The underlying study presents an overview of the scientific findings on the role and function of vitamin C in skin health with a special focus on its effect against hyperpigmentation. The results of various scientific studies were evaluated for this purpose.
The skin usually contains high concentrations of vitamin C, which performs important functions such as stimulating collagen synthesis or protecting against skin damage induced by UV radiation via an antioxidant effect. Vitamin C also works effectively against damage caused by oxidation in tissues and suppresses the formation of carcinogens such as nitrosamines. It also plays a role in immunomodulation and reduces the melanin content of the skin, which explains its role as a natural remedy against hyperpigmentation.
Vitamin C interacts with copper ions in the active center of the enzyme tyronsinase and thus inhibits its activity, which in turn reduces the formation of melanin. It also has a depigmenting effect by binding to melanin after entering the tissue, which is a reservoir for copper, calcium and ROS (reactive oxygen species) within the cells. The binding of vitamin C to melanin creates a deficiency of ROS, copper and calcium, which in turn causes a reduction in melanin production. It also acts on the perifollicular pigment.
To evaluate the study situation on the efficacy of vitamin C against hyperpigmentation, seven studies were selected from 22,580 studies according to the following inclusion criteria:
1. randomized control studies, experimental studies, case-control studies and cohort studies.
2. full-text articles published in English-language journals that have been successfully peer-reviewed.
3. investigations of vitamin C levels, tyrosinase levels and melanin pigmentation levels.
The pigmentation of the skin is caused by melanin, which is produced in the melanosomes of the melanocytes. The melanin produced there is then gradually transferred to the keratinocytes. The majority of skin lightening agents use the inhibition of tyrosinase activity to reduce melanogenesis. Tyrosinase is a key enzyme in melanin synthesis.
When selecting a suitable depigmentation agent, it is important to distinguish between agents that are toxic to the melanocytes and agents that have an inhibitory effect on the key steps of melanogenesis. Vitamin C belongs to the latter category due to its inhibition of tyrosinase activity.
Vitamin C is essential for various processes in human skin, such as collagen synthesis, antioxidation or anti-aging related processes. Acidification of melanocytes by vitamin C is thought to inhibit the catalytic activity of tyrosinase, the rate-limiting enzyme required for the biosynthesis of melanin. Vitamin C also has good photoprotective properties against phototoxicity caused by UVA radiation.
In a double-blind, placebo-controlled study conducted by Shimida et al., the effects of a vitamin C gel on gingival melanin pigmentation were investigated. It was found that gingival melanin pigmentation was successfully inhibited by the vitamin C gel.
Furthermore, vitamin C is used in dermatology in the form of tablets (Ratnam et al., 1977), creams (Kameyama et al., 1996, and Kim et al., 2017) and vitamin C concentrate (Jaros A. et al., 2018) for skin depigmentation, with all studies producing successful results.
Conclusion
Vitamin C is a natural and important essential nutrient with various biological and pharmaceutical functions. It inhibits melanin synthesis by reducing the activity of the tyrosinase enzyme. In dermatology, vitamin C is successfully used to depigment hyperpigmented spots on the skin. Based on the studies evaluated, the underlying study comes to the conclusion that vitamin C has a demonstrable effect on the reduction of melanin pigmentation and is well suited as a skin depigmentation agent.
Underlying study:
Sanadi RM, Deshmukh RS: The effect of vitamin C on melanin pigmentation – A systematic review; in: J Oral Maxillofac Pathol 2020;24:374-82.