Why is the gut microbiome so important for our health?

The microbiome: a genuine forgotten organ

The gut microbiome refers to all the microorganisms living naturally in our digestive tract. It includes tens of trillions of bacteria, but also viruses, yeasts and other microorganisms that live in balance with our body.

Far from being mere « passengers », these microorganisms perform essential functions:

• digestion of certain foods;
• production of vitamins;
• synthesis of beneficial metabolites;
• protection against pathogenic bacteria;
• regulation of the immune system;
• participation in brain function through the gut-brain axis.

Today, many researchers consider the microbiome to be a genuine functional organ.

Is there a perfect microbiome?

Contrary to a widespread belief, there is no universal definition of an « ideal » microbiome. Each person has a unique bacterial composition, comparable to a fingerprint. Two perfectly healthy people can have very different microbiomes.

Researchers are now more interested in the functions the microbiome performs than in the bacterial species themselves. We now speak of a « functional core », that is, a set of essential biological functions that can be carried out by different bacteria depending on the individual.

Fibre: the fuel of the microbiome

Dietary fibre is the main energy source for many gut bacteria. Unlike ordinary carbohydrates, it is not digested in the small intestine. It reaches the colon, where it is fermented by the microbiome.

This fermentation produces short-chain fatty acids, notably butyrate, a particularly important molecule. Butyrate:

• nourishes the cells of the colon;
• strengthens the intestinal barrier;
• has anti-inflammatory properties;
• helps regulate the immune system;
• may help reduce the risk of certain metabolic diseases.

Why is dietary diversity essential?

Specialists now stress a fundamental point: it is not only the quantity of fruit and vegetables that matters, but also their diversity. Each plant species provides specific fibres and compounds that feed different bacterial populations.

The recommended goal is to eat around 30 different plants per week, including:

• fruit;
• vegetables;
• legumes;
• whole grains;
• nuts;
• seeds;
• aromatic herbs.

The greater this diversity, the richer and more resilient the microbiome tends to be.

Ultra-processed foods: a factor of imbalance

Conversely, some ultra-processed foods may disrupt the intestinal balance. Research carried out notably at the Institut Pasteur shows that certain food emulsifiers are liable to alter the microbiome.

In some people, these changes could promote low-grade chronic inflammation, implicated in several diseases such as:

• type 2 diabetes;
• obesity;
• certain inflammatory bowel diseases.

However, the response is not identical in all individuals. Some people seem very sensitive to these additives, while others show greater resistance. This variability remains an important topic of research today.

Microbiome tests: are they really useful?

For a few years now, several companies have offered gut microbiome analyses to personalise nutrition. These tests use metagenomics technologies, which make it possible to directly analyse the DNA of the bacteria present in stool.

These tools offer an interesting snapshot of the microbiome. However, current science does not yet allow a reliable personalised diet to be built from these analyses alone.

Researchers agree that these tests remain mainly research or exploratory tools. To date, they do not make it possible to precisely determine which foods individually suit each person.

What we know today

Scientific knowledge nonetheless allows several solid recommendations to be made:

• favour a plant-rich diet;
• vary fibre sources;
• regularly eat legumes and whole grains;
• limit ultra-processed foods;
• engage in regular physical activity;
• preserve good sleep;
• avoid antibiotics when they are not essential.

These habits promote a diverse and functional microbiome.

What science cannot yet assert

At present, it is not possible to:

• define a « perfect » microbiome;
• identify an ideal bacterial composition valid for everyone;
• build a personalised diet from a stool analysis alone;
• accurately predict disease risk from the microbiome alone.

Research is progressing rapidly, but many questions remain open.

The Valorian analysis

The gut microbiome represents one of the most promising fields of modern medicine. Its influence goes far beyond digestion and also concerns the immune system, metabolism, chronic inflammation and, probably, healthy ageing.

However, it is essential to distinguish established scientific data from commercial promises. To date, the best evidence primarily supports a varied, plant-rich, minimally processed diet, rather than ultra-personalised nutrition approaches based on a simple microbiome test.

At Valorian, we consider gut health to be a fundamental pillar of preventive medicine and longevity medicine. Recommendations must be based on robust scientific evidence and integrated into comprehensive patient care.