Vitamin C is an effective antioxidant, brightens the skin tone, and reduces signs of aging. In its pure form, Vitamin C is unstable in water. Magnesium Ascorbyl Phosphate (MAP) is a water-soluble derivative of Vitamin C. It is more stable in water but it is less potent than direct L-Ascorbic Acid. It is compatible with water but higher concentrations cannot be offered in a low-viscosity serum format and require emulsification to form a cream. This formula is a light cream that offers 10% pure MAP (very high solubilized concentration). Aside from the general benefits of pure Vitamin C, MAP has been shown to offer specific skin brightening benefits, more so than other derivatives of Vitamin C. (Note: some brands offer "powder" formulations that offer up to 15% MAP. Such powders would offer less direct availability of MAP as compared to an emulsion such as this formula which has solubilized the complete 10% concentration of MAP. It is extremely difficult to solubilize higher concentrations of MAP in non-powder formulations.)