What is the intestinal microbiota ?
The intestinal microbiota, formerly called intestinal flora, is an important organ of our body that participates in our health and well-being. It consists of a complex and diverse ecosystem of microorganisms that reside on the surface of the intestinal mucosa : mainly bacteria, but also yeasts and viruses.
The intestinal microbiota is specific to each individual : it can be considered as our identity card. In fact, one-third of the bacteria are common with others while the remaining two-thirds are unique.
Each individual is housed about 100,000 billion bacteria, which is ten times the number of human cells. Nearly 800 to 1,000 bacterial species known are distributed along the digestive tract. The maximum bacterial concentration is observed in the colon.
Strict anaerobic bacteria are the most abundant in the intestinal microbiota. They correspond to more than 99% of the bacteria present in the digestive tract : the dominant microbiota. Optional facultative anaerobic bacteria which are present in lesser amounts, form the subdominant microbiota. There is also a transient microbiota, meaning that certain bacterial species only transit through the intestine.
How is the gut microbiota established ?
The flora acquisition is established at the birth . The bacteria quickly and significantly colonise the newborn’s organism, due to the immaturity of its immune system. Its diversity and its composition depend on several factors such as the mode of delivery, the environment, diet, consumption of antibiotics …
Its composition will gradually become more complex with age and its maturity is reached around the age of 2-3 years.
Generally stable, it can evolve transiently over the course of life depending on the diet, the environment, the health status or stress episodes. The gut microbiota nevertheless tends to return to its initial state in 1 or 2 months.
What are the main roles of the intestinal microbiota ?
The intestinal microbiota has an important role in maintaining our health. It acts especially in the digestion context. In fact, it allows to ferment in the colon undigested food, thereby ensuring digestive comfort and the release of vitamins, short-chain fatty acids and other beneficial substances to our body.
It acts in support of the deployment of immune defenses thanks to the barrier effect, protecting the digestive tract from the spread of pathogens according to various mechanisms. It also participates in the development and the maturation of the immune system : nearly 70% of immune cells are housed in our intestines.
The gut microbiota is a key element of our well-being and our health, so we must take care of it in order to take advantage of all its beneficial actions.