What is Sodium Ascorbyl Phosphate?
Sodium Ascorbyl Phosphate (often shortened to SAP) is a water-soluble, stable form of vitamin C. A phosphate group is attached to the vitamin, which stops it from breaking down quickly in air and light.
It works at a nearly neutral pH, so it is typically gentler than pure L-ascorbic acid. SAP is popular in products for oily and acne-prone skin because it has both antioxidant and mild anti-bacterial research behind it, in addition to the usual vitamin C benefits like brightening.
Source
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Found in |
Sodium Ascorbyl Phosphate (INCI name) |
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Origin |
Made in a lab from vitamin C |
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Also known as |
SAP, vitamin C phosphate |
Top features and benefits
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Stable form of vitamin C |
Gentler than L-ascorbic acid |
Studied for acne-prone skin |
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Antioxidant protection |
Helps brighten dull skin |
Works at a skin-friendly pH |
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Lightweight and water-based |
Suits oily and combination skin |
Longer shelf life than pure vitamin C |
How Does It Work?
Skin enzymes called phosphatases remove the phosphate, turning sodium ascorbyl phosphate into active vitamin C right on the skin. That keeps the ingredient stable in the bottle but still lets it act as an antioxidant once applied.
SAP stands out because of a small clinical study on acne. In that research, a lotion with 5 percent SAP was linked to fewer inflamed pimples after several weeks. Laboratory tests also found that it could slow the growth of the bacteria involved in acne. This is why it is often used in products for oily, pimple-prone skin.
As with other derivatives, the conversion to active vitamin C is not perfect, and far fewer studies exist on SAP than on L-ascorbic acid. It is a gentle, useful ingredient, but it should not be expected to give the same strength of brightening results as a well-made pure vitamin C serum.