Why do I have black skin?

The colour of the skin is the result of a complex biochemical mechanism leading to the production of melanin by specialised cells: the melanocytes, which produce it deep down (basal layer of the epidermis) and send it to the surface in the form of small grains of pigment (colour): the melanosomes.

The intensity of the pigmentation depends on the number of melanosomes, their size and above all their distribution in the epidermis. The more numerous the melanosomes, the larger their size and the closer they are to the surface, the darker the skin.

Melanocytes are in identical numbers in all skins of different phototypes. The difference in colour is due to a difference in the way they function, resulting in a greater or lesser production of melanin. This production is genetically defined, but it is also modulated by the sun, hormonal state and age.

In addition, it can be disturbed by all the inflammations that affect the skin, from a simple pimple to extensive eruptions. These disturbances often lead to a transient increase in melanin production: post-inflammatory hyperpigmentation.

Moreover, the production of melanin is not completely homogeneous and the skin colour is not really uniform. In fact, it is made up of horizontal bands whose limits are hardly visible except on the inner side of the upper arms where it is often quite clear.

The colour of the skin plays an essential role in its protection. Indeed, melanin constitutes a sort of natural shield that protects the skin from the sun by reducing the passage of UV rays.

Ultraviolet rays (UVA and UVB) have a destructive action on many elements of the skin: elastin and collagen fibres in particular, leading to ageing. More seriously, they act on cell reproduction by damaging cell nuclei and can lead to skin cancers.

This natural photoprotection is essential for life. People who lack it, such as albinos, have serious protection problems from childhood onwards, and need to make a greater effort to protect their skin.