Hi

Hair turns gray as we age because the follicles at the base of the hair shaft cease to produce melanin. Each follicle contains a finite number of pigment cells. These pigment cells produce melanin, a chemical that gives the hair shaft, the visible strands, its color, whether that be black, brown, blonde, red, or any shade in between. The darkness or lightness of the hair depends on how much melanin each strand contains. Melanin is the same pigment that makes skin tan upon exposure to the sun.

With age, the pigment cells in the follicle gradually die off. As they do so, that strand will no longer contain as much color and will show up as silver, gray, or white as it grows. Eventually, all the pigment cells will die and the hair becomes completely gray.

thanks