Encyclopedia
Reference entry
Physiology
Keratin
The structural protein hair is made of.
Soumm · Physiology
Definition
A fibrous protein forming the bulk of the hair shaft, produced by cells in the follicle before the hair emerges from the scalp.
Hair above the surface is not living tissue, which is why damage to it cannot be repaired, only managed.
Practical implication
Products can improve the appearance and handling of the shaft. They cannot restore its structure.
See also: Hair Cycle.
A note on evidence
Hair responds to many things at once: sleep, nutrition, hormonal changes, scalp condition and stress among them. Published here for education only; individual concerns should be discussed with a qualified healthcare professional.