14/02/2026
For a long time, microbes were seen mainly as enemies. That view changed when large microbiome studies revealed something surprising. The human body hosts roughly as many microbial cells as human cells. These bacteria, viruses, and fungi live mostly in the gut but also on the skin and in the mouth. Rather than causing harm, many of them perform essential jobs. They help digest fibers humans cannot break down, produce vitamins, and guide how the immune system learns what to attack and what to tolerate. Some even release chemical signals that interact with the brain, influencing mood and behavior.
One of the most striking discoveries was how personal the microbiome is. Each person carries a unique microbial pattern shaped by diet, environment, medications, and early life exposures. Even identical twins do not share the same microbial makeup. Researchers have linked certain microbial patterns with obesity, gut inflammation, allergies, and mental health conditions. These links suggest microbes do not just reflect health, they help shape it.
This insight has led to new therapies. Transferring gut microbes from healthy donors has successfully treated stubborn infections and is now being studied for other diseases. The body emerges not as a lone organism, but as a complex ecosystem built on cooperation.