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Playtime -

When it comes to how children spend their time, the various benefits of playing outside are well established.

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The great outdoors -

By ditching electronics and heading outdoors, kids have the opportunity to get some exercise, as well as gain some valuable learning experiences.

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The modern reality -

In today’s urban world, there are many children who never play outside, and those who do often have parents who don’t like them getting dirty.

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The downside -

Of course, it can be a pain for parents when their kids come home covered in mud, particularly if they carry it through the house.

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The upside -

New research suggests, however, that exposure to dirt can have important benefits for our health. Of course, this idea is not new.

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Hygiene hypothesis -

During the late '80s, there emerged the "hygiene hypothesis." In a nutshell, the idea was that childhood infections were important for training the immune system.

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The idea in a nutshell -

It was thought that a reduction in childhood infections over the course of the 20th century had compromised people’s immune systems and caused them to overreact to the slightest stimulation.

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Falling out of favor -

This hypothesis quickly fell out of favor, however, since experts believed it discouraged important hygiene practices, such as handwashing.

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Problematic -

Indeed, the hygiene hypothesis has been described as “quite problematic from a public health perspective.”

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Caveat -

That does not mean, however, that all organisms we come across outside are detrimental to our health. In fact, quite the opposite is true.

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Friendly bacteria -

Experts now believe that the non-infectious organisms we come into contact with while in nature are very beneficial to our immune system.

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Old friends -

Referred to by scientists as “old friends,” these organisms have been around throughout our evolutionary history and are generally harmless.

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Learning to moderate -

They are believed to be beneficial to our immune system because they train it to moderate its own activity, rather than overreacting to a potential invader.

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Evidence -

There is a growing body of evidence that supports this idea. For example, studies show that people who grew up on farms are less likely to develop asthma, allergies, or autoimmune disorders, such as Crohn’s disease.

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Childhood exposure - This is because their childhood exposure to a wider range of organisms helped their immune systems learn to self-regulate more effectively.

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Stress -

It is even thought, somewhat amazingly, that friendly organisms can help regulate our response to stress.

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Evolutionary stress response -

Whenever we feel vulnerable or threatened, the level of inflammation in our bodies goes up. Our bodies evolved this way to protect us against whatever threat we were facing.

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Stress in today's world -

We may have evolved this way, but the reality is this inflammation is less useful for the kinds of stressors we are exposed to today.

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The problem with inflammation -

In fact, chronic inflammation can have serious consequences for our long-term health and can contribute to a number of conditions, including depression.

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Research -

Research shows that children who grew up in a rural setting tend to have a reduced inflammatory response to stressful events, such as public speaking.

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Control factors -

This even remained true when researchers controlled for other factors, such as the children’s socioeconomic status.

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What this all means -

With all this interest in friendly bacteria, researchers are looking at ways to encourage our children to have greater contact with nature.

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Forest bathing -

One discipline that is gaining in popularity is "forest bathing," the act of talking a gentle, meditative walk through the woods.

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Atopic dermatitis - symptom relief -

This may not sound particularly child-friendly, but in fact forest bathing has been shown to improve symptoms in children who suffer from atopic dermatitis.

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Friendly organisms -

It is likely that by touching the leaves and the soil of the forest as they walked, the children picked up friendly organisms that enriched their skin microbiomes.

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Finnish initiative -

In Finland, one initiative attempted to bring nature to the children. In four day-care centers, researchers replaced the schoolyard asphalt and gravel with soil vegetation transplanted from the forest.

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Gardening at school -

The children were then given planting boxes for gardening, which encouraged further contact with the soil and all its friendly microbes.

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Impact on immune function -

After just one month, the children showed improved immune function, as well as signs of heightened microbial diversity on their skin and in their guts.

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Impact on inflammation -

The proportion of anti-inflammatory molecules in their blood plasma had also increased (which indicates a better regulated immune system).

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All in all -

Getting a little dirty, then, is not a bad thing for a child. Playing outside is to be encouraged!

Sources: (BBC) (Healthline)

See also: The sustainable cities made of mud

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