Feb. 25, 2009 -- Scientists may have figured out why hair turns gray, and their finding may open the door to new anti-graying strategies.

New research shows that hair turns gray as a result of a chemical chain reaction that causes hair to bleach itself from the inside out.

The process starts when there is a dip in levels of an enzyme called catalase. That catalase shortfall means that the hydrogen peroxide that naturally occurs in hair can't be broken down. So hydrogen peroxide builds up in the hair, and because other enzymes that would repair hydrogen peroxide's damage are also in short supply, the hair goes gray.

Putting the brakes on that chemical chain reaction "could have great implications in the hair graying scenario in humans," write the researchers, who included Karin Schallreuter, a professor clinical and experimental dermatology at England's University of Bradford.

The study appears online in The FASEB Journal; the FASEB is the Federation of American Societies for Experimental Biology.