Want to Boost Your Kids Immune System? Let them Play in the Dirt!

An ambitious science experiment conducted in Finland proved that children’s immune systems can be boosted simply by being more in contact with greener environments from an early age.

“There is this ‘biodiversity hypothesis,’ that in the absence of diverse environmental microbiota, people are more likely to get immune-mediated diseases,” says Aki Sinkkonen, an evolutionary ecologist at the Natural Resources Institute Finland. “But no one had really tested this with children.”

Seventy-five children ages 3 to 5 took part in the one-month long experiment. For uniformity reasons, all kids had similar families, pets, habits, and diet. Plus, they were fed three identical meals daily. Kids played for 90 minutes each day on a forest-supporting soil (scruffy shrubs, shin-high berry bushes, wispy meadow grasses, and velvety mounds of moss) that contained 500 times as many microbes as an urban sandbox.

Skin and blood samples were taken before and after the experiment: in that short period of time, children had more diverse communities of friendly bacteria living on their skin than the negative controls. The sooner microbes are introduced to an immune system, the sooner it develops to decipher what is dangerous and what isn’t. “I think that every child should have access to this kind of environment. They have more to win and more to lose.”