A very stable and promising form of skincare superstar, Vitamin C. If you do not know why Vitamin C is a big deal in skin care, you can catch up here. In short, Vitamin C has three proven magic abilities: antioxidant, collagen booster, and skin brightener. The problem with it, though, is that it's very unstable, turns brown and ineffective in no time (after a few month) and the cosmetic industry is trying to come up with smart derivatives that are stable and have the magic abilities of pure Vitamin C.
Ethyl Ascorbic Acid, or in short EAC is an "etherified derivative of ascorbic acid" that consists of vitamin C and an ethyl group bound to the third carbon position. This makes Vitamin C very stable and soluble both in water and oil.
But for a Vitamin C derivative to work, it's not enough to be stable, they also have to be able to absorb into the skin and convert there to pure Vitamin C. We have good news regarding the absorption: on top of manufacturer claims, there is some data (animal study) demonstrating in can get into the skin, and it seems to be better at it than another vitamin C derivative called Ascorbyl Glucoside.
Regarding conversion, we can cite only a manufacturer claim saying that EAC is metabolized in the skin to pure ascorbic acid (and the ascorbic acid content of EAC is very high - 86,4% - compared to the usual 50-60% Vitamin C content of other derivatives).
As for the three magic abilities of Vitamin C, we again have mostly only manufacturer claims, but at least those are very promising. EAC seems to have both antioxidant and anti-inflammatory effect, and it's claimed to be able to boost skin's collagen production. The strong point of EAC, though. is skin-brightening. On top of manufacturer claims, there is also clinical in-vivo (tested on real people) data showing that 2% EAC can improve skin tone and whiten the skin.
All in all, Ethyl Ascorbic Acid is not (yet) a fully proven but a very promising Vitamin C derivative. Especially if you are after Vitamin C's skin-brightening effect it's worth a try.
- Journal of Cosmetic Dermatology, Volume 11 (4) – Dec 1, 2012, Stability, transdermal penetration, and cutaneous effects of ascorbic acid and its derivatives