Magnesium Ascorbyl Phosphate
INCI · Magnesium Ascorbyl Phosphate · also MAP, vitamin C phosphate
How it works
Magnesium ascorbyl phosphate (MAP) is a phosphate ester of ascorbic acid bound to magnesium, designed to remain stable in aqueous formulations at near-neutral pH. Skin phosphatase enzymes cleave the phosphate group, releasing free ascorbic acid that can then function as an antioxidant and support tyrosinase inhibition relevant to pigmentation.
The evidence
Early laboratory and clinical research demonstrated that topical MAP can be absorbed by skin and converted to biologically active ascorbic acid, with observed effects on melanin synthesis pathways in cultured melanocytes. Clinical studies report improvements in photoaging parameters and pigmentation with regular use, though MAP is generally regarded as less potent, molecule-for-molecule, than direct L-ascorbic acid due to the conversion step required.
Suitability
MAP's neutral pH and water solubility make it one of the better-tolerated vitamin C forms for sensitive and reactive skin, and its non-comedogenic profile suits acne-prone users as well.
- Sensitive skin: preferred over low-pH ascorbic acid
- Acne-prone skin: some evidence also supports antibacterial contribution against acne-associated bacteria
- Pregnancy: considered a safe vitamin C option
Concentration
Typical formulations use MAP between 3% and 10%, with most clinical work reflecting concentrations around 3%.
Conflicts & combinations
MAP combines well with ferulic acid and vitamin E for antioxidant synergy, and can be layered with niacinamide without the destabilization concerns once attributed to vitamin C pairings.
- Synergistic with ferulic acid and tocopherol
- Compatible with niacinamide and most humectants
- hyperpigmentation
- dullness
- anti aging
- Effective from
- 3%
- Max safe
- 10%
Is magnesium ascorbyl phosphate good for acne?
Some research suggests it may help with acne-related concerns due to antibacterial and anti-inflammatory properties, in addition to its antioxidant role.
Is MAP gentler than L-ascorbic acid?
Yes, its near-neutral pH makes it significantly less irritating than traditional low-pH L-ascorbic acid formulations.
Does magnesium ascorbyl phosphate lighten dark spots?
Clinical and cell-based studies support its role in reducing melanin synthesis, which can help fade hyperpigmentation over time.
Can I use magnesium ascorbyl phosphate while pregnant?
Yes, it is generally regarded as a safe vitamin C derivative during pregnancy and breastfeeding.
How does MAP compare to magnesium ascorbyl phosphate's other vitamin C cousins?
MAP, sodium ascorbyl phosphate, ascorbyl glucoside, and THD ascorbate are all stabilized derivatives; they differ mainly in solubility, oiliness, and conversion efficiency rather than mechanism.