Stable water-soluble vitamin C derivative. Weaker antioxidant activity than L-ascorbic acid, but it spares sensitive skin and works at neutral pH.
Topical application
BLimited evidence. One RCT or several controlled studies with limitations.
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.
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.
Irritation potential
LowAllergen risk
LowPregnancy
SafeSuitable for
Works well with
RetinolРетинол
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.
RetinaldehydeРетиналь
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.
The Evigrade extension adds an evidence panel to iHerb, Sephora, Druni and 12 more stores. This ingredient and every other one in the product show evidence-tier, allergen risk and pregnancy/lactation flags at a glance.
Magnesium Ascorbyl Phosphate is considered safe during pregnancy at typical cosmetic concentrations. Systemic absorption through the skin is minimal.
Magnesium Ascorbyl Phosphate suits: normal, dry, oily, combination, sensitive.
Stable water-soluble vitamin C derivative.
The INCI name is Magnesium Ascorbyl Phosphate. It may also appear as: MAP, Магний аскорбил фосфат, MAP витамин С.
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