About Hair PigmentIt is well known that the gray hair is a result of the reduction of the pigment, while completely white hair contains no pigment at all. But why it happens for many remains a mystery. In the very beginning of life, human hair is white. Later, it gets natural color made from melanin. Formation of melanin begins even before birth. The natural color of hair that person will have depends on the layout, type and amount of melanin in the middle layer or the coat of hair. Hair has only two types of pigments: dark (eumelanin) and light (feomelanin). There is a whole range of different colors of hair that are formed by mixing only these two pigments in various combinations. Melanin is composed of special pigmented cells called melanocytes. They build up in the follicles - openings on the skin surface hairs grow through. As the hair forms in the root, melanocytes inject pigment (melanin) to cells that contain keratin (a protein that is found in hair, skin and nails). Over years, melanocytes continuously inject pigment in the keratin, giving the hair a specific and unique color. But this process does not last forever. With years starts the reduction of melanin, the hair becomes gray and, if melanin reduction continues long enough, it becomes quite white, sometimes even completely white.
Why Exactly Hair Becomes Gray or White?Each hair follicle has a melanogenetic clock that slows or completely stops the activity of melanocytes, and thus reduces the amount of pigment that is released into the hair. Besides this cause, hair becomes gray due to age and genetic predisposition because genes regulate depletion of pigment potential of each individual follicle. Therefore, all this takes different amount of time to happen for different hair follicles. For some people the whole process happens rather quickly, while in some people this process lasts for several decades. In February 2005, scientists from Harvard submitted a claim in a published article, that graying hair can be caused by the failure of melanocytes stem cells, which may occur as a result of interruption in brain sending the signal that causes the production of color in hair.
There are many other factors that may affect the change in pigmentation of hair making it lighter or darker. Scientists generally divide these factors in internal and external.
Internal factors include: genetic defects hormone levels constitutionage External factors include: climatic conditions the presence of contaminants toxins exposure to chemical preparations