“The aim of cleaning, then, should be to reduce bacteria numbers—but not to zero. Even harmful bacteria can be good for us when the immune system uses them for training. A couple of thousand Salmonella bacteria in the kitchen sink are a chance for our immune system to do a little sightseeing. They become dangerous only when they turn up in greater numbers. Bacteria get out of hand when they encounter the perfect conditions: a protected location that is warm and moist with a supply of delicious food.” HealthHygiene Book:Gut: The Inside Story of Our Body's Most Underrated Organ Source: Gut: The Inside Story of Our Body's Most Underrated Organ
“When we clean obsessively we do indeed get rid of everything, both bad and good. This can not be a good kind of cleanliness. As it happens the higher the hygiene standards in a country the higher that nations incidents of allergies and autoimmune diseases. The more sterile a household is the more its members will suffer from allergies and autoimmune diseases. Thirty years ago about 1 person in 10 had an allergy. Today that figure is 1 in 3. At the same time, the number of infections has not fallen significantly. This is not smart hygiene.” ScienceResearchHygieneAllergies Book:Gut: The Inside Story of Our Body's Most Underrated Organ Source: Gut: The Inside Story of Our Body's Most Underrated Organ