To be healthy we need exposure to microbes

In recent decades, especially in wealthy countries, health problems caused by the immune system reacting inappropriately have risen sharply. Instead of focusing only on harmful infections, the immune system increasingly attacks harmless substances like pollen, peanuts, or pet dander (allergies), targets the body’s own tissues (autoimmune diseases), or drives chronic gut inflammation (inflammatory bowel disease). Many people also show a persistent, low-level inflammatory state linked to higher risks of heart, metabolic, and mental health issues.

A major reason for this immune dysregulation is reduced exposure to microorganisms that help guide the development of organs such as the gut and brain and, crucially, “educate” the immune system and regulate its responses. This text explores how our need for microbial exposure evolved, which microbes are important, how they support health, why modern life limits our contact with them, and what can be done to address this deficit.