Skip to main content

Sodium Ascorbyl Phosphate

Home / Ingredient Glossary / Sodium Ascorbyl Phosphate

Sodium Ascorbyl Phosphate (SAP) is the esterified sodium salt of ascorbic acid (vitamin C). It is touted as an extremely stable and non-irritating derivative, meaning it has a long shelf life and won’t easily oxidize when exposed to light and air. SAP is also readily bioavailable, so it’s able to penetrate the outer layer of the skin efficiently without causing irritation. Once absorbed, SAP is transformed enzymatically into ascorbic acid at the cell membrane.

SAP is an excellent free radical scavenger. It can help protect cells from damage and visibly brightens the complexion by inhibiting melanin synthesis.1 As a bonus, SAP is effective in the treatment of facial acne vulgaris and shows great promise in skin wound healing.2 3 It’s a well tolerated, multi-benefit form of vitamin C.

Why choose SAP over traditional vitamin C (l-ascorbic acid)?

L-ascorbic acid is prone to oxidation when exposed to water, light and air. Water-based products containing l-ascorbic acid have a shelf life of a few months at most and begin losing potency immediately, even when precautions are taken. When vitamin C oxidases, it is no longer an effective antioxidant (and some say it may be harmful to skin cells). SAP’s unmatched stability negates risk of oxidation so it remains potent and effective over time.

L-ascorbic acid has a high potential to irritate, so many skins cannot tolerate its use. Ascorbic acid must be kept at an extremely low pH (usually < pH 3) and this can cause sensitization, redness and stinging on application. SAP is gentle and prefers a skin-friendly pH near 6.5.

[1]Jurkovič, P., Šentjurc, M., Kristl, J., Pečar, S., & Gašperlin, M. (2004). Comparison of two ascorbic acid derivatives effectiveness for scavenging ultraviolet-induced free radicals in the skin. Journal Of Drug Delivery Science And Technology, 14(3), 229-233. doi: 10.1016/s1773-2247(04)50105-3
[2] An open study comparing efficacy of 5% sodium L-ascorbyl-2- phosphate lotion with 1% clindamycin gel in the treatment of facial acne vulgaris. (2008). Journal Of The American Academy Of Dermatology, 58(2), AB2. doi: 10.1016/j.jaad.2007.10.025
[3] Deng, Q., Huang, S., Wen, J., Jiao, Y., Su, X., Shi, G., & Huang, J. (2020). PF-127 hydrogel plus sodium ascorbyl phosphate improves Wharton’s jelly mesenchymal stem cell-mediated skin wound healing in mice. Stem Cell Research & Therapy, 11(1). doi: 10.1186/s13287-020-01638-2


Products with Sodium Ascorbyl Phosphate