A microbe is a microscopic organism—a bacterium, virus, fungus, or protozoan—that is invisible to the naked eye but ubiquitous in our environment and within our own bodies. Their relationship with humans is far from being solely antagonistic: the vast majority of microbes that colonize our bodies are harmless, and in some cases even essential to our health. These are called commensal microbes, and they make up the microbiota—the microbial ecosystem that inhabits our intestines, skin, and oral and vaginal mucous membranes. Only a minority of microbes are pathogenic, meaning they are capable of causing disease.
The distinction between pathogenic and commensal microbes is not always absolute: some normally harmless microbes can become pathogenic when the immune system is weakened (immunosuppression, prolonged antibiotic therapy, chronic stress), a phenomenon known as opportunistic infection. This is why maintaining a balanced immune system is just as important as directly fighting pathogens.
The gut microbiota—formerly known as the intestinal flora —is home to approximately 100,000 billion microorganisms belonging to more than 1,000 different species. Far from being passive, this microbiota plays essential physiological roles:
Dysbiosis—an imbalance in the microbiota—is associated with numerous conditions: recurrent digestive infections, functional bowel disorders, inflammatory diseases, and increased susceptibility to viral and bacterial infections. Probiotics (Lactobacillus, Bifidobacterium) and prebiotics (fermentable soluble fiber) help support and restore this microbial balance, particularly after taking antibiotics, which profoundly disrupts gut bacterial diversity.
Protection against pathogenic microbes relies on two complementary approaches: barrier measures and strengthening the immune system. Barrier measures include washing hands with soap and water (the gold standard), the use of disinfectants and hand sanitizers in high-risk settings, thorough cooking of food, and vaccination against microbes for which an effective vaccine exists (influenza, hepatitis, pneumococcus).
From a nutritional perspective, several micronutrients directly support resistance to microbial infections: vitamin C stimulates the production and migration of leukocytes, vitamin D3 activates macrophages and strengthens antiviral defenses, and zinc is essential for T-cell proliferation.Echinacea (with well-established use according to the EMA) is a recognized herbal remedy for mild viral respiratory infections, taken as a 2- to 4-week course of treatment. Finally, the skin microbiota, just like the gut microbiota, acts as a natural barrier against pathogenic microbes and should be preserved through proper hygiene—neither too harsh nor too lax.
