Our hair constantly renews itself. The average hair life cycle for men lasts 3 years. For women, the cycle is longer, varying between 4 and 5 years. Every hair grows continuously throughout this period. When a hair dies, it is immediately replaced by another one. But dead hair does not fall out immediately, and is only definitively ejected from the hair follicle after 2 or 3 months.
The hair life cycle
Between 25 and 30 hair life cycles are genetically programmed in the course of a lifetime.
A four-phase scenario:
1. The growth or anagen phase
The hair is full of life. Its keratin grows constantly and regularly, and the root fills the hair follicle to the base.
Duration: 2 to 5 years, depending on gender and the individual.
2. The regression or catagen phase
The hair is between life and death. It retracts (involution); the root rises towards the epidermis, loses some of its volume and suddenly ceases being active. The hair stops growing and becomes detached from its root, without actually falling out. Then it waits for the new growth that will replace it.
Duration: 15 to 20 days.
3. The release or telogen phase
The hair is now dead and ready to fall out, like ripe fruit falling from a tree. But it remains attached to its follicle until the root of its replacement is strong enough to expel it.
Duration: 2 to 3 months.
4. Fall and new growth
The new growth reaches the surface of the scalp and the old hair falls out.
When the pace speeds up...
Hair loss occurs when the life cycle of the hair accelerates. The trouble starts when the androgens step up the rhythm of the anagen phase, forcing the hair into the telogen phase too quickly, without leaving the hair follicle enough time to produce quality keratin.
The hair then enters a vicious circle. The more the production of the hair is “rushed”, the sooner the hair will fall out. And as the hair life cycles succeed one another more quickly, they produce hair that is weaker and shorter than the preceding cycle.
Ultimately, the stock of hair cycles is used up and the prematurely aged follicle becomes totally unproductive.
Structure and composition of the hair
Hair bulb (blood capillaries of the dermal papilla):
It is essential to bring the constitutive elements of the hair to the bulb. Sulphur-containing amino acids such as cystine and methionine are the most common amino acids found in keratin fibres. Through strong cross-linkages between disulfide bridges, cystine is able to add rigidity to the keratin structure. More rigid keratin results in stronger, more resilient hair. The amino acids complex (cystine, methionine and arginine), from which keratin is partly constructed, provides the primary components of the hair structure.
Root:
This is where keratinisation or hair growth takes place - in other words, it is here that the amino acids, the main components of the keratin fibres, are incorporated. The metabolisms of methionine and cystine depend strongly on the action of Vitamin B6. Ideally, then, supplementations in Vitamin B6 and these two sulphur-containing amino acids should be combined.
Hair fibre:
The keratin fibre is produced during the hair life cycle’s longest phase and lasts an average of 2 to 5 years, which is a fairly long time! Consequently, it is important to take good care of it to avoid any damage which can lead to split ends, brittleness or high porosity.
Sebaceous gland:
This is where sebum is produced. Sebum protects your scalp and hair by lubricating them with a lipid film. The sebaceous gland produces varying amounts of sebum, resulting in hair that is more or less prone to oiliness.