Playing in the greenery and litter of the undergrowth of a mini-forest for just a month can be enough to change a child’s immune system, according to an experiment in Finland.
When the educators unrolled a lawn, planted forest undergrowth (such as dwarf heather and blueberries) and allowed the children to look after the crops in planters, the diversity of microbes in the intestines and on the skin of the young children looked healthier in a very short period of time.
Compared to other city children who play in standard urban daycares with meters of sidewalk, tiles and gravel, the 3, 4 and 5 year olds in these green daycares in Finland showed an increase in lymphocytes. T and other important immune systems. markers in their blood within 28 days.
“We also found that the gut microbiota of children who received greenery was similar to the gut microbiota of children visiting the forest every day,” environmental specialist Marja Roslund from the University of Helsinki explained in 2020. , when the research was published.
Previous research has shown that early exposure to green spaces is somehow linked to a well-functioning immune system, but it’s still not clear whether this relationship is causal or not.
The experience in Finland is the first to explicitly manipulate a child’s urban environment and then test for changes in their microbiome and, in turn, in a child’s immune system.
While the results do not hold all the answers, they support one central idea – namely that a change in environmental microbes can relatively easily affect a well-established microbiome in children, giving their immune systems a helping hand. process.
The idea that an environment rich in living things has an impact on our immunity is known as the âbiodiversity hypothesisâ. Based on this hypothesis, a loss of biodiversity in urban areas could be at least partially responsible for the recent increase in immune-related diseases.
“The results of this study support the biodiversity hypothesis and the concept that low biodiversity in the modern living environment can lead to an uneducated immune system and therefore increase the prevalence of immune-mediated diseases,” explained the authors in the study.
The study compared environmental microbes found in the backyards of 10 different urban daycares, caring for a total of 75 children between the ages of three and five.
Some of these daycares contained standard urban courtyards with concrete and gravel, while others took the children to spend daily time in nature, and four had their updated courtyards with grass and undergrowth. foresters.
Over the next 28 days, the children of these last four daycares had time to play in their new yard five times a week.
When the researchers tested their skin and gut microbiota before and after the test, they found improved results compared to the first group of children who played in daycares with less greenery for the same amount of time.
Even during this short duration of the study, the researchers found that microbes on the skin and intestines of children who regularly played in green spaces increased in diversity – a characteristic linked to an overall healthier immune system.
Their results broadly matched the second group of daycare children who had daily outings in nature.
Among the children coming out – playing in the dirt, grass, and among the trees – an increase in a microbe called gammaproteobacteria appeared to strengthen the skin’s immune defense, as well as increase helpful immune secretions in the blood and reduce interleukin content. -17A, which is linked to immune-mediated diseases.
“This confirms the hypothesis that contact with nature prevents disorders of the immune system, such as autoimmune diseases and allergies,” Sinkkonen said.
The results are inconclusive and will need to be verified in larger studies around the world. Yet the benefits of green spaces seem to go beyond our immune system.
Research shows that being outside is good for a child’s eyesight as well, and being in nature as a child is linked to better mental health. Some recent studies have even shown that green spaces are linked to structural changes in children’s brains.
What drives these incredible results is not yet clear. It could be related to changes in the immune system, or something about breathing healthy air, sunning, exercising more, or having greater peace of mind.
Considering the complexity of the real world, it’s really hard to control all the environmental factors that impact our health in studies.
While rural children tend to have fewer cases of asthma and allergies, the available literature on the link between green spaces and these immune disorders is inconsistent.
The research here had a small sample size, found only a correlation, and cannot explain what children were doing outside of daycare hours, but the positive changes observed were enough for Finnish scientists to give advice.
“It would be better if the children could play in the puddles and everyone could dig organic soil,” said environmentalist Aki Sinkkonen, also from the University of Helsinki.
“We could take our kids out into the wild five times a week to impact germs.”
The changes are simple, the harms small, and the potential benefits large.
Connecting with nature from childhood is also good for the future of our planet’s ecosystems. Studies show that kids who spend time outdoors are more likely to want to become environmentalists as adults, and in a fast-paced world, that’s more important than ever.
Just make sure everyone is up to date with their tetanus vaccinations, Sinkkonen said.
The study was published in Scientists progress.
An earlier version of this article was published in October 2020.