Premature graying of hair is often a great concern for younger adults in their 20s or 30s as gray hair make them look much older than they are.
The problem can be caused by factors like a genetic predisposition, poor nutrition, hormonal fluctuations, smoking, pollution, stress, use of unsuitable hair products, and certain diseases such as chronic colds, sinusitis, and thyroid disorders.
Basically, strands of hair turn white or gray due to low amounts of melanin, the pigment that gives your hair its natural color. The melanocyte activity slows down with age and the body gradually stops producing melanin.