Although many persons consume
large oral supplements of this vitamin, biologic control
mechanisms limit the amount that can be absorbed
and subsequently transported to skin. Therefore,
the only way to get large concentrations into
skin is to apply L-ascorbic acid topically, in this way
targeting the area to be protected. To achieve percutaneous
delivery, the pH of the formulation must
be below 3.5 to accomplish protonation of the ascorbic
acid.