Vitamin C is the most abundant naturally occurring antioxidant in nature. It is also the most plentiful antioxidant in human skin and functions to protect the skin from reactive oxygen species (ROS) . When skin is exposed to UV radiation, pollution, smoking, and other such factors, ROS such as superoxide ions, peroxides, and singlet oxygen molecules are generated. ROS molecules start a cascade of reactions that cause damage to cellular DNA, cell membranes, and cellular proteins -including collagen! Vitamin C protects cells from oxidative stress by undergoing oxidation (losing an electron) and neutralizing free radicals. Oxidation of vitamin C causes it to convert into a non-reactive form, which can no longer function as an antioxidant. Therefore, the more the exposure to ROS, the less the availability of vitamin C in the skin, or more the need for vitamin C replenishment.
Most plants and animals are able to synthesize vitamin C in vivo, using glucose. Humans, however, lack the enzyme L-glucono-gamma lactone oxidase which is essential for vitamin C generation. Hence, they rely entirely on external sources such as citrus fruits, green leafy vegetables, strawberries, papayas, and broccoli [3,4].
UVA & UVB Radiation (Sun exposure)
Ultraviolet-A (320-400 nm) penetrates 30-40 times deeper into the dermis, as compared to ultraviolet-B (290-320 nm) radiation, which mostly affects epidermis (top layer of skin). UVA, however, mutates and destroys collagen, elastin, proteoglycans, and other dermal cellular proteins. Therefore, UVA causes skin ageing and possibly melanoma formation (dark spots, pigmentation, discoloration). While UVB causes sunburn, ROS, epidermal mutations, and skin cancer .
Sunscreens, when applied properly, can prevent UV-induced damage by blocking up to 55% of the free radicals produced by UV exposure. To optimize UV protection, it is important to use sunscreens combined with topical antioxidants -such as vitamin C. Although vitamin C does not absorb UV light, it exerts a UV-protective effect with neutralization of free radicals.
Laboratory studies have shown that application of 10% vitamin C reduces UVB damage by 52% and sunburn cell formation by 40-60% .
Vitamin C is available in several active forms, but the most biologically active and well studied form is L-ascorbic acid. L-ascorbic acid is a hydrophilic and charged molecule with poor penetration into skin. The molecule on its own is very unstable and requires to be paired with other molecules for optimized function. Vitamin C works best in conjunction with vitamin E or vitamin B in topical formulations . Vitamin E is a lipophilic antioxidant, making its combination with vitamin C ideal for protection of both hydrophilic and lipophilic compartments of the cell . Other superior combinations of L-ascorbic include ethyl ascorbic acid, which has immense stability and is quick to penetrate in skin. It is also proven to be fast acting and produces long-term inhibitory effect on cell damage.
Topical supplementation of vitamin C is largely safe for regular and long-term use. It can also be safely used in conjunction with other common topical anti-ageing products containing zinc, tretinoin, alfa hydroxy acids (glycolic acid), etc. Too strong of vitamin C concentrations can cause skin irritation, stinging, dryness, or yellow discolouration -all of which can be easily treated with hydrating products and moisturizers [1,2,4]. It is not recommended to use vitamin C around the eyes, unless specifically prescribed by a doctor.
Facts to know
Application of vitamin C to treated surface after microdermabrasion and CO2 resurfacing increases trans-epidermal penetration by up to 20 times [2,7]. Smoking has been known to cause decreased vitamin C levels in skin, similar to UV-damaged skin. Another useful application for topical vitamin C is for treating striae (pregnancy stretch marks). Studies have shown that routine application of vitamin C with 20% glycolic acid, over a period of 3 months, significantly improves the appearance of striae .
In summary, vitamin C is a naturally occurring antioxidant with multiple desirable effects. It has an excellent safety profile and has shown tremendous results in healing photoageing, hyperpigmentation, tissue inflammation, and cell damage. There is ongoing research into improving its delivery into the dermis for increasing collagen production and diminishing free radicals. Vitamin C is an essential nutrient that should be a part of your daily skincare regime.
Product: La VieSage Vita C+ serum