'Dirt Is Good': Why Kids Need Exposure To Germs

Jul 16, 2017
Originally published on July 18, 2017 5:47 pm

As a new parent, Jack Gilbert got a lot of different advice on how to properly look after his child: when to give him antibiotics or how often he should sterilize his pacifier, for example.

After the birth of his second child, Gilbert, a scientist who studies microbial ecosystems at the University of Chicago, decided to find out what's actually known about the risks involved when modern-day children come in contact with germs.

"It turned out that most of the exposures were actually beneficial," Gilbert says. "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."

Gilbert is now the co-author of a new book called Dirt is Good: The Advantage of Germs for Your Child's Developing Immune System. Presented in a Q&A format, the book seeks to answer many of the questions Gilbert has fielded from parents over the years.

This interview has been edited for length and clarity.


Interview Highlights

What are some things that parents get wrong?

Some of the main things are over-sterilizing their environment, keeping their children from ever getting dirty. So going out into the backyard and playing in the mud, and then as soon as they're filthy, bringing them in and sterilizing their hands with antiseptic wipes, and then making sure that none of the dirt gets near their faces. Also, keeping them away from animals. The dogs and cats, sure, but also, other animals. 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. In fact that could be extremely beneficial for the child's health.

What about hand sanitizer? Good or bad?

Usually bad. Hot, soapy water is fine. Even mildly warm, soapy water is fine, and it's probably less damaging to the child's overall health.

How about the five-second rule? The idea that if something falls on the ground and is there for under five seconds, it's clean.

The five-second rule doesn't exist. It takes milliseconds for microbes to attach themselves to a sticky piece of jammy toast, for example. But it makes no difference. Unless you dropped it in an area where you think they could be a high risk of extremely dangerous pathogens, which in every modern American home is virtually impossible, then there's no risk to your child.

Wash a pacifier or lick it if it falls on the ground?

Lick it. A study of over 300,000 children showed that parents who licked the pacifier and put it back in — their kids developed less allergies, less asthma, less eczema. Overall, their health was stronger and more robust. [Editor's note: See the correction below. Just 184 children were involved in the study.]

Are things like allergies an unintended consequence of trying to protect our kids too much?

Absolutely. In the past, we would have eaten a lot more fermented foods, which contain bacteria. We would have allowed our children to be exposed to animals and plants and soil on a much more regular basis. Now we live indoors. We sterilize our surfaces. Their immune systems then become hyper-sensitized. You have these little soldier cells in your body called neutrophils, and when they spend too long going around looking for something to do, they become grumpy and pro-inflammatory. And so when they finally see something that's foreign, like a piece of pollen, they become explosively inflammatory. They go crazy. That's what triggers asthma and eczema and often times, food allergies.

Give us some advice. What should I allow my child to do?

Oftentimes, it's hard to get your kid to eat a healthy diet. I would strongly try to encourage the consumption of more colorful vegetables, more leafy vegetables, a diet more rich in fiber as well as reducing the sugar intake. But just generally, allow your kid to experience the world. As long as they're properly vaccinated, there's no threat, and they will actually get a stronger, more beneficial exposure.

Jordana Hochman, Lucy Perkins, Ned Wharton and Sophia Boyd produced and edited this interview for broadcast, and Andrea Hsu adapted it for the Web.

Copyright 2017 NPR. To see more, visit http://www.npr.org/.

LULU GARCIA-NAVARRO, HOST:

It's summertime. And if you have a young kid, chances are they're covered in a film of sweat and dirt. It can be kind of gross. We went to New York Avenue Park in Washington, D.C., and asked parents how comfortable they are with the yucky stuff.

JEANINE MCGINNISS: Probably I was a little bit more of a germ freak. And then once you have a kid, you start getting comfortable with more germs.

DOROTHEA THOMAS: You know, every possible chance that if there is a germ or whatever, I make him wash his hands.

WENDY CHRISTMAS: I work hard to make sure that they're clean.

GERALD SMITH: Make sure they wash their hands constantly, all the time, soap and water.

GARCIA-NAVARRO: A quick survey there of parents Jeanine McGinniss, Dorothea Thomas, Wendy Christmas, and Gerald Smith. But are we too quick to rush kids to the bath at the end of the day? Our next guest says that dirt is good. Dr. Jack Gilbert is professor of surgery at the University of Chicago, and he's co-author of a book for new parents guiding them through the world of germs, the microbiome and obviously dirt. He joins us from our member station WBEZ in Chicago. Good morning.

JACK GILBERT: Good morning, Lulu.

GARCIA-NAVARRO: Why did you write this book?

GILBERT: Well, as a parent - I have two children now - I can say that when I had my first child, I got a lot of different advice on the kinds of things that I should do to look after my kid. If they have a snotty nose, consider taking antibiotics, to make sure their pacifier was always sterilized, to sterilize their food and make sure it was always boiled before you gave it to them. And so for me, it was interesting to go back and look at the data, especially after my second child, where I got a lot more lax in terms of how much of that preparation I put in.

And so we went and looked at the literature, went and delved into the science and tried to understand what we actually knew about the risks that our modern-day children could experience from those kinds of exposures. Turned out that most of the exposures were actually beneficial.

GARCIA-NAVARRO: You mentioned a few of them already, but what are some of the main things that parents get wrong?

GILBERT: Some of the main things are over-sterilizing their environment, keeping their children from ever getting dirty. So going out into the backyard and playing in the mud, and then as soon as they're filthy, bringing them in and sterilizing their hands with antiseptic wipes and then making sure that none of the dirt gets near their faces. Also keeping them away from animals. 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. In fact, that could be extremely beneficial for the child's health.

GARCIA-NAVARRO: Let's get to some of these questions. You tell me good or bad. Hand sanitizer?

GILBERT: Usually bad. Hot soapy water is fine, even mildly warm soapy water is fine. And it's actually probably less damaging to the child's overall health.

GARCIA-NAVARRO: All right, five-second rule. If something falls on the ground, you know, that thing if it's there for under five seconds it's clean, if it's over five seconds you've got to wash it.

GILBERT: The five-second rule doesn't exist. It takes milliseconds for microbes to attach themselves to a sticky piece of jammy (ph) toast, for example. But it makes no difference. Unless you dropped it in an area where you think that could be a high risk of extremely dangerous pathogens, which in every modern American home is virtually impossible, then there's no risk to your child.

GARCIA-NAVARRO: All right. Wash a pacifier or lick it if it falls on the ground?

GILBERT: Lick it every time. A study of over 300,000 children showed that parents that lick the pacifier and put it back in, their kids developed less allergies, less asthma, less eczema. Overall, their health was stronger and more robust.

GARCIA-NAVARRO: And how often should I give my daughter a bath? This is a very important question, by the way, because she hates them.

GILBERT: I know, exactly. Especially when they're small children under the age of 6 months, so infants up to about 18 months, you don't need to get them off every day. In fact, you could go for a couple of days. Wiping down the area with a warm wet cloth. Overall, over-washing can actually damage the skin and lead them to have a higher likelihood of infections and over-inflammatory reactions like eczema.

GARCIA-NAVARRO: One of the things that we are seeing, especially in America, is the rise of allergies. Do you think these two things are linked because we try to protect them so much that, you know, the unintended consequence of that is that actually they are more susceptible to things like allergies?

GILBERT: Absolutely. So the basic premise is that in the past, we would have eaten a lot more fermented foods, which contain bacterial products and bacteria. We would have allowed our children to be exposed to animals and plants and soil on a much more regular basis. Now we live indoors. We sterilize our surfaces. Their immune systems then become hyper-sensitized.

You have these little soldier cells in your body called neutrophils. And those neutrophils, when they spend too long going around looking for something to do, they become grumpy and pro-inflammatory. And so when they finally see something that's foreign, like a piece of pollen, they become explosively inflammatory. They go crazy, right? And that's what triggers asthma and eczema and oftentimes food allergies.

GARCIA-NAVARRO: So I was going to ask you just finally to give us some advice. I mean, as a mother, what should I be allowing my daughter to do? And what is still something that I should not allow her to do?

GILBERT: Right. So oftentimes, it's hard to get your kids to eat a healthy diet, right? I know this more than any parent. But I would strongly try and encourage the consumption of more colorful vegetables, more leafy vegetables, a diet more rich in fiber, as well as reducing the sugar intake. But just generally, allow your kid to experience the world. As long as they're properly vaccinated, there's no threat. And they will actually get a stronger, more beneficial exposure.

GARCIA-NAVARRO: Dr. Jack Gilbert. He's the co-author of "Dirt Is Good." Thank you so very much.

GILBERT: Thank you. It's great to be here.

[POST-BROADCAST CORRECTION: During this conversation, researcher Jack Gilbert mistakenly says a study of more than 300,000 children showed that children whose parents licked their pacifiers developed fewer allergies and other health problems. In fact, while the work was part of a study involving more than 300,000 children, only 184 of them were part of the research involving pacifiers. ]

(SOUNDBITE OF PENGUIN CAFE ORCHESTRA'S "DIRT") Transcript provided by NPR, Copyright NPR.

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