The dirt on dirt

It's good for you. I wish I could get my son to accept this, but the fact is, when I drop food on the ground as I prepare dinner, it's better that he doesn't know that I just pick it up and put it back in the bowl.

Perhaps Dr. Yulia Iossifova of the University of Cincinnati should come to dinner to help me explain (as we pick cat hair off the fallen lettuce). Here's what she has to say:

The immune system's protective effects only appear to occur when there are high levels of microbial exposure. Cleaner environments do not have enough microbial components to trigger the immune system response.

She and her colleagues enrolled 574 families with newborn infants as part of the Cincinnati Childhood Allergy and Air Pollution Study. At least one parent in each family tested positive on a skin prick test for a panel of allergens.

The investigators then crawled around the family homes in an infantile sort of way collecting samples of dust and mold from the babies' environments. They checked the house sweepings for levels of a protein found in the cell wall of fungi; the higher the levels, the more mold at baby level. This protein is believed to cause respiratory symptoms in adults. Months laters, the tots were studied for allergic responses to skin tests and a history of wheezing episodes, and signs of allergies were correlated with levels of mold in the house.

Turns out, the moldier the floorboards, the less likely the offspring to wheeze in an allergic sort of way. Conversely, those babes in households where the parents actually found time to scrub and disinfect under chairs and in corners were far more likely to suffer from allergy-related respiratory distress.