Maximum Vitamin C Concentration

A well-informed lady commented today regarding the maximum possible concentration of Vitamin C in L-Ascorbic Acid form in a cosmetic product. Naturally, the answer depends on the form the cosmetic product takes. A product may be stricitly in powder form, in which case, it can be 100% L-Ascorbic Acid, as is the case in many brands' offerings. This powder, however, must be first diluted or somehow mixed in a liquid formulation to be applied to the skin and absorbed, so we will disregard this form. The other possibility is to dilute the Vitamin C in a water-based formulation. The maximum possible concentration of L-Ascorbic Acid in water is just higher than 33%, above which level such solubility is chemically unfeasible in a topical formulation. Water-based formulations, however, are not suitable for Vitamin C treatments, because the active is oxidized in water and turns orange in colour. At that time, the antioxidant potential of Vitamin C turns into a prooxidant potential -- the exact opposite effect than intended. In water-free formulations, however, Vitamin C is completely stable in its pure free form and does NOT require any other antixodiants (Vitamin E, Alpha Lipoic Acid, L-Cysteine, etc.) to form an antioxidant network to maintain its stability over time. Depending on the particle size, concentrations more than 18% become very difficult to achieve in these types of formulations and more than 23% becomes almost impossible. Interestingly, 23% appears to also offer the optimal concentration as a topical. A particular study compared the effects of a 23% solution against a 20% solution with surprisingly significant efficacy improvement.

The well-respected Journal of Cosmetic Dermatology has published an article on this topic: it can be downloaded from this link: www.complex31.com/articles/JCD-T2-Asc-Immi.PDF.

Vitamin C and Its Many Faces

There has been so much information and misinformation published about Vitamin C, its stability, its variations and its effects on the skin that it has become almost impossible to find concise and accurate facts about this vitamin. The most significant of these issues focuses on what forms this ingredient takes and which ones are useful.

Firstly, Vitamin C can only be utilized by the skin (or the human body) in the pure form of L-Ascorbic Acid. All other derivatives (including ascorbyl palmitate, magnesium ascorbyl phosphate, sodium ascorbyl phosphate, DHEA-ascorbate, ascorbyl glucoside, etc.) must first be coverted to L-Ascorbic Acid. Not only is this conversion guaranteed or easy, but also the final concentration of L-Ascorbic Acid will be much lower than the actual concentration of the derivative used. A similar comparison can be made between retinoic acid (for example, Retin-A, available by prescription), retinol and retinyl palmitate. A 0.1% concentration of pure retinoic acid can make a dramatic impact to the skin's texture, while a 1% concentration of retinol offers almost 20 times less benefit and retinyl palmitate offers less than 100 times the effectiveness. When using Vitamin C products topically, it is most important to pay attention to the concentration, particle size, formulation and, most importantly, to the type of Vitamin C -- if it is not pure, free-form L-Ascorbic Acid, its utilization will be highly impaired if existent at all.