Vitamin C is a common clinical vitamin supplement with various biological effects, including antioxidant, detoxification, wound healing, anti-allergy, inhibition of virus replication, maintenance of vascular elasticity, etc. Therefore, its dosage is also increasing.
In a survey of vitiligo triggering factors, it was found that there were 479 cases of 904 vitiligo patients with clear triggering factors, of which 11 cases were triggered by excessive application of vitamin C, accounting for 2.27%. It can be seen that the excessive application of vitamin C is also one of the triggering factors of vitiligo. Some experts pointed out that the daily application of vitamin C1~3 grams for 1~6 months, some vitiligo susceptible people can develop.
Vitamin C affects melanin synthesis from multiple pathways.
(1) Promote the reduction of the melanin precursor substance dopaquinone to dopa, thus blocking the process of melanin biosynthesis.
(2) Inhibits the absorption of copper ions in the intestinal mucosa and reduces the activity of serum copper oxidase, thus affecting the activity of tyrosinase and reducing melanin synthesis.
(3) Promotes neuromediator synthesis, resulting in increased tyrosine consumption and decreased melanin synthesis.
(4) Maintains sulfhydrylase activity and promotes synthesis of the sulfhydryl compound glutathione, which competes with tyrosinase for copper ions, resulting in reduced tyrosinase activity and decreased melanin synthesis.
In view of the extensive biological role of vitamin C and the mechanism of inducing or aggravating vitiligo, vitiligo patients or susceptible persons should avoid long-term high-dose application of vitamin C, and also eat less vitamin C-rich foods, especially in the progressive stage of vitiligo, high-dose vitamin C should be prohibited.