Hair loss is a common phenomenon encountered daily. Thus, it is normal to find a few strands on the pillow, on clothing, or in the shower. But do you know the reasons for this hair loss? We explain everything in this article.
The progression of the hair life cycle.
The skin naturally has hair follicles. There are approximately 1 million on the head, which can produce up to 150,000 hairs depending on the individual. Each hair is composed of a hair shaft divided into three parts: the medulla, the cortex, and the cuticle. Originating from a hair follicle, each has its own life cycle that unfolds in three stages:
The Anagen Phase: This is the growth phase of the hair during which there is proliferation of the matrix cells that form the inner sheath of the root, the cortex, and the medulla of the hair shaft. The synthesis and pigmentation of the hair shaft only occur during this phase. Its duration determines the length of the hair.
The catagen phase: The first sign of the catagen phase is the cessation of melanin production, the pigment responsible for the color of our hair, in the hair bulb. The hair stops growing but remains attached to its hair follicle.
The telogen phase: After the catagen phase, the follicles rest in a dormant stage, the telogen phase. The hair shaft eventually detaches from its follicle, which is already starting to produce a new hair beneath the skin.
Thelifespan of a hair strand lasts between 2 to 7 years depending on the individual. Once its cycle is complete, the hair follicle begins a new one. It is estimated that each hair follicle will undergo an average of twenty cycles until it is exhausted.
Losing hair every day is normal.
Each hair has its own life cycle. When a hair dies, it falls out to make room for another. Since each hair has an independent life cycle, they do not all fall out at the same time.
It is estimated that our hair is composed of approximately 85 to 90% of hairs in the growth phase. The 10 to 15% remaining are dead hairs or are in the resting phase, that is, about to fall out. These dead hairs are what we find each day on our hairbrush, on our pillow, etc. Generally, we lose about 50 to 150 hairs per day. However, this quantity can vary from one individual to another.
Hair loss associated with health issues.
It is normal to lose hair every day. Hair loss can be occasional or chronic, depending on several factors. However, when you notice that you are losing a lot of hair or that your scalp is starting to thin, it could be a sign of a health problem.
Certain diseases can lead to an increased loss of hair. These may include infectious diseases or thyroid problems. However, there are periods during which hair loss intensifies, such as pregnancy, childbirth, and menopause.
The various diseases known to cause hair loss include: androgenetic alopecia, alopecia areata, seborrheic dermatitis, scalp psoriasis, and lupus erythematosus...
Diet, the foundation of healthy hair
Daily hair loss can also be promoted by a deficiency in the diet. A lack of iron often increases the number of hairs that fall out daily. That's why hair loss is pronounced among vegetarians or among women during menstruation.
Vitamin D also plays a crucial role in hair loss. Indeed, hair follicles have Vitamin D receptors (VDR: Vitamin D Receptor) that, once activated, promote the initiation of the anagen phase. Therefore, a lack of Vitamin D does not facilitate the transition between the telogen-anagen phases.
A hormonal imbalance due to stress or depression
When the body is under stress, it impacts the production and functioning of many hormones. Estrogen is the hormone that plays a crucial role in maintaining hair health. A higher amount of testosterone than estrogen can thus accelerate the hair production process. The rate of hair renewal will therefore increase, but within a short cycle.
PRICE V. H. Treatment of hair loss. The New England Journal of Medicine (1999).
RASHEED H. & al . Serum Ferritin and Vitamin D in Female Hair Loss: Do They Play a Role? Skin Pharmacology and Physiology (2013).