Vitamin C (L-ascorbic acid, VC)

• is a water-soluble antioxidant necessary for collagen polymerization.
• A key role of vitamin C is in the synthesis of connective tissue, especially collagen. It also provides tensile strength to the newly formed collagen, which would otherwise be unable to stretch without tearing. Furthermore, vitamin C is an important antioxidant that can remove and neutralize oxidants in the body. This is especially important in the epidermis.
• Healthy skin contains high concentrations of vitamin C, which supports important and well-known functions, stimulating collagen synthesis and providing antioxidant protection against UV-induced photodamage. This knowledge is often used to justify the addition of vitamin C to topical applications, but the effectiveness of such treatment, unlike optimizing dietary vitamin C intake, is poorly understood.
• Vitamin C acts as a cofactor for proline and lysine hydroxylases, which stabilize the tertiary structure of the collagen molecule, and also promotes collagen gene expression.
• The dependence of collagen hydroxylase enzymes on vitamin C has been demonstrated in many studies with fibroblast cells and confirms that the stability of collagen cross-links is largely dependent on the availability of vitamin C.