White or grey hair is sometimes also called “Pepper and Salt”, when part of the hair becomes white in brown people. With age the other hairs of the body whiten also and in humans also the whitened beard. We are talking about canitie to design this phenomenon of whitening hair and hair with aging.
The color of the hair depends mainly on the presence or absence of pigments called melanins (the same ones that give its color to the skin). They are produced by cells called melanocytes, which are located in the hairy bulb, at the base of the Strand. At least two different types of melanins are distinguished: eumelanin and Phéomélanines. The latter are at the origin of the blonde shades to redheads, whereas the presence of eumelanin gives rather brown colors. Both types can be present in a single person and it is the variation of the proportions of these two pigments that explains the wide variety of hair color. This proportion of pigments and the resulting hair color is inscribed in our genes, but it can also be influenced by the external environment (sun, air, ect.) and therefore vary slightly over time. The hair can be lightened by the effect of the sun.
Grey or white hair is not caused by a pigment of grey or white colour, but rather by a lack of pigmentation of melanin.
The most common cause of hair whitening is aging. Like most cells in the body, the cells that produce melanin (melanocytes) have a limited lifespan. There is a stock of stem cells (i.e. capable of becoming melanocytes among others) close to the hair follicles that can replace them, but over time, this stock runs out and some cells disappear without being replaced. The remaining ones also produce less and less melanin. Ultimately, the melanocytes disappear and the hair is no longer pigmented, they appear white in color.
More rarely, some genetic diseases may have a hair whitening. In this case, we’re talking about Leucotrichie. Examples include:
Albinism, a defect in the production of melanin;
Menkès’s disease, a failure to absorb copper;
Telangiectasia ataxia, a genetic disorder that affects DNA repair mechanisms;
Waardenburg syndrome, a congenital disease that affects hearing, but also pigmentation of the skin and hair;
Vitamin B12 deficiency.
There is also a popular belief that a violent emotional shock can cause the whitening of a person’s entire hair in one night. However, there is no scientific evidence of this phenomenon.
Possible Evolution and complications
Hair whitening with age evolves gradually. Usually it touches first some hair and then gradually extends to the whole of the hair. Initially the hair may appear rather gray and finally become completely white. The same is the case for other hairs, such as beards and eyebrows.
Treatment and prevention: what solutions?
There is no treatment or means of prevention to prevent hair bleaching, but many cosmetic products make it possible to dye the hair to conceal them.
Some people think that waxing a white or grey hair causes the regrowth of two white hairs. It is a myth, but this will not prevent the waxed hair from inexorably pushing back the same color. The ideal is therefore to dye the hair or better, to get used to its new look!