Alternative Health Blog
Everyone knows that graying hair is a sign of aging, but scientists have never been sure why it happens, according to The Week. The cause, a new study says, is stress--though not the kind that might be keeping you awake at night. Healthy hair gains its color from pigment-producing cells in the scalp called melanocytes, which are replenished by a waiting supply of stem cells. In theory, the supply of stem cells should allow people to retain hair color into old age. But these stem cells turn out to be acutely sensitive to "genotoxic" stress--environmental assaults that damage a cell's DNA, such as ultraviolet radiation from sunlight, air pollution, and household chemicals.
These stem cells, says Japanese researcher Emi Nishimura, "can encounter 100,000 DNA-damaging events per day." In a study with mice, a research team from Harvard University and Japan found that stem cells in the scalp react to the DNA damage accumulated over decades by maturing before they're needed. Without fresh stem cells left to form pigment cells, new strands of hair grow in colorless, or white. Research David Fisher tells ScienceNow.com that further reserach is needed to find out whether emotional stress also damages stem cells and contributes to graying. I'll keep you posted as the research develops! May you always be blessed with good health (and good looks ;-)