The lexicon of microbiota

Microbiota, microbiome, eubiosis, intestinal barrier… It is not always easy to make sense of the lexicon of microbiota. In this article, we review the definition of the main terms related to microbiota to help you get a better understanding.

Gut flora, microbiota & microbiome: false friends

The first piece of good news is that gut flora and gut microbiota are synonymous. Gut flora is simply the term historically used to refer to the gut microbiota. It refers to all the microorganisms forming an ecosystem in your digestive tract. These microorganisms are of different types (e.g., bacteria, yeasts, viruses, fungi, protozoa) and live in symbiosis with us. That is to say that we maintain a relationship with them for mutual benefits: on the one hand, we provide them with food on a daily basis, and on the other, they produce nutrients that are essential to us. It is important to note that we usually hear about “the” microbiota, but in reality, each of us has several microbiotas: the famous intestinal microbiota, of course, but we also have microbiota in our mouth, our lungs and our skin.

Another trap to avoid in the lexicon of microbiota is the confusion with the term microbiome. The latter does not refer to the microorganisms that make up our microbiota but to all their genes.

Eubiosis, dysbiosis and associated pathologies

The microbiota is a fragile ecosystem, and its composition can change over time. Eubiosis is the state of equilibrium of the microbiota in good health. A state in which the intestinal flora is composed mainly of “friendly” bacteria. Dysbiosis, on the other hand, is a state of imbalance of the microbiota in which pathogenic bacteria take precedence over beneficial bacteria. Dysbiosis can be the cause of many diseases, including digestive diseases when it comes to the intestinal microbiota. 

The intestinal walls act as an intestinal barrier: they prevent potentially harmful substances from entering our body. In the case of dysbiosis, this filter function can be altered, and these walls can let more bacteria, viruses or other pathogens through. In the lexicon of microbiota, this is called intestinal hyperpermeability.

This problem of sealing the intestinal barrier can be accompanied by digestive disorders (e.g., diarrhea, constipation, gas in the digestive tract) or even pathologies, including digestive diseases such as IBD or IBS. The term IBD (Inflammatory Bowel Disease) includes two digestive diseases: Crohn’s disease and ulcerative rectocolitis, which are characterized by the inflammation of a part of the digestive tract. IBS (Irritable Bowel Syndrome) is characterized, in addition to dysbiosis, by intestinal motricity disturbances and an increased intestinal sensitivity. What are the causes or consequences of the disease? Nothing is certain yet, the mechanisms of occurrence of these pathologies are still poorly understood.  

Many points remain to be clarified in the study of the microbiota, even beyond the digestive sphere. Research is particularly focused on the links between disorders of the intestinal microbiota and cardiometabolic disorders, food allergies or depression.

Key elements in the lexicon of microbiota: biotics

You may have already heard that biotics, in addition to a healthy diet and lifestyle, form part of solutions to take care of your microbiota, especially in cases of dysbiosis. But among all the biotics, what are the most essential and relevant to you? Here is a brief outline of commonly used terms:

  • Prebiotics are compounds that promote the development of “good” bacteria in the microbiota. To provide a more specific example, certain fibers are characterized as prebiotics. As we are not able to digest them by ourselves, these fibers arrive intact to our intestinal microbiota. The microbiota then feeds on them and transforms them into compounds that are beneficial to our health. The perfect illustration of symbiosis!
  • Probiotics are “good” bacteria which, when ingested alive and in sufficient quantity, have a beneficial effect on our health. These beneficial bacteria can be found in certain foods, food supplements or medicines.
  • Synbiotics are a combination of prebiotics and probiotics: they enrich the microbiota with “good” bacteria and feed them with prebiotic compounds.
  • Postbiotics are perhaps the least known of the biotic family. However, they are by no means the least significant since they also provide notable health benefits. Their particularity: postbiotics are inanimate and do not need to be a whole microorganism. They can be whole but inanimate bacteria and/or fragments of inanimate microorganisms, with or without compounds from their culture medium.

We hope these definitions help you to better understand the lexicon of microbiota.

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