Vitamin C acids are widly used in our lemon plus vitamin C natural skin lightening product line. Vitamin C magnesium ascorbyl phosphate, L-ascorbic acid, ascorbyl glucosamine, and ascorbic acid are various forms of vitamin C considered stable and effective antioxidants for skin. There are very few studies showing them to have benefit for inhibiting melanin production, but what little there is has been positive. The problem is that the concentrations of these ingredients were high (more than 5%), which is rarely used in cosmetic formulations. However, in combination with other treatments, vitamin C is an extra step that can help reduce skin discolorations (Sources: International Journal of Dermatology, August 2004, page 604; Dermatology, April 2003, pages 316-320; and Journal of the American Academy of Dermatology, January 1996, pages 29-33).