Recently, I read an article on FutureDerm and replied to a few comments asking about the idea of how silicones trap active ingredients, preventing them from reaching the skin. Here’s a breakdown of what happened:
Nicki of FutureDerm fame stated:
“While beneficial skin care ingredients can have some documented effects in cosmetics with a silicone base, the effects will not be as profound as if the ingredients were in creams or serums with other delivery systems. This makes sense, but I was never sure until I read reports micronized zinc oxide cannot penetrate the skin if it is presented in creams with silicones (Dermatologic Therapy, 2007). If micronized zinc oxide cannot penetrate the skin, then I wouldn’t imagine many other cosmetics ingredients embedded in silicones could either.”
Then two readers, Nicholas and Erin, asked the following two questions, respectively:
- Speaking of the antioxidants embedded in silicones, have you reviewed any of the Paula’s Choice Serums? I’m using the Resist Antioxidant Serum and I’d like to know your opinion on that one. Thanks!
- Just a question… you were mentioning that skin care ingredients like micronised zinc wouldn’t penetrate the skin well if it were in a silicone base. What would happen then if I were to use a silicone based antioxidant serum, then top it off with a moisturizer and a zinc oxide or chemical sunblock? Would the initial silicone serum prevent the moisturizer and sunblock from exerting its effects as well?
I proceeded to answer their questions with my own slightly logical (or illogical) musings:
“You know, when Nicki mentioned this idea of silicone “entraption,” I kind of stopped and wondered, “Hm, maybe that has some merit to it.”
From personal experience I’ve definitely seen improvement in my skin from silicone-based serums, like the Paula’s Choice RESIST one Nick mentioned. However, without proper examination tools, I can’t histologically attribute these improvements to specific ingredients, because I can’t witness the exact interaction mechanism. Perhaps my skin’s improvement was just from being more moisturized, or maybe it’s something completely else, like glycolic and salicylic acid.
But here’s some food for thought, and I’d love to see some real documentation about this intriguing topic. Maybe I’ll do some research myself and write a follow-up post… We’ll see. xD
Now, many prescription medical products employ silicone-derived vehicular bases as delivery systems for topical drugs. So that at least, gives some weight to the fact that silicone-based products are not completely ineffective. Obviously, a water-based serum with chemical penetration enhancers would be (on a case by case basis) preferred.
As for the “micronized” zinc oxide not being able to penetrate into the skin, concept… try to think of it in another one. Silicone is used a suspending agent; basically it holds all the other ingredients in place. So if you think of the silicone molecules as people, collectively holding up a heavy object such as epigallocatechin gallate (EGCG), the smaller the object, the easier (or less strength) is required to hold it up. So something as small as micronized zinc oxide would be very easy to hold, since it’s so small.
So something like EGCG or a lipid-soluble palmitic-acid based vitamin C derivative, such as ascorbyl tetraisopalmitate AKA tetrahexyldecyl ascorbate, would require a LOT of additional “strength” to hold up, or to prevent from penetrating the skin. So naturally, these much larger molecules would slowly “fall” through the silicone suspension, eventually reaching the skin. Think of it passive transport through a semi-permeable membrane, or something.
But again, this is a very general, simplistic, and slightly over-reaching analogy, but just think about it. It does make (a little) sense. So yeah, I hope that puts some of your minds to ease. If you’ve been using silicone-based serums, know that it wasn’t ALL in vain.
I just found that dicussion that lead to a big discussion, but didn’t make the topic of it clearer to me. I am still wondering if a silcon gel base serum for anhydrous ascorbic acid makes sense or not like futurederm came out with. I understood that the ascorbic acid can penetrate skin through water chanels in the epidermis. But I didnot understand the point with the lattice that it is formed by the vehicle used. If I apply a waterbased serum or a moisturiser on top of such a serum, do the actives in it penetrate trought the silicone layer and thereby able to penetrate the skin?
Yeah, I agree that the source post from which this discussion was derived, is very vague. As for the FutureDerm product, I’ll be reviewing it extensively (with particular emphasis on the vehicular base/structure and all the claims they made) as soon as I receive the product. I have my reservations about it from a theoretically standpoint, and I’d like to give them the benefit of the doubt, before writing a formal review. For the time being however, I’d recommend that you hold off on purchasing it.
I dont think this about the silicon entrapment can be true, as you mention, many prescription medical products employ silicones delivery systems for topical drugs. If silicon was not a good vehicle these medicines wouldnt be FDA approved right?.
Wish to see some research about this issue cause besides my overly simplistic analysis I like silicons a lot and it would be soo dissapointing that they dont deliver other ingredients properly. I would also like to know what a cosmetic chemist has to say about this.
Speaking about silicon entrapment theories, many people complain about getting acne or rashes after using products with silicones. Ofcourse other ingredients could be causing the problem but someone came up with the idea that this may be caused by silicons cause they layer the skin with an almost impermeable barrier trapping bacteries (I guess the problem wouldnt be p.acnes since its anaerobic) and impurities.
Im prone to acne and havent had any problem with silicones but this idea kept me thinking, maybe its possible with the formulas that contain hight percentage of non volatile silicons like dimethicone?, or the people who has reactions to silicones are just sensitive or allergic as we can be to any other ingredient?.
You definitely bring up some great points. I also don’t think that the idea of silicone entrapment is completely true, but it’d be interesting to have some study compare it to other delivery systems for the most widely used skin care ingredients like the various forms of vitamin C, A, E, B, green tea etc… Although I have seen several studies use different vehicular bases, and the active ingredient got through to the skin for all of them. But they didn’t remark HOW much got through, since it wasn’t the goal of the study. So yeah, I too am eager to see more research about this.
As for silicones breaking people out, it’s possible, but not very likely. Even non-volatile silicones are quite large, and shouldn’t clog intact skin. But who knows, it could be an allergic or irritation reaction, so the trial and error aspect will always exist in skin care. And you’re right that it’s probably another ingredient or combination of ingredients in a silicone product, that’s breaking someone out.
Thanks for commenting.
I find it remarkable that no one checks a source cite before jumping on bandwagons. It’s the EWG effect. The study cited there from Derm Therapy 2007 actually doesn’t say that silicone prevents zinc oxide from penetrating the skin. It does say that neither micronized or nano-sized titanium dioxide or zinc oxide penetrates to a significant extent, citing a 2006 Derm Clinics paper, “Human Safety and Efficacy of Ultraviolet Filters and Sunscreen Products” of which assesses multiple bases, oil, oil/water, etc. that all showed the same conclusions. The focus isn’t the vehicle, the focus is the fact that in multiple compositions neither zinc oxide nor titanium dioxide penetrates the stratum to a notable extent.
These are easy misunderstandings if one doesn’t have the education to truly comprehend what research is REALLY saying. Doing your own research is really only helpful if you have the training to understand the content. Otherwise it is just confusing, or ripe with opportunity for misunderstandings like these.
Also, let’s have perspective, as interesting as these discussions are, FutureDerm nor TripleHelix aren’t chemists’ pages. I think these discussions are good opportunities to evaluate concepts in skin care, but it would be more helpful if both understood their limitations when evaluating the chemistry of skin care products. I, for example like to think of Cyn’s apropos quote from Working Girl in moments like these, “Sometimes I sing and dance around the house in my underwear. Doesn’t make me Madonna. Never will.”
Thanks for commenting! Like with the previous comment author, I haven’t seen you comment before. I hope you’ll contribute with your insights in future posts!
Now I wouldn’t say that NO ONE checks a source cite, because I did! 🙂 But unfortunately, because I am yet to be affiliated with any medical association or publication, I can’t see the full article without paying some exorbitant fee. (I tend to use PMC articles to support my claims, or at least ones with clear abstract). And that could be used to argue and strengthen your point that people like me, with no formal medical or professional education, are easily confused by simple topics.
Well, I’m sure it’s happened in the past. But not here, at least for my part. I do know that micronized inorganic sunscreens don’t largely penetrate past intact stratum corneum. I was merely playing around with the idea that silicones may not be the most effective carrier fluid when it comes to product penetration. It at least has some merit.
But perhaps you weren’t specifically addressing me, but rather the field at large of pseudo-scientific blogs. And I agree with your assertion. However, even those with proper training have made glaringly large mistakes. Clearly, the factor in question is how often those mistakes happen. And yes, generally-speaking, the “experts” do tend to get it right more ofteh than the Others.
And in the end, the goal of this blog and I’m guessing of FutureDerm, is to unite these two branches into lively discussions (like this), to seek the facts. So maybe when the Others do their own research, the results are confusing, but it’s necessary for those who truly care and to spread the “truth” around. And in my Disclaimer, I acknowledge that there are limitations to my blog, which is why we all need many opinions on a certain fact, in order to make more informed decisions, whether or not that information is incorrect or correct. It’s all about broadening the perspective.
I really hope to see more comments from you Jack! Thanks again for commenting.
Funny, this post by Jack July 15 2012 – which I am just now reading sounds like fundamentalist religious teaching! – suggesting that only those with a certain level of education or special ability can devine truth and should have the prerogative to disseminate it, everyone else must surrender their own judgement to those qualified to ‘interpret’, we ourselves not having the capacity (intelligence or otherwise) to gather, consider and determine personally the value and significance of relevant information even though it is freely available.
I do believe the adage ‘a little knowledge can be dangerous’ BUT should that stop anyone trying to increase that knowledge by the sharing of ideas and information sources (which are routinely cited by the author of this site whom you seek to discredit), after all ‘AN IDIOT IS SOMEONE WHO DOESN’T KNOW SOMETHING YOU LEARNED YESTERDAY’
No one has ‘arrived’ in terms of knowledge and understanding, there is no end point no matter how smart or educated a person may be or how many resources they may have at their disposal,an elitist mentality will not save them from mistakes either. The point of Triple Helix as I understand it is to assist us (to whatever degree we are capable) in arriving at a better understanding of the knowledge available when there is so little of the former and such abundance of the latter.
By the way, I personally feel some of the so called ‘experts’ dominating the internet in regard to skincare information, simplified for the public, with their exhaulted reputations and teams of researchers, are in danger of becoming stalled and stale. It is as though they believe no possibility of further significant advances should be seriously considered and I see only the old positions reiterated with no indication of follow up, adjustments to previous conclusions or indication of any positive possibilities currently under investigation even considered. Surely such a site should be dynamic meaning something is updated from time to time as new findings, are revealed or is all the research being done turning up absolutely nothing worth mentioning and for a long time now?
I value the opportunity to share and learn that this site provides, it serves, among other purposes, as a conduit for information between the intelligencia to which you refer and the various levels of ‘limitation’ with which the rest of us work to ‘evaluate’ the claims of thousands of skincare marketeers.
The individual you refer to as lacking the necessary training and ability to evaluate the chemistry of skincare, makes his bio available at every point, not laying claim to any more than his current education and experience entitles him to do, his opinions are clearly stated as such so we who follow his posts should be fully informed – our responsibility!
Just because someone sings and dances around the house in their underwear doesn’t make them a talentless frump. I have no doubt Madonna sang and danced in just the way described, before she hit the stage – probably still does!
I am not John’s mother! I definitely do not know the man but I have great respect for what he’s doing at Triple Helix Liason, he has a young fresh approach toward helping understand this very complex subject. I find his optimism refreshing, new ground will be broken in this field and he’ll be the first to let us know when it is – maybe others are commercially invested in the status quo, that would explain the vitriol no?
Thank you Robyn! You present so many insightful, thoughtful, and astute points in your response that I’m tempted to just copy and paste everything you said into my Disclaimer or something haha!
YOU = AWESOME!!
Unfortunately, while I always encourage diversity; that in itself entails all pathways of thinking–both positive and negative. All we can do is to keep believing in what WE think is correct, and to work together as a team to further mature and develop!
You obviously spent a lot of time and thought while writing this response. Hmm, I’m trying to think how to best promote it… I’ll have to get back to you. Regardless, I’m super, SUPER impressed!
I really don’t want to sound mean or unsupportive (because I am CERTAIN this blog has helped many people struggling with skin issues), however: this silicone issue is complete and utter nonsense. I know you are a fan of Paula Begoun, and I also know you think some of her own research is off, but still: http://www.cosmeticscop.com/cosmetic-ingredient-dictionary/definition/1345/silicone.aspx The properties of silicone are not anecdotal, they’re facts — with many, many years of research and product development behind them.
The Futurederm blog is very frustrating. It’s, to be blunt, so chock-full of misinformation and nonsense — the silicone issue being a perfect example. (And alcohol is factually a skin irritant, among its other properties).
My frustration lies in the fact that Paula Begoun has spent 3 decades doing research, and has an actual science background, on skincare; yet anyone can have a blog and call themselves experts without really knowing what they’re talking about.
I’m so glad you decided to comment. I haven’t seen any comments from you before (that I can remember), and that could be because you’re not a regular reader… But that’s okay!
Anyways, I’m completely not offended by your comments. In fact, they’re quite exciting! While it’s nice to have everyone agree with me, it gets a bit I don’t know, boring, when that’s all I see. Now, I have seen Paula’s entry on silicones, and I agree with most of them in part. At least I hope that’s what my “musings” in the discussion came off as. But I wouldn’t be so quick to dismiss the discussed topic about silicones as complete nonsense.
As Paula states, and it makes sense, that, “Some of those ingredients remain on the surface some absorb…” So perhaps another delivery system other than with silicones, may be more effective when it comes to product penetration. Clearly, that’s true as the existence of chemical penetration enhancers substantiates such a concept.
As for the FutureDerm blog, unfortunately I have to agree. With the introduction of SO many new contributors, the consistency in quality and meticulous-ness isn’t as high as I’d prefer. But again unfortunately, that’s something I can’t change.
Also, ethanol isn’t really an “irritant” in the sense that it contains compounds that can trigger some form of dermatitis or allergic reaction. For example, grapefruit juice contains a form of furanocoumarin, a class of compounds that can trigger this type of reaction. The “irritation” from the ethanol on the skin is attributed to its drying action. And naturally dry skin is more prone to external assault (leading to inflammation), than oilier skin types. And when applied topically, ethanol doesn’t generate significant amounts of free radicals. I don’t know if you saw my post on ethanol and the comments where I responded to several follow-up questions… but yeah. Ethanol’s not factually a skin irritant, it can just make the skin more prone to irritation. There is a difference.
Finally, I’ve said this many times before but just because Paula has 3 decades of experience, doesn’t make all her research correct. In fact many of the topics she attemps to address, didn’t even exist a decade ago. Everyone, including her, is always learning. And with that process, mistakes will be made. In fact, in my Part II of retinol metabolism, I’ll be responding and constructively critiquing a post she did on retinol and AHAs/BHAs. You’ll see that she made a few errors in that post, which again, happens to everyone including myself.
I always say that it’s not the speaker who makes the words correct. The words do.
So yeah, thanks for taking the time to write. I hope you’ll see the desire to comment again on subsequent posts. 🙂
Just a quick point, I am not sure you’ve the credibility to critique or comment on retinol from a chemical structure/stability standpoint. I’ve read your post on Paula’s retinol serum, where you wondered of the pH of the retinol serum, but the serum ingredient list shows it’s a silicone base. No water. No pH. So yeah, retinol doesn’t have a need for pH (that’s something I can’t totally blame you for not knowing, it’s more of the formulator’s end of things) and silicone has no pH (that is something I really do blame you for not knowing, given the nature of your site.) There is distinct difference there. I appreciate that you have a disclaimer on your site, but you certainly don’t convey that this disclaimer is present when you advise those who comment here or on FutureDerm. That you’ve commented below of the fact you don’t have the access to studies means you come to conclusions based upon abstracts–this is truly unforgivable from a scientists perspective–you certainly should make those instances very clear with every post or comment you make.
It’s sort of maddening to read posts on a site like this, which despite your disclaimer, is absolutely structured to position you as an expert, of which wonders of the pH of a formula totally devoid of water. I may not agree with the tone of Paula Begoun’s site or opinions, but the point is she isn’t the only one commenting, she is working with an entire staff of people and chemists of whom those without at least a profession experience in chemistry shouldn’t be publicly claiming as flawed, unless you are working with a team of people (of whom consists of chemists or other similarly profession formulators.) And as you’re wondering of the pH of silicone and drawing conclusions from paper abstracts, I think we can agree that you do not, and are not, working with such experienced and educated science professionals. .
Hi Jack again!
Okay, so credibility is important, but the facts are even more so. Many credible people, like Paula apparently, have been wrong multiple times.
Now, with the pH in a silicone base issue, okay well you got me there. Though technically, even non-aqueous solvents can have quantified pH measurements, as pH is an acidic function that measures the activity of the hydrogen ion (H+). You don’t have to have water! Granted, these pH values can’t be directly compared with those in aqueous solutions. But still, that’s something. Lol!
As for whether or not retinol needs a certain pH, the approximate pH ranges I stated in Part I of the retinol metabolism post, are those necessary to optimize function of the enzymes that convert retinol to tretinoin, not that retinol needs that specific range to function. “There is a distinct difference there.”
As for drawing conclusions from abstracts, well I try to not do that, and/or I use the citation that another “credible” author like Leslie Baumann, etc… used to substantiate a similar claim. While I admit this practice isn’t perfect, it’s the best that I can do. And if you’re thinking that I shouldn’t be giving people advice with this “faulty” practice, well that you need to just accept. Be real. There are so many facialists, sales associates, product consultants, etc… that give the WORST advice ever and people just follow them blindly. I’m at least doing what I can, free of charge and loyalty, to help anyone, in your words with “seemingly inaccurate” information. And if that is so ethically awfully, then please correct me in every post so I don’t “harm” anyone. I will absolutely appreciate and accpet your contribution.
As for you being mad at me about positioning myself as an expert, well that’s your perception. I’ve always told my readers that I am just one of many to consider. (See common themes in Disclaimer.); and to take my advice with a grain of salt. Or grains! Also, if you’re calling me out as a phony just because of two errors, then almost everyone on this planet would be a phony. For example, I am going to respond to a post Paula did on retinol and AHA/BHA combined use. In that post, she referred to “all-trans-retinol” as the prescription form, when in fact that’s all-trans-retinoic-acid. It seemed pretty clear that she didn’t realize that “all-trans” only refers to direction and configuration, and not on the compound’s identity. Furthermore, she also “seemingly” didn’t know about retinol metablism, because she spoke about retinol esterification and how that didn’t prove that retinol needed a certain pH range to convert to tretinoin. She didn’t even mention that retinol esterification is moving in the opposite direction of the metabolic pathway, on which retinol eventually converts to tretinoin. On another note, Paula also used a (full) article on how orally-consumed ethanol generates significant amounts of free radicals interally, to substantiate that topically-applied ethanol does the same. That is certainly not true.
So with these three errors and according to your system of evaluation, she too would be a phony. And I think if she had an entire team of experienced chemists, formulators, etc… it’s even worse that she committed the same degree of error as me. Or even worse. Okay, I made a few mistake, so what? In my premier FutureDerm post, I spoke of the first 5 most obvious mistakes that I made when giving advice to people. Clearly, I’m not afraid to admit my mistakes. The important thing is to correct oneself, let the readers know, and have a keener sense of awareness moving forward. That’s what matters.
Thanks again for commenting!
I would like to know what Paula Begoun has “wrong multiple times” about? Can you present the evidence. I know she has changed her position over the years on many issues (which she freely admits), but this is because the science demonstrates otherwise. But I seriously want to know what she’s wrong about? As Jack pointed out, she works with a team of scientists and does not exist in a bubble — nor does she present her information as though she does. She cites the studies for practically everything she writes. The most anecdotal thing I have ever seen her write was that she thinks mineral/physical sunscreens work better, and even when she wrote that she was careful to say that the research does not necessarily support that. But I digress. I really would like for you to point out the flaws in her work. I am curious.
My discussion with Jack is proceeding along similar lines, so you it’d probably be easier if you just went back and read through our entire conversation. I mentioned a few (retinol with AHA/BHA used together at once, ethanol) to Jack, and another one that I can think of off the top of my head, would be that Paula says that a broad-spectrum UVA and UVB foundation alone (either liquid, powder, cream) will be adequate protection against the sun. That isn’t true because you won’t apply anywhere near the adequate amount to achieve the labeled SPF rating.
I hope that’s okay. 🙂
First, I think Paula is right about about alcohol and the retinol with BHA/AHA issue. She and her staff have researched this extensively because they are asked constantly due to 1. blogs like this and 2. dermatologists who really don’t know what they’re talking about (Also, on an anecdotal level: I have been using retinol and BHA on a daily basis for a decade–with fantastic results). Also, Paula doesn’t say say “foundation alone”; she says 1. only if you apply liberally (and she admits that most people don’t/won’t) and 2. if you don’t, use a powder with at least an SPF 15 in conjunction. This is not irresponsible advice. Furthermore, she usually only recommends this for people with very oily skin, or for people who just can’t stand the feel of products/sunscreen (which would be me, actually). Finally, Paula has NEVER said that a powder anything is sufficient. She must have this written literally hundreds of times on Beautypedia.
It’s a shame you champion her products and trash her research — yet I don’t understand why you think you have the credentials/authority to do so. As Jack mentioned, Paula works with a team of researchers — all with degrees, backgrounds AND experience in science, chemistry, skin care and formulations. To my mind, it’s quite arrogant to refute her claims without even understanding how or why she draws her conclusions.
Well good morning to you too!
Okay, you have your free will and you can believe whatever you want. There’s really no point in me discussing anything further with you, because you ignore everything that I say.
But for others reading, I didn’t say retinol and HAs can’t be used together, just that they’ll function better when used separately. And that could mean HA application, wait one hour, and then retinol application. And yes she does say foundation alone, because in many of her reviews, she’ll say that a foundation with an SPF of 10 won’t be adequate as the sole SPF product, which of course implies that if it were at SPF 15 and has UVA protection, would be eenough. Not to mention that in the “Skin Care Facts” section of her site, she says that you can use liquid foundation w/ a pressed powder if you “dislike the feeling of regular sunscreens.” Or something along those lines. Again, look at the language.
I don’t trash her research. I’ve always championed both her products and her vision, and most of her research. She gets most of the things right. There are just a few things that based on research doesn’t quite fit with her claims. And when I disagree with something, I always have reasons and evidence. I don’t just call her out for nothing. Why would I do that? What would I gain?
But call me names, arrogant, whatever. I’m going to keep doing what I’m doing because I know it’s the right thing to do. Not to mention that you don’t even pay attention to the research I mention; you just keep going back to how Paula is experienced, and works with a team of formulators, etc… which apparently makes her always correct. What about all those other major corporations that work with experienced formulators and chemists that turn out bad products? Are they just lost too? Like me? In case you didn’t notice the language, that’s a rhetorical question.
OK, it’s good that we can agree retinol needs not be at any pH in a topical formula to function as intended—this nonsense of retinol needing to be combined in special ways with some skin care products and not others because of pH differences in formulary vehicles, it’s just silly. That truly makes my head hurt at the misinformation lobbed back and forth on the internet and by well-meaning, but chemistry-handicapped dermatologists and skin professionals.
I should clarify that I don’t think there is anything wrong with you having a website like this, because it’s a great thing for anyone to take a stronger interest in science—it is a tragedy that so many choose to stay misinformed about the fundamentals of chemical science. However, that others are misinformed or make statements of which aren’t supported by an accurate grasp of the research should never be an excuse for you to do the same. The difference you can make is understand when an expert says something that appears, in your opinion, to not make sense, that you do not yet (depending on where you are, or if you are, in school) possess the knowledge and application to categorically assume the expert is incorrect.
A note: I am glad you welcome the discussion, not everyone can or is willing to do so, especially when it’s an issue of inaccuracies. Where the mention of errors and Paula’s post on AHA/BHA with retinol, that took me a little searching to find, but after reading it you’ve got errors confused with “typo.” That is, if we have the same conversation:
Yes, she did use the term “all-trans-retinol” in what may have been inexact terminology to a lay-audience, but if you notice, she did correct herself and then clarified the difference between tretinoin and the OTC variety. It is acceptable for experts have flexibility with terminology (albeit when discussing between professionals who are expected to understand the difference, it isn’t unlike using an abbreviation when having a conversation about chemicals in a non-clinical setting.) You will find reviews in journals that refer to tretinoin as all-trans retinol, or use the terms retinoids and retinol interchangeably. It’s not perfect, but sometimes, when it’s not completely relevant, it is permissible to have flexibility with nomenclature because such journals aren’t intended for the layperson, and when it does matter ensure that you correct yourself or clarify the intent, which is what Paula did in the conversation above. This is why I used water as a reference point for the topic of pH (which is the common reference for pH discussions, thus we have the experience/education again.)
With the esterification comment, I wouldn’t say that is an error, the point is topical applications of retinol and that the pH of a topical vehicle doesn’t affect how skin benefits from retinol, esterification isn’t a part of that discussion and it would be needlessly confusing to the lay audience (and irrelevant to the topic of topical retinol formulas.) The discussion that was had in the study she cited is entirely about how retinol functions in the skin, not how pH of the vehicle affects how it benefits skin. It would be as unnecessary to wander into the areas of how retinol is utilized by skin in that conversation as it would be to discuss how surfactants worked via polarity to coax dirt and oil off skin when discussing whether a cleanser is worth using or not for your particular needs.
As far as ethanol is concerned, this is an example of how experience and education make a difference. That a compound generates radicals when consumed is indeed relevant to topical application, depending on the compound and the argument used. In this instance, ethanol is thought to produce radicals in a various ways, some of which would be conceivably duplicated in topical application (depending on how much is applied topically) so the hypothesis that ethanol generates radicals when applied topically isn’t to be dismissed—that is not a bad hypothesis. To claim that this ISN’T true is not possible, as you can’t prove a negative in the scientific process and given that there is a lack of study of the effect of topically applied alcohol, one would take care not to make such declarative statements when one may not totally understand the fundamentals of chemistry. When you’re at the beginning of your education, it is much more beneficial for you to ask “why” rather than to simply state that an expert is “wrong” when you may not totally understand the question to begin with.
Yes I agree with your first statement. It’d be a whole lot easier for all of us if everyone in the world was well-informed. I wouldn’t have had such bad acne from the start if I actually knew what to do. But anyways, I’m not saying that retinol requires a certain pH, just that a certain pH range may be more optimal for retinol conversion.
As for not questioning experts and not calling them out as incorrect, well if I think they’re incorrect based on the evidence I’ve complied, then I will call them out on it. And if there is any doubt to whether or not my claim has any validity, I note that after whatever I’m saying.
For example, with the all-trans-retinol issue, I didn’t perceive that as a typo because from my POV, I saw that just because she saw it as all-trans-something that she automatically attributed that as the prescription form. Yes, she later says retinoic acid, but with the exclusion of the all-trans prefix, it read as if she didn’t know or was confused with the identities. However, your claim that experts interchange similar terms when speaking to laypersons, does have some merit. Perhaps that’s what occurred. I just didn’t see it that way.
With the esterification issue, I thought it was relevant because as noted in the studies I cited in Part I, the enzymes involved in retinol’s oxidation to tretinoin, function optimally at a more neutral pH, while the enzymes for the reverse reaction, tend to require more acidic pH ranges, which coincide more closely with the pH ranges necessary for chemical exfoliation. How I saw her statements was that, yes, she pointed out some of the fallacies in the logic of those who cited the esterification article, but by missing that concept mentioned above, her points are less relevant. And the pH of the vehicle is important, not because retinol requires it, but because the skin does to optimally convert it. If you for example, apply a glycolic acid serum with a pH of 3.5 on to the skin, and immediately followed it with a retinol serum, the pH of the skin (being influenced by the two vehicles at the moment), will not be at the (again) optimal pH. And while I realize that the pH of the skin will eventually return to the natural range (homeostasis), for the reason of not having an optimal environment to function correctly, is why I don’t recommend retinol and HAs to be used together. It’d be best to at least wait an hour or so between application if both treatments are deemed necessary or appropriate in everyday use.
As for the ethanol issue, no I still don’t think that the cited study has much relevance for Paula’s argument. She says that ethanol causes free radical damage and will lead to collagen breakdown. In skin care, the ethanol content will evaporate in minutes after application. So I think it’s great that you pointed out that only for certain arguments (not Paula’s) and conditions (like a sustained duration of presence), will allow for her hypothesis to have any validity. I documented my findings and answered follow-up and relevant questions (including the citations that Paula used) in my FutureDerm post. Instead of retyping everything, as it’d just be a regurgitation of that post, I’ll simply link it:
Also, it’s important to note that I didn’t say no free radicals are produced, as any that get into the bloodstream and is metabolized into acetaldehyde can generate free radicals, if not quenched by antioxidants. I said that no significant amounts are generated, probably no more than those that occur from everyday autoxidation reactions. Though of course, this is just another “hypothesis.” I didn’t say her claim couldn’t be true, I just said that it isn’t relevant. And in the end, I still recommended for ethanol to be avoided in leave-on skin care products. You should read through that article and the comments below. I’d like to hear your comments on that afterwards.