Intestinal microbiota

Intestinal microbiota

Made up of billions of micro-organisms, the intestinal microbiota is essential for the human body to function properly.
Alterations (dysbiosis) to the healthy microbiota are involved in the development of various diseases, mainly metabolic, such as obesity or type 2 diabetes.
Correcting dysbiosis primarily involves the adoption of an adapted diet and the supplementation of beneficial microbial strains.


Micro-organisms working in partnership

A microbiota refers to all of the micro-organisms (bacteria, fungi, viruses) coexisting in each individual, in a localized, harmonious system. The host and his or her microbiotas, of varying composition depending on the colonized area, maintain close physiological relations and interact in a manner that is mutually beneficial to promoting their proper functioning.


An independent organ

The largest and most diverse human microbiota is found in the gut and was previously referred to as the “intestinal flora”. A full-fledged “organ”, it plays multiple roles in the body, particularly in relation to digestive, metabolic, immune and neurological functions.


100 000

billion germs (more than the number of cells in the human body).


1 to 3

kg, and is mainly composed of bacteria, including dozens of species with diverse mechanisms of action.

A fluctuating environment vulnerable to external aggressions

The intestinal microbiota is formed at birth, upon contact with maternal and environmental germs. Influenced by diet, hygiene levels, medicinal treatments and the environment, its composition evolves over the first years of life, before finally stabilizing. However, various events may disrupt this balance: disease, a viral, bacterial or parasitic infection, medicinal treatments (especially antibiotics), immune deficiency, stress, etc. This qualitative and functional alteration of the microbiota is called dysbiosis and represents an area of research for better understanding certain diseases.


Dysbiosis and metabolic diseases

Some connections have been made between dysbiosis and metabolic diseases linked to nutritional imbalances, namely type 2 diabetes, obesity and NASH. The development of metabolic diseases and certain comorbidities (associated problems and complications) can be explained by a “miscommunication” between the disturbed microbiota and the intestinal immune system, as well as the central nervous system, via the gut-brain axis which enables the two organs to communicate and influence one another.
Recently, numerous studies have also shown the major role of the dialogue between the intestinal microbiota and the liver, the deregulation of which contributes to the development and maintenance of fatty liver diseases such as NASH.


Re-balancing the microbiota

The fight against intestinal dysbiosis rests primarily on the intake of prebiotics or probiotics. Probiotics are living micro-organisms that are beneficial for our health (generally certain families of bacteria or yeasts), while prebiotics are substrates that promote the growth of these “good” microbes. The process of combining them in a single formula is known as “symbiotic”.
At the same time, it is recommended that patients adopt a diet rich in fiber and fermented products, great sources of prebiotics. For more extreme cases, a fecal transplant (transferring a healthy microbiota through the natural route) may be prescribed to correct the dysbiosis.

Sources: FRM; Inserm; Rémy Burcelin, Simon Nicolas et Vincent Blasco-Baque. Le microbiote : cet inconnu qui réside en nous.Med Sci (Paris), Volume 32, Number 11, Novembre 2016