hygiene hypothesis

The hygiene hypothesis suggests that reduced exposure to microorganisms in early childhood, due to factors like smaller family sizes and increased hygiene, may lead to a higher risk of developing allergies, autoimmune disorders, and chronic inflammatory diseases. This is because exposure to diverse microbes helps the immune system develop proper regulatory mechanisms, preventing inappropriate responses to harmless substances. Limited contact with these natural environmental factors, particularly in urban settings, is associated with an increased prevalence of these conditions. The immune system protects against infection but can also cause disease when it malfunctions, either by failing to prevent infection or by attacking the body's own antigens.123