Understanding the human microbiota: essential microorganisms


The human microbiota comprises all the microorganisms (bacteria, fungi, and viruses) that live within the human body. This includes hundreds of billions of microorganisms which live together in harmony with our cells. They are found in the nose, mouth, and ears as well as on the skin and in the eyes, and in the bronchi and lungs.

However, it is primarily in the gastrointestinal tract that the microbiotic environment is the most important, mainly in the small intestine and the colon. We also talk about “intestinal flora.”

2 kg
Is the weight of the microbiota found in the gastrointestinal tract: it is heavier than the human brain!
X 150
There are more than 3 million microbial genes in our intestinal microbiota, ie, 150 times more genes than in the human genome.
is the number of bacterial species that live in our intestinal microbiota.

An ecosystem within the human body

The intestinal microbiota of the gastrointestinal tract is the biggest, with one hundred billion microorganisms, ie, 2 to 10 times more than the number of cells in our body. It is essential to the proper functioning of the intestinal immune system. It obtains the resources required for the creation of its metabolism from our diet (in particular food fiber). At the same time, the intestinal microbiota plays a direct role in digestion (fermentation, absorption of nutrients, vitamin synthesis, etc.)


The shortcomings of intestinal flora. When a dysfunction or imbalance of the intestinal flora is observed, it is referred to as “dysbiosis.” Several causes are involved: regular use of antibiotics or antacids, excessive alcohol consumption, stress, previous gastrointestinal tract diseases, a diet low in fiber or excessively high in refined sugars or processed foods. Dysbiosis can cause a certain number of chronic inflammatory bowel diseases, and in particular Crohn’s disease and ulcerative colitis. Another effect of dysbiosis: the potential appearance of cancers (colorectal, gastric, breast). Finally, research has shown a possible link between intestinal flora imbalance and the appearance of certain neuropsychiatric diseases (there are more than 200 million neurons in the nervous system associated with the intestine), including autism, schizophrenia, anxiety, depression, and bipolar disorders.

Towards more accurate and personalized treatments

The importance of intestinal microbiota in the body was always suspected, but until recently technology did not allow accurate analysis of its content. The possibility of reproducing these bacteria in the laboratory and the development of high-throughput sequencing techniques for the human genome revolutionized knowledge of the intestinal microbiota and gave fresh impetus to research in the field. Such cutting-edge techniques have greatly advanced the therapeutic perspectives, both in the search for innovative new drugs and in the treatment of patients. Knowledge of the microbiota also allows earlier diagnosis of diseases and therefore initiation of more accurate and personalized therapies for each patient.

Greater knowledge today

Specifically, today we know more about the nature of the interactions between the microbiota and foreign agents and about the interactions between the microorganisms themselves. We also know how to measure the impact of these interactions on health. The study of the intestinal microbiota has progressively become central to health research, increasingly mobilizing research teams throughout the world. At stake is the discovery of new mechanisms of action which could be used to treat or even cure patients.

Clearer lines of research

Currently, research concentrates on the analysis of the microbiota of patients, by exploring their intestinal flora. The use of information technology, eg, big data, now allows us to examine the microbiota from many patients and to establish a relationship between these samples and some diseases. Specifically, the main objective is to identify the cause of the dysfunctions observed, stop harmful microbial production, and activate renewal of intestinal flora, by proposing a suitable therapeutic response: introduction of new bacteria, fecal transplants, use of food or bacterial peptides.

Servier is involved in this cutting-edge research

Servier has been involved for several years in research on the microbiota and currently wishes to develop new partnerships, such as the collaboration initiated with Harvard University in 2019 concerning certain mechanisms of action of the intestinal microbiota in the treatment of nonalcoholic fatty liver disease and type 2 diabetes, with the objective of obtaining a drug candidate towards 2022.