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Sodium Ascorbyl Phosphate

Stable vitamin C

Well toleratedAntioxidantantioxidantbrighteningskin conditioning

No meaningful concern for most people; irritation is possible but rare.

Also written as: SAP · Ascorbyl Phosphate Sodium

What it is

Sodium ascorbyl phosphate is ascorbic acid with a phosphate group attached and sodium salts added, which protects the vulnerable part of the molecule from oxidising. Skin enzymes cleave off the phosphate to release vitamin C gradually. Because it is stable near neutral pH and does not discolour easily, formulators favour it for gentler products, sheet masks and anything packaged in a way that lets in air.

What it does well

  • Delivers vitamin C without the irritation of a low-pH formula

    SAP is stable and effective around pH 6-7, so products can avoid the acidity that makes pure ascorbic acid sting. The trade-off is that conversion to active vitamin C in skin is partial.

    Moderate evidence

  • May help reduce inflammatory acne lesions

    A small controlled study of SAP combined with ascorbyl palmitate reported improved sebum control on facial skin. Evidence for acne specifically is preliminary and comes from small trials.

    Limited evidence

  • More stable in the bottle than pure vitamin C

    Reviews of vitamin C derivatives consistently rank SAP among the most stable options, which means less browning and less loss of potency over a product's life.

    Strong evidence

Worth knowing

  • Weaker direct evidence than pure ascorbic acid

    Most clinical evidence for vitamin C in skin was generated with L-ascorbic acid. How much SAP actually converts to active vitamin C in human skin is not well quantified, so its potency is likely lower at the same percentage.

    Matters most toPeople choosing a vitamin C product primarily for maximum anti-pigment effect.

Where the EU stands

No specific restriction

Not listed in any restriction or prohibition annex of the EU Cosmetics Regulation; permitted at the formulator's discretion under the general safety requirement.

Sources (2)

Every link goes to the original: a journal, a PubMed record or an EU document.

  1. [1]
    Assessment of Combined Ascorbyl Palmitate (AP) and Sodium Ascorbyl Phosphate (SAP) on Facial Skin Sebum Control in Female Healthy Volunteers

    Drug Research · 2017 · doi:10.1055/s-0042-118171

    A controlled trial found a combined ascorbyl palmitate and sodium ascorbyl phosphate formulation measurably reduced facial sebum over the study period.

  2. [2]
    A review of topical vitamin C derivatives and their efficacy

    Journal of Cosmetic Dermatology · 2022 · doi:10.1111/jocd.14465

    Concludes that derivatives such as sodium ascorbyl phosphate offer far better stability than ascorbic acid but that evidence for equivalent clinical potency remains limited.

Masks that contain Sodium Ascorbyl Phosphate