General Definition of the Gut Microbiome
The gut microbiome, also known as gut flora, refers to the microorganisms found in the digestive tract, including the stomach and intestines. It is the most significant microbiome in terms of population, consisting of 100 trillion microorganisms, which is ten times the number of cells in the body, and weighs approximately 2 kilograms.
What is the Composition of the Gut Microbiome?
The gut microbiome is composed of 90% bacteria. Although the composition varies between individuals, four bacterial phyla (or groups) are consistently present in all individuals: Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. These form the core of the microbiome.
How Does the Gut Microbiome Develop?
Development of the Microbiome Over a Lifetime
The gut microbiome begins to form at birth. Its composition is influenced by several factors throughout life, which can disrupt its bacterial diversity. First, at birth, the microbiome depends on how the baby is delivered—whether by vaginal birth or C-section—and on gestational age. During a traditional birth, the newborn comes into contact with the mother's vaginal microbiome.
These vaginal bacteria are the first to colonize the newborn’s digestive system. However, during a C-section, the baby first encounters the skin microbiome and is not exposed to the vaginal bacteria. Additionally, differences arise depending on whether the baby is breastfed or formula-fed.
This discrepancy causes variations in bacterial composition. The weaning process also marks a shift in the bacterial composition of the gut microbiome. From birth to weaning, typically around 2.5 years of age, the gut microbiome is very unstable and, therefore, vulnerable.
Factors Influencing the Gut Microbiome
After 2.5 years of age, the microbiome stabilizes and becomes similar to that of an adult. However, it continues to evolve throughout life when exposed to factors such as antibiotics, illnesses, stress, diet, geographic location, health status, etc.
For example, antibiotics significantly reduce the bacterial diversity in the microbiome, weakening the body’s defense mechanisms against pathogens.
Imbalances in gut flora, more commonly known as dysbiosis, are linked to diseases such as neurodegenerative disorders (Alzheimer's, Parkinson’s), metabolic diseases (diabetes, obesity), cancers, allergies, and more. Dysbiosis is characterized by an imbalance in the gut microbiome and is often the result of reduced bacterial diversity, favoring the growth of pathogenic species.
What Are the Roles of the Gut Microbiome?
The gut microbiome plays several essential roles in the human body. First, it helps protect the body by defending against pathogens. It is also involved in metabolic functions, aiding in the absorption and production of nutrients. Finally, it plays a key role in the immune system.
There is a real symbiosis between the microorganisms of the gut microbiome and the host, ensuring good health—the host and gut flora cannot thrive without each other.
How Can You Analyze Your Gut Microbiome?
Today, it is possible to analyze the genes present in the bacteria of a stool sample to determine the composition of your gut microbiome. Metagenomic analysis, which studies the entire set of bacterial genomes, can reveal bacterial richness, an individual’s enterotype, the balance of gut flora, the distribution of bacterial phyla (or groups), short-chain fatty acid production, and more.
How Can You Act on the Microbiome?
Given its key role in maintaining the body’s equilibrium, it is essential to preserve the microbiome. Diet plays a significant role in maintaining the bacterial diversity and balance of the microbiome. There are several options available today to protect and nurture the microbiome.
A Varied and Balanced Diet
First, a varied and balanced diet, rich in fiber, promotes bacterial diversity. Additionally, consuming fiber helps protect against cardiovascular diseases and certain cancers, such as colorectal or esophageal cancer.
A Diet Rich in Prebiotics
Consuming prebiotics is beneficial for the host because they are non-digestible substances that promote the development and activity of beneficial gut bacteria. Different sources of prebiotics include inulin, FOS (fructo-oligosaccharides), GOS (galacto-oligosaccharides), and fructans, which can be found in vegetables (artichokes, broccoli, leeks, tomatoes), legumes (kidney beans, lentils, chickpeas), fruits (bananas, apples, dried fruits), roots (chicory, parsnips, Jerusalem artichokes), and nuts (almonds, walnuts, pistachios).
A Diet Rich in Probiotics
A diet rich in probiotics can also help enrich the gut microbiome. Probiotics are live microorganisms that provide health benefits by fighting against pathogenic microorganisms in the intestine. Probiotics include bacteria such as Lactobacillus, Bifidobacteria, and Streptococcus, found in foods like yogurt, kefir, and sauerkraut.
Fecal Transplants
Finally, fecal transplants can be performed by a doctor to treat a limited number of pathologies. This involves transferring stool from a donor into the digestive tract of a recipient to restore the altered gut flora. Fecal transplants must be conducted under strict medical supervision, as they pose serious health risks.
Conclusion
In conclusion, the gut microbiome is an essential organ that must be preserved to ensure it performs its functions and maintains overall health. When the microbiome malfunctions, dysbiosis occurs. Today, it is possible to prevent dysbiosis by addressing factors such as diet. Microbiome analysis, like the one offered by Nahibu, is widely used to detect a reduction in gut microbiome diversity and provide personalized nutritional guidance to address the issue. A varied and balanced diet helps maintain microbiome diversity.
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