What could be used as a substitute for vitamin C?

The vitamin C plays a central role in cosmetics due to its multiple benefits for the skin. As a potent antioxidant, it contributes to neutralising reactive oxygen species generated by UV radiation and pollution, supports collagen synthesis as an enzymatic cofactor, assists in enhancing skin radiance and regulates melanogenesis, the process responsible for skin pigmentation. These various mechanisms of action of the vitamin C explain why it is so frequently used.

Vitamin C can be identified in ingredient lists by its INCI name "Ascorbic Acid".

However, despite these well-documented benefits, the use of the vitamin C is not always optimal or suitable for all skin types or formulations. In its active form, L-ascorbic acid is inherently unstable and highly prone to oxidation, which imposes strict formulation constraints, notably a pH below 3.5. Yet, the skin’s pH being around 5.5, this acidic pH can compromise the skin barrier and cause irritation and discomfort in sensitive or already compromised skin. Moreover, its hydrophilic nature limits its cutaneous penetration without specific conditions, and its efficacy is strongly dependent on concentration, vehicle and application method. For these reasons, it may be appropriate to consider alternatives that can reproduce some or all of the biological effects of vitamin C, while offering improved stability or enhanced tolerance.

When seeking to replace vitamin C, the aim is to identify active ingredients capable of mimicking its biological mechanisms. Several options are available, the relevance of which depends on the intended purpose.

• Vitamin C derivatives.

  The most logical alternative to vitamin C is undoubtedly its derivatives. In cosmetics, these modified forms of ascorbic acid have been developed to overcome its main drawbacks: instability in aqueous solution, the need for a highly acidic pH and the potential to irritate certain skin types. Vitamin C derivatives, such as Sodium Ascorbyl Phosphate or the Ascorbyl Tetra Isopalmitate, offer superior chemical stability and can be more easily formulated at physiological pH. Once applied to the skin, they gradually convert into active ascorbic acid, thereby providing the same benefits as vitamin C.

  The interest in these derivatives is supported by several experimental studies. One study in vitro specifically focused on their ability to sustain collagen synthesis, one of the principal mechanisms of vitamin C. The results show that L-ascorbic acid dose-dependently stimulates type I collagen production by human fibroblasts, while vitamin C phosphate (VicC-P) and vitamin C glucoside (VicC-Glu) induce comparable biological responses. In a reconstructed dermis model, these derivatives also promote extracellular matrix contraction, indicating reinforcement of the collagen network. The authors conclude that these stabilized forms can be considered genuine provitamins.

• Other antioxidant active ingredients, such as green tea extract, ferulic acid, resveratrol or even astaxanthin.

  Vitamin C is not the only active ingredient capable of neutralising the free radicals and limiting the oxidative stress. Other molecules also exhibit a pronounced antioxidant activity, via complementary mechanisms. The green tea extract, rich in catechins such as epigallocatechin gallate, primarily acts by trapping reactive oxygen species. The ferulic acid, on the other hand, is a polyphenol capable of stabilising free radicals while protecting cellular membrane lipids from peroxidation, thereby helping to preserve the integrity of the skin barrier. The resveratrol, notably found in grape skins, can also trap free radicals while activating certain antioxidant enzymes in the skin, such as sirtuin-1.

  Finally, the astaxanthin exhibits a unique molecular structure that allows it to integrate into cell membranes and shield both their inner and outer surfaces from oxidation. This dual localisation gives this compound a remarkable efficacy in limiting oxidative damage. Studies in vitro have also demonstrated that astaxanthin’s antioxidant capacity may surpass that of vitamin C, making it an especially interesting alternative for individuals seeking to bolster their skin’s antioxidant defences.

• Other brightening actives, such as niacinamide, liquorice extract or tranexamic acid.

  If the aim of using vitamin C is to reduce pigmentation spots and even out the complexion, it is helpful to know that it is not the only molecule capable of acting on melanogenesis. Other brightening agents, such as niacinamide, the licorice extract or even the tranexamic acid, have also demonstrated significant efficacy against hyperpigmentation in various clinical studies. Their modes of action are not all identical, as they can affect the transfer of melanin to keratinocytes, tyrosinase activity or the inflammatory pathways involved in the post-inflammatory hyperpigmentation. Although these studies do not directly compare their efficacy with that of vitamin C, they show that these agents represent credible alternatives for targeting pigmentation spots, as summarised in the table below.

• BERNARD B. A. et al. Effect of vitamin C and its derivatives on collagen synthesis and cross-linking by normal human fibroblasts. International Journal of Cosmetic Science (2001).

• MONCADA B. et al. A double-blind, randomised clinical trial of 4 % niacinamide versus 4 % hydroquinone in the treatment of melasma. Dermatology Research and Practice (2011).

• TELANG P. Vitamin C in dermatology. Indian Dermatology Online Journal (2013).

• NAEINI F. F. et al. Topical tranexamic acid as a promising treatment for melasma. Journal of Research in Medical Sciences (2014).

• EKPE V. et al. Antioxidant effects of astaxanthin in various diseases: a review. Journal of Molecular Pathophysiology (2018).

• RAKHMINI A. et al. Comparison of 10%, 20% and 40% liquorice extract cream as a skin-lightening agent. International Journal of Medical Reviews and Case Reports (2018).

• WINN D. & al. A novel topical derivative of tranexamic acid for enhancing the appearance of hyperpigmentation and reducing inflammation in sun-damaged skin. Journal of Cosmetic Dermatology (2021).

• LAURENT A. & al. Initial clinical safety and efficacy assessment of a topical 3% tranexamic acid cream and serum regimen for addressing facial hyperpigmentation in Caucasian patients. Cosmetics (2024).