PEER-REVIEW | DERMATOLOGY | with this, there is also a four-fold increase in partially
degraded collagen in aged skin compared to young skin. Vitamin C is essential for collagen biosynthesis and is thought to have an anti-ageing effect. More importantly, it serves as a co-factor for prolyl and lysyl hydroxylase, key enzymes that cross-link and stabilise collagen fibres38
.
Table 1 Significant studies and their findings STUDY
IMPORTANT FINDINGS
Chen L, Hu JY, Wang SQ. J Am Acad Dermatol 2012
Sato Y, Arai KY, Nishiyama T, et al. J Invest Dermatol 2012
Matsui MS, Hsia A, Miller JD, et al. J Invest Dermatol 2009
Hwang SW, Oh DJ, Lee D, et al. J Cutan Med Surg 2009
Murray JC, Burch JA, Streilein RD, et al. J Am Acad Dermatol 2008
Lin FH, Lin JY, Gupta RD, et al. J Invest Dermatol 2005
Farris PK. Dermatol Surg 2005
Sauermann K, Jaspers S, Koop U, Wenck H. BMC Dermatol 2004
Lin JY, Selim MA, Shea CR, et al. J Am Acad Dermatol 2003
Humbert PG, Haftek M, Creidi P, et al. Exp Dermatol 2003
Fitzpatrick RE, Rostan EF. Dermatol Surg 2002
Kobayashi S, Takehana M, Itoh S, et al. Photochem Photobiol 1996
Kameyama K, Sakai C, Kondoh S, et al. J Am Acad Dermatol 1996
Darr D, Combs S, Dunston S, et al. Br J Dermatol 1992
Kurata S, Hata R. J Biol Chem 1991
Bissett DL, Chatterjee R, Hannon DP. Photodermatol Photoimmunol Photomed 1990
Inhibition of AP-1 by vitamin C leads to inhibition of MMPs
Mice deficient in vitamin C developed significant UVB-induced pigmentation
Vitamin C containing topical solution shown to prevent the reduction of CD1a-expressing Langerhans cells upon UV radiation
Topical L-ascorbic acid shown to improve melasma
Triple antioxidant containing L-ascorbic acid, vitamin E, and Ferulic acid shown to have UV-protective mechanisms including reduction in thymine dimers
Addition of vitamin E and ferulic acid to L-ascorbic acid increases the photoprotective ability by factor 8
In vitro study showing the inhibition of elastin by L-ascorbic acid
Topically applied vitamin C increases the density of dermal papillae in aged human skin
The addition of vitamin E to L-ascorbic acid increases the photoprotective ability by factor 4
Topical vitamin C shown to reduce skin furrows with histological improvement in a placebo- controlled study
Split-face study showing a reduction in wrinkling by the application of 10% L-ascorbic acid
Magnesium ascorbyl phosphate has shown to protect against UVB irradiation by scavenging free radicals. Increase in collagen production was also shown
10% Magnesium ascorbyl phosphate cream demonstrated significant improvement in melasma and freckling
Reduction of UVB-induced erythema by topical L-ascorbic acid in a porcine model
L-ascorbic acid promotes collagen production in cultured human fibroblasts
Animal model study showing the reduction of wrinkling by the application of vitamin C cream
Vitamin C also directly activates the transcription factors involved in collagen synthesis and stabilises pro-collagen mRNA that regulates Type I and III collagen synthesis. In addition, vitamin C increases the gene expression of collagen and synthesis of the tissue inhibitor of metalloproteinase-1 (TIMP-1), which decreases collagen degradation24
.
. The anti-ageing effects of vitamin C have
been demonstrated in a clinical study showing that daily application of topical vitamin C was shown to increase the density of dermal papillae in aged human skin39
Replenisher of vitamin E Aside from its anti-ageing and photoprotective effects, vitamin C is also known to be the primary replenisher of vitamin E. Vitamin E is a liphophilic antioxidant and has a primary role in protecting cell membranes against oxidative stress and maintaining the collagen network in the skin. Similar to vitamin C, its levels are rapidly depleted after UV exposure24
. Due to the role of vitamin
C maintaining active vitamin E stores, there are an increasing number of products containing a combination of vitamin C and E on the market. Studies have shown that the addition of vitamin E increases the protection 4-fold40
. Due to the
role of vitamin C maintaining active vitamin E stores, there are an increasing number of products containing a combination of vitamin C and E on the market.
Such
photoprotection was augmented and doubled to 8-fold when ferulic acid was added to the mixture of vitamins C and E41
.
Anti-inflammatory effect An anti-inflammatory effect of vitamin C has also been observed both clinically and in cultured human cells. Laboratory studies have shown that vitamin C
inhibits activation of transcription factor NFκB, a transcription factor responsible for the production of a number of pro-inflammatory cytokines such as TNF- alpha, IL-6 and IL-8. These cytokines are responsible for a number of inflammatory pathways implicated in a wide range of inflammatory dermatoses. Studies have shown that vitamin C can promote wound healing and prevent post-inflammatory hyperpigmentation3
. 30
However, the evidence remains limited and vitamin C is not widely used in practice for inflammatory dermatoses.
January/February 2016 |
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