Hygiene Hypothesis
Print This PageAllergies to pollens, foods, and animals. Asthma. Eczema. Why do so many more children and adults than ever before suffer from these ailments?
No one knows for sure. One possible explanation is the "Hygiene Hypothesis." As a society, we are much cleaner and more hygienic than prior generations. Some might say we are obsessed with cleanliness. Our homes are built tighter to keep drafts out. We keep our floors, tables, and counter tops clean. We don't allow our children to track dirt through the house. We emphasize hand washing and avoidance of germs. We take daily showers or baths. By keeping dirt out of our lives, we reduce our exposure to bacteria and viruses that can make us sick.
This may seem like a good thing. But our immune system exists to protect us from microbes that cause illnesses. What happens if our immune systems are not under a constant barrage by these microbes? According to the Hygiene Hypothesis, in the absence of germs, the immune system looks for other things to attack. It goes for invaders that don't make us sick: pollens, dust, molds, foods and animal dander. The resulting immune response is what causes our symptoms and can trigger asthma and eczema.
It is possible that we are too clean. There is evidence that children who grow up on farms have a lower incidence of allergies than those who grow up in the city.
Maybe there is something to the ten-second rule!