The cutaneous microbiota, the ally of our skin!

The skin microbiota, or skin flora, is a set of microorganisms living on our skin. It is mainly made up of bacteria, but also some viruses and fungi. Recent studies show that the good bacteria are real allies for our skin and that an imbalance of the microbiota is not without consequences. Follow all our hygiene advice to respect your skin microbiota!

The skin microbiota:valuable microbes for the skin

We call commensal bacteria , the bacteria usually present in our permanent flora. This term, which could be translated as “at the same table”, means that they feed by exploiting our resources, a bit like guests. In fact, recent scientific studies have shown that the bacteria in the microbiota do us great favors in return!

The role of the microbiota on skin balance

The microbiota maintains the balance of our skin in several ways:

• it prevents excessive inflammation of the skin by regulating immune responses;
• it helps to maintain the pH (i.e. the acidity) of the peel around 5.5. This value is an average, the normal pH of the skin can vary from 4 to 7:our skin is naturally acidic and the microbiota takes pleasure in it.

The protective and anti-infective role of the microbiota

Commensal bacteria protect us from infections in several ways:

• they occupy skin space and consume the nutrients present on our skin. They leave nothing to eat for pathogenic bacteria (responsible for diseases) which can no longer develop. This phenomenon is called the barrier effect. »;
• some species secrete anti-bacterial toxins capable of killing pathogenic bacteria;
• commensal bacteria, such as Staphylococcus epidermidis , are able to send signals to stimulate our immune system and counter the attack of pathogenic bacteria;
• they seem to play an important role in the development of the immune system and its ability to respond to infections. Commensal bacteria have even been discovered in the deeper layers of the skin such as the dermis or the hypodermis!

The repairing role of the skin microbiota

The microbiota helps repair the skin:

• it is able to stimulate epidermal cells (keratinocytes) and immune cells so that they defend themselves against infectious agents in the event of wounds on the skin;
• if it is slightly degraded, the microbiota is able to replenish itself quickly and strengthen the epidermis again to fully fulfill its role as a protective barrier.

Imbalanced skin microbiota:what consequences?

The imbalance of the skin microbiota directly impacts the acidity of the skin, and the immune and inflammatory processes in which commensal bacteria participate.

What is dysbiosis?

Dysbiosis is the name given to the imbalance of the microbiota of the skin. It can be the cause of many inconveniences and skin pathologies. In case of dysbiosis, the immune responses of the skin can be modified and certain pathogenic bacterial species can develop further.

As a general rule, if the commensal flora is reduced, the risk of infection and inflammation of the skin is greater.

Dysbiosis in skin diseases

Recent studies show the link between dysbioses and several skin diseases. We find in particular:

• acne for which the development of a particular strain of a bacterium, Propionibacterium acnes , is responsible for inflammation of the pilosebaceous glands;
• the psoriasis whose inflammatory lesions seem to present a proliferation of particular bacteria;
• hidradenitis suppurativa or Verneuil's disease , which shows a significant bacterial proliferation as well as a greater diversity of bacteria than in the normal microbiota;
• atopic dermatitis with a microbiota less diversified than normal and which benefits the proliferation of a specific bacterial species, Staphylococcus aureus (Staphylococcus aureus).

Skin hygiene that respects the microbiota

To respect your skin microbiota, you sometimes have to review your hygiene habits and choose suitable products.

To make the toilet less aggressive to the microbiota

The “hygienist theory » considers that excessive hygiene of the premises and the body in our developed countries would be responsible for a poor maturation of the immune system. She holds it responsible for the increase in inflammatory and allergic diseases, too low exposure to bacteria and allergens, especially during childhood.

After washing the skin with soapy water, the commensal flora is partially destroyed in certain areas of the skin. Skin pH increases to become alkaline. If the normal skin flora takes too long to recolonize the vacant lots and lower the pH, this is the time for the development of pathogenic bacteria.

Habits to adopt

Washing the skin too frequently is detrimental to the skin microbiota, which cannot renew itself quickly enough.

As a general rule, specialists consider that a full shower 2 to 3 times a week enough. On the other days of the week, they recommend a simple cleaning of the armpits, feet and groin with a washing product so as not to generate olfactory nuisances. It is also best to respect a moderate water temperature (below 37°C).

Most people take soapy showers more frequently, and even every day for 57% of French people according to a BVA survey. During the heat of summer, after physical work or after practicing a sport, it is difficult to avoid the shower! It is therefore all the more important to choose the right cleansing product in order to best respect your skin microbiota.

Washing products to choose

To respect the commensal flora, choose soap-free products such as surgras cleansing care, or even syndets... These products must be formulated at physiological pH of the skin (approximately pH 5.5), also called "neutral pH". Avoid Marseille soap or Aleppo soap which are far too alkaline and detergents. Prolonged use of anti-bacterial soaps can also destabilize skin flora. Unless there is a medical reason, avoid using them.

Some cleansing products are enriched with probiotics . These are strains of bacteria that are usually commensal, capable of reseing the skin flora. Other cleansing products are enriched with prebiotics . These are foods (fibers) that promote the growth of good bacteria in the skin microbiota.

Review your cosmetic routine

If the scrubs can exfoliate the skin and rid it of its impurities, they can attack the skin flora when they are made too frequently. Only one exfoliation per week enough to sublimate the skin.

emollient and moisturizing treatments do not destabilize the skin flora and can be applied daily. Milks, creams, balms, or even vegetable oils help moisturize and restore the lipid (fatty) film of the skin. Some formulations are enriched with probiotics and prebiotics .