Understanding Gray Hair Color: Why Does Hair Turn Gray with Aging?

Understanding Gray Hair Color: Why Does Hair Turn Gray with Aging?
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Why Does Hair Turn Gray With Aging?

Long hours in the office, traffic jams, and unruly kids have all been blamed for kick starting the graying process. The reality however, of why hair turns gray with aging is more to do with our genes and biological makeup as a team of European researchers found out when they discovered the root cause of gray hair.

The scientists were studying vitiligo, a genetic defect that creates patches of skin with no pigment. The late superstar Michael Jackson claimed to have the disease. It is a complex disorder that is not fully understood, but people with the condition have low activity of an enzyme called catalase which breaks down hydrogen peroxide. Faults with the enzyme create an accumulation of hydrogen peroxide. As gray hair also results from a lack of pigment the scientists thought that catalase and hydrogen peroxide may play some role in the salt and pepper effect. It turns out that they were right.

Gray Hair Color

All hair cells produce a tiny amount of hydrogen peroxide, but researchers discovered that a huge build up of the chemical in our hair follicles blocks the normal synthesis of melanin and bleaches hair from the inside out. They studied cell cultures in the lab and found that the accumulation was caused by a reduction in catalase, which turns hydrogen peroxide into water and oxygen. And adding to the problem are low activities of MSR A and B, two enzymes that usually step in to repair the damage caused by hydrogen peroxide. The research appeared in the FASEB Journal in February 2009.

Gray Hair Reversal

Science now has a better understanding of how hair turns gray with aging, and this could not only lead to better treatments to reverse gray hair, but also to a deeper understanding of the cellular basis of aging and cancer.

Cancer is caused by the proliferation of damaged cells, yet many faulty cells are able to switch off and die so as to prevent further damage. Some skin and hair cells tend to be a little bit tougher and can carry on dividing when damaged, although stem cells responsible for hair coloring can shut down. They cause graying when this happens and further investigations into the mechanisms may provide a way of tackling melanomas. Perhaps this might tell researchers how they can switch off or kill cancerous cells.

It’s likely that the relationship between hydrogen peroxide and gray hair is just one part of the picture; genetics is also key. Caucasians tend to gray first, followed by Asians, and then Africans - why is this so? There is still so much that we don’t understand, but the work on catalase and hydrogen peroxide represents a landmark moment.


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