Hair loss is the loss of more than 100 hairs a day. Alopecia is a hair loss so important that the thickness of the hair is visibly reduced.
The limit between natural hair loss and pathologic hair loss is not precise. A certain quantity of hair loss is totally normal since each hair is constantly being renewed. During this regeneration, the “production site” of a hair, the hair follicle and it root, goes through a three-phase cycle:
- Growth phase (anagen phase)
- Transitional phase (catagen phase)
- Shedding phase (telogen phase)
In the anagen phase, the hair is nourished from the root and grows. This cycle can last several years in healthy persons. During the growth phase, the cells are especially vulnerable to external factors. If this happens, this phase may be cut short.
During the catagen phase, which lasts only a couple of weeks, hair nourishment ceases and the cells stop dividing. The hair then enters in a rest phase (shedding), the telogen phase, lasting about four months. Towards the end of this period, the hair falls out and a new cycle begins. Alopecia can occur if the vital cycle of the hair follicle is altered.
The typical pattern for male baldness begins at the hair line which gradually recedes and forms an "M". finally the hair becomes finer, thinner and shorter and makes a u-shaped pattern around the sides of the head.
The prevention of male hair loss (alopecia) is conditioned by its cause. Nevertheless, generally prevention is limited or impossible.
Neither androgenic allepecia nor alopecia areata can be prevented. On the contrary, certain types of diffuse alopecia can be slowed by adopting a healthy and balanced nutrition. This impedes the development of hypoproteinemia and a deficit of iron or other nutrients that contribute to hair loss.
Gene or region studied
- PAX1, FOXA2