A Finnish study suggests that increasing urbanization, and lower exposure to nature, has led to increased rates of allergies and asthma in children. A possible warning sign about changing lifestyles.
Research undertaken by the Department of Biosciences, University of Helsinki, led by Ilkka Hanski, has studied if reduced human contact with nature and biodiversity affects rates of asthma and other allergies.
According to the research summary, the researchers specifically studied whether reduced contact with nature influences the composition of the bacteria found on the skin and if this affects allergen sensitivity. The study took a sample of 118 teenagers living in eastern Finland.
E-science notes that the scientists found that subjects living on farms or near forests had more diverse bacteria on their skin and lower allergen sensitivity when compared to the teenagers who lived in areas with less environmental biodiversity, such as urban areas.
The issue of allergen-sensitive related to one type of bacteria. Further studies showed that these teenagers had lower diversity a type of bacteria called gammaproteobacteria (particularly a bacterium called Acinetobacter), on their skin when compared to the more 'healthy' teenagers. The presence of Acinetobacter was associated with the expression of the anti-inflammatory marker IL-10 in the blood of the 'healthy' teenagers. That suggested to the scientists that gammaproteobacteria in the skin microbiota probably enhances immune tolerance.
The findings suggest that the increasing prevalence of inflammatory diseases like asthma may be associated with the changing biodiversity of the environment.
The research paper was:
Environmental biodiversity, human microbiota, and allergy are interrelated. Ilkka Hanski et al. Proceedings of the National Academy of Sciences, May 7, 2012