Why does our hair turn grey??

I have often heard women say " Look at all the grey hair my kids have given me!" In theory this is great, and while stress is a factor in turning hair grey scientists have made breakthrough discoveries to explain in more detail why it occurs. In time, everyone’s hair turns gray. Your chance of going gray increases 10-20% every decade after 30 years.

Initially, hair is white. It gets its natural color from a type of pigment called melanin. The formation of melanin begins before birth. The natural color of our hair depends upon the distribution, type and amount of melanin in the middle layer of the hair shaft or cortex.
Hair has only two types of pigments: dark (eumelanin) and light (phaeomelanin). They blend together to make up the wide range of hair colors.
Melanin is made up of specialized pigment cells called melanocytes. They position themselves at the openings on the skin’s surface through which hair grows (follicles). Each hair grows from a single follicle.

As the hair is being formed, melanocytes inject pigment (melanin) into cells containing keratin. Keratin is the protein that makes up our hair, skin, and nails. Throughout the years, melanocyctes continue to inject pigment into the hair’s keratin, giving it a colorful hue.
With age comes a reduction of melanin. The hair turns gray and eventually white.

So why does our hair turn gray or white?

Dr. Desmond Tobin, professor of cell biology from the University of Bradford in England, suggests that the hair follicle has a “melanogentic clock” which slows down or stops melanocyte activity, thus decreasing the pigment our hair receives. This occurs just before the hair is preparing to fall out or shed, so the roots always look pale.
Moreover, Dr. Tobin suggests that hair turns gray because of age and genetics, in that genes regulate the exhaustion of the pigmentary potential of each individual hair follicle. This occurs at different rates in different hair follicles. For some people it occurs rapidly, while in others it occurs slowly over several decades.

 Harvard scientists proposed that a failure of melanocyte stem cells (MSC) to maintain the production of melanocytes could cause the graying of hair. This failure of MSC maintenance may result in the breakdown of signals that produce hair color.

Another discovery was made by scientists in Europe. They described how hair follicles produce small amounts of hydrogen peroxide. This chemical builds on the hair shafts, which can lead to a gradual loss of hair color.