First read the article from the popular press below then read details of the research on which it is based. The research findings bear virtually no resemblance to the advice given. And the advice is dangerous. There are many ailments that can be acquired through contact with dirt -- the terrifying necrotizing fasciitis for a start

The popular article fails to mention: 1). That the research concerns mice -- and the large differences between the mouse and human brains render the generalizability of the findings to humans unknown;

2). The effect is temporary; the mice actually had to be FED the live bacterium to get the results;

3). The effect on mood, making the mice less cautious, could have its own dangers;

4). It may only be the effect on mood rather than any increase in ability that got the mice through the maze more quickly. Mice are naturally very hesitant and cautious

Sadly, the willingness of the researchers to speculate seems to be largely at fault for the dangerous advice. Two articles below:

Playing in the dirt makes kids smart

PARENTS, step away from the baby wipes and put that hand sanitiser away - eating dirt could actually make your child smarter.

Research published in the current issue of Kidsafe NSW's playgrounds newsletter shows the positive side of a soil-borne bacteria that is likely to be inhaled when children are playing outside.

Academics discovered that mice that were fed the dirt bacteria Mycobacterium vaccae navigated complex mazes twice as fast as those which were not.

The research, presented in the US earlier this year, was welcomed by Kidsafe NSW Playground Advisory Unit program manager Kate Fraser as another reason kids should be encouraged to get outside and get dirty.

"Over the past few years terms like 'cotton wool kids' and 'helicopter parents' are becoming really common," Ms Fraser said. "So we thought it was time to air the laundry on what's happening with our play spaces and make sure we are offering kids challenges. "We need to make playgrounds safe, but also offer a certain amount of risk and controlled risk. It's a real balancing act."

It is believed the bacteria increases levels of serotonin, reduces anxiety and may also stimulate growth in certain neurons in the brain.

Ms Fraser said that while playing in the dirt was great, parents should take care around potting mix, which can contain harmful bacteria. "But as long as safety directions are followed, that can be a great learning experience, too," she said.

The research will be a relief to the parents who know it's almost impossible to stop children getting dirty. Nicole Livisianos, of Zetland, said her one-year-old Sebastian loves to get messy. "We come to the park almost every afternoon and he is always into something dirty," she said. "There's no point trying to stop him."

Providing natural play environments is a topic at the Kidsafe NSW Playground Conference next week. "Many pre-schools and schools are planting sustainable garden beds and are teaching kids how plants grow," Ms Fraser said. "They learn about the environment and where their food comes from. The benefits are endless. The trend is definitely to make the most of the natural environment."


A soil bacterium fed to mice appears to make them temporarily smarter

Exposure to specific bacteria in the environment, already believed to have antidepressant qualities, could increase learning behavior, according to research presented at the 110th General Meeting of the American Society for Microbiology in San Diego.

"Mycobacterium vaccae is a natural soil bacterium which people likely ingest or breath in when they spend time in nature," says Dorothy Matthews of The Sage Colleges in Troy, New York, who conducted the research with her colleague Susan Jenks.

Previous research studies on M. vaccae showed that heat-killed bacteria injected into mice stimulated growth of some neurons in the brain that resulted in increased levels of serotonin and decreased anxiety.

"Since serotonin plays a role in learning we wondered if live M. vaccae could improve learning in mice," says Matthews. Matthews and Jenks fed live bacteria to mice and assessed their ability to navigate a maze compared to control mice that were not fed the bacteria. "We found that mice that were fed live M. vaccae navigated the maze twice as fast and with less demonstrated anxiety behaviors as control mice," says Matthews.

In a second experiment the bacteria were removed from the diet of the experimental mice and they were retested. While the mice ran the maze slower than they did when they were ingesting the bacteria, on average they were still faster than the controls.

A final test was given to the mice after three weeks' rest. While the experimental mice continued to navigate the maze faster than the controls, the results were no longer statistically significant, suggesting the effect is temporary.

"This research suggests that M. vaccae may play a role in anxiety and learning in mammals," says Matthews. "It is interesting to speculate that creating learning environments in schools that include time in the outdoors where M. vaccae is present may decrease anxiety and improve the ability to learn new tasks."



There was for a time a view that early exposure to dirt protected children from developing autoimmune diseases such as asthma and diabetes. That theory has however by now been largely discredited. For instance: Tribal Australian Aborigines normally live in very squalid and dirty conditions by Western standards yet have HIGH rates of autoimmune diseases such as asthma and diabetes. Asthma in particular seems to be highly hereditary, though the "triggers" do vary from person to person

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