The other day I spotted a brand called Yu-Be that claims to a number-one-best-seller in Japan with little more than glycerin as the active ingredient. Now, I regard glycerin as the cosmetic equivalent of wearing a T-shirt in winter: It's better than nothing, but not exactly a heavy gun in terms of protection. Still, there was something about Yu-Be that stopped me in my tracks. Then Mary Beth left left a comment on a review of a Tilvee cream saying she avoids glycerin at all costs. I checked Truth In Aging's posts and found that they could be summed up as contradictory. I was going to have to find out more about glycerin.
Now here's what's confusing about glycerin. The most commonly stated claim about glycerin is that it helps the skin attract and retain moisture. Then the next thing that you'll read is that glycerin draws moisture from your own dermis up to your epidemis. Your skin might feel moisturized, but you have just borrowed from Peter to pay Paul and ultimately it will get dryer. I also found plenty of references claiming that in order for glycerin to attract water from the atmosphere, humidity must be higher than 70%. Glycerin may work in Singapore (when I was there, humidity was 96%), but isn't going to be much use in a dry New York winter. My T-shirt analogy was beginning to hold up.
The Truth About Glycerin
But where was the hard evidence to back up all these claims? Well after several hours of digging around, clinical research seems to back up the idea that glycerin is friend not foe.
One of the most impressive studies was conducted by Appa et al on 394 patients with severely dry skin. 16 moisturizers were tested against two high-glycerin creams over a five-year period. The glycerin won hands down and resulted in an increased thickness of the corneocytes. This is backed up by other research. For example, in a placebo-controlled, double-blind study at the Friedrich Schiller University Department of Dermatology in 2008, researchers investigated the effects of glycerin on atopic dermatitis on human subjects who were treated twice daily for four weeks. The patients receiving the glycerin showed significant improvement in the hydration of the outer layer of skin, and the skin's normal protective barrier function was restored.
A blend of glycerin and dimethicone got the thumbs up another study which found that epidermal thickness increased, barrier function improved and melanin intensity decreased. The researchers concluded that "even nonxerotic, photoaged skin may appear younger, benefiting structurally and functionally from routine use of moisturizers containing dimethicone and glycerine" (source).
There's no two ways about it, though: glycerin does make skin feel much softer. So something must be going on. In turns out that recent studies have shown that glycerin helps degrade the corneodesmosomes that hold skin cells together. The end effect of this degradation is more consistent desquamation (shedding of the outer layer of skin) and ultimately smoother-looking skin. The thing is, I'm not sure I really want to degrade my corneo-whatsits.
Glycerin in Yu-Be's Soft Touch
Yu-Be's soft touch is enhanced by adding in glyceryl stearate, which is made by reacting glycerin with stearic acid, a fatty acid obtained from animal and vegetable fats and oils. This creates a film over the skin that will feel soft to the touch. It is possible that it does prevent moisture loss by forming a barrier.
Glycerin can come from palm or other plant oils, but also from petroleum. Unfortunately, we are rarely given the source by cosmetic makers.
Having said all of this, Yu-Be's moisturizer isn't bad for $16. In addition to aforementioned, it has vitamins E and B, as well as anti-inflammatory licorice.
Ingredients in Yu-Be Moisturizing Skin Cream: Glycerin, Water, Isopropyl Myristate, Stearic Acid, Glyceryl Stearate SE, Triethanolamine, Tocopheryl Acetate (Vitamin E), Glycyrrhetinic Acid, Camphor, Riboflavin (Vitamin B2), Hydrogenated coco-glycerides, Stearyl Alcohol, Polysorbate 80, EDTA, Methylparaben.