The skin barrier is the outer protective layer of the skin, also called the stratum corneum . It plays a vital role in the health and appearance of the skin, being responsible for protection against external aggressions and preserving hydration. Here are its main functions and composition:
1. Protective function
The skin barrier acts as physical protection against external aggressions such as:
- Pollutants
- Microorganisms (bacteria, viruses)
- Chemical irritants
- UV rays
2. Moisture retention function
This barrier limits transepidermal water loss, that is, the evaporation of water through the skin, which is essential for keeping the skin hydrated. A healthy skin barrier keeps the skin soft, supple and well hydrated.
3. Composition
The skin barrier is composed of:
- Dead cells (corneocytes): arranged in tight layers like bricks.
- Lipids : mainly ceramides, cholesterol and fatty acids, which act as "cement" between cells. They form a kind of protective layer around the cells and prevent water from escaping.
4. Impact of a weakened skin barrier
When the skin barrier is damaged or weakened, it can no longer perform its functions effectively. This can lead to:
- Excessive water loss, which causes dehydrated, dry or rough skin .
- Increased sensitivity, with redness, irritation or eczema.
- Greater exposure to pollutants and microorganisms, which can promote skin infections and inflammation.
5. Causes of skin barrier disruption
- Excessive use of harsh or exfoliating products.
- Weather conditions (cold, wind, extreme heat).
- Stress, poor diet or dehydration.
- Skin diseases such as atopic dermatitis or psoriasis.
6. How to restore and protect the skin barrier
- Use gentle products : Choose non-irritating, sulfate-free cleansers.
- Hydrate intensely : Use products containing ceramides , hyaluronic acid and essential fatty acids to nourish and repair the lipid barrier.
- Protect from the sun : Use sunscreen to prevent UV damage.
- Avoid hot water : Water that is too hot can dry out the skin and damage the barrier.
- Limit exfoliants : Excessive exfoliation can weaken the skin barrier.
A well-maintained skin barrier is the key to healthy, luminous skin that is resistant to aggressions.