[n.m] Our body is inhabited by a multitude of living microorganisms (bacteria, fungi, yeasts, etc.) that collectively form what is called the microbiota or flora.

• The intestinal microbiota in our digestive ecosystem.
• The cutaneous microbiota on the skin.

The intestinal microbiota or intestinal flora is composed of some 100 trillion microorganisms. Each human’s flora is unique, evolving throughout the host’s life and, when in balance, performing several essential functions:

• Food digestion: the microbiota’s microorganisms work to ferment indigestible food, make vitamins, digest fibres, etc.
• Immunity support: while many bacteria have a beneficial effect on the body, some can be harmful. The intestinal microbiota protects the body against harmful bacteria, helping make our immune system more mature. Nearly 60% of the human body’s immune cells are located in the intestine.

The skin microbiota is composed of a variety of microorganisms. It is unique to each individual, just like the intestinal flora, and depends on a number of variables, such as skin PH, living environment, age, etc. The microbiota is the outermost layer after the stratum corneum and plays several roles:

• Balancing skin acidity: it keeps the skin’s PH at around 5.5, a slightly acidic level that protects against harmful bacteria and harsh external elements.
• Protection, anti-infective: the bacteria naturally present on our skin (also called commensal bacteria) protect our body by strengthening the skin barrier and stimulating our immune system to fight pathogenic bacteria.
• Repair: even if it has been damaged, the skin microbiota can reconstitute on its own to quickly return to acting as a protective barrier. If the skin is wounded, the microbiota will stimulate keratinocytes and immune cells to protect the area from infectious agents.