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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 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 ↗
emergingVitamin 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 ↗

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

Niacinamide (Vitamin B3) · works together ↗Vitamin E (Tocopherol) · works together ↗Ferulic Acid · works together ↗Alpha Arbutin · works together ↗

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