I first wrote about the snail facial back in 2015, in response to an article in the Herald on Sunday on that very topic. Today, the fact that there's a story on the very same subject on the Stuff webpage suggests that there is always an appetite for woo (although when I read the story just now, I was happily surprised to see that all the comments so far were very skeptical). So I thought I would rework that original post a trifle.
Back in 2015 we were told that one could (if one had a sufficiency of funds) already purchase Snail Soap, which contained "snail slime, virgin olive oil, honey and extracts from medicinal plants". The slime component supposedly helped 'beat' wrinkles (what's wrong with a bit of character?) & reduced scarring. The Herald article included the comment that "No one has come back and said it is rubbish or doesn't work," but then, it might be a tad embarassing to have to 'fess up to spending $25/bar on soap that didn't meet one's expectations.
At the time it seemed that the next contribution gastropods had to make to our outer beauty was the snail facial: snails crawl about over your face, leaving their silvery mucus trails behind them. This probably does leave your face feeling a bit tighter, when the trails dry. But saying that "snail facials are believed to be very good" may well be an example of wishful thinking, especially in the absence of supporting data.
Snail slime does contain lectins, which are a class of glycoprotein; the amount & type of this substance vary with the species of snail. (Many years ago now, my Significant Other used to go out collecting them on dewy mornings, so that the lectin could be extracted and analysed.) It also contains other proteins such as collagen & elastin, which probably comes in helpful for the slug species that indulge in balletic aerial s*x at the end of a mucous bungee cord. But as far as I can see the claims that smearing one's face with this slimy mix will encourage skin cells to make more of these proteins lack support. And indeed, quite why putting protein molecules (which are highly unlikely to be absorbed through your skin) on the dead outer surface of your skin would encourage the cells beneath to spring into activity, is not immediately clear.
Lectins are 'sticky' molecules produced by plants (& algae), animals, fungi & prokaryotes, and are involved in communication between cells, defence against pathogens, fertilisation, metastasis of tumours, and appear to generate an inflammatory response (something that's picked up on by various 'alt.health' sites such as mercola.com). Those from snail slime may have anti-microbial activity, but in absence of actual infection that would not be a burning reason to use it on one's face. And indeed, I think there's need for caution in their use, as it seems that bacteria such as E.coli can survive for quite some time in snail faeces: I'd certainly want to be sure that the snails had been kept long enough to evacuate their bowels prior to crawling over my skin!
I see that ads for the facial products promoted in today's Stuff story (which, were it not for the inclusion of rather negative feedback from some users, would perhaps best be called an advertorial) claim that
[this] highly concentrated essence contains 96% snail mucin, a powerful ingredient known to aid in skin repair, hydration, brightness, and tone.
This is interesting as the actual ingredients list states - with no mention of proportions -
Snail Secretion Filtrate, Betaine, Butylene Glycol, 1,2-Heandediol, Sodium Hyaluronate, Panthenol, Arginine, Allantoin, Ethyl Hexanediol, Sodium Polyacrylate, Carbomer, Phenoxyethanol.
So no mention of actual mucin (which is actually a class of glycoproteins), and a bunch of other chemicals that are found in a range of skin products... At least in 2018 they don't claim that this elixir contains the chemical known as "Helix Asperia Muller - just as well, really, as there is no such thing. As one Smut Clyde pointed out to me 3 years ago, when he expanded on this very subject. the phrase is actually a typo (?) for the old taxonomic name of the actual garden snail, Helix aspersa (Muller), Muller being the chap who first described it. The species has now apparently been reclassified as Cornu aspersum. I didn't know that, until he told me.
Also - & unsurprisingly - the ad provides no link to research supporting these claims. As it happens there is some preliminary evidence that the stuff might be useful for some types of skin damage (here, for example), but the top Google Scholar links for a search on mucins and skin hydration relate to people's very own mucins, not those from a snail. Adding Helix to the search string produces nothing either, & nor does using Cornu (the current taxonomic name for garden snails).
I'd like to say I'm shocked, but I'm not.