What is the primary component that affects the growth of hair?

Blood circulation is the primary component that affects the growth of hair because it plays a crucial role in delivering essential nutrients and oxygen to the hair follicles. Healthy blood flow ensures that the follicles receive what they need to produce hair effectively. This circulation supports the various biological processes involved in hair growth, including the cycling of hair through the growth phases (anagen, catagen, and telogen).

While factors like vitamin intake are important for overall hair health, they primarily act as supplementary support. Sun exposure, while it can influence hair health due to its effects on the skin and vitamins, does not directly impact the biological process of hair growth as significantly as circulation. Proper shampooing contributes to cleanliness and scalp health but does not have a direct impact on the physiological growth of hair. In summary, optimal blood circulation is essential for nourishing the hair follicles and promoting healthy hair growth.