Going Grey

Aging hair bleaches itself with hydrogen peroxide

February 2009 - Why does hair go grey as we get older? European scientists have come up with an explanation.

A research report in The FASEB Journal concludes that hydrogen peroxide, rather than wisdom, is at the root (literally) of greying hair. According to the researchers, the process of going gray is caused by a massive build up of hydrogen peroxide because of wear and tear on our hair follicles. The peroxide blocks synthesis of melanin, the natural pigment that gives hair its natural colour.

Gerald Weissmann, MD, Editor-in-Chief of The FASEB Journal commented:

"Not only blondes change their hair colour with hydrogen peroxide. All of our hair cells make a tiny bit of hydrogen peroxide, but as we get older, this little bit becomes a lot. We bleach our hair pigment from within, and our hair turns gray and then white. This research, however, is an important first step to get at the root of the problem, so to speak."

The team identified this process when they examined cell cultures of human hair follicles. The build up of hydrogen peroxide, they found, was caused by reduction of an enzyme (catalase) responsible for breaking up hydrogen peroxide into water and oxygen.

The researchers also observed the inability of hair follicles to repair damage caused by hydrogen peroxide due to low levels of enzymes (MSR A and B) that normally serve this function. Moreover, high levels of hydrogen peroxide and low levels of MSR A and B are responsible for disrupting formation of another enzyme (tyrosinase) involved in the production of melanin in hair follicles. Melanin is the pigment responsible for colour in hair, skin and eyes. The team have speculated that a similar breakdown in skin may be responsible for vitiligo, a chronic condition characterised by white patches on the skin.

Gerald Weissmann added:

"As any blue-haired lady will attest, sometimes hair dyes don't quite work as anticipated. This study is a prime example of how basic research in biology can benefit us in ways never imagined."

Study details

J. M. Wood, H. Decker, H. Hartmann, B. Chavan, H. Rokos, J. D. Spencer, S. Hasse, M. J. Thornton, M. Shalbaf, R. Paus, and K. U. Schallreuter. Senile hair graying: H2O2-mediated oxidative stress affects human hair color by blunting methionine sulfoxide repair. FASEB J. doi:10.1096/fj.08-125435. http://www.fasebj.org/cgi/content/abstract/fj.08-125435v1