Dirty and Healthy

I have previously mentioned what has become known as the hygiene hypothesis. Basically, it's

a 17-year-old theory that the sanitized Western world may be partly to blame for soaring rates of human allergy and asthma cases and some autoimmune diseases... The theory figures that people's immune systems aren't being challenged by disease and dirt early in life, so the body's natural defenses overreact to small irritants such as pollen.

It's one of two main theories as to the the growth of allergies in our modern world; the other being the prevalence of everyday chemicals.

Recent research has, however, bolstered the case for the validity of the hygiene hypothesis. The study showed that certain rats have better, more effective immune systems. Which would you think it is: dirty sewer rats or clean raised-in-a-pristine-lab rats? Yep, you guessed it, the sewer rats.

...the wild mice and rats had as much as four times higher levels of immunoglobulins, yet weren't sick, showing an immune system tuned to fight crucial germs, but not minor irritants.

Human studies have also long given credence to the hygiene theory, showing that allergy and asthma rates are higher in cleaner industrialized areas. So the lesson is, make sure you let kids play in the mud and eat dirt, play with animals, and most of all, don't overuse antibacterial soap on them. Strategically expose your kids to that which will make them dirty in order that they end up healthy.