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ShareLondon: Experiments on mice suggest that having grey hair may tender protection against cancer, say researchers.
Emi Nishimura, of Tokyo Medical and Dental University in Japan, points out that melanocytes are the cells that produce the pigments that colour hair, and that their numbers are kept topped up by stem cells.
According to Nishimura, hair goes grey when the number of stem cells in hair follicles declines.
The researcher says that a new study conducted at the university has now revealed what causes this decline in mice.
During the study, the researchers exposed mice to radiation and chemicals that harm DNA, and found that damaged stem cells transformed permanently into melanocytes.
Nishimura and colleagues say that that eventually led to fewer melanocytes, meaning that there were fewer stem cells capable of topping up the melanocyte pool.
Writing about their findings in the journal Cell, the researchers have revealed that the mice also went grey.
They believe that the same process leads to the reduction in stem cells in the follicles of older people, especially as DNA damage accumulates with the as they age.
David Fisher, a cancer researcher at Harvard Medical School, thinks that such processes may discourage the proliferation of stem cells with damaged DNA, which could pass on mutations, and thereby protect people against cancer.
"One likely beneficial effect is the removal of potentially dangerous cells that may contain pre-cancerous capabilities," New Scientist magazine quoted him as saying.
