Ascorbyl Palmitate (AP) is a lipid-soluble ester of vitamin C developed primarily to enhance formulation stability. Compared to ascorbic acid, AP offers better resistance to oxidation in emulsions but has limited evidence for conversion to active vitamin C in skin [1].

Formulation Advantages & Skin Properties

Scientific studies highlight distinct differences and limitations of AP:

• Stability in Formulations: AP demonstrates improved stability compared to ascorbic acid, particularly in emulsions and lipid-containing systems. In a 28-day test, AP retained ~37% of its content while L-ascorbic acid degraded to ~8% in the same conditions [2]. However, AP remains unstable when compared to other vitamin C derivatives [3].

• Lipid Affinity and Penetration: Ascorbyl Palmitate (AP) is lipophilic and readily penetrates the stratum corneum and upper epidermis, as shown in animal and human studies, but its conversion to free ascorbic acid in skin appears limited. For example, while AP increased skin vitamin C in vitamin C-deficient guinea pigs, studies in human and pig skin found no significant increase in ascorbic acid levels following AP application compared to L-ascorbic acid, suggesting poor in situ conversion and limited dermal bioavailability [1]. Tape-stripping studies further confirmed that AP mostly remains in the stratum corneum with minimal penetration into deeper layers [1].

• Antioxidant and anti-inflamatory effects: topical application of AP has been shown to reduce UVB-induced erythema by approximately 50% in clinical observations [4]. Some clinical reports also suggest anti-inflammatory benefits, with improvements in inflammatory dermatoses when AP is applied topically [5].

Safety and Tolerability

• Low Irritation and Sensitization Potential: Human repeated insult patch tests with concentrations up to 5% showed no or minimal irritation or sensitization, with AP classified as non-irritating and non-sensitizing in standard cosmetic use ranges [1].

• Potential Pro-Oxidant Activity in Specific Contexts: While one in vitro study on keratinocytes reported increased lipid peroxidation and cytotoxicity under UVB exposure when AP was used alone—likely due to the formation of pro-oxidant ascorbyl radicals in the absence of other antioxidants [6]—the Cosmetic Ingredient Review (CIR) panel reviewed this evidence and concluded that these findings do not indicate phototoxicity or any clinically relevant pro-oxidant behavior in real-world cosmetic use [1]. Thus, while formulation context matters, AP remains a safe and effective antioxidant when properly stabilized and is not considered a pro-oxidant risk in consumer products.

Conclusion

Ascorbyl Palmitate offers enhanced oxidative stability and favorable safety in topical formulations, particularly those with lipid-rich or emulsified bases. While its skin penetration is confirmed, its conversion to active vitamin C appears limited, and its biological efficacy is mainly attributed to surface-level antioxidant and anti-inflammatory effects. Importantly, although in vitro studies have raised concerns about potential pro-oxidant behavior under UV stress, regulatory review by the CIR panel concluded that such effects are not relevant in cosmetic use. Overall, AP remains a useful, well-tolerated antioxidant for stabilizing formulations and supporting surface-level skin protection, though it is less bioactive than some newer vitamin C derivatives.

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References

1. Johnson, W., et al. (2022). Safety assessment of ethers and esters of ascorbic acid as used in cosmetics. International Journal of Toxicology, 41(Supplement 2), 57S–75S.
   https://cir-reports.cir-safety.org/view-attachment/?id=55dd0cb4-0c4c-5834-93b4-d57172fc4433

2. Smaoui, S. (2014). Stability studies of L-ascorbic acid and ascorbyl palmitate in topical cosmetic formulations. H&PC Today – Household and Personal Care Today, 9(1), 17–18.
   https://magistralbr.caldic.com/storage/product-files/1911641408.pdf

3. Sasidharan, O., Gholap, A., & Rastogi, R. (2023). A review of clinical efficacy of topical vitamin C and its derivatives. Pharmaceutical Science and Technology, 7(2), 20–26.
   https://www.researchgate.net/publication/373795104_A_Review_of_Clinical_Efficacy_of_Topical_Vitamin_C_and_Its_Derivatives

4. Ravetti, S., Clemente, C., Brignone, S., Hergert, L., Allemandi, D., & Palma, S. (2019). Ascorbic acid in skin health. Cosmetics, 6(4), 58.
   https://www.mdpi.com/2079-9284/6/4/58

5. Jovanović A., et al. (2024). Liposomal encapsulation of ascorbyl palmitate: Influence on skin performance. Pharmaceutics, 16(7), 962.
   https://www.mdpi.com/1999-4923/16/7/962

6. Meves, A., et al. (2002). Vitamin C derivative ascorbyl palmitate promotes ultraviolet-B-induced lipid peroxidation and cytotoxicity in keratinocytes. Journal of Investigative Dermatology, 119(5), 1103–1108.
   https://pubmed.ncbi.nlm.nih.gov/12445199/