The hairs of young people, in particular, contain many such cells and proteins.
However, as we get older, these cells and proteins in the hair shaft gradually fall out, and the inside of the hair becomes empty. When air enters the hair shaft, the hair looks white like milk when viewed from the outside. This is called "white hair. In other words, a hair that is full of air is called a "shiraga.
Some people are more prone to developing white hairs than others, with some people starting to develop white hairs around the age of six, and many others, on the other hand, do not develop any white hairs at all, no matter how old they get. This is not because they are rare or ill, but because it is their natural disposition.

The pigment that determines hair color is melanin pigment. The difference between blonde and black hair depends on the amount of melanin pigment in the hair, but the cause of hair loss has nothing to do with the amount of pigment.