An experiment by the University of Helsinki took ordinary playgrounds, removed the pavement and gravel, and covered them with grass, moss, and forest soil. The instruction for the children was simple: play as usual.
In just 28 days, the analyses showed something the researchers did not expect to find so quickly: a significant increase in beneficial bacteria on the skin and a higher concentration of regulatory cells in the blood, two direct indicators of a more robust immune system with a lower predisposition to allergies and autoimmune diseases.
Everyday contact with the soil’s biodiversity had reprogrammed the body’s defenses in less than a month. The study does not talk about medications or diets. It talks about dirt.