Scientists figure out why our hair turns grey - and may know how to 'reverse ageing'

Your hair turning grey could be down to your body's stem cells, according to scientists who say their discovery could lead to ways of preventing or even reversing the signs of ageing.

The study suggests stem cells may get "stuck" as hair grows older and therefore lose their ability to mature and maintain hair colour.

Led by researchers from NYU Grossman School of Medicine, in New York, USA, the study focused on cells in the skin of mice that are also found in humans called melanocyte stem cells, or McSCs.

It is these cells' chameleon-like function that is likely responsible for greying and loss of hair colour.

The scientists suggested that if their findings hold true for humans, they could open up a potential way to reverse or prevent the greying of hair.

Grey hair could be a thing of the past (Getty Images/Westend61)

The report says that hair colour is controlled by whether continually multiplying pools of McSCs within hair follicles get the signal to become mature cells that make the protein pigments responsible for colour.

Researchers found that during normal hair growth, such cells continually move back and forth as they transit between compartments of the developing hair follicle.

According to the findings, as hair ages, sheds, and then repeatedly grows back, increasing numbers of McSCs get stuck in the stem cell compartment called the 'hair follicle bulge'.

They remain there, do not mature and do not travel back to their original location where they would have been prodded to regenerate into pigment cells.

Study lead investigator Qi Sun said: “Our study adds to our basic understanding of how melanocyte stem cells work to colour hair.

“The newfound mechanisms raise the possibility that the same fixed-positioning of melanocyte stem cells may exist in humans.

“If so, it presents a potential pathway for reversing or preventing the greying of human hair by helping jammed cells to move again between developing hair follicle compartments.”

Study senior investigator Mayumi Ito added: “It is the loss of chameleon-like function in melanocyte stem cells that may be responsible for greying and loss of hair colour."