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In a since-revised October 28, 2007 blog post, I erroneously attacked the form of vitamin C known as ascorbyl glucoside, due to the fact that there was little established research on the ingredient. However, luckily for me, I was recently contacted by the North American Cosmetic Ingredient Sales and Technical Support Representative for Hayashibara International, the manufacturer of ascorbyl glucoside since 1990, who provided me with a plethora of the company’s research on the ingredient. Again, my apologies to the company. It may also be noted that all of the research cited below is from Hayashibara International, unless cited otherwise.
What is ascorbyl glucoside?
Ascorbyl glucoside has a structure in which the C2-hydroxyl group of L-ascorbic acid is masked with glucose. Once selectively permeated through the skin, ascorbyl glucoside is broken down into L-ascorbic acid and glucose by the enzyme alpha-glucosidase. Because ascorbyl glucoside is broken down into L-ascorbic acid, it has the same functions as L-ascorbic acid: exhibiting high antioxidant activity, acting as a coenzyme for enzymes involved in collagen synthesis (namely prolyl and lysyl hydroxylase), and inhibiting the synthesis of melanin. Although Hayashibara International maintains that this breakdown process leaves a high concentration of vitamin C in the skin, a competitor maintains that ascorbyl glucoside use maintains vitamin C at only a low level. Clearly, more independent, non-company affiliated research involving ascorbyl glucoside needs to be done!
So what are the benefits of using products with ascorbyl glucoside as opposed to the usual vitamin C found in skin care formulations (L-ascorbic acid)?
Ascorbyl glucoside has greater stability than L-ascorbic acid, which tends to break down in heat, light, in the presence of oxygen, and in certain pH levels (hence why your vitamin C cream turns dark yellow or brown after a few uses). According to the research by Hayashibara International, ascorbyl glucoside has excellent stability in heat, light, and in the presence of oxygen and metal ions when compared to other forms of vitamin C. This means, according to Hayashibara International researchers, that ascorbyl glucoside lasts over twice as long as other forms of vitamin C, and thereby delivers the effects of vitamin C to the skin for a longer period of time.
In what products is ascorbyl glucoside found?
Ascorbyl glucoside is found in a multitude of products, including:
*Clarins Intensive Age Control Brightening Program (pictured above; $145.00, Amazon.com). Features ascorbyl glucoside in a fairly high concentration (based on the ingredients list) to brighten the skin, reduce the appearance of dark spots (probably not as well as hydroquinone, but still…), and to provide antioxidant protection.
*Garnier Nutritioniste Skin Renew Daily Regenerating Serum ($12.63, Amazon.com). Features ascorbyl glucoside, magnesium, and lycopene. The lycopene is the reason I do not like this product; for more information, please visit my review of this product.
Are there any possible detriments to ascorbyl glucoside?
One foreseeable detriment is the presence of additional glucose in the skin. After alpha-glucosidase breaks ascorbyl glucoside into L-ascorbic acid and glucose, does the glucose contribute to the formation of advanced glycation endproducts (which can age/harden collagen) via the Maillard pathway? Or does something else happen to the glucose entirely? Based on current research, it is impossible to tell if ascorbyl glucoside contributes to the overall concentration of sugars that feed into the Maillard pathway in the skin.
The other foreseeable detriment is that ascorbyl glucoside’s concentration is not listed on the product, unlike some products with L-ascorbic acid, which state that they are 5%, 10%, or 15% L-ascorbic acid. One may argue that ascorbyl glucoside is more stable than L-ascorbic acid, so a higher concentration of L-ascorbic acid does not dictate higher potency than a lower concentration of ascorbyl glucoside. Still, there is hope for labeling with concentrations of ascorbyl glucoside in the future, with this study by Lin et. al. suggesting that high-performance liquid chromatography with on-line microdialysis sampling can be used to determine the concentration of ascorbyl glucoside in skin care formulations.
So, overall, is ascorbyl glucoside a beneficial skin care ingredient?
Based on current research by the manufacturer of ascorbyl glucoside, yes, ascorbyl glucoside does seem beneficial, due to the fact that it provides the benefits of vitamin C to the skin in a more stable (and hence longer-lasting) formulation. In the meantime, it would be interesting if researchers investigate the effects of additional glucose from ascorbyl glucoside in the skin, as it could possibly be detrimental. However, based on what is currently known, ascorbyl glucoside seems like an excellent way to get the benefits of vitamin C without having to worry as much about your product breaking down in the air, heat, or light. I will give more information if and when it surfaces on this exciting ingredient!