While many people attribute gray hair to age, a new, Japanese study has revealed that it really is a sign of stress. A cellular stress. This study was published in the June 12, 2009 issue of Cell journal.
Stress which damages DNA is referred to as genotoxic stress. In this case, when specialized cells, called melanocyte stem cells, (MSCs) are damaged, it ultimately results in a malfunction of those cells which express hair color. Genotoxic stress can deplete the MSCs in hair follicles that make the pigment-producing melanocytes. However, when exposed to the stress, the MSCs actually differentiate into mature melanocytes, as opposed to dying off. This means that if the genotoxic stress can be limited, graying may actually be halted.
Virtually all cells are exposed to some form of genotoxic stress, every day. However, cells are built to handle the stress and repair damaged DNA, and even work to prevent the damage from being passed on to daughter cells.
clipped from: bio-synthesis.blogspot.com