Within 30 days of playing in the forest soil and leaf litter, Finnish preschoolers had increased T-cell counts and far more diverse gut bacteria
In a fascinating experiment, Finnish researchers recreated the environment of a forest floor on the playgrounds of four urban daycare centers.
They covered the play-yards with forest soil, moss, meadow grasses, dwarf heather, blueberries and crowberries and installed planter boxes for annual garden crops.
Daycare workers instructed the preschool-aged kids to play in the greenery and soil for an hour and a half a day for a month.
Their gut and skin microbes were analyzed before and after the experiment and compared with those of children from normal urban daycare centers with standard sterile play-yards.
After just 28 days, the diversity of their intestinal and skin bacteria increased dramatically, as did their T-cell counts and other important immune markers in their blood.
“The results of this study support the biodiversity hypothesis and the concept that low biodiversity in the modern living environment may lead to an un-educated immune system and consequently increase the prevalence of immune-mediated diseases,” the authors write.
One of the microbes acquired from the forest floor was gammaproteobacteria, which appeared to boost the skin’s immune defense, as well as increase helpful immune secretions in the blood and reduce the content of interleukin-17A, which is connected to immune-transmitted diseases.
“This supports the assumption that contact with nature prevents disorders in the immune system, such as autoimmune diseases and allergies,” says research scientist Aki Sinkkonen, who led the study.