In an interview with NPR, Sharyn Clough, a philosopher of science, talks about why dirt is good for our kids. She incorporates her philosophical theories to defend a notion that's been bantered about for years.
According to the hygiene theory of disease--something bantered among public health folks a generation ago--children who are raised too clean do not develop sturdy immune systems. The upshot is that they may be more prone to allergies or autoimmune diseases, all the kinds of sicknesses linked to immunity gone awry.
I am a huge believer in the hygiene theory. For one, it makes sense. You need to see foreign substances to teach your body to fight them. Sort of like the way vaccines work. And secondly, the theory gave a great excuse for being a messy mother. I couldn't be bothered washing my kids all the time and screaming at them not to eat that M&M that just fell on the floor. We share drinking straws, lick off each other's ice cream cones, and eat off of each others' plates. (For the record, I do promote hand washing after using the rest room.)
Still, I thought Clough's arguments were rather weak. She focuses on girls being more sickly than boys. The reasons: Well, young girls are more likely to wear dresses to school, which she says is linked to cleaner play during recess. I have two girls and two boys and I can tell you that the outfit does not dictate the play.
The research that I found that bolstered the hygiene theory (again in a very circuitous way) is in the January 21st issue of Science magazine. A study by Japanese researchers found that mice treated with antibiotics as pups were more susceptible to inflammatory responses later on compared with untreated mice. Antibiotics, in a way, are like cleansing the gut--or like keeping yourself too clean and mucking up the healthy bacteria. Inflammatory responses seen in the mice were similar to the sorts of things you see in the guts of people who suffer from Crohn's disease and other autoimmune illnesses.
They conclude that their research hints to a potential way to prevent these kinds of inflammatory bowel disorders or allergies by tinkering with a person's intestinal flora---or adding something loaded with good bacteria to their diet. I know it's a stretch, but it seems to me that maybe there is something going on in the guts of these children early on that make them more susceptible to these illnesses. Could it be that we need a bit of dirt or a wide variety of food to promote a healthy gut?