Finally, someone who’s confirming the health benefits of outdoor play for children:

Let the children play ..

.. 🗻 Outside!  🌲 In Nature 🌲!

 in the dirt 🐷 !

Let them..

..besmirch each other!

Let them..

..role in it!

Let them..

.. eat it!

Why, because in this way micro organisms get ingested, which help to strengthen the gut flora and stimulate the immune system so that the latter has more than enough on its to-do list to not turn to the body’s own molecules.

Data shows that children, who have grown up at farms and who consequently have been exposed to a wide range of micro organisms, are much less sensitive to allergies and asthmas..

Similar ideas, including the benefits of eating fermented foods, are explored in Dr Shetreat-Klein’s book called: Healthy Food, Healthy Gut, Happy Child

Another aspect of being in contact with soil bacteria is that these also stimulate serotonin production in the brain. Serotonin is a molecule that contributes to feelings of happiness and well-being.

One of the soil bacteria that stimulates the production of serotonin is Mycobacterium vacae. When antigens from this bacteria were brought into the throat of mice, it lead to activation of the local (peripheral, and not in the blood) immune system through an increase in the levels of the cytokines interleukin-1β and tumor necrosis factor-α.  This increase seemed to be connected with the activation of type II serotonergic neurons in particular.  These neurons seem to have direct connections to the limbic system (responsible for emotion) and in that way may be able to influence mood directly.

To evaluate whether their behavior could be affected, mice were  subjected to a forced swim test (in which they have to swim in a tank from which they cannot escape. Mice with symptoms of depression will be immobile for a longer period of time and this behavior is reduced when they are given antidepressants).

In contrast to control treated mice, the mice that were pre-immunized with M. vaccae had a reduced immobility, indicating less anxiety. The effect was no longer visible after 36h.