In details

Why does white hair appear


Most of us find our first gray hair in our early thirties, usually at the temples, and later all over the scalp.

While many people find the gray look appealing, others are dedicated to hiding these signs.

Dermatology professor at Melbourne University Epworth Hospital Rodney Sinclair explains in an article published on The Conversation that the “golden rule” of gray hair is that at age 50, half the population loses their hair. color on 50% of your hair.

When the researchers tested this rule, they found that 74% of people aged 45 to 65 had gray hair, with an average intensity of 27%. Generally, men have more white hair than women, and Asians and Africans have less gray hair than Caucasians.

Hair color is produced by cells known as melanocytes, which migrate to the hair bulb as hair follicles develop in the womb. Melanocytes produce the pigment that is incorporated into growing hair fibers to produce a huge range of natural hair shades.

The color of the strands depends on the presence and proportions of two groups of melanins: eumelanines (brown and black pigments) and pheomelanines (red and yellow pigments). Although variations in the proportion of these pigments can produce a large number of colors and shades, siblings often have remarkably similar hair colors.

Color also varies by body location, with lashes darker because they contain high levels of eumelanine. Those that come out of the scalp are usually lighter than pubic hair, which often has a reddish tinge due to the presence of more pheomelanin pigments. The reddish tone is also common in underarm and beard hair, even in people with essentially brown hair on their scalp.

Hormones, such as the melanocyte stimulating hormone, can darken lighter hair, as well as the high levels of estrogen and progesterone that are produced during pregnancy. Certain medications, such as those to prevent malaria, may lighten your hair, while some epilepsy medications may darken it.

Blond children tend to see their hair darken around the age of seven or eight. The mechanism for this is unknown and probably unrelated to hormones, as darkening precedes puberty by a few years.

Also, first-time parents often find that their baby's first coat of hair is darker than expected. This is because it is not until this first wave of hair is eliminated and replaced, between eight and twelve months of age, that there is a clear indication of the actual color of our hair.

Human hair growth is cyclic. During the anagen phase, hair continuously grows at a rate of 1 centimeter per month. This phase can last from three to five years on the scalp and produce hair that grows 36 to 60 inches long.

At the end of the anagen phase, the follicle shuts down, stops hair growth, and stays off for three months. Near the end of this resting phase (telogen), the hair falls out and the follicle remains empty until the anagen phase of the cycle is resumed.

Pigment production also turns on and off in coordination with the hair cycle. When pigment cells turn off at the end of one cycle and do not turn back on at the beginning of the next cycle, the hair turns gray.

Genetic factors seem to be important in determining when we get gray. Identical twins appear to be gray with similar age, proportion, and pattern, yet we have not yet identified the genes that control this process.

There is no evidence to link the onset of white hair to stress, diet or lifestyle. Certain autoimmune diseases, such as vitiligo and alopecia areata, can damage pigment cells and induce whitening of the strands. However, these conditions are unusual and may explain only a small fraction of the process.

Early whitening occurs in early aging syndromes, such as Huntchinson-Gilford and Werner syndromes, where all aspects of aging in the body are accelerated. People affected by pernicious anemia, autoimmune thyroid disease, or Down syndrome may also have gray hair prematurely.

At the end of each hair cycle, some pigment-producing melanocytes are damaged and die. If the melanocyte stem cell reservoir at the top of the hair follicle replenishes the bulb, it retains pigment production. But when the reservoir runs out, pigment production stops and the hair turns gray.

According to Sinclair, to prevent hair from turning gray, it would be necessary to either extend the life of melanocytes in the hair bulb - protecting them from damage - or expand the melanocyte stem cell reservoir at the top of the hair follicle to continue to replace it. the lost pigment cells.

A group of French scientists have identified a new series of agents that protect hair follicular melanocytes from damage at the end of the hair cycle. This allows pigment production to resume as soon as the next hair cycle begins.

The agents work by mimicking the action of an enzyme called dopachrome tautomerase. This enzyme is the natural antioxidant of the hair bulb, which protects melanocytes from the negative effects of oxidation. By doubling the effects of dopacromo tautomerase, melanocyte metabolism and survival improves.

The new agents should turn into a product that can be applied as a spray or shampoo serum, but will not make the color return to white hair or resurrect dead cells that produce hair color. Instead, they protect their melanocytes.

So for those who can't take on the gray look, new options are on the horizon.

Source: hypescience.com/