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Are oils/emollients bad for skin?
Indeed, frequent use of natural oil-based moisturizers can result in unwanted consequences. One such negative outcome can be disruption of tightly packed and uniformly organized lamellar membranes in the stratum corneum. When applied to the skin, vegetable oil triglycerides will be hydrolyzed by endogenous lipases into their constituent free fatty acids that in turn will integrate into the highly rigid structure of the lipid lamellae, which are composed of ceramides with mostly saturated very-long-chain fatty acids, free fatty acids, and cholesterol. This induces phase separation with discontinuities in the extracellular matrix. Furthermore, unsaturated fatty acids in natural oils can be easily oxidized and bring additional disorder into lamellae lipid membranes. Finally, natural oils such as olive oil are known to facilitate penetration of allergens across the stratum corneum into the deeper skin regions.Besides natural oils called out here, wouldn’t synthetic esters and other liquid thin emollient would do the same - disrupting the tightly packed and uniformly organized lamellar membranes in the stratum corneum because of the different polarity and quick absorption?Also ceramides containing product - If ceramides the waxy stuff can be solublized by the oils or emulsifiers here, wouldn’t the product solublize my own ceramides if I apply it onto my skin? -
5 Replies
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@zetein Nice studies! The main points had been hypothesized many years ago before these studies revealed and showed scientifically that many moisturizers can be harmful to the human skin. Indeed, some ingredients or combinations are able to disrupt the structure of the Stratum Corneum and lead to unwanted issues, especially when they come into contacts with prone to sensitization skin. But let’s don’t forget about 3 major things - epidermal/dermal homeostasis, dosage and time - this system of homeostasis (including buffering system) works perfectly well to maintain the balance and protective properties of healthy skin.
Most likely, your own ceramides ( along with another important constituents of the lipid layers) won’t be solubilized - the lipid ingredients of the product will be incorporated into the lipid layers to some extend. However, frequent use of some mixtures may change the structure of those layers resulting in disrupting of epidermal barriers, which in turn will cause the inflammatory events. That is why the use of penetration enhancers should be so conscious since most of them just disrupt the barriers ( including the lipid barriers) in order to increase the permeability of skin. -
Interesting. I could not access the article unfortunately but I will surmise this makes a compelling argument for using petrolatum, mineral oil and dimethicone as emollient vehicles in skincare. No lipid integration problem with those - ever.
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@chemicalmatt Of course, petrolatum, mineral oils or dimethicone can not be integrated. There have been few studies published and discussed recently. All of them are discussing the role of some ingredients in terms of altering the skin barriers, including lipid bilayers in SC during long term use, which in turn may lead to food allergies, etc. In one study they show that Olive, Sunflower and other natural oils may cause the symptoms of irritated skin and Atopic Dermatitis. Another article states that “…In 13 of the 17 emollients, at least 1 hapten was identified. The haptens found in the preparations were as follows: lanolin, isopropyl myristate, phenoxyethanol, benzyl alcohol, sorbitan oleate, sorbitan sesquioleate, tocopheryl acetate, tocopherol, sorbic acid, propylene glycol, panthenol, ethylhexyl glycerin, cetearyl alcohol, cetyl alcohol, and stearyl alcohol…”
Another work that shows that trilipid cream (ceramides, fatty acids and cholesterol) has more moisturizing potential than the regular mineral oil/petrolatum based moisturizers, but the article seems to be biased, since some authors declare a conflict of interests.
Here are some links to read more about the data and results:
Potentially harmful substances in moisturizers - Journal of Allergy and Clinical Immunology (jacionline.org) -
@chemicalmatt @vitalys There are a couple studies discussed paraffin and silicone oils and it’s quite interesting:VPJ neither forms nor acts like an epicutaneous impermeable
membrane; instead, it permeates throughout the SC interstices, allowing
normal barrier recovery despite its occlusive properties.Apparently petrolatum does get in touch with SC lipids. But instead of disrupting them, it replaces them and their function, and gives good result. Not sure about long-term use.
—Conclusion: Both oil types remain in the superficial layers of the SC (0-20% of the SC thickness). Skin treated with mineral- and plant-derived oils shows significantly higher disordered lateral and lamellar packing order of ICL in these layers of the SC compared to intact skin. Plant-derived oils significantly changed the ICL ordering in the depths of 30% and 70-90% of the SC thickness, which is likely due to the penetration of free fatty acids in the deeper layers of the SC.Mineral oil affected here but not as intense as triglycerides.
—With the exception of dimethicone 100, cetearyl iso-octanoate and caprylic/capric acid triglycerides, all vehicles showed characteristic alterations of the phase-transition temperatures and enthalpies of the stratum corneum lipids. Mineral oil and isopropyl myristate caused a reduction of the enthalpy and a decrease of the phase-transition temperatures. These two vehicles are thought to fluidize the lamellar-gel phase of the stratum corneum lipids, and possibly partially dissolve the lipids. Dibutyl adipate and caprylic/capric acid triglycerides containing 5% phospholipids decreased the phase-transition enthalpy only, probably due to dissolution or extraction of the stratum corneum lipids.Not so sure. Mineral oil had similiar effect with IPM, a known penetration enhancer. Dimethicone seems to be as inert as emollients can be. And the phospholipids-containing oil did solublize inherent lipids here, but the vehicle itself didn’t ????. This one was on isolated skin though.
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Yes, and it comes into conclusion with that moisturizers smell good, feel good, make skin look soft and supple, good to touch etc. but they are as temporary as a makeup fundation and don’t really help with skin function as some would advertise.Interestingly, a aesthetically better skin may not be a physiologically better skin.
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