Study: Adolescents Who Spend Time Outdoors Develop Less Allergies than Urbanites
OutdoorHub Reporters 05.08.12
An apple a day keeps the doctor away, but spending time outdoors at a young age keeps the allergies away, or so they say. They being the authors behind a recent research project that looked into the connection between early exposure to nature and biodiversity (including environmental microbiota) and how that exposure affected an individual’s tolerance to allergens.
Research published in the Proceedings of the National Academy of Sciences (PNAS) showed that children who spent a significant amount of time in natural environments develop and maintain epithelial (protective animal tissue) cell integrity and tolerance, meaning they are more tolerant to chronic inflammatory disorders such as allergic and autoimmune diseases.
“It is predicted that by 2050, some two-thirds of the global human population will live in urban areas with little green space and limited contact with nature and biodiversity. At the same time, an increasing fraction of the urban population will suffer from chronic inflammatory disorders, of which allergic and autoimmune diseases are prime examples.” From page 1 of the study (pdf).
It was also noted that children who grow up in a farming environment are especially de-sensitized to allergens, while those living in urban areas suffer more from inflammatory diseases and are over-sensitive to allergens.
The study, titled Environmental Biodiversity, Human Microbiota and Allergy are Interrelated, randomly sampled 118 adolescents who either lived in a small town, villages of different size or isolated houses within a 100 by 150 km (62 x 93 mile) region in eastern Finland.
The research team found that those adolescents who spent time on farms or near forests had more diverse bacteria on their skin and also showed less sensitivity to allergens. The researchers pointed out one type of gammaproteobacteria, called Acinetobacter, that was “strongly linked to the development of anti-inflammatory molecules.”
“Basically, our study showed that the more you had of this particular gammaproteobacteria on your skin then you had a immunological response which is known to suppress inflammatory responses ( to pollen, animals etc),” said co-author Dr. Ilkka Hanski from the University of Helsinki in an interview with the BBC.
Dr. Hanski said there was a higher prevalence of gammaproteobacteria in vegetative environment, such as forest and agricultural land, much more so than in developed areas and water bodies. Hence, urbanizaion inhibits people from interacting with the biodiversity of the natural environment making it difficult for people to develop immunity to allergens so as not to over-react to them by means of allergic symptoms such as coughing, sneezing, itchy eyes, throat constriction, and so on.
Dr. Hanski admits it’s not an option to reverse the global trend of urbanization, but that the need to reserve space for natural and green spaces must be included in city planning.
In a separate study published on April 16, 2012 in the Journal of Allergy and Clinical Immunology found that Amish children raised on rural farms in northern Indiana have lower allergy and asthma rates than other farming children, namely Swiss farm children, who are known to be relatively free from allergies.
The Reuters report said that may be from possible factors of the “farm effect,” the theory that farm-raised children are more protected from asthma and allergies than city dwellers. Even though the study did not conclude why Amish children are more likely to be immune, the authors did allude that it may because of various factors such as exposure to microbes, contact with cows and drinking cow’s milk.
