How does hair grow?
We have between 100,000 and 150,000 hairs (up to 200,000 for red hair) implanted in our scalp. Each one is made up of a root or hair bulb and a hair shaft, which is the hair itself. Hair is essentially composed of keratin and melanin, the pigment that provides its natural colour. Hair growth occurs when bulb cells multiply and are pushed up, forming the shaft. Therefore, it’s very important that the scalp—or in other words, the area where the bulb is implanted—is healthy and provides the nutritional elements needed to keep hair alive. A hair’s lifecycle has three stages:
1) the anagen phase, a period that lasts three to seven years when the hair is growing about 2 mm per week. The root produces the keratin hair shaft, which is the hair’s visible section;
2) the catagen phase, a short one to two-week period when the hair stops growing and dies; and
3) the telogen phase, a period of about three months when the dead hair remains attached to the scalp before falling out. This is the amount of time it takes for the cells to move back down to the root to start a new cycle. Each bulb produces between 20 and 25 hair shafts in one lifetime.
What are the most common scalp imbalances?
Even though effects are visible on the hair, all the action takes place on the scalp.
. An irritated scalp:
Many people complain about stinging, itching, discomfort, heating and sometimes redness. The triggering factors include heat, cold, pollution, emotions, dry or moist air, water and shampoos. Scalp irritation corresponds with a skin disorder linked to a succession of physiological disruptions. A stressor, such as the use of a traditional shampoo containing irritating agents (detergent surfactants and other potentially poorly tolerated ingredients), often causes the disruptions. This stress on the scalp alters the hydrolipidic film and causes an imbalance in the skin barrier. The result? Water evaporates more easily and the skin dries out, which can allow irritants to penetrate and cause clinical signs of irritation, itching, discomfort, tightness and more.
. Oily hair:
They are heavy, lack volume and usually look oily, especially at the roots. The root cause of these effects is hyperseborrhoea, which can have multiple causes. The excess sebum accumulates on the roots, which then look oily.. Hair is heavy and flat, tangling together and often looking dirty because sebum traps dirt in the air and making it stick easily to the hair.
. Dry hair:
This is the opposite situation. The hair is dry, brittle, fragile, difficult to untangle and style, and has split ends. A dry scalp leads to dry hair. This is caused by a sebum deficiency, which can be an inherent characteristic in people who naturally secrete very little sebum. Or, it can develop later when dryness is linked to external stresses such as the sun, wind, pollution, sea or pool water, intense brushing or straightening, bleaching or perms. In all cases, the skin barrier no longer fulfils its role, water loss accelerates and hair becomes dry, brittle and rough. Since it lacks hydration, hair is difficult to style and prone to static electricity.
How can I keep my hair clean?
For all hair types, you need to cleanse it without irritating it or removing the hydrolipidic film so you do not disrupt the hair bulb’s physiology. Only a non-detergent shampoo can preserve the hair’s biological balance. This type of shampoo does not contain surfactants that would be too harsh on the hair fibre. You should usually wash your hair every day if you wear a hat, play intense sports or live somewhere with high pollution. So it is critical to choose a true non-detergent shampoo. Some medicated shampoos can be non-detergent.
What are the signs of abnormal hair loss?
Losing less than 100 hairs per day is absolutely normal because it corresponds to the natural hair cycle. If you lose more than this, you should be concerned about the state of your hair. When it is not genetic (baldness), excessive hair loss is often related to:
. A temporary situation: stress, fatigue, pregnancy (after childbirth), change of seasons (particularly in autumn), nutritional deficiencies (particularly iron, silicon, B group vitamins, zinc, essential fatty acids, sulphur-containing amino acids, trace elements), convalescence and hormonal problems.
. An external stress that is physical (helmet-wearing profession), chemical (pollution, over-use of dyes and perms, hot blow dryer, aggressive cosmetic products particularly those for oily hair, etc.), infectious (yeast infection) or parasitic (lice).
All of these factors will inevitably have an effect on the hair. In addition to hair loss, this may result in fragile, lifeless and dull hair or else oily and fine hair.
Taking a nutritional supplement may be beneficial for hair. In order for it to stimulate, strengthen and densify your hair, this supplement should contain nutrients that stimulate the production of high-quality keratin, limit hyperseborrhoea and promote hair growth. If it is enriched with magnesium, this nutritional supplement may also help combat stress, which can cause hair loss.
If you are experiencing significant and persistent hair loss, you should see a dermatologist.
Why does hair get oily?
Oily hair is primarily due to increased sebum secretion by sebaceous glands in the scalp. Called hyperseborrhoea, this phenomenon alone is not responsible for oily hair. Oily hair may be caused by:
. Qualitative changes in the sebum, which becomes more fluid and therefore migrates more quickly and more easily to the hair shaft,
. Calcium salt formation when sebum comes into contact with calcium in tap water during washing. These salts weigh down the hair and make it look shiny.
Note that washing hair too frequently and using overly detergent shampoos risk causing reactive hyperseborrhoea. Indeed, when sebum has been removed after aggressive cleansing, the sebaceous glands may get “excited” and over-secrete, thus making the hair and scalp even oilier.