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Kids & allergies

Is your house "too clean"? Research shows exposure to dust, dander and germs actually can bolster children's immune systems.

When our first child was born, my wife and I were diligent about the hygiene of the house. We figured that because our daughter would be crawling on the floors, they needed to be immaculate. At mealtime, any food that inadvertently ended up on the floor was immediately thrown away to keep her from popping something dirty into her mouth.

This is a natural reaction of many first-time parents. Needless to say, by the time our second child came around, the rules were a bit more lax. With him we generally followed the "five-second rule" -- if the food had been on the floor for less than five seconds, it was still fit for consumption (as long as you picked off any visible debris before handing it back to him). By the time our third child came along, we had pretty much dispensed with any rule. As long as the food wasn't gobbled up by the dog, it was generally deemed fit for human consumption!

Although we felt a little guilty about our casual approach to our youngest children's food hygiene, in retrospect the younger two did just fine. No mysterious intestinal infections. No weird allergic reactions to an inadvertent bite of dog food. Perhaps our obsessive-compulsive concern about our firstborn's need for a clean environment was misguided. On the other hand, maybe we were just lucky that our youngest didn't contract some strange ailment from popping contaminated food into his mouth. What's a parent to do?

Well, as it turns out, research over the past few years seems to suggest that kids growing up in environments that are "too clean" might be at increased risk of developing allergies and other immune-system problems. Why? Some researchers theorize that as children grow, their immune systems need to be challenged a bit along the way. Exposures to dust and other allergens, viruses and bacteria may help a maturing immune system develop its sparring skills.

After all, your immune system is your bodyguard. Its job is to protect you from environmental marauders. You want your bodyguard to be experienced, and he can gain this only by honing his skills. To put it bluntly, you wouldn't want a bodyguard who's never been in a fight. By the same token, it may be that a child's immune system needs the periodic challenges presented by allergens and minor infections. Such tests may help a youngster's immune system function more normally as she grows to adulthood.

Studies have shown that kids raised on farms have fewer allergies than kids in non-farm communities. And there's evidence that children exposed to pets are less sensitive to allergens. A study published in The Journal of the American Medical Association in 2002 reported a reduction of at least 50% in sensitivity to allergens in kids living in households with two dogs, compared with their counterparts in households with no dogs! Although the mechanism for this reduced sensitivity is a matter of speculation, it is assumed that children exposed to animals face day-to-day minor "challenges" to their immune system. Such exposure may allow for a fine-tuning of the system.

Of course, if your child has a history of allergies, it's a bad idea to fill your house with pets. Exposure to excessive allergens after the fact certainly doesn't make sense. Any benefit is likely derived from exposure along the way with immune systems that are not already out of kilter.

Nonetheless, the new data are encouraging to those of us with kids. Who knows? That chocolate-chip cookie with dog hair on it that I let my youngest eat when he was a baby may actually have helped his health. Well, at least that's what I'm telling myself!

Contributing Editor Tedd Mitchell, M.D., is medical director of the Wellness Program of the renowned Cooper Clinic in Dallas.

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