On average, every person has up to 100,000 hairs on their head, in which case
the number varies depending on hair colour. For instance, redheads have an average
of 85,000 hairs, brunettes 100,000 or blond-haired people even 140,000 hairs
on their head; however, blonds tend to have the finest hair. Incidentally, redheads
have the thickest hair. A hair has a diameter of ca. 0.07 mm (vellus hairs,
i.e. downy hair) up to ca. 0.12 mm (terminal hair, i.e. head hair). On average,
a hair grows 1 cm a month. In terms of growth, 16.8 kilometres of hairs grow
on a blond person in a year!
Hairs are horn fibres which consist of the protein keratin as well as water,
fat and sulphur. They originate in the hair root — a tubular invagination
in the skin that is only a few millimetres long. The hair root – also
called follicle – is supplied with nutrients and building substances by
tiny blood vessels. The hair is roughly structured in three layers:
The first layer – called the squama or cuticular layer – consists
of flat, imbricate cells comparable with a fir cone. It consists of six to ten
such cellular layers. The cuticular layer is important insofar as this shows
the hair’s physical condition in the most obvious manner. With healthy
hair the cuticular layer clings flatly, and thus reveals a smooth translucent
surface. Light is optimally reflected and thus reveals the hair’s healthy
The hair’s main body is the fibrous layer (or fibrous stem, cortex).
All of the chemical processes relevant to the hairdresser take place here. The
cortex consists of a large number of the finest keratin fibres, the fibrilla.
These presumably originate due to the fact that cortex cells rest on each other.
The connection between the two cells is made through the cellular membrane complex,
which one can imagine as a type of cement substance. The hair’s resistance
to tearing and the hair’s elasticity are attributable to this cementation.
In the inside of the hair we find the medullary canal (medulla). It consists
of cell walls, decomposition products of the cortex walls and fats. The medullary
canal is presumably insignificant for the hair’s composition and structure.
Very few skin regions are completely devoid of hairs — namely the soles
of the feet, palms of the hands, fingernail bed, toenail bed and lips.
Hairs have a lifecycle which is subdivided into three phases: A growth phase, a transitional phase and a resting phase. During the growth phase (anagenetic phase), the hair grows 0.2 to 0.4 millimetres per day. On average, 85-90% of the hairs on the scalp are found in this phase. It lasts up to four years with men and up to six years with women, in which case the actual duration is hereditarily predetermined. After an approximate four-week transitional phase (catagenic phase), in which the hair is no longer supplied with nutrients and the growth stops, the resting phase (telogenetic phase) follows: The hair shaft keratinises, and the hairs increasingly loosen up until they loosen from the scalp through combing, brushing, washing the hair, etc. About 18% of the hairs on the scalp are found in this final phase. A new hair can now grow again up to twelve times successively in the old hair root. After that the hair follicle dies off.
The term is unfortunately somewhat misleading, since it simply describes any
loss of hair — for whatever reason. Basically, the following can be said:
Every person loses hairs, this is an everyday occurrence and thus predetermined
by nature. Depending on the hair colour as well as factors as age and sex, the
number varies between 20 to 100 hairs per day. As long as this loss can be spread
out over the entire head, one can speak of quite ordinary “non-diminishing
This is rather alarming only if several hairs fall out every day over a longer
period or the loss is concentrated on certain areas of the head (e.g. such as
with the androgenetic hair loss: only on the top of the head or on the temples),
and then one can speak of “diminishing hair loss”.
In turn, this can be subdivided into “increased hair loss”*
and “disease-related hair loss”.
Diminishing hair loss is quite widespread in industrial nations. Whereas men
were particularly affected in earlier decades, today women also increasingly
suffer from hair loss.
*Is a slight to moderate hair loss not conditioned by disease; amongst other
things, the following types are known:
Genetic hair loss (androgenetic alopecia)
Men as well as women can be affected by genetic hair loss. With young men in
which familial disposition prevails, genetic hair loss usually starts on the
front of the head and on the temples. This form of hair loss is described as
premature or simplex alopecia. Subsequently, a complete alopecia can then come
about. Genetic hair loss usually appears in women only after menopause. If the
body produces excess testosterone (as is the case with many men, but also women),
the testosterone is converted through specific enzymes (5-alpha reductase Type
I and II) into dihydrotestosterone (DHT). This damages the hair root with a
hereditary hypersensitivity to dihydrotestosterone: The hair’s uptake
of nutrients is restricted. The hair starts to atrophy and finally falls out.
Hair loss which is evenly distributed over the entire head (diffuse
alopecia), also called telogenetic effluvium
This form of hair loss of terminal hairs through augmented transition in the
telogenetic phase applies frequently and equally to men and women. The hair
on the entire head thins out, and more than 100 hairs fall out every day. Diffuse
hair loss is often a symptom for a temporary organic, non-pathological disturbance
such as high fever or a flu-like infection. But hormonal fluctuations (after
pregnancies, in the menopause), stress and iron deficiency can also be a trigger.
A hereditary deficiency in the vitamins from the B group (such as B1, B2 and
B6), biotin (also known as vitamin H) as well as the trace elements zinc or
selenium – which can occur through lopsided diets carried out over a longer
period – is also regarded as a trigger.
Disease-related hair loss is a strong or severe hair loss triggered by a disease.
Amongst other things, the following types are known:
Circular hair loss (alopecia areata) or pelada; Areata celsis
By that one understands a circular, locally-restricted abnormal hair loss. The
bald spots are smooth, sunk in, non-scaling, and the hair follicles are retained.
Additional changes of the fingernails with dimples, grooves or sandpaper-like
rough spots frequently exist. This abnormal form must be treated by a physician.
Total hair loss (total alopecia)
In extreme cases the hair loss leads to complete baldness on the head or even
on the entire body (universal alopecia). Scientists suspect a disturbance of
the immune system or a psychological illness as a cause of abnormal hair loss.
This abnormal form must be treated by a physician.
Too much stress can lead to increased hair loss*. Messenger substances –
which negatively influence the growth of the hair, which is surrounded by nerve
fibres – are then secreted. If this occurs during the hair’s transition
from the growth phase into the transitional phase, a premature cessation of
hair growth can come about, and a premature loss of hair would be the result.
Insufficient nutrient supply, e.g. with regard to diets
If the diet is exaggerated, and the body is deprived of essential nutrients
and building substances, this deficiency symptom also has an effect on hair
growth. An increased metabolism, which is influenced through biochemical sequences,
is necessary for the formation of hair in the hair follicle. If this process
is interrupted through a deficiency in nutrients as a result of undersupply,
this has a negative effect on hair growth. The hairs become thinner or increased
hair loss* emerges.
Hormones safeguard many tasks in the body, and are involved in the most varying
ways in almost all processes in the body. And so the lifespan of the hair cycle
as well as its distribution activities – which also ultimately have an
effect on hair loss – is also influenced. This is why the body’s
hormonal changes can lead to increased hair loss*. Increased hair loss* also
frequently ensues after birth. As a rule, this is regulated on its own again
after the hormonal change. Increased hair loss* can also be observed after one
stops taking the birth control pill or in menopause, which announces its arrival
through hormonal fluctuations. The production of female sex hormones diminishes,
and instead the male sex hormones (androgens) increases. This is why long-term
increasing hair loss and increasingly thinner hairs ensue amongst many women.
A man’s typical constitutional hair loss (androgenetic alopecia) due to
hormonal changes in the body is amongst the most frequent triggers for increased
General symptoms of old age
The efficiency of hair growth diminished with increasing age. The diminishing
production of sex and growth hormones – which also have an effect on hair
loss – is to blame for this: For instance, as early as age 20 the body
starts to produce a lesser amount of the human growth hormone (HGH) somatotropin.
Approximately every ten years the production declines by another 14 percent.
Thinning hair and hair loss can increase at old age.
* The formulation “increased hair loss”
describes a non-illness-related, slight to moderate hair loss