Is THD Ascorbate the Best Vitamin C?

Is THD Ascorbate the Best Vitamin C?

Fast Facts:

  1. Vitamin C is highly unstable, making L-ascorbic acid a very irritating active and not well tolerated by those with sensitive skin.
  2. THD ascorbate is a derivative of vitamin C that is much more stable and better penetrates than any other vitamin C derivative.
  3. It is also very mild to the skin, allowing people with sensitive skin to reap the benefits of THD ascorbate such as promoting collagen formation and minimizing fine lines.
  4. It is also known to help reduce the production of melanin pigments in human melanoma cultures by 80%.

Read on for more details:

Wait THD ascorbate is vitamin c? In fact, in the world of vitamin C actives there are many different kinds – L-ascorbic acid being the most common, and bioactive form, but it is the least stable. Some common stable derivatives (vitamers) are magnesium ascorbate, magnesium ascorbyl phosphate, sodium ascorbate, sodium ascorbyl phosphate, calcium ascorbate, and tetrahexyldecyl (THD) ascorbate all with varying effectiveness. Formulators pick and choose which vitamer they will use depending upon the chemistry of the formulation and the intended function of the vitamin C. 

Since there are so many, and as the title suggests – I will only ramble on about THD ascorbate, which, in my opinion, is the best vitamin C derivative. Ascorbic acid being the bioactive form of vitamin C is essential to our survival as it plays an important role in the proper synthesis of collagen (the cement holding your cells together).[1]  Without it, you would develop scurvy and begin to melt! Just kidding you don’t melt, but your skin will begin to look thin, saggy and easily bruised.

Vitamin C is highly unstable – it is easily oxidized in light, heat, pH changes, and in the presence of other ions. Not to mention the need for the formula’s pH to be quite low (~3.5) so ascorbic acid can remain stable for longer – making L-ascorbic acid a very irritating active and not well tolerated by those with sensitive skin. But not all hope is lost as this has led to the innovation and the development of various vitamin C derivatives that are more stable while retaining their efficacy. This instability makes formulating with vitamin C very tricky and requires careful thought as to which derivative to use and why. In walks THD ascorbate…

THD ascorbate is an amazing vitamer of vitamin C. It retains all its metabolic activities and dermal benefits, however is exceptionally better in many areas. First off, it’s far more stable, if not the most stable vitamer of vitamin C.[2] This is thanks to the ester linkages that have been placed on the molecule protecting what is called the moiety (active part of vitamin C) from oxidation. These ester linkages are long hydrocarbon chains which make the molecule oil soluble. THD ascorbate is not only more stable, but is able to penetrate much further than other vitamers. When compared to L-ascorbic acid, THD ascorbate still absorbs faster even when the ascorbic acid concentration was 25 times that of THD.[3] Lastly, it appears to even be mild to the skin making it a great way for people with sensitive skin to benefit from vitamin C. This is of course due to the physical properties of THD and it being more stable, allowing it to be formulated at a pH that is agreeable to the acid mantle – pH 5.5 – 6.0.[4]

What’s not to love about this form of vitamin C? It behaves better, performs better and has all the same activity as you would expect from ascorbic acid, including reducing the production of melanin pigments in human melanoma cultures by 80%![5]

By Jamie Stanton, B.Sc, @Jamie_the_Chemist 


[1] – “Which kind of vitamin C is best for skin? Episode 31.” The Beauty Brains, May. 2014, ode-31/ 

[2] – “All about Vitamin C in Skincare.” Derm.Talk, 8 Oct. 2020, 

[3],[5] – Fitzpatrick, Richard E., and Elizabeth F. Rostan. “Double-Blind, Half-Face Study Comparing Topical Vitamin C and Vehicle for Rejuvenation of Photodamage.” Dermatologic Surgery, vol. 28, no. 3, 2002, pp. 231–236., doi:10.1046/j.1524-4725.2002.01129.x. 

[4] – “Tetrahexyldecyl Ascorbate: the Best Form of Vitamin C for Your Skin.” Dr.Brandt, 4 Feb. 2021,