- Why hair turns gray: causes and characteristics
- How to prevent
There is a legend according to which Marie Antoinette is completely turned gray in the night before her death. For a long time there is no doubt that the reason for this was the stress associated with the upcoming beheading. According to scientists, it is very unlikely, but stress can still play a role in the appearance of gray hair - but in a more gradual.
The first gray hair
The first gray hair usually appear about 30 years for men and about 35 years - for women. This, however, average; in some individuals, they appear much earlier or later.
The process by which appears gray, begins in the hair follicles or follicles. The scalp of the person is, on average, 100,000 of these cavities having the shape of drops, each of which is capable for life "grow" a few hairs. At the bottom of each hair follicle is a "factory" for the production of hair where hair cells form. Keratinocytes (skin cells) form the hair from root to tip, overlapping one another and gradually dying, leaving behind mostly keratin, a colorless protein that gives hair its strength and texture. (Keratin is also a major component of the nail, the outer layer of the skin, hooves and tusks of animals).
While keratinocytes are engaged in the formation of hair next to the melanocytes produce melanin, which comes in keratinocytes in small "packages" - melanosomes.
There are two basic shades of melanin, which determines hair color - eumelanin (dark brown or black) and pheomelanin (yellow or red). Their combination in different proportions determined by a wide range of hair colors, which can be found in humans. Hair, lost most of melanin, have more or less light gray; When hair loses all of the melanin, they become completely white.
At any time, 80-90% of the hair on the human head are in the active growth phase, which may last for two to seven years. At the end of this phase, the hair follicle shrinks keratinocytes and melanocytes undergo programmed cell death (apoptosis), and follicle enters the resting phase, during which the hair falls out.
To begin to grow new hair, "factory" inside the follicle must be rebuilt. Fresh keratinocytes and melanocytes "hired" from among progenitor cells (stem cells) are also located at the bottom of the follicle. For some unknown reason, the stem cells from which the keratinocytes, live much longer than those of which overlook the melanocytes. It is a gradual depletion of stem cells
Stem cells: on the edge of scandal
for melanocytes and is the root cause of hair graying.
According to doctors and scientists
What affects the size of the population of melanocytes? Stress hormones can affect the survival and / or activity of melanocytes, but a clear link between stress
How to beat stress? Create an oasis
and gray is not revealed.
Graying hair can result in chronic damage caused by free radicals. Stress hormones produced systematically or locally (by cells of hair follicles) can cause inflammation that triggers the production of free radicals - unstable molecules that damage cells. There is a possibility that these free radicals can affect the production of melanin.
There are indications that stress hormones may be involved in signaling that instructs supply melanin in melanocytes keratinocytes. If stress hormones disrupt the signal, supplies will be disrupted and the hair will be left without pigment.
Many doctors say that those of their patients who are within two to three years, regularly exposed to stress, go gray earlier than others.
Many scientists agree that the appearance of gray hair is predetermined by genetics, but stress and lifestyle can delay or speed up the time for 5-10 years. However, scientific evidence to establish a causal connection is not enough.
So what happened to Marie Antoinette? There are at least three possible explanations. Her hair would turn gray as a result of alopecia areata - a rare autoimmune disorder that causes rapid loss of pigmented hair, leaving only gray. Perhaps a lot of stress led to the invasion of free radicals on the hair follicles, resulting in unstable molecules were destroyed and hair pigment. Or maybe she just did not put on her wig (or she was not allowed to put it on) - and her hair had already been gray. The latest version is not supported by historical documents, but it looks the most plausible.