Anhydrous vitamin C combo. Making the best of vitamin C skin care.

One approach to improving vitamin C stability and reducing the potential for skin irritation is to use anhydrous vehicle, i.e. a topical base cream containing no water. Since water acts as a catalyst of vitamin C oxidation, anhydrous environment reduces the rate of vitamin C degradation. Anhydrous vitamin C is more stable not only during storage but also on the skin after the application. This is an important advantage, even compared to some stabilized water-based vitamin C formulas, which may store well but still oxidize quickly on the skin surface. Furthermore, anhydrous vitamin C tends to be less irritating than regular ascorbic acid products because the irritation is caused mainly by hydrogen ions generated by acid dissociating in water.

More importantly, evidence indicates that ultrafine microcrystalline vitamin C in an anhydrous vehicle can stimulate collagen synthesis. In a 2006 study published in the Journal of Cosmetic Dermatology, Dr Geoffrey K. Heber and co-workers studies the effects of 20 - 23% ultrafine microcrystalline anhydrous vitamin C on the collagen synthesis in the sections of human skin. The researchers found an increased production of both type I and type III collagen (both of these types of collagen are important for youthful skin).

Vitamin C derivatives

Another solution is to use of vitamin C derivatives, which may provide skin benefits similar to the unmodified vitamin C (L-ascorbic acid) but tend to be more stable and less irritating (see our article on vitamin C derivatives.) Unfortunately, vitamin C derivatives have limitations of their own. While a number of vitamin C derivatives appear promising as collagen boosters, more studies are needed to definitively determine which ones are as effective as vitamin C itself. Also, due to variation in individual skin biochemistry some people who respond to vitamin C do not respond to its derivatives and vice versa.

Anhydrous vitamin C combo, possibly the best of both worlds

There is some evidence that combining water soluble and oil-soluble forms of vitamin C may provide synergistic skin benefits through broader antioxidant protection and better penetration. However, combining high concentrations of oil and water-soluble active ingredients is often technically difficult using typical skin care vehicles. Fortunately, in the case of vitamin C, some anhydrous vehicles allow to combine high potency vitamin C with its oil-soluble derivatives while providing the extra stability of water-free base. For example, one can combine L-ascorbic acid (water soluble) and tetrahexyldecyl ascorbate (oil-soluble) in an anhydrous vehicle. A study of such a formula, conduced by Drs Fitzpatrick and Rostan, was published in Dermatological Surgery (a peer-reviewed journal) in 2002. The researchers used a combination of L-ascorbic acid and tetrahexyldecyl ascorbate in anhydrous polysilicone gel base applied to one-half of the face vs. inactive polysilicone gel base applied to the opposite side. The researchers concluded that the formulation produced "clinically visible and statistically significant improvement in wrinkling when used topically for 12 weeks" and that "the improvement correlated with biopsy evidence of new collagen formation."

While many biocompatible organic vehicles may be used as an anhydrous base (e.g. glycerin), the best results seem be obtained either with siloxanes/polysilicones or a mixture of oil and emulsifying wax. Siloxanes and polysilicones are related silicon-containing organic compounds often used as skin protectants. They appear particularly effective in forming an anhydrous film that protects the skin surface from irritation, oxidation, and other offenses. The mixture of oil and emulsifying wax is another anhydrous alternative, which, in one laboratory study, appeared to be even more effective than polysilicone vehicle. More research is needed to determine optimal anhydrous vehicle for real life use as well as to compare various regular and anhydrous vitamin C formulas head-to-head.

Unfortunately, as of the time of this writing, no commercial product seems to be an anhydrous vitamin C combo. Non-anhydrous products with vitamin C derivatives are available. So are a few anhydrous L-ascorbic acid products, although they tend to be rather expensive. While waiting for an anhydrous vitamin C combo to become commercially available, you can try to use both of these types of products. If you do, apply them at least a few hours apart. Applying a regular product (i.e. a product containing water) together with an anhydrous one reduces the benefits of the latter.

Alternatively, you can take a DIY route. Skin-friendly anhydrous bases are readily available. With minimal effort and expense, you can make anhydrous vitamin C and/or anhydrous vitamin C combo yourself. You can even enhance it with Vitamin E, which is known to potentiate antioxidant effects of vitamin C. (See DIY Anti-Aging Skin Care Infopack for specific instructions).