Préparation oral anglais microbiote

Préparation oral anglais : Microbiote

Introduction: Présentation microbiote

There are many different microbiotas in our bodies, and the most important of these is the gut microbiota. So today we will introduce you to the gut microbiota, what roles it plays in our body, and what impact it can have on our health.

The microbiota is the name given uniformly to the hundred trillion micro-organisms commensals residing in our digestive tract, including the stomach, which represents10 times the number of cells in the body itself. However, most of the microorganisms in the large intestine are found in the colon, the longest part of the large intestine. There are 3 main families of bacteria in microbiota: Firmicutes, Bacteroidetes and Actinobacteria, including the famous bifidobacteria.

The microbiota is specific to each person, like a bacterial fingerprint, and is formed from birth up to three years in function of variables that are:

Nutrition (for example, the microbiota will be more diversified if the baby is breastfed)

Mode of delivery (the microbiota will not be the same if the baby is born vaginally or if he born by cesarian section)

Genetic

Geography

Age

Early exposure (to pollution, antibiotics...)

Exercise

The microbiota has an important role in many functions of the body but more particularly on digestion and the immune system.

Digestion:

Everything we eat and drink that is neither digested or absorbed down the digestive tract to the colon and distal colon where it is consumed by the microbiota. The microbiota has a thousand (1000) different species of bacteria which represents 99.97% of the digestive enzymes of our body. This large number of bacteria and enzymes will allow the microbiota to degrade these foods that we are not able to digest alone. The microbiota allows the fermentation of certain carbohydrates such as resistant starch (part of the starch that was not digested), non-amylaceous polysaccharides and certain indigestible oligosaccharides, in shortened chain fatty acid such as acetic acids (C2) propionic (C3) and butyric (C4) by anaerobic bacteria

It also allows the production of vitamins necessary for our body such K1, B1, B2, B8, B12 and it help (especially bacteria) the body break down carbohydrates, proteins and sugars into nutrients.

And finally, it allowing to break down foods that we can’t digest, such cellulose and complex sugars, into simple sugars.

Immune system:

Our microbiota acts on our immune system in different ways. First, it has a barrier effect against pathogens. The intestinal mucosa is a selective barrier that only lets through the elements of interest like vitamins or minerals but prevents the passage of other micro-organisms. the microbiota, by colonizing the mucosa will create a conflict between its bacteria and external pathogens, preventing them from adhering to the surface, passing through the mucosa and colonizing the intestine.

Then it also stimulates immunes cell by immune pathway. The immune pathway occurs when certain microbiota compounds cross the epithelial barrier of the gut and activate immune cells. The latter will produce cytokine hormones that will act either by blood or by nerve.

In addition, it should be noted that shortened chain fatty acids produce by fermentation during digestion serve as food for the cells of the intestinal mucosa and allows their proper functioning. the intestinal mucosa being an important part of the intestinal immune system the production of shortened chain fatty acid has therefore a great importance in the intestinal immune system.

All this happens when the microbiota is in eubiosis, that is when it is in "normal" conditions. if the microbiota is dysbiosis, under "abnormal" conditions it will cause side effect that may appear in the form of illness/disease. (babies born by caesarean section are more likely to have a dysbiosis microbiota)

illness/diseases that may be caused by dysbiosis of the microbiota are for example:

-asthma,

- Alzheimer's,

- obesity,

-type 2 diabetes,

- haemorrhagic recto colitis,

-Crohn's disease,

-autism,

-depression

-irritable bowel syndrome whose real cause is still unknown (not all diseases are mentioned because too many)

We will only go into the details of two diseases, the most commons in this case and which are obesity and depression.

Depression: Studies show that the microbiota and the brain communicate continuously through the gut-brain axis which is made up of two communication

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