Should we expose our children to bacteria?

A recent research article from The New England Journal of Medicine (02/24/2011) studied two groups of children.  One group of children were raised on a rural farm, and the other group did not consist of farm-raised children.  The study included 16,511 children between the ages of 6 and 13.  Scientists discovered that children living on farms had a 25% lower prevalence rate of asthma than children not raised on farms.  They attributed the difference in asthma rates to the fact that indoor microbial exposure is much more common and diverse in the farming environment than in the non-farming environment.  The risk of asthma decreased significantly with an increase in the number of detectable bacteria and fungi.  This supports the idea that the greater diversity of microbial exposure among children is associated with protection from the development of asthma.  The reason for this is because microorganisms such as bacteria and fungi trigger the innate immune system, creating a prominent type 1 helper T cell response.  Children with asthma and other auto-immune diseases display a predominance of type 2 helper T cells.  (One major cause of a predominant type 2 helper T cell response is antibiotic usage prior to the age of 2).  Therefore, this study suggests that exposing our children to microorganisms will create balance in their immune system and lead to protection against auto-immune diseases such as asthma.