If you've ever examined your gray hairs in the mirror and wondered why this unwelcome phenomenon occurs, researchers at the University of Bradford, UK may have an answer. They studied live human hair follicles and determined that the loss of melanin — the pigment that gives hair its color — along with a buildup or hydrogen peroxide may be what's behind the gradual bleaching that occurs with age.

...[K]nowing the cause of gray hair may open the door for developing methods for 'intervention or reversal...'

The team of researchers, led by J.M. Wood, used a process called spectroscopy to determine what compounds were present in the aging hair follicle. They found that the breakdown of melanin production was actually the end result of a chain of events which involved the loss of activity of four different enzymes.

The first step in the process was the harmful accumulation of hydrogen peroxide in the hair follicle, which occurred due to a reduction of the enzyme catalase. This enzyme normally breaks hydrogen peroxide into its two component parts — oxygen and water — which are harmless and easily to get rid of. Even worse, the hair follicles were unable to reverse the damage that occurred due to the buildup of hydrogen peroxide because of low levels of two other key enzymes, MSR A and B, which normally repair the damage. The last step in this unfortunate chain of events was the reduction in the enzyme tyrosinase. The combination of high hydrogen peroxide levels and low MSR A and B levels inhibited the production of this important enzyme, whose job it is to generate melanin from its precursor parts.

The researchers say that while it has long been hypothesized that the buildup of hydrogen peroxide was the underlying cause of graying hair, it has not been demonstrated experimentally until now. They also say that this process may be the cause of the disorder vitiligo, in which patches of light or de-pigmented skin begin to appear, but further research will be required to address this idea. Finally, on an encouraging note, the researchers say that now knowing the cause of gray hair may open the door for developing methods for "intervention or reversal," which the lab is currently working to address.

This research was published in the February 23, 2009 issue of The FASEB Journal.