About Vitamin C (L-ascorbic acid)

Vitamin C (L-ascorbic acid) is one of the very few skin care ingredients that is supported by strong and reliable scientific research and evidence.

However, it is also one of the most difficult products to formulate with, because it is extremely unstable.

As soon as l-ascorbic acid is mixed with water it starts oxidizing. This makes the l-ascorbic acid ineffective and also dangerous, because oxidized L-ascorbic acid is a pro-oxidant which may increase the formation of free radicals.

So, the challenge has been to make stable L-ascorbic acid products, or to make l-ascorbic acid itself stable.

Currently there are three ways this has been done:

1. The Skinceuticals Vitamin C Plus Ferulic Acid + Vitamin E formulation: The Skinceuticals study and patent shows that Ferulic acid stabilizes L-ascorbic acid, and in a lab this is probably true. However, the reality is that by the time customers get their bottle of Skinceuticals C+E+Ferulic it has been sitting on the shelves for too long, and when they open their bottle the product has turned orange, which means the L-ascorbic has started oxidizing and has become pro-oxidant.

2. Anhydrous C: “Anyhydrous” means “without water,” and this is a great way to formulate with the unstable Vitamin C. Instead of dissolving the vitamin C powder in water, it is mixed and dispersed into a silicone gel. W hen the silicone is applied to the face it acts like a dermal patch. The l-ascorbic acid will slowly be dissolved by the natural moisture in the skin, and the L-ascorbic acid will then be absorbed into the skin.

3. Vitamin C derivatives: To improve the stability of vitamin C in skin care, scientists have been looking for alternative solutions. One of these has been to create Vitamin C derivatives. Usually these are made by combining ascorbic acid with other molecules. Examples of these are the water soluble Magnesium Ascorbyl Phosphate and the oil soluble Tetrahexyldecyl Ascorbate (which is also known as Ascorbyl Tetraisopalmitate)

Vitamin C derivatives

Magnesium Ascorbyl Phosphate (MAP)

Magnesium Ascorbyl Phosphate is a water-soluble vitamin C derivative. Magnesium Ascorbyl Phosphate is not acidic so it does not irritate the skin and it is more stable than vitamin C.

Studies have shown that Magnesium Ascorbyl Phosphate is JUST as effective at boosting skin collagen synthesis as L-ascorbic acid.

Magnesium Ascorbyl Phosphate has proven to be an effective skin lightener, reducing hyperpigemnetation in some test subject.

Finally, studies have shown that Magnesium Ascorbyl Phosphate protects against UVB induced skin damage, such as inflammation and free radical formation, both duuring and after exposure to sunlight.

Even Magnesium Ascorbyl Phosphate is a lot more stable than L-ascorbic acid, it still degrades slowly when exposed to light and air.

Tetrahexyldecyl Ascorbate ( Ascorbyl Tetraisopalmitate)

Tetrahexyldecyl Ascorbate is the latest development in Vitamin C derivatives.

Tetrahexyldecyl Ascorbate is oil soluble, just like your skin, which means that it easily penetrates into the skin. It is not acidic and it does not require a low pH to get it to penetrate the skin so it does not sting. It is also stable in air and water for up to 18 months, which means it will work as an anti-oxidant long after you start using it.

Studies have shown that Tetrahexyldecyl Ascorbate is an effective skin care product. It effectively suppresses UVB-induced skin pigmentation, possibly through its anti-oxidative activity.

Tetrahexyldecyl Ascorbate also prevented UVA induced oxidative stress, and it boosted collagen synthesis.

Magnesium Ascorbyl Phosphate (MAP) References

Kameyama K, Sakai C, Kondoh S, Yonemoto K, Nishiyama S, Tagawa M, Murata T, Ohnuma T, Quigley J, Dorsky A, Bucks D, Blanock K. Inhibitory effect of magnesium L-ascorbyl-2-phosphate (VC-PMG) on melanogenesis in vitro and in vivo.

Geesin JC, Gordon JS, Berg RA. Regulation of collagen synthesis in human dermal fibroblasts by the sodium and magnesium salts of ascorbyl-2-phosphate.

Austria R, Semenzato A, Bettero A., Stability of vitamin C derivatives in solution and topical formulations.

Kobayashi S, Takehana M, Kanke M, Itoh S, Ogata E. Postadministration protective effect of magnesium-L-ascorbyl-phosphate on the development of UVB-induced cutaneous damage in mice.

Kobayashi S, Takehana M, Itoh S, Ogata E. Protective effect of magnesium-L-ascorbyl-2 phosphate against skin damage induced by UVB irradiation.

Tetrahexyldecyl Ascorbate ( Ascorbyl Tetraisopalmitate References

Xiao L, Kaneyasu K, Saitoh Y, Terashima Y, Kowata Y, Miwa N. Cytoprotective effects of the lipoidic-liquiform pro-vitamin C tetra-isopalmitoyl-ascorbate (VC-IP) against ultraviolet-A ray-induced injuries in human skin cells together with collagen retention, MMP inhibition and p53 gene repression.

Ochiai Y, Kaburagi S, Obayashi K, Ujiie N, Hashimoto S, Okano Y, Masaki H, Ichihashi M, Sakurai H. A new lipophilic pro-vitamin C, tetra-isopalmitoyl ascorbic acid (VC-IP), prevents UV-induced skin pigmentation through its anti-oxidative properties.

Fitzpatrick RE, Rostan EF. Double-blind, half-face study comparing topical vitamin C and vehicle for rejuvenation of photodamage.

Recent posts on various DIY skin care forums have discussed the issue of the penetration of L-ascorbic acid suspended in a silicone base into the skin.

More precisely, a few posters have started promoting the idea that L-ascorbic acid cannot penetrate into the skin, because silicone forms a barrier on the skin.

I would like to address this issue in more detail.

Background: Stable L-ascorbic acid products for skin care

The DIY skin care community has long struggled with the formulation of a stable L-ascorbic acid skin care product. In fact, professional skin care companies and formulators have also struggled with the same problem.

Some attempts have been made by professionals to develop a stable vitamin C skin care product.  The best example of this is the Skinceuticals C+E+Ferulic product.  This is based on the 2006 study “Ferulic acid stabilizes a solution of vitamins C and E and doubles its photoprotection of skin” by Pinnel and others.

This study claimed that

“Ferulic acid is a potent ubiquitous plant antioxidant. Its incorporation into a topical solution of 15% L-ascorbic acid and 1% tocopherol improved chemical stability of the vitamins (C+E) and doubled photoprotection to solar-simulated irradiation of skin from 4-fold to approximately 8-fold as measured by both erythema and sunburn cell formation.” http://www.nature.com/jid/journal/v125/n4/full/5603565a.html

However, consumers have found that skinceuticals C E ferulic product is often orange tinted.  This color usually indicates that the L ascorbic acid has oxidized, thus making it pro-oxidant.  So, even though Ferulic acid may stabilize l ascorbic acid in the lab, in practicality there appear to be some serious issues that have not been addressed.

DIY skin care formulators are able to work around this.  By making a CE Ferulic product at home, it is possible to have a fresh supply every week, thus reducing (but not eliminating) the amount of vitamin C oxidization.

Solution: The Fitzpatrick study

Another study of interest is the 2002 “Double-blind, half-face study comparing topical vitamin C and vehicle for rejuvenation of photodamage” by Fitzpatrick.

Even though this study predates the CE+Ferulic study, it did not start getting discussed on the DIY skin care forums until quite recently.

Fitzpatrick’s method was as follows:

“Ten patients having facial photodamage were recruited for a double-blind pilot study of a newly formulated vitamin C complex having 10% ascorbic acid, a water soluble acid, and 7% tetrahexyldecyl ascorbate, a lipid soluble analog.

Both of these are combined in an anhydrous polysilicone gel base, which acts as a ‘dermal patch,’ releasing the water soluble acid slowly and the lipid soluble analog rapidly. The active vitamin C complex was applied to one side of the face and the inactive placebo base was applied to the opposite side of the face once a day.” http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=11896774&query_hl=7&itool=pubmed_ExternalLink

Now, this is where a very few posters start having some issues.  The base used is an anhydrous silicone gel, and the doubt seems to be in the fact that a very few posters believe that silicone forms a barrier and therefore hinders the absorption of active ingredients.

However, let’s look at the next part of Fitzpatrick’s study:

“Biopsies showed increased Grenz zone collagen, as well as increased staining for mRNA for type I collagen. This formulation of vitamin C results in clinically visible and statistically significant improvement in wrinkling when used topically for 12 weeks. This clinical improvement correlates with biopsy evidence of new collagen formation.”

Now, if silicone prevents the absorption of active ingredients, than there would not have been an increase collagen.

So, this should put to rest the claims that using silicone as a base prevents the absorption of active ingredients.

Flawed study

There is one troubling aspect about the Fitzpatrick study.  The study did not test the use of each key ingredient separately.

The two key ingredients in the anhydrous C product are L-ascorbic acid (which is water soluble), and Ascorbyl Tetraisopalmitate (also known as Tetrahexyldecyl Ascorbate ) which is oil soluble.

So, even though the study shows that the combination the two active ingredients in a silicone base led to an increase of collagen, we do not know if this was caused by the Tetrahexyldecyl Ascorbate, the Vitamin C, or the combination of the two.

This brings us back full circle to the original problem! We do not know which active is responsible for the increase in collagen. So it is possible to claim that the L-ascorbic acid is in fact not absorbed by the skin, and that the increase of collagen is cause by the Tetrahexyldecyl Ascorbate.

The blame for this confusion can be put purely with Fitzpatrick. It seems a simple matter to have tested the activity of both l-ascorbic and Tetrahexyldecyl Ascorbate in anhydrous silicone, separately. However, he chose not to do this.

So, we remain with his original statement.

“Both of these are combined in an anhydrous polysilicone gel base, which acts as a ‘dermal patch,’ releasing the water soluble acid slowly and the lipid soluble analog rapidly.”

To me the dermal patch idea makes sense, and I personally put more trust in this than the doubt caused by a very few (but very ‘vocal’) posters on skin care forums.

In the end the choice is yours.

I will continue to use the anhydrous C product as my number one weapon in anti aging skin care.  Why? Because no matter which active did the job, somehow this product has improved my skin and that is ultimately what I want.

http://www.bulkactives.com/siliconegel.htm

http://www.bulkactives.com/ascorbicacid.htm

http://www.bulkactives.com/ascorbyltetraisopalmitate.htm