straight onto after shower damp skin, or hair ends.

    Loved the article, and ADORED the sarcasm. How can you not be sarcastic when people pull ideas out of their butts as though they’re facts?

    For the love of God, we would all be dead already if our skin absorbed stuff.

    Love you,

  20. After reading the paper from Lipid Technology Oct 2006 Vol 18 No 10 “Cosmetic emollients with high stability against photo-oxidation”, I have determined that the proportion of PUFA in any product should not exceed 3-4%. Once it exceeds that, then it is not stable against photo-oxidation. I think that PUFA are good in very small amounts. Like maybe it would be good to oil-cleanse with PUFA-dense oils but that creams/moisturizers should mostly made of stable saturated fats. I’m still researching and could be wrong, but this is what I have concluded so far.

    • The 3-4% number from that paper is the amount of polyunsaturated fatty acid that can be protected from photooxidation in vitro by a specific type of fractionated canola oil enriched in vitamin E. It’s not a number that can be generalised to any other situation.

  21. Thank you Michelle. I stumbled upon that person’s article while looking into skincare options and considering Hemp Oil cleansing has been the only thing to successfully rid me of my acne, I was mortified to think it could be aging me instead.

  22. Thank you soooo much for this, Michelle. I’d stumbled on Beautyeditor’s post and was getting all paranoid about my rosehip oil use and was about to press order on TO’s Squalane.Great to know that Ray Peat’s a quack. Love your evidence base, which I find missing from all too many beauty blogs.
    Just one question: I’m using a face oil with cod liver oil as its main ingredient. I am loving it but the oil in question is sooooo expensive. Is there a similar ingredient? I’m guessing that it has very good linoleic acid qualities as the oil production on my face has completely normalised since using it. Your thoughts?

  23. Don’t the radically shorter shelf lives of some PUFA oils indicate increased susceptibility to oxidation?
    I mean if they tell you that Rosehip Seed Oil needs to be kept in a dark cool place with a shelf life of 4 months. Compared to Jojoba oil that has a shelf life of 5 years.

    Are we really going to assume that these oils aren’t more susceptible to oxidation when they sit on your face in broad daylight?
    You saying the oils don’t absorb makes that problem even worse.

    There was a study cited about photo oxidation above and you simply dismissed it on the basis of “not applicable in any other situation”. I’m not sure what you mean by that. It’s still a piece of evidence with regard to susceptibility to oxidation of certain fatty acids.

    • They may oxidise, but in practice the amount that’s oxidised isn’t enough to cause harm to skin, as evidenced by clinical studies where people applied these oils to their skin.

      What I said re: the photooxidation paper is this: “The 3-4% number from that paper is the amount of polyunsaturated fatty acid that can be protected from photooxidation in vitro by a specific type of fractionated canola oil enriched in vitamin E. It’s not a number that can be generalised to any other situation.” It was in response to this statement: “After reading the paper from Lipid Technology Oct 2006 Vol 18 No 10 “Cosmetic emollients with high stability against photo-oxidation”, I have determined that the proportion of PUFA in any product should not exceed 3-4%. Once it exceeds that, then it is not stable against photo-oxidation.” I think in that context it is pretty clear what I meant – that you can’t say that the proportion of PUFA in any product should not exceed 3-4% based on that paper alone.

  24. This is what’s up! I had come across someone’s article (not the one you reference to), and they were saying how terrible PUFAs are for your skin, etc etc. I had to leave a very contradicting comment, as what they were saying went against every real scientific study, like, ever.

    PUFAs (I use a lot of hemp seed oil, pumpkin seed oil, and rosehip when I can find a quality one) have saved my skin! I suffered from adult acne, and I also have psoriasis. Clear skin 95% of the time. I may see a total of two pimples a month that quickly fade, and I might see a plaque or two every few months.

    My infants daughter started developing eczema at 6 weeks old, and it became very severe on her cheeks. A combination of coconut oil (for the Lauric acid… would have used my breast milk, but I had concerns that it may have been something in my diet that caused a reaction) and and the same high Linoleic oils that I use for my skin. Her skin has cleared, and is behaving wonderfully. 🙂

  25. Sad to read this around ray peat and I can see that you have simply grabbed a few basic points or his and inserted them without any further checking out of what he means and why he says what he says.

    Even if nothing else it is clear you are not understanding what pufa does in the body and the actions upon cells – the membranes of which can be made up of ANY kind of fat – so basically you become what you eat – not to mention the kind of fat they are made up of if the body gets to choose is saturated – if you eat no fat at all the body will still make cholesterol and saturated fats from the carbs you consume and use this in cell membranes – this in itself tells me that this is what the body prefers to do.

    And this whole “essential” thing…..poor and unfortunate and yet probably purposeful use of the word “essential” – leaves people thinking that we “need” something yet actually only signifies we don’t make it already – in other words it is not important enough for the body for the body to feel like it needs to make it itself.

    All the “essential” amino acids are the ones that, when lowered in the diet, mean we get healthier…..yes we need maybe a tiny tiny amount of them…..but very very little.

    Whereas all the “non-essential” amino acids, when we consumer more of them, also make us healthier and live longer….that should tell you perhaps where to look when thinking next time about what is *essential” and what not.

    You know what is important enough to the body for it to make it itself?

    Saturated fat….cholesterol….sugar/glucose…..

    • “it is not important enough for the body for the body to feel like it needs to make it itself”

      Wow, I never thought I’d meet someone who’s never heard of NUTRITIONAL DEFICIENCIES. Maybe learn basic biology before reading quack theories.

  26. Hi Michelle❤️, just loving your science based nerdy posts?. Would you please like to share your thoughts on saturated fatty acids too? Whether it’s good for bad for our skin. Recently I am using a moisturizer which contains saturated fatty acids… do i need to switch it for a unsaturated fatty acid based on moisturizer or a facial oil?? I am very prone to breakouts and hyperpigmentation.?

  27. Brilliant article, thank you. I’m just getting more into facial oils since the nice one I use got discontinued and I have to go DIY

  28. I prefer to use squalane oil on my face as other oils have given me adverse reactions. Are you saying using this oil is actually bad for the skin? That it has no benefits? Manythanks for your time.

  29. Dr. Alexis Stephens has said that saturated fats (palmitic, stearic) can worsen hyperpigmentation. Does that statement have any evidence to back it up? Those ingredients are in a lot of things, and right now I’m avoiding them for that reason. Of course, she also still says that inorganic sunscreens reflect light while organic sunscreens absorb it (leading to her recommend the former over the latter), so she’s not infallible.

    • I’ve only seen in vitro evidence, which isn’t very convincing – if in vitro evidence always translated to macroscopic effects, cancer would be cured a thousand times over. But if you’ve seen in vivo evidence (even animal studies), please let me know!

      • I will, thanks for your response! Would you say, then, that you are not personally concerned about saturated fats in your own skin care? Or do you skirt them just in case?

        • Not concerned! I did try a tallow product for a while and my skin seemed pretty fine with that, so I don’t think it’s an issue, for my skin at least.

      • I’ve been given tretinoin 0.05% for my melasma and the second ingredient is stearic acid so I’m worried whether I should continue to use, Dr. Stephens seems wonderful and knowledgeable, more so than my NYC board certified derm it seems, as she never seems to give me any definitive answers. I am half way through the 50 gram, over $100 tube and wondering now should I continue…. So far my skin has neither worsened nor become better when it comes to melasma, but is definitely more glowy and because of that looks less dull and more healthy, if that makes sense. I have had minimal peeling and irritation that lasted a week. I’m oily/combination and 34 yrs old. Would you recommend because there have not been human trials suggesting stearic acid could Increase melanin production I should just continue to use it!? Thank you for all your wisdom fellow Aussie xoxo

        • It sounds like stearic acid isn’t making a difference, so keep using it. If there was a real link I’d expect more evidence by now, stearic acid is pretty common in products…

    • Gosh!!! Thank you John for this question. I’ve been asking the same on Instagram and every other legit forum or platform. I asked my derm who is board certified and in NYC and she didn’t seem to have much to say. And it seems everyone I take an appt just to ask a question that they won’t answer on the phone/ email I’m slapped with a $250 bill. Anyhow…. I’ve been given tretinoin for my melasma and the second ingredient is stearic acid so I’m worried clearly whether I should continue to use….

      • You’re welcome, Pixie! My local derm can’t answer any of my questions either. She still thinks “chemical” sunscreens are a suboptimal choice because she’s only familiar with the older, less effective options we have available in the States. She didn’t know about all the great new formulations from Asia, like Tinosorb S and Uvinul A Plus, that aren’t approved to be sold here. That makes me question her other recommendations, too, and how are you supposed to find a derm that is actually knowledgeable about current skin care without spending a fortune in time and money? I feel like I’m more up to date on some subjects by watching YouTubers like Michelle than doctors who went to school!

  30. I didn’t read all the comments, but I disagree with this article. Your skin does absorb everything you put on it in a very high amount. All oils are not good and do cause aging when oxidized. My family follows the ray peat diet and his advice. We are healthier and happier than ever. I’d die before I put rosehip oil, sunflower oil, safflower oil, etc on my face or body. For the most part, I make all our skincare products or order from a pufa free company. This is just my opinion backed by tons of research, not from the medical field. Science based, yes, but not from government agencies. I’m sorry, but the FDA literally says canola oil is healthy and safe…umm no it’s not. Anyway, sorry to rain on your parade with my thoughts. I know I didn’t write a hugely thought out piece, but definitely didn’t agree with a lot of this. I do agree that aging is caused by diet and not the sun. We don’t actually wear sunscreen. we also don’t burn, because we use a lot of body butters that I make, where some actually have some spf properties all on their own!


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