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Vitamin C in Skincare: Understanding Different Forms

By Aristotle Cosmetics. . 6 min read.

Vitamin C is one of the most recognized ingredients in skincare, yet the name on a label can refer to several different molecules. Understanding those differences helps explain why formulas vary so much, and why no two vitamin C products should be assumed to behave the same way.

The role of vitamin C in skin

Healthy skin naturally contains high levels of vitamin C. It is a powerful antioxidant, and it is also required by the enzymes that build and stabilize collagen, the protein that gives skin much of its structure. Humans cannot make vitamin C, so it must come from the diet, and researchers have long been interested in whether applying it to the skin can add to what reaches it from within.

Antioxidant protection

Everyday exposure to ultraviolet light and pollution generates unstable molecules called free radicals, or reactive oxygen species. Antioxidants such as vitamin C can neutralize these molecules before they damage the lipids, proteins and DNA of skin cells. This is why vitamin C is often described as supporting the skin’s defenses. It does not replace sunscreen, but it is frequently used alongside it.

Vitamin C and a brighter-looking complexion

Vitamin C can interfere with tyrosinase, an enzyme involved in the production of melanin. Through this activity, topical vitamin C has been studied for improving the appearance of dullness and uneven tone. Dermatology reviews describe these effects while also noting that results depend heavily on the form and formulation used.

Why derivatives exist

The pure form, L-ascorbic acid, is the most extensively studied, but it is notoriously unstable. Exposed to air, light and water, it oxidizes and loses activity, and it typically needs an acidic formula to penetrate skin well. To address this, cosmetic chemists developed vitamin C derivatives: modified versions designed to be more stable in a formula and gentler on the skin.

The trade-off is that derivatives generally have a smaller body of published evidence than L-ascorbic acid, and they differ from one another in how they behave in the skin and how readily they are thought to be converted into active vitamin C. A scientific review of ascorbic acid and its derivatives highlights exactly these differences in stability and penetration. That is why we avoid suggesting that every vitamin C derivative performs identically.

Tetrahexyldecyl Ascorbate

Tetrahexyldecyl Ascorbate is an oil-soluble ester of vitamin C. Because it dissolves in oils rather than water, it is well suited to silky, lightweight formulas and is valued for its stability. It is used in skincare to support a brighter, more even-looking complexion.

Sodium Ascorbyl Phosphate

Sodium Ascorbyl Phosphate is a water-soluble salt of vitamin C that is considerably more stable than pure ascorbic acid. It contributes antioxidant benefits and is used to help improve the appearance of dull skin.

Why concentration and formulation matter

A vitamin C product is more than its headline ingredient. The form of vitamin C, its concentration, the pH of the formula, the packaging and the other ingredients alongside it all influence how stable and effective it is. Some antioxidants, such as ferulic acid, have been studied specifically for their ability to help stabilize vitamin C in solution. You can read more in Ferulic Acid, Resveratrol, and the Role of Antioxidants in Skincare.

Two forms of vitamin C in Brightening Silk Glass Serum

Brightening Silk Glass Serum features two vitamin C derivatives: Tetrahexyldecyl Ascorbate and Sodium Ascorbyl Phosphate. One is oil-soluble and one is water-soluble, and they are included to support the appearance of brighter, more even-looking skin while providing antioxidant benefits. During daytime use, always finish your routine with broad-spectrum sunscreen.

This article is for general education and is not medical advice. If you have a skin condition, known allergies, or concerns about an ingredient, speak with a qualified healthcare professional.

Sources

  1. Pullar JM, Carr AC, Vissers MCM. The roles of vitamin C in skin health. Nutrients. 2017;9(8):866. https://pubmed.ncbi.nlm.nih.gov/28805671/
  2. Al-Niaimi F, Chiang NYZ. Topical vitamin C and the skin: mechanisms of action and clinical applications. Journal of Clinical and Aesthetic Dermatology. 2017;10(7):14-17. https://pubmed.ncbi.nlm.nih.gov/29104718/
  3. Telang PS. Vitamin C in dermatology. Indian Dermatology Online Journal. 2013;4(2):143-146. https://pubmed.ncbi.nlm.nih.gov/23741676/
  4. Stamford NPJ. Stability, transdermal penetration, and cutaneous effects of ascorbic acid and its derivatives. Journal of Cosmetic Dermatology. 2012;11(4):310-317. https://pubmed.ncbi.nlm.nih.gov/23174055/
  5. Lin FH, et al. Ferulic acid stabilizes a solution of vitamins C and E and doubles its photoprotection of skin. Journal of Investigative Dermatology. 2005;125(4):826-832. https://pubmed.ncbi.nlm.nih.gov/16185284/
  6. American Academy of Dermatology. How to apply sunscreen. https://www.aad.org/public/everyday-care/sun-protection/shade-clothing-sunscreen/how-to-apply-sunscreen