Researchers in Finland conducted an experiment and found that exposure to greenery changed children’s immune systems.
- Daycare centers created a ‘forest floor’ where children could play and care for plants.
- After 28 days, the children exposed to greenery showed increased T-cells among other vital immune markers.
- Environmental ecologist Aki Sinkkonen: “This supports the assumption that contact with nature prevents disorders in the immune system, such as autoimmune diseases and allergies.”
The study looked at 10 different urban daycares which looked after a total of 75 children.
It compared the environmental microbes which were found in the yards of the ten daycares. The 10 daycares can be divided into three groups:
- Daycares with concrete and gravel yards.
- Daycares that take children out for daily nature time.
- Daycares (4) with grass and forest undergrowth in the yards.
The experiment took 28 days and looked at a total of 75 children, ages 3-5. Over the course of the experiment, the children in the last group were given time to play in their new green yard five times a week.
Researchers found improved results in the final group of children.
When they tested the microbiota of children’s skin and gut before and after the trial, researchers discovered improved results in the children from the third group compared to those in the first. Moreover, they found that microbes on the skin and guts of the children who played in greenery had increased in diversity. While the results of the third group differed greatly from the first group, they largely matched the second group which had daily nature outings. Environmental scientist Marja Roslund from the University of Helsinki commented on the study’s findings:
We also found that the intestinal microbiota of children who received greenery was similar to the intestinal microbiota of children visiting the forest every day.
This is the first study to explicitly manipulate a child’s urban environment and test for changes in their microbiome.
While prior research has found that early exposure to nature is linked to a stronger immune system, researchers are not certain if the relationship is causal. The ‘biodiversity hypothesis’ is the notion that living in a green environment that is rich in living things can impact our immunity. Based on the biodiversity hypothesis, it is believed that a loss of biodiversity in cities and urban areas can be – at least partially – responsible for the recent increase in immune-related illnesses. According to the study’s authors:
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 research had a small sample size and only found a correlation.
As the study had a small sample size and cannot account for what children were doing outside of their time at the daycare, the findings are not conclusive. Nevertheless, they do support the leading idea that a change in environmental microbes has the power to easily affect a well-established microbiome in children. Environmental ecologist Aki Sinkkonen commented on the research saying that it “supports the assumption that contact with nature prevents disorders in the immune system, such as autoimmune diseases and allergies.” Furthermore, Sinkkonen advised:
It would be best if children could play in puddles and everyone could dig organic soil […] We could take our children out to nature five times a week to have an impact on microbes.