Vitamin C Serum
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  • Yayınlanan: ROOT
  • Oluşturulma Tarihi: 2018-06-08
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Vitamin C

Vitamin C (L-Ascorbic Acid)

Vitamin C is one of the body's primary protectants from reactive oxygen damage, but it is depleted during ultraviolet injury. Vitamin C serves as the major aqueous phase antioxidant in skin. It not only neutralizes reactive oxygen species destructive to the skin but also actively recycles vitamin E, which serves to protect lipids and cell membranes from these oxidative insults. Human beings cannot synthesize vitamin C; they must ingest it, and body control mechanisms limit absorption and subsequent delivery to tissues. Skin comprises about 8% of body tissues and gets approximately the same amount of oral vitamin C. Half-life after ingestion is 12 to 20 days.

Topical L-Ascorbic Acid

The Duke-patented technology solved the problem of how to stabilize the very unstable molecule, l-ascorbic acid, and get it into skin, which usually is an excellent barrier to foreign substances.2 L-ascorbic acid has been formulated in high concentration in a stable aqueous formulation. L-ascorbic acid is un-ionized at acid pH (<3.5). In its un-ionized form, vitamin C applied topically passes into skin in higher concentrations than ever is possible by oral ingestion.

Because body control mechanisms limit the amount of ingested vitamin C available to skin, applying stable L-ascorbic acid topically yields higher concentrations that provide additional protection. And unlike most sunscreens, once vitamin C gets into skin, it cannot be rubbed or washed off or run off with perspiration. The protection seems to last unchanged for days. Topical vitamin C also prevents ultraviolet immunosuppression, a reaction that has been implicated in both melanoma and nonmelanoma skin cancers.

Photoprotection

The added levels of L-ascorbic acid achieved by topical application provide photoprotection to skin. Photodamage, which is measured histologically as sunburn cells, can be lessened by L-ascorbic acid (whether produced by UVB or UVA), with protection against UVA damage appearing especially good.8 Because L-ascorbic acid does not absorb UVB or UVA light, its mechanism of action is different from that of sunscreens. L-ascorbic acid seems to protect by neutralizing reactive oxygen species generated by ultraviolet light. Topical ascorbic acid can even be used to treat sunburn, presumably by neutralizing inflammation. Results to date indicate that topical vitamin C is a useful adjunct to sunscreens.

Ultraviolet Immunosuppression

Immunosuppression by ultraviolet light for both contact and delayed-type hypersensitivity occurs in one of three individuals. However, almost everyone with melanoma or nonmelanoma skin cancer has this reaction. In animals, ultraviolet immunosuppression is associated with more aggressive metastatic behavior. Unfortunately, sunscreens don't protect very well against ultraviolet immunosuppression. In contrast, topical L-ascorbic acid prevents ultraviolet immunosuppression.9

Collagen Synthesis

Vitamin C is the only antioxidant that has been proven to increase collagen synthesis. In human skin fibroblasts in culture, L-ascorbic acid stimulates collagen synthesis without affecting other protein synthesis. L-ascorbic acid is known to be necessary for prolyl hydroxylase, an enzyme essential for producing a stable collagen molecule. In addition, L-ascorbic acid is necessary for lysyl hydroxylase, an enzyme necessary for cross-linking one collagen molecule to another collagen molecule, which is required for tissue strength. Finally, L-ascorbic acid signals collagen genes to synthesize collagen, a reaction that is important in wound healing.

 

 

Effective Topical Vitamin C Products

For a topical vitamin C formulation to work, it must first penetrate skin and then remain stable and be available in high enough concentrations to have a biologic effect. Research to date indicates that the gold standard is stable L-ascorbic acid at high concentration (more than 10%) and low pH (<3.5).

Clinical Studies

Topical vitamin C is used for its photoprotective and anti-inflammatory effects. Because L-ascorbic acid is essential for collagen synthesis, it is also used for its wound healing effects. In photoaged skin, anecdotal improvement has been reported; physicians and their patients particularly note improved skin clarity and color. The results of such observations are encouraging; double-blind studies are underway.

Topical vitamin C also has been used in patients undergoing CO2 laser resurfacing. In a published half-face study, the side receiving topical l-ascorbic acid demonstrated less erythema.

Summary

A stable aqueous solution of L-ascorbic acid has been developed that delivers higher doses of vitamin C into skin than ever can be achieved by diet. Topical application augments the normal reservoir present in skin and neutralizes reactive oxygen species, adding photo- and anti-inflammatory protection and preventing ultraviolet immunosuppression. Because UVA has been identified as an important photocarcinogen and photoaging influence, additional antioxidant protection should be beneficial. Properly formulated, topical vitamin C seems to be a useful adjunct to sunscreens and other forms of sun protection (such as hats, protective clothing, and sun avoidance when feasible). Topical vitamin C also seems to be useful in speeding wound healing, reducing wrinkling, and preventing the erythema associated with laser resurfacing




Etiketler: Vitamin C

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