...Its enough to turn you grey

UK and German researchers have now unlocked the secret of hair turning white or gray in old age. According to them, free oxygen radicals are to blame for those pesky greys.

Scene of the crime – excess H2O2  halts the production of melanin in the hair follicle

“The originator of the entire process is hydrogen peroxide, which we also know as a bleaching agent,” explains Professor Heinz Decker of the Institute of Biophysics at Mainz University. “With advancing age, hydrogen peroxide builds up in larger amounts in the hair follicle and ultimately inhibits the synthesis of the color pigment melanin.” The biophysicists in Mainz together with dermatologists from the University of Bradford have revealed the molecular mechanisms of this process for the first time.

Hydrogen peroxide (H2O2) is a by-product of metabolism and is generated in small amounts throughout the human body - including hair follicles. With increasing age, the quantity builds up, because the human body can no longer keep up neutralizing the hydrogen peroxide. In their work, the team showed that in aging cells the enzyme used to break down H2O2 is only present in very limited concentration.

This has dramatic consequences. Hydrogen peroxide attacks the enzyme tyrosinase by oxidizing an amino acid - methionine. As a consequence, this key enzyme - which normally starts the synthesizing pathway of the coloring pigment melanin - does not function anymore.
Oxidation by hydrogen peroxide not only interferes with the production of melanin, but also inhibits other enzymes that are needed for the repair of damaged proteins. As a result, a cascade of events is set off, at the end of which stands the gradual loss of pigments in the entire hair from its root to its tip. With this research work, the scientists from Mainz and Bradford not only solved – on a molecular level – the age-old riddle of why hair turns gray in old age, but also have pointed out approaches for future therapy of vitiligo, a skin pigment disorder. For melanin is not only the pigment in hair, but it is also responsible for color in skin and eyes.