Form of vitamin C that is considered stable and an effective antioxidant for skin (Sources: Photochemistry and Photobiology, June 1998, pages 669–675; and Journal of Pharmaceutical and Biomedical Analysis, March 1997, pages 795–801). This form of vitamin C is also known to increase skin’s hydration levels and improve its elasticity (Source: Skin Research and Technology, August 2008, pages 376–380).
For skin lightening, there is only a single study showing it to be effective for inhibiting melanin production (Source: Journal of the American Academy of Dermatology, January 1996, pages 29–33). The study concluded that a moisturizer with a 10% concentration of magnesium ascorbyl phosphate “suppressed melanin formation…. The lightening effect was significant in 19 of 34 patients with chloasma or senile freckles and in 3 of 25 patients with normal skin.” We’re only aware of one product (Dermalogica MAP-15 Regenerator) that contains the amount of magnesium ascorbyl phosphate the study indicated is necessary for lightening skin.