Weakens excessive cleanliness our immune system?

Today we are much better for hygiene than before. The only good thing?

Not even very thorough cleanliness weakens the body's immune system, it is very important to avoid infectious diseases.

Hygiene is now much better than before, but at the same time, the number of allergy sufferers has exploded in the western world. It has given birth to a hypothesis that a sterile environment increases the risk of developing allergies, because the immune system is not kept in the form of such infectious diseases.

It therefore runs amok and react strongly to harmless substances. The hypothesis are not proven, and other studies suggest the contrary that such repeated influenza infections increase the risk of developing asthma.