Hair pigmentation is governed by the production of melanin within the hair follicles, specifically by melanocytes located in the bulb region. Melanin is the pigment responsible for hair color, and its synthesis is tightly linked to the availability of nutrients, minerals, and cellular energy. When hair follicles are deprived of essential nutrients or affected by oxidative stress, hormonal changes, or aging, melanocytes gradually lose their ability to produce melanin.

As a result, hair begins to lose its color and turns progressively grey. This process reflects a decline in melanogenic activity and is often accompanied by structural changes in the hair fiber and follicle.