*Cosmetic Topical Use of Vitamin C DOI: http://dx.doi.org/10.5772/intechopen.109644*

in his Treatise on Scurvy (1753) [11]. We can also find other research that has been carried out on skin disorders and abnormalities due to vitamin deficiencies and their correction with oral or topical supplementation [12].

The content of vitamin C in the skin is highly variable, being 425% higher in the epidermis than in the dermis, although these figures vary depending on the studies reviewed, possibly influenced by the difficulty of handling the samples and the area studied, and donor age. In turn, we found that there is a concentration gradient of ascorbic acid in the keratinocytes of the epidermis. The lowest concentration of vitamin C is found in the most superficial part of the epidermis, while the highest is found in the deeper layers, possibly due to the depletion of the most superficial cells by their continued exposure to the environment [12, 13].

We also know that vitamin C levels are lower in people who are photoaged or who suffer any degree of skin damage due to continuous exposure to the sun. Sun exposure, among other factors, generates reactive oxygen species (ROS), such as superoxide anion and hydrogen peroxide, against this increase in ROS, the body sets, in motion, a series of endogenous antioxidant mechanisms to try to neutralize them, and we refer to oxidative stress when these endogenous mechanisms are unable to completely neutralize ROS. This oxidative stress can produce changes in the genetic load of the individual and it has been observed that excessive exposure to oxidative stress caused by UV radiation or environmental pollution is associated with a reduction in levels of vitamin C present in the epidermis [13].
