What is the hygiene hypothesis?

The hypothesis that child’s environment can be too “clean”.

It is proposed that in very  “clean” environments, where children aren’t exposed to germs and certain infections, their immune system does not develop properly and they become more susceptible to allergic diseases. Therefore it is important young children are encouraged to play outside, eat different types of food and interact with other children and adults to reduce their risk of developing allergies later in life.