Clinical Formulations
with Integrity.
  • Bazaar 2018 Award
  • Byrdie / Curated 2017 Award
  • Sunday Times Style Beauty Awards 2017 Winner
  • CEW Beauty Award Winner 2017
  • Tatler Beauty Awards Winner 2017
  • Grazia Beauty Awards 2016 Breakthrough Brand Award
  • The Pool Beauty Awards 2016 Award
  • Glamour Beauty Power List 2017 Award
  • Into The Gloss Top 25 Award Winner
  • Look Beauty Awards 2017 Winner
  • Bazaar 2018 Award
  • Byrdie / Curated 2017 Award
  • Sunday Times Style Beauty Awards 2017 Winner
  • CEW Beauty Award Winner 2017
  • Tatler Beauty Awards Winner 2017
  • Grazia Beauty Awards 2016 Breakthrough Brand Award
  • The Pool Beauty Awards 2016 Award
  • Glamour Beauty Power List 2017 Award
  • Into The Gloss Top 25 Award Winner
  • Look Beauty Awards 2017 Winner

A Discussion of L-Ascorbic Acid and Dehydroascorbic Acid in Skincare

Background

Vitamin C, or L-Ascorbic Acid (LAA), has been used in skincare extensively in response to a vast body of independent scientific and consumer studies showing the benefits it offers to fight visible aspects of aging. Most skincare formulations containing LAA also contain water, which causes LAA to oxidize over time. Such formulations are offered by both small and established brands globally, with several brands owning patents surrounding their use and stability of LAA.

LAA progressively oxidizes in presence of water and formulations develop a gradually darkening orange hue as this oxidation advances. Many new formulations exist on the market that counteract this oxidative effect either by avoiding use of water in LAA formulations or by using forms of Vitamin C (not LAA) that are resistant to oxidation. However, for many brands, the very core regimens that they promoted since their inception contain LAA and water, raising questions by many. In response to these questions, many have attempted to justify these formulations by referring to several studies around how LAA and its oxidation affects the skin.

DECIEM is completely against using LAA and water––ever. We have prepared this summary to help consumers navigate around the confusing array of published information defending formulations that contain LAA and water.

Discussion

When LAA oxidizes, it turns into Dehydroascorbic Acid (DHAA) as an initial step. DHAA can convert back into LAA through an enzymatic reaction which requires the presence of the antioxidant amino acid, L-Glutathione. Brands whose formulations contain LAA and water have directly and indirectly used this fact around LAA and DHAA conversion to justify that using LAA and water together is OK because DHAA can penetrate the skin and eventually convert back into LAA, largely backed by a study that examined the application of DHAA topically and its effect on visible aging.

Despite the fact that all of these complex arguments are relying on a few studies involving a few people, there are several issues that need to be considered when evaluating the validity of these conclusions in the context of these studies:

  1. DHAA itself is not stable. When LAA oxidizes into DHAA in the presence of water, it then further irreversibly converts to Diketogulonic Acid (DGA), specially well so when the pH of the formulation is not harsh to the skin (any pH above approximately 4). When this conversion occurs, that converted amount of both LAA and DHAA will no longer exist in the formula. For this very reason, the rare study1 that actually did find visible benefits from application of pure DHAA to the skin clearly stated that “Solutions of Dehydroascorbic acid (DHA) were remixed every 3 days in order to maintain their refreshness and concentration levels.” In a product containing LAA and water being in market distribution, no such refreshness of neither LAA nor DHAA would be available. The chart below shows the reversible reaction of LAA to DHAA as well as the irreversible reaction of DHAA to DGA, which simply requires presence of water.
A chart displaying the reversible reaction of LAA to DHAA as well as the irreversible reaction of DHAA to DGA
  1. In a topical formulation containing LAA and water, the oxidation is progressive. In other words, the ratio of LAA/DHAA/DGA will vary over time (shown clinically2), progressing toward more of DHAA and then to more of DGA. As most skincare products spend several months to years from production time to use by the end consumer in transit and on shelf, it is insensible to rely on a formulation that would have progressively varying degrees of LAA (good based on several studies), DHAA (maybe good based on one study) and DGA (bad by every measure) depending on the time between production and purchase.
  2. Additionally, if a product’s position is so particularly focused on what a study concludes on the benefits of DHAA, it is insensible to use LAA and water, knowing that some of the LAA will convert to DHAA over time. One could always work on a stable formulation of just water and DHAA itself so there is always a consistent product offered to the consumer without varying amounts of LAA and DHAA (and eventually DGA) depending on the time between production and purchase.
  3. Any benefit from DHAA is from its conversion to LAA since it is shown clinically that DHAA itself has no biological value on its own and, in fact, seems to indicate deficiency of LAA (From Banerjee S.3 “The accumulation of dehydroascorbic acid seems to be an indication of ascorbic acid deficiency.”) While some studies have tried to establish independence of DHAA conversion to LAA, further studies4 have shown that this conversion is significantly impaired in absence of L-Glutathione5. Assuming, despite the earlier points, that a consistent formula of stable DHAA is actually provided to the consumer, which isn’t the case generally today (if not ever), DHAA requires the presence of L-Glutathione in the skin to convert efficiently back to LAA. While younger consumers have good and consistent amounts of the antioxidant amino acid L-Glutathione present, L-Glutathione drops in concentration dramatically as we age. In effect, the younger consumer (who would benefit from an anti-aging formulation containing Vitamin C less than an older consumer) would have a more reliable benefit from a hypothetical formulation of stable DHAA than would an older consumer, which is insensible. In this context, it’s also notable that the half-life of DHAA is milliseconds.
  4. Finally, if brands take the position that it’s acceptable and even good for LAA to oxidize in their water-based formulations, then it is unclear why those very brands have also filed several patents showing attempts to stabilize LAA in water, which despite patentability, none of the solutions achieve stability of LAA (a patent grants a right but does not validate a function). Furthermore, if this oxidation is acceptable, then the consumer can simply purchase the amount of LAA powder used in the formulations directly for approximately 1%6 of the cost of LAA skincare formulations from several such brands on the market and mix at home with water for topical use without infringing on any patent.

DECIEM’s position is that arguments around unstable LAA formulations containing water are not justified given that options exist to avoid LAA and water together. DECIEM’s portfolio offers a comprehensive array of stable Vitamin C formulations:

Ethylated L-Ascorbic Acid Offerings

NIOD’s Ethylated L-Ascorbic Acid 30% Network and Hylamide’s C25 Booster use a water-free solution of Ethylated L-Ascorbic Acid (ELAA), which unlike Vitamin C derivatives, does not require conversion to LAA and is directly usable by the skin. These formulations are solutions that can penetrate very efficiently into the skin because they do not contain water despite full solubility (the skin repels water contrary to common misconceptions and so water solutions are less efficient for penetration than water-free solutions). The only disadvantage of ELAA over LAA is that the material costs up to fifty times more than LAA.

Pure L-Ascorbic Acid Offerings

The Ordinary offers two formats of suspensions of LAA that contain no water: Vitamin C Suspension 23% + HA Spheres 2% and Vitamin C Suspension 30% in Silicone. These formulations would not offer the same penetration efficiency as solubilized ELAA offerings within NIOD and, as such, they maximise the concentration of LAA powder to allow dermal uptake over time. (Dermal LAA uptake, regardless of how LAA is formulated, depends on several factors per person and environmental factors. Some studies have suggested that higher LAA concentrations are absorbed less than lower LAA concentrations but these studies have completely disregarded the several factors that impact absorption from person to person and from environment to environment on the same person. More LAA availability, especially in suspension form, allows for maximum uptake as the skin is never short of LAA availability in such a case. Furthermore, the only credible studies analyzing the maximum absorption of LAA have been performed on pig skin and not human skin, which has no relevance to our discussion here.) Finally, The Ordinary will be offering 100% pure L-Ascorbic Acid powder in a very fine 325 mesh on its own for mixing with other formulations or even with water on a per-application basis to avoid degradation over time in the case of a premixed water formula. This product is listed online as of the timing of this document but will not be available for purchase until late summer of 2017.

Vitamin C Derivative Offerings

The Ordinary also offers Vitamin C derivatives that are far more stable than LAA but require conversion to LAA. These solutions offer the gentlest formulations but don’t have the same availability of LAA as pure LAA or ELAA formulations. These formulations are Ascorbyl Glucoside Solution 12% (water-based), Ascorbyl Tetraisopalmitate Solution 20% in Vitamin F (oil-based) and Magnesium Ascorbyl Phosphate 10% (emulsion).

References:

1 http://kylenorton.healthblogs.org/2014/07/10/dehydroascorbic-acid-dha-12-concentration-regained-the-youthfulness-of-forearm-between-the-wrist-and-elbow-in-stimulated-reproduction-of-collagen-against-sagging-skin/
2 Conclusions referenced in this publication: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3167265/
3 https://www.ncbi.nlm.nih.gov/pubmed/407155
4 https://www.degruyter.com/downloadpdf/j/znc.1982.37.issue-10/znc-1982-1015/znc-1982-1015.pdf
5 https://www.ncbi.nlm.nih.gov/pubmed/8001837
6 Comparison of cost of 6 grams of generic LAA powder from VitaminShoppe.com to produce 30ml (approximately 30 grams) of a 20% Vitamin C solution in water against the cost of a 20% Vitamin C formulation without any other materially significant active ingredient offered on SkinStore.com both on August 3, 2017.
  • Bazaar 2018 Award
  • Byrdie / Curated 2017 Award
  • Sunday Times Style Beauty Awards 2017 Winner
  • CEW Beauty Award Winner 2017
  • Tatler Beauty Awards Winner 2017
  • Grazia Beauty Awards 2016 Breakthrough Brand Award
  • The Pool Beauty Awards 2016 Award
  • Glamour Beauty Power List 2017 Award
  • Into The Gloss Top 25 Award Winner
  • Look Beauty Awards 2017 Winner