Why do hair grow grey?

The root of every strand of hair is surrounded by a tube of tissue under the skin that is called the hair follicle. Each hair follicle contains a certain number of pigment cells. These pigment cells constantly make a chemical called melanin that gives the growing shaft of hair its color of brown, blonde, black, red, and anything in between.

As we get older, the pigment cells in our hair follicles gradually die. When there are fewer pigment cells in a hair follicle, that strand of hair will no longer contain as much melanin and will become a more transparent color like – gray, silver, or white — as it grows. As people continue to get older, fewer pigment cells will be around to produce melanin. Eventually, the hair will look completely gray.