Why is microbiome diversity important?

The intestine is the largest immune organ in the human body — it contains about 70–80% of all immune cells. This is explained by the fact that the intestine is constantly in contact with a vast number of antigens: from food, bacteria, viruses to metabolic products.

To control this flow, a powerful immune system, called gut-associated lymphoid tissue (GALT), is developed in the intestinal mucosa.

Why is the microbiome important for immunity?

The gut microbiome — is a collection of trillions of microorganisms, including bacteria, viruses, and fungi, that live in symbiosis with humans. It plays a key role in training and modulating the immune system. Below are the main mechanisms:

Training the immune system. In newborns, the immune system is still "tuned randomly." As the body matures, it learns to distinguish pathogens from harmless antigens, and the microbiome is an important "trainer." Beneficial bacteria stimulate the production of regulatory T cells, which help prevent autoimmune reactions.

Maintaining the barrier function of the intestine. The microbiota stimulates the production of mucin, immunoglobulin A (IgA), and antimicrobial peptides. This strengthens the intestinal mucosa and prevents pathogens from entering the bloodstream.

Regulating inflammation. The diversity of the microbiome contributes to the balance between pro-inflammatory and anti-inflammatory responses. For example, the bacteria Faecalibacterium prausnitzii produce butyrate — a short-chain fatty acid that suppresses inflammation.

Competing with pathogens. The richer the microbiome, the less "food" and space there is for pathogens. This is called colonization resistance: beneficial microbes prevent harmful bacteria from establishing themselves.

What happens when microbiome diversity decreases?

• Increased intestinal permeability (leaky gut syndrome)
• Activation of inflammatory pathways (via TLR — toll-like receptors)
• Disruption of food tolerance
• Increased risk of autoimmune and allergic diseases (Crohn's disease, type 1 diabetes, asthma, etc.)

How to maintain a diverse microbiome?

• Diverse diet, especially rich in fiber (vegetables, greens, legumes)
• Fermented products (kefir, yogurt, sauerkraut)
• Limiting antibiotics
• Spending time in nature, contact with animals
• Minimizing ultra-processed foods

Thus, a diverse gut microbiome — is not just "beneficial bacteria," but a complete immune ecosystem on which human health depends.