Since the exploration of the genome thanks to scientific progress, we know much better about the intestinal flora and the skin flora. Specialists have more precisely identified their compositions, giving them the opportunity to give them a new name “microbiota”. As with the belly microbiota, the skin microbiota is closely linked to skin health.

The skin microbiota: what is it?

In the past, we talked about skin flora without really knowing it until the day Professor Richard Gallo, President of the dermatology department at the University of California San Diego, looked into it. 20 years ago, this professor began to analyze and decipher this skin flora to which he gave the name skin microbiota. This microbiota which covers the entire skin envelope is in fact a colony of 100 billion living microorganisms called probiotics. It consists of bacteria (75-80%), viruses (10-20%) and yeasts or fungi (5-10%). There are around 1 million of these micro-organisms per cm² of skin which even slip into skin folds and crevices, from pores to pilosebaceous follicles where they each play a very specific role. Microorganisms that collaborate or even compete with each other. The main families of bacteria are staphylococcus, corynebacterium, propionibacterium, cutibacterium. That is to say a thousand varieties (of probiotics but around 500 of bacteria) - with sub-varieties - which coexist in perfect symbiosis with our cells. These essential probiotics feed on our own skin secretions (lipids from sebum, proteins from dead cells, sugars, water from sweat, etc.). It was not until 2001 that the World Health Organization recognized probiotics as “live microorganisms which (…) exert positive effects on health” and which ensure the good balance and good health of our microbiota.

What is the role of the skin microbiota?

The skin microbiota plays a crucial protective role for the skin. In fact, its micro-organisms compose an army of sentinels to preserve the integrity of the skin barrier. This skin microbiota forms a protective film which reinforces this barrier and thus blocks the penetration of so-called “pathogenic” viruses and bacteria, which could cause diseases. But this collaboration with the hydrolipidic film has many other functions. The skin microbiota maintains the physiological pH of the skin around 5.5, which repels pathogenic bacteria that favor basic pH, around 8. The skin microbiota also stimulates skin cell renewal and plays an important role in the immune system of the skin. the skin. It helps them recognize aggression and adopt the most appropriate response. In addition, the skin microbiota promotes healing and repair of the skin. It is also involved in the secretion of antimicrobial peptides (which are like little soldiers which will attack intruding bacteria to destroy them) by skin cells, anti-oxidant, antibacterial and anti-inflammatory substances. In short, the role of the skin microbiota is decisive for the good health of the skin.

What are the factors that influence the skin microbiota?

Throughout life, the skin microbiota varies even if each individual has their own microbiota.

Everyone has their own skin microbiota. It is a kind of personal signature just like DNA or fingerprints. This skin microbiota is transmitted to the baby by his mother during vaginal delivery. Then it will evolve and diversify throughout life, particularly during each major hormonal change (adolescence, pregnancy, menopause/andropause). Its composition, or at least the proportion of varieties of microorganisms, differs depending on the part of the body (scalp, armpits, arms, etc.). Indeed, certain bacteria prefer dry environments (arms, legs), others humid regions (mucous membranes, armpits, folds, etc.), or oily regions that contain sebum (inside the ears, scalp, face, etc.). The skin microbiota also changes according to age, sex and ethnic origin. The microbiota is the image of the “exposome” of its host, that is to say the environment and the pollution in which it lives but also its lifestyle, its stresses, its diet, its lifestyle, his age, his gender, the medications he takes without forgetting the people and animals who share his life. This explains why we have several skin microbiota, all different and variable (unlike our DNA which does not vary).

We now know that skin health comes from the balance and good diversity between probiotics within the skin microbiota. Thus, as soon as a variety takes over or an intruder enters, there is an imbalance (or dysbiosis) which leads to inflammation which can cause disease. Indeed, we have discovered that atopic eczema (or atopic dermatitis), acne or dandruff in particular, are linked to an imbalance in the microbiota caused and accentuated by living conditions: pollution, taking medications, stress, UV rays, excessive hygiene and certain cosmetic components. Acne comes in part from an overpopulation of cutibacterium acnes. Atopic dermatitis shows a great imbalance where we see that Staphylococcus aureus (Staphylococcus aureus) is predominant. Dandruff is linked not to a bacteria, but to the proliferation of a fungus present on the scalp called malassezia. But are these excess probiotics the cause or the consequence of the condition? Researchers don't know yet...

Furthermore, several studies have shown that pollution modifies the composition of the microbiota, which is then similar to that of an elderly woman. Could the microbiota have a link to premature aging? Researchers assume so. But the discovery of the skin microbiota is only around fifteen years old, even if its study is progressing rapidly, we are far from understanding all the mechanisms and the extent of its influence.

How can the skin microbiota protect the body?

The skin, the largest organ in the body, is also our main interface with the outside world. It is a protective barrier within which the microbiota plays a vital role. By strengthening the immune system, the skin microbiota protects the skin from infections, external aggressions and inflammation. This protection, which extends to the entire surface of the body, fights against transcutaneous intrusions.

Cosmetic products and/or food supplements enriched with prebiotics, probiotics and postbiotics help to preserve and rebalance the skin microbiota to maintain healthy skin.

Probiotics are live microorganisms (bacteria, yeast in particular) which make up the microbiota and which maintain its balance. If they are found in dairy products and fermented but unpasteurized vegetables, they are absent in cosmetics where it is impossible to include a living organism. On the other hand, we find in certain treatments fragments of probiotics (lactococcus, bifidobacterium, lactobacillus, etc.), deactivated either by heat or by fermentation which are recognized and assimilated by the skin's probiotics. For marketing convenience, cosmetic brands indicate “with probiotics”. Their anti-oxidant and anti-inflammatory actions ensure an ecosystem beneficial to the microbiota.

Prebiotics are simple or complex sugars, fatty substances or amino acids that nourish and promote the proper development of skin bacteria. A kind of fertilizer for the microbiota that is particularly interesting in cosmetics. In food, these are fibers from fruits and vegetables, and in particular from chicory, garlic, artichoke, psyllum… In cosmetics, the best known are inulin, from chicory and yakon. But certain ingredients, such as glycerin, squalane and polyphenols, used for a long time in cosmetics, also turn out to be prebiotics.

Postbiotics are molecules secreted by probiotics. These waste products, metabolites or probiotic membranes, mimic them and balance the ecosystem in which a healthy microbiota lives. For example, lactic acid belongs to the postbiotic family. Some dermocosmetic brands prefer to develop their own tailor-made postbiotics, often from bacteria cultivated in thermal water to correct a specific problem: acne, atopy, dry skin, etc.

The Blue Skincare brand has chosen to incorporate pre- and or postbiotics into all its care products and also into its cleansing products in order to offer formulas that respect the balance of the skin microbiota, including prebiotics (inulin and sugars), postbiotics (probiotic complex obtained by lysis of fermented Lactococcus Lactis bacteria and also lactic acid). To be found in the Nacre Eclat range, dedicated to dull and tired skin and in the Xero Nacre range dedicated to uncomfortable skin prone to atopic dermatitis and psoriasis. All formulas have been developed to be at the physiological pH of the skin.

How to restore the skin microbiota?

To restore the skin microbiota and maintain its balance, here are 6 simple actions to adopt:

Reduce passages under water. Having a pH of 7, the water can, with baths that are too long and too hot, destabilize the microbiota.

Choosing good hygiene products: the discovery of these “beneficial bacteria” has changed the “hygienist” vision adopted since Pasteur. It was believed that bacteria and viruses were necessarily harmful. We now know that there are good and bad ones and that we must favor the “good” probiotics naturally present on the skin. So, no more “bactericidal” products at all costs. Shower gels that have overly aggressive surfactants unbalance the microbiota, which takes more than 4 hours to reconstitute itself after each shower. So, one shower per day maximum, and with the gentlest cleanser possible.

Lipid-Replenishing Cleansing Oil, a beneficial cleansing oil with a physiological pH composed of a unique complex of ultra-gentle cleansing agents, a trio of vegetable oils and prebiotic (inulin and sugar) which cleanses the skin while respecting the hydrolipidic film and the skin microbiota.

Respect the pH of the skin microbiota. Microbiota and pH of the skin are closely linked through the hydrolipidic film which houses the microbiota. As this film is called “the acid mantle”, we avoid any product with a bad pH: the famous Marseille soap, or any other soap, has a basic pH (above 7). We therefore prefer superfatted bread. For the same reasons, but because of their very acidic pH, fruit acids should be used reasonably and with the right indications. We therefore choose products called “physiological pH” and not “neutral pH”, which means that they respect the pH of the skin whereas a neutral pH is 7.

Avoid cosmetics that are too aggressive (or limit their use), such as grainy scrubs or cosmetics containing a lot of alcohol.

Remove make-up gently, without aggression, without rubbing, avoiding aggressive cotton. The ideal is to remove makeup with your finger using massages to gently remove all types of impurities. To be used in a circular massage, Le Baume Métamorphose is ideal for removing makeup and cleansing the skin effectively and effortlessly while maintaining the balance of the skin microbiota thanks to its formula enriched with pre & postbiotics. And in the morning, don't strip yourself: a suitable floral water is enough or use Milky Micellar Water, also rich in pre- and postbiotics. Fresh as water and soft as milk, it will delight combination to oily skin and is used in massage to gently remove all impurities.

Eat balanced and varied food. Diet has an impact on the condition of the skin and the study of microbiota has revealed intestine/brain axes, but also intestine/skin. To have a rich and varied intestinal, but also skin, microbiota, we eat products rich in prebiotics and probiotics such as garlic, onion, all fruits and vegetables which are rich in fiber, vitamins and minerals. Spices and aromatic herbs have anti-inflammatory properties and help destroy pathogenic bacteria. And if that is not enough, you can swallow food supplements (Skin Perfecting Food Supplement, rich in active mother-of-pearl powder highly concentrated in calcium and amino acids coupled with pre and probiotics, hyaluronic acids, vitamin C and zinc: the essential supplement for all tired skin, lacking radiance and prone to imperfections)

The discovery of the skin microbiota and its role has brought a new vision of cosmetics. From now on, laboratories are trying to formulate treatments in such a way as not to disturb it, by limiting or even removing certain ingredients which could cause its imbalance or even its deterioration. These are mineral oils and silicones, but also emulsifiers (what foams like sulfates) and emulsifiers (what binds emulsions, creams or fluids). Preservatives have also been blamed, but ultimately it seems that they have no impact on the microbiota.