What r the reasons for white hair?what precautions can prevent from white hair?

Each hair on our heads is made up of two parts:

* a shaft - the colored part we see growing out of our heads

* a root - the bottom part, which keeps the hair anchored under the scalp

The root of every strand of hair is surrounded by a tube of tissue under the skin that is called the hair follicle (say: fah-lih-kul). Each hair follicle contains a certain number of pigment cells. These pigment cells continuously produce a chemical called melanin (say: meh-luh-nin) that gives the growing shaft of hair its color of brown, blonde, red, and anything in between.

Melanin is the same stuff that makes our skin's color fair or darker. It also helps determine whether a person will burn or tan in the sun. The dark or light color of someone's hair depends on how much melanin each hair contains.

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.

You cant prevent it, but you can dye your hair.