Gray Hair Caused by Stress
Emi Nishimura of Tokyo Medical and Dental University has found clues as to why hair turns gray. It seems that gray hair is caused by cell stress. The DNA in the hair cell follicles becomes damaged due to environmental stresses - chemicals, ultraviolet light, radiation. Gray hair seems to be caused by the pigment producing cells becoming depleted.
A single mammal cell can encounter up to 100,000 events a day that damage DNA, Nishimura added in a statement.
The stem cells within hair follicles responsible for color are the most impacted by this irreparable DNA weathering.
The study included animal models that were exposed to environmental conditions that are believed to cause graying of hair due to stress.
It was speculated that the vulnerable to damage pigment producing cells mature more quickly, leaving fewer and fewer to produce hair color may be a protective mechanism. Gray hair may be the visible signal that damaged cells have been purged from the body. Cells with damaged DNA are more likely to turn cancerous.
Gray hair is a universal sign of aging in mammals.