So
Sodium Ascorbyl Phosphate
Sodium Ascorbyl PhosphateAntioxidant
Stable water-soluble vitamin C derivative. Less potent than L-ascorbic acid but easier to formulate.
What it does
Sodium ascorbyl phosphate is a stable form of vitamin C that converts to ascorbic acid on the skin. It's the most stable of the common vitamin C derivatives, with an effective pH range that's friendlier to formulation than the pH 3.5 needed for L-ascorbic acid. SAP also has documented activity against acne-causing bacteria, which is why it shows up in acne-positioned brightening serums. Effects are gradual.
The evidence, graded
strongVitamin C, vitamin E, and ferulic acid show synergistic photoprotection. The combination is more stable and doubles photoprotection compared to vitamin C alone.Lin 2005 · Journal of Investigative Dermatology ↗
strongVitamin C shows brightness and tone-evening improvements in 4-8 weeks. Collagen-mediated firmness benefits take 12+ weeks. Photoprotection benefits are immediate when paired with sunscreen.Humbert 2003 · Experimental Dermatology ↗
Graded per the methodology: strong · moderate · emerging · expert consensus. A weak source on a strong claim gets the weaker label.
Also known as
sap, vitamin c, ascorbic acid
Pairs worth knowing
This page is public and indexed on purpose (unlike profiles and drops, which are unlisted) — it’s the citation behind shared ingredient cards, and it should be findable.
Want more like this?
Get Drop, free. Every flag cites its source, the app tells you when your routine is complete, and it helps you simplify — instead of selling you more products.