Although it has long been known that the human intestine contains an astronomical number of intestinal bacteria, the functions of these microorganisms in human health continue to surprise us. In fact, several recent discoveries have helped greatly advance our understanding of the tremendous impact these “friendly” bacteria have on our health.
The bacteria of the intestinal flora have the ability to break down fiber through the fermentation process and thereby produce several health-promoting nutrients at the same time (vitamins B9 and K, short-chain fatty acids). However, recent discoveries indicate that this digestive function is just one facet of the many roles these “friendly” bacteria play in the body. For example, we know that the presence of gut bacteria is essential for the development and maintenance of the immune system against disease-causing bacteria or viruses.
From the belly to the brain
Recently, researchers made the amazing discovery that the action of bacteria in the gut flora is not limited to the digestive system, but can also affect the brain. In fact, the researchers observed that the composition of the gut flora had an impact on the levels of certain cerebral neurotransmitters and could modulate certain behaviors such as anxiety, stress and depression. So it seems that the composition of the gut flora plays a leading role in maintaining physical and mental health.
Diet affects the quality of gut bacteria
Another study suggests that this composition of the gut flora is strongly modulated by the type of diet. For example, people who eat foods typical of Western countries that are rich in animal proteins and fats have a flora mainly composed of bacteria of the genus Bacteroides. In humans, whose diet consists mainly of plants rich in plant fibers, this flora mainly contains the genus Prevotella.
Since the Western diet is associated with an increased incidence of several chronic diseases, these observations suggest that these differences in gut flora composition may play an important role in the development of these diseases. The positive influence of a plant-rich diet would therefore not only be due to a direct effect of secondary plant substances, vitamins and minerals on physiological functions, but also to the development of an intestinal flora with beneficial effects. We are what we eat, even when it comes to the bacteria that live in our gut!
A diet rich in probiotics promotes good bacteria
Under normal conditions, the composition of the intestinal microflora is very stable and changing it requires a long-term change in dietary habits. However, a recent study suggests that it is possible to modify the activity of this flora with fermented products rich in “friendly” bacteria called probiotics. The researchers observed that regular consumption of a product containing several strains of probiotics (bifidobacteria, lactobacilli, lactococci) did not significantly alter the composition of the flora, but nevertheless caused a notable increase in the breakdown of xylooligosaccharides, a very common class of carbohydrates Plant.
This effect is interesting because other studies have shown that this breakdown of xylooligosaccharides is associated with protection of the intestinal mucosa and a reduction in the development of colon cancer. Regular consumption of probiotic products is therefore an easy way to improve the “performance” of the gut bacteria, while allowing them to positively influence the proper functioning of the body.
Well done JA et al. Ingestion of Lactobacillus strain regulates emotional behavior and central GABA receptor expression in a mouse via the vagus nerve. proc. national Acad. science USA, 108: 16050-55.
Wu GD et al. Linking long-term dietary patterns to gut microbial enterotypes. Science;334:105-18.
McNulty NP et al. The impact of a consortium of fermented milk strains on the gut microbiome of gnotobiotic mice and identical twins. Science Transl Med;3:106ra106.
* Presse Santé strives to convey health knowledge in a language accessible to all. In NO CASE can the information given replace the advice of a doctor.
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