Intestinal flora (microbiota): role, replenish it

There intestinal floraalso called gut microbiota is the most important microbiota in the body. What is its role in immunity, digestion or weight maintenance? What microorganisms and bacteria is it made up of? What foods to eat to replenish it?

What is the definition of intestinal flora (microbiota)?

The intestinal flora also called “intestinal microbiota”is made up of a set of micro-organisms (non-pathogenic bacteria, viruses, parasites and fungi) naturally present in the organs that make up the digestive tract. “The intestinal microbiota is made up of billions of microorganisms and bacteria that are important in the regulation of intestinal health, in immunity and in absorption of certain nutrients“, defines Professor Jean-Christophe Saurin, head of the hepato-gastroenterology department at the Lyon University Hospital. This flora is mainly located in the small intestine and the colon. The intestinal flora is in perpetual motion: every moment, bacteria die and others are born, hence the importance of maintaining a good balance through food.

What is the role of the intestinal flora?

The intestinal flora performs several functions:

• She acts like a barrier against pathogenic bacteria and is therefore an integral part of intestinal immune system.
• It is essential for digestion and contributes to good transit: “The more the intestinal microbiota is composed of varied microorganisms, the better the intestinal health“, says Prof. Jean-Christophe Saurin.
• It ensures the fermentation of substrates and indigestible food residues.
• It facilitates the assimilation of nutrients thanks to a set of enzymes that the body does not have.
• It participates in the synthesis of certain vitamins (vitamin K, B12, B8).
• It ensures the hydrolysis of starch, cellulose and polysaccharides (carbohydrates made up of a large number of simple sugars), regulates the absorption of fatty acids and contributes to weight maintenance.

What is the intestinal flora made up of?

The intestinal flora “houses no less than 10¹² at 10¹⁴ micro-organisms, i.e. 2 to 10 times more than the number of cells that make up our body“, indicates Inserm on its website. And like the fingerprint, the intestinal microbiota is unique to each individual :

► In adults, the intestinal microbiota is composed of different microorganisms: among the 160 species of bacteria that make up the intestinal microbiota of a healthy individual, Firmicutes, Bacteroidetes, and Actinobacteria are the most recurrent bacteria. The intestinal flora would consist of 2 kg of micro-organisms.

► In childrenthe composition of the intestinal microbiota evolves according to the mode of delivery, diet, environment, hygiene and possible medical treatments, until it resembles the intestinal microbiota of the adult.

What are the causes of a fragile intestinal flora?

“Schematically, the more bacteria there are in the microbiota, the better the intestinal health. On the other hand, when the bacteria in the microbiota are reduced in number or poorly diversified, the flora is weakened. This is particularly the case for people who have been in intensive care for example or who have received lots of antibiotics.“, summarizes the gastroenterologist. The intestinal flora can indeed be weakened by taking certain medications such as antibiotics which tend to destroy “good” bacteria. And a change in the quality or quantity of the intestinal flora leads to an imbalance (called dysbiosis), potentially causing inappropriate immune reactions or metabolic disorders. “An unbalanced intestinal flora or one that does not contain a rich enough set of microorganisms can lead to the appearance of chronic pathologies or functional disorders such as Crohn’s disease, ulcerative colitis or irritable bowel syndrome“, alerts our interlocutor. In the long term, an unbalanced and insufficiently diversified flora can also increase the risk of colorectal cancer.

What is the examination to assess the quality of the intestinal flora?

“Stool samples make it possible to quantify the number of bacteria as well as the variety of strains“, wishes to underline Professor Saurin. This is what is called a coproculture. Although this bacteriological examination of the stool does not give the exact composition of the intestinal flora, it does make it possible to know whether the flora is healthy or not. It is used to search for and identify pathogenic bacteria or viruses that may be responsible for digestive infections, particularly in the event of diarrhea or a foodborne infection. The bacteria most commonly sought during a stool culture are the SalmonellaTHE ShigellaTHE Campylobacter or some Escherichia Coli.

What to eat to rebuild your intestinal flora?

Diet plays a considerable role in the intestinal flora. Certain foods can help replenish its intestinal flora:

• yoghurts containing lactic ferments and natural probiotics (Activia© or active bifidus yoghurts)
• fermented milks such as kefir or buttermilk
• legumes which are sources of fiber (split peas red beans, beans, lentils, white beans, etc.)
• whole grains, also rich in fiber (whole wheat, whole oats, whole rye, wild rice, bulgur, quinoa, spelled, etc.)
• fermented cabbage or sauerkraut which boost beneficial gut bacteria and are rich in calcium, vitamin C, phosphorus and potassium.
• honey which is a natural antibacterial and antioxidant and which stimulates the proliferation of good bacteria.
• kombucha, a soft drink obtained by the fermentation of yeasts and bacteria cultured in green tea or black tea.
• the plants whose bulbs are eaten such as garlic, onion, shallot or leek are prebiotics which serve as food for bacteria and promote their development.

What probiotics to rebuild your intestinal flora?

take probiotics (lactobacilli (genus Lactobacillus) and bifidobacteria (genus Bifidobacterium longum)or yeasts (Saccharomyces) in food supplements helps restore the intestinal flora and repopulate it with “good” bacteria. Before taking a cure, ask your doctor or pharmacist for advice.

Probiotics, prebiotics: what’s the difference?

Thanks to Professor Jean-Christophe Saurin, head of the hepato-gastroenterology department at the CHU de Lyon.