Magnesium Ascorbyl Phosphate
Stable water-soluble vitamin C derivative. Weaker antioxidant activity than L-ascorbic acid, but it spares sensitive skin and works at neutral pH.
Evidence by route
Topical application
At 3–10% it converts in the skin to ascorbic acid, gently brightens and supports collagen synthesis. Weaker than L-AA but more resistant to oxidation.
- Kameyama K et al. J Am Acad Dermatol. 1996;34(1):29-33. PMID 8543691
- Pinnell SR. J Am Acad Dermatol. 2003;48(1):1-19. PMID 12522365
How to read tiers A–F
- BLimited evidence. One RCT or several controlled studies with limitations
Tolerability and safety
- Irritation potential
- Low
- Allergen risk
- Low
- Pregnancy
- Safe
- Suitable for
- Normal, Dry, Oily, Combination, Sensitive
Combinations with other ingredients
Works well with
Retinaldehyde
MAP works gently at neutral pH, so it is compatible with retinal. A good choice for sensitive skin that cannot tolerate L-AA plus a retinoid in one routine.
Retinol
MAP is stable at neutral pH, so there is no pH conflict with retinol. On sensitive skin this pair tolerates better than L-AA + retinol: no need to alternate.
About this ingredient
Magnesium Ascorbyl Phosphate (MAP) is a stable water-soluble vitamin C derivative, a phosphorylated form of ascorbic acid with magnesium as the counterion. One of the four classic stable C derivatives (alongside ascorbyl glucoside, sodium ascorbyl phosphate, tetrahexyldecyl ascorbate). Mechanism. Skin phosphatases cleave the phosphate bond and release free ascorbic acid. Activity is lower than L-ascorbic acid – conversion is limited by enzymatic activity of skin (Pinnell 2001). Suppresses tyrosinase in melanocytes, stimulates collagen synthesis in fibroblasts, neutralizes free radicals. Where applied. Serums and creams for hyperpigmentation brightening, anti-aging products. Stable at neutral pH (6.5–7), which allows inclusion in formulas with niacinamide, retinol, and acids without separation. Concentration 1–10%. In Spain in Sesderma C-Vit, Martiderm Photo-Age, Mesoestetic Energy C, Endocare C. Evidence base. The Kameyama 1996 RCT (n=34) showed 35–50% reduction in melasma and post-inflammatory hyperpigmentation over 6 months of 10% MAP. The Khoshzaban 2011 RCT confirmed efficacy for post-acne pigmentation. Weaker than L-ascorbic acid for anti-aging but better tolerated. Safety. CIR/SCCS confirmed safety at concentrations up to 10%. Hypoallergenic, non-irritating, non-comedogenic, does not photosensitize. Well tolerated by sensitive skin unlike L-ascorbic acid. Pregnancy and lactation – safe. First-line agent for gestational melasma alongside niacinamide, azelaic acid, and SPF 50+. Who it suits. Sensitive skin, rosacea, melasma, post-acne pigmentation, photoaging. Combines well with niacinamide, ferulic acid, tocopherol, retinol.
Frequently asked questions
Is Magnesium Ascorbyl Phosphate safe during pregnancy?
Magnesium Ascorbyl Phosphate is considered safe during pregnancy at typical cosmetic concentrations. Systemic absorption through the skin is minimal.
What skin types is Magnesium Ascorbyl Phosphate for?
Magnesium Ascorbyl Phosphate suits: normal, dry, oily, combination, sensitive.
What is Magnesium Ascorbyl Phosphate and what does it do in cosmetics?
Stable water-soluble vitamin C derivative.
What's the INCI name for Magnesium Ascorbyl Phosphate?
The INCI name is Magnesium Ascorbyl Phosphate. It may also appear as: MAP.
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