Declining levels of biological diversity may be contributing to the rise in allergies, asthma, and inflammatory diseases among people worldwide, a new study suggests.
Newly emerging evidence indicates that microbes living on your skin, in your airways, and in your gut protect against inflammatory diseases. Not much is currently known about what determines which microbes those are, however.
The lead author of the new study on this matter was Ilkka Hanski, of the University of Helsinki’s Department of Biosciences. He investigated whether reduced contact with nature and biodiversity changes the composition of commensal skin bacteria and allergen sensitivity.
The study was done on 118 random teenagers living in eastern Finland.
The study found that the subjects living on farms or near forests had more diverse bacteria on their skin and lower allergen sensitivity than subjects living near urban areas, or near large bodies of water.
The most allergen-sensitive subjects, also, had lower diversity of one class of bacteria in particular, gammaproteobacteria. The presence of a specific type of gammaproteobacteria, Acinetobacter, was associated with the expression of an anti-inflammatory marker in the blood of healthy subjects.
The authors of the study interpret this to mean that the presence of gammaproteobacteria in the skin microbiota may enhance the subjects’ immune tolerance.
The study suggests that the increase of inflammatory diseases, such as allergies, is due to a loss in the biodiversity of people’s living environment and their commensal skin bacteria.