Recently someone asked me my thoughts about an article they came across which painted glycerin in skin care products in a very disparaging light. You can see the post and the comment here. along with the link to read the article for yourself.
Glycerin is often demonized - it’s not the first time I have encountered this. But with a request to investigate I decided it was time to dig deeper.
Misinformation, exaggeration and misrepresentation are so common these days. Sleuthing takes time and most of don’t have any extra to go peering into the literature looking for answers. So sit back and relax … I got this!
I could not investigate the reference material sited in the article - there wasn’t any. I also could not id the author. So armed with nothing but speculation, conjecture, anecdotal reports and search terms I scrounged through all of my textbooks, then spent days reading published papers via research portals like pubmed & google scholar. I really wanted to unearth everything I could find - good, bad, or ugly. So down the rabbit I went ….
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Glycerin (aka Glycerol) is a naturally occurring compound found in every animal and plant.
Glycerol plays a very important role in biosynthesis - it’s intrinsic to life itself.
But could the purified form used in skin care be connected somehow to the rise of nonalcoholic fatty liver disease in women even when applied to the skin (as stated in the article)?
We should take this very seriously! Let’s investigate!
First … the bad … a few people are allergic to it.
But is it toxic or worse, causing disease?
AN ALLERGEN? Allergy to topically applied glycerin does occur but is considered very rare. I did find enough anecdotal evidence for this in the blogosphere to suggest that if you are someone who reacts to skin care products, your routine show always include testing every new product with a patch test (I tell you how to do that here) and/or consult an allergist for testing.
IRRITATING OR DEHYDRATING? 100% pure, undiluted glycerin applied directly to skin can cause localized skin dehydration in certain climates, and temporary skin blistering in test subjects with normal skin. Sound familiar? Many naturally occurring compound which are harmless or beneficial in proper amounts can cause a negative reaction depending on how it is used and how much of it.
DIGGING DEEPER: I found a detailed assessment of glycerin in skin care formulations published in 2015 by the Personal Care Product Council linked here This panel looks at scientific literature and unpublished data relevant to assessing the safety of cosmetic ingredients and makes recommendations based on their findings. From the assessment:
The Panel noted the high frequency of use reported for glycerin (over 15,000 cosmetic uses) and the low instances of reports of toxicity, irritation, and sensitization in the literature and that glycerin is GRAS for food packaging and as a multiple-purpose food substance. This information helped to further reduce the Panel’s concern about the use of this cosmetic ingredient.” .
The data demonstrated low oral and dermal toxicity for multiple animal species and humans, in both acute and long-term studies.
There were little or no reproductive or developmental effects observed in oral studies using rats, mice, and rabbits.
Glycerin was not genotoxic in multiple in vitro tests and was not carcinogenic to rats in a long-term feeding study.
This ingredient was not a dermal or ocular irritant and was non-sensitizing to guinea pigs and humans.
But … could Glycerin be causing a rise in nonalcoholic fatty liver disease in women?
The panel states: “Data on dermal absorption, distribution, metabolism, and excretion of glycerin were not found in the published literature nor were unpublished data provided.”
Could there be support for the allegation that glycerin applied topically is being absorbed into the bloodstream where is might be involved in a liver disease process?
More than 15,000 cosmetic products include glycerin, it’s the third most common ingredient in cosmetics behind water #1 and fragrance #2, and it has been extensively studied. Would concerns have been raised by now to warrant more research? Perhaps. To date there have not been any published studies testing this hypothesis. I, for one, will certainly be paying attention!
WHAT IS GLYCERIN?
WHAT ROLE DOES IT PLAY IN NATURE?
What does it do for our skin?
Glycerin is a sweet, syrupy liquid which dissolves completely in water. It was discovered somewhat by accident by a Swedish chemist in 1779. It’s vast potential for use in diverse industries, and it’s benefit to skin were discovered later.
Glycerin (aka Glycerol) is a glycol molecule. It is an organic compound found abundantly in nature in the form of triglycerides in all living cells.
A fat or oil from any animal or plant is composed of a glycol molecule and three attached "oil" molecules. Processing the oil/fat by exposing it to hydrogen (hydrolysis) releases the oils and the water soluble glycerin in a chemical reaction called “saponification”. Glycerin is also created during the fermentation of sugars, occurring naturally in wine, beer and bread. It can be synthetically manufactured from petroleum oils for commercial applications.
Some people claim that “animal glycerin” treats them nicely, but not “vegetable glycerin”. Either way Glycerin produced from any animal fat during saponification is chemically identical to glycerin derived from any oil, even a petro-oil. So there is no such thing as "tallow glycerin" or "animal glycerin."
Organic standards matter: even if all pure glycerin, regardless of what it is made from is chemically identical - I hope you will choose Organic and Non-GMO kosher grade glycerin. Production methods You can find it produced today commonly from coconut oil and soy.
Glycerin is an “Alcohol”, or more correctly, a Fatty Alcohol.
Fatty alcohols are about as related to skin-damaging alcohol/ethanol as a shot of whiskey is to a shot glass of olive oil.
Distinguishing FATTY alcohols, ALL of which benefit skin, from DRYING alcohols like denatured alcohol, a petrochemical by-product, is vital to choosing skin care. Fatty alcohols in skincare include cetyl alcohol, stearyl alcohol, oleyl alcohol are naturally derived. All Fatty Alcohols play an important role in preserving and restoring healthy skin function.
Denatured alcohol has long been known to cause “systemic eczematous contact dermatitis” and chemical sensitivities. These alcohols are drying to the skin yet commonly found in skin care because they are preservatives - many herbalists who make skin care use denatured alcohol because it is “natural” - buyer beware!
A little understanding of how glycerin functions and how it supports conditions associated with dry skin are important when looking to relieve these conditions (and debunking myths).
Maintains Water Balance (homeostasis): Glycerin in the body fills in the intercellular matrix between cells by attracting the right amount of water from the body to maintain the skin's homeostasis. It has been proven that glycerin is a powerful humectant in humid climates, forming a reservoir in the stratum corneum which lasts a long time, reducing the evaporation of moisture from the skin’s surface.
In low humidity conditions, rather than performing as a humectant, glycerin maintains the fluidity of the lipid membrane, a thin membrane made of two layers of lipid molecules in the stacked lipid bilayers, this is the glue that holds the corneocytes, dead skin cells, together and traps water. So when humidity is low, glycerin in these interior layer of the skin helps skin lipids do their jobs better. When the mercury really plummets Glycerin, being a glycol, has properties which make skin lipids more flexible and moisture at the skins surface from freezing. This same property makes glycol in other applications very valuable also - it is not “antifreeze” per se but it does reduce the temperature at which water freezes. I live in a super cold place and I love to ski! I am often out all day in the cold - My skin is stays noticeably more flexible and doesn’t freeze solid when I use glycerin rich skin care.
Promotes Skin Cell Maturation: Researchers found that glycerin applied to the skin signals cells to mature in a normal manner. Psoriasis is a skin condition where the skin cells don't mature properly, they shed before they are mature, leading to thick, scaly skin. This research showed that topical glycerin helps those with psoriasis.by stimulating the skin cells to fully mature before shedding.
Improves the Appearance of Skin: In addition to keeping moisture levels high, glycerin is a natural emollient with mild exfoliating properties. helping maintain softness and suppleness. When skin is plump and hydrated it looks, feels and functions better. It does this by locking lipids within the stratum corneum and the effects of just on application are long lived.
Removes dead cells: Our skin cells are held together with the help of proteins. These proteins can clump the dead cells together which prevents new ones from forming. Glycerin has mild cleansing properties assisting the break down of the proteins, and lubricating properties helping slough off dead cells.
… the best news: Healing properties & barrier repair
Not only is glycerin extremely moisturizing, new research indicates that glycerin has a repairing action on the barrier function showing it doesn’t just relieve dry skin conditions, it can actually HEAL them. This article presents the evidence in great detail; Corneotherapeutic Benefit of Glycerine.
Topically, glycerin promotes the synthesis of lipids in the epidermis, guiding cells to grow and mature properly, accelerating wound healing and reducing bruising. Glycerin has also been shown to help treat fungal infections in disorders like eczema and psoriasis.
Topical 90% medical grade Kanuka honey and 10% glycerin is shown to be a safe, natural and effective rosacea treatment, according to a study published June 24, 2015 in the British Medical Journal.
Kanuka honey originates from a variety of tree species in New Zealand related to the Manuka species.
The bottom line … Glycerin heals and supports healthy, resilient skin
“Biosynthesis” is the life process itself - the complex, multi-step, enzyme-catalyzed biological process where a substrate (a substance on which an enzyme acts) is converted into a more complex compound where it performs numerous roles supporting all life.
Glycerin plays an important role in this process in every plant and animal.
It really IS one of nature's wonders
Until I uncover peer reviewed evidence to support claims to the contrary, I’ll continue singing the praises of glycerin (and glycerites) in skin care. So unless you are one of the unlucky few allergic to this miraculous compound - I recommend it highly as a beneficial ingredient which recent research shows may assist in the healing of an impaired skin barrier.
I am more inspired than ever to make my glycerites - pure glycerin infused with medicinal herbs which I then incorporated into in my creations.
Further reading and source material:
Natural (Mineral, Vegetable, Coconut, Essential) Oils and Contact Dermatitis https://www.researchgate.net/publication/321669861_Natural_Mineral_Vegetable_Coconut_Essential_Oils_and_Contact_Dermatitis
Contact urticaria syndrome and protein contact dermatitis caused by glycerin enema. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4810294/
Glycerin May Help Skin Disease, Study Finds https://www.sciencedaily.com/releases/2003/12/031203075525.htm
Glycerine - An Overview. https://www.aciscience.org/docs/Glycerine_-_an_overview.pdf
Glycerol - Glycerin, Manufacture, Chemical, and Oil. http://science.jrank.org/pages/3065/Glycerol.html#ixzz5bN9Jaa80
Comparatively Speaking: Fatty Alcohols vs. Fatty Acids vs. Esters. https://www.cosmeticsandtoiletries.com/research/chemistry/97861099.html
Glycerol — Just a Moisturizer? Biological and Biophysical Effects http://www.scientificspectator.com/documents/personal%20care%20spectator/Glycerol%20a%20Moisturizer.pdf
Glycerol replacement corrects defective skin hydration, elasticity, and barrier function in aquaporin-3-deficient mice https://pdfs.semanticscholar.org/9f4c/70aefb80f873853a6a198ae652262307db9d.pdf
Safety Assessment of Glycerin as Used in Cosmetics 2015 https://www.cir-safety.org/sites/default/files/glycerin_0.pdf
Intercellular Matrix and Natural Moisturizing Factors. American Journal of Contact Dermatitis, September 2000, pages 165–169; and Acta Dermato-Venereologica, November 1999, pages 418–421. ).
The Corneotheraputic benefits of Glycerine. http://www.educatedtherapists.com/the-corneotherapeutic-benefit-of-glycerine/