Phenylalanine is an essential amino acid that plays a vital role in treating vitiligo thanks to its action, which is a precursor to the synthesis of tyrosine, and, by extension, of melanin.
The human body uses amino acids to produce proteins with the aim of helping the body perform specific functions such as growing, repairing body tissues, etc. Phenylalanine is an essential amino acid, and as such, cannot be synthesised by our body: it must be ingested through diet.
In the case of phenylalanine, it is one of the components needed in the melanin formation phases. An added boost of this component in people with skin pigmentation problems can strengthen the production of melanin by the melanocytes. This is why phenylalanine, combined with sunlight exposure or phototherapy, is essential in treating vitiligo.
Phenylalanine is not phototoxic, which is why it can also be used in children, it has no major side effects and it helps tolerate sunlight exposure in de-pigmented areas, which tend to burn in vitiligo patients.
Administrating phenylalanine improves the colouration of de-pigmented areas of the skin thanks to three action mechanisms: it prevents the production of antibodies against the melanocytes, it activates the altered melanocytes combined with radiation (UVA or sunlight), and it stimulates the migration of melanocytes from pigmented areas to non-pigmented areas.