Letting kids get dirty has lifelong health benefits

To the parent of the child who continues eating a snack from the ground well after the five-second rule expires...

To the parent of the child who isn't content unless their hands are at least a little muddy...

To the parent of the child who is perfectly happy to share sips of water from a friend's cup...

There is good news: Exposure to dirt and germs helps children's immune systems. Jack Gilbert, Ph.D., a scientist who studies microbial ecosystems at the University of Chicago—and a father of two who continually faced messy situations—looked into the effects of those potential germs on little bodies for a study published in The New England Journal of Medicine.

What he and his co-authors discovered about the relationships between kids and germs was incredibly reassuring. “It turned out that most of the exposures were actually beneficial," he told NPR's Weekend Edition. "So that dirty pacifier that fell on the floor—if you just stick it in your mouth and lick it, and then pop it back in little Tommy's mouth, it's actually going to stimulate their immune system. Their immune system's going to become stronger because of it."

Now the co-author of Dirt is Good: The Advantage of Germs for Your Child's Developing Immune System, Gilbert said his bigger concerns is with the extreme sanitization we see today.

“It's fine to wash their hands if there's a cold or a flu virus around, but if they're interacting with a dog, and the dog licks their face, that's not a bad thing," Gilbert said. “In fact that could be extremely beneficial for the child's health."

So, what's the reason why small amounts of dirt and germs help kids?
Gilbert said the infection-fighting neutrophil cells in our bodies become “grumpy and pro-inflammatory" when they're waiting for something to do. So, without small amounts of germs of fight off along the way, those neutrophils become “explosively inflammatory" when they finally do get to tango. As he said, “That's what triggers asthma and eczema and often times, food allergies."

As for the common dirty dilemmas parents face, here are the verdicts Gilbert gave to NPR...

Should children use hand-sanitizer?
Gilbert said that hot, soapy water is the better bet in most cases.

Is it okay for a kid to eat something more than five seconds after it fell on the floor?
Gilbert said this is actually a case of all-or-nothing: Because it takes microbes less than a second to attach to food, the bigger question is just how contaminated do you think the surface really is? In most homes, he said this isn't too big of a concern.

Should you wash or lick a pacifier after it fell?
Good news to the mamas who never got around to buying those pacifier wipes: Gilbert cited a study of more than 300,000 children, which showed children of moms in the habit of licking off dirty pacifiers actually had lower rates of asthma, allergies and eczema. As he said, “Overall, their health was stronger and more robust."

Next time your toddler eats a handful of dirt, remember this: You're just doing your part in raising a healthy kid.