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Dirty Kids: How Germs Can Be Your Child's Best Friend

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I must admit, when my shiny new baby boys were brought onto the planet nearly six years ago, I certainly had my doubts about the value of letting their soft and innocent bodies roll, crawl and toddle amongst the dirt and doggy-doo. But since then -- especially after learning what I'm about to share with you -- I've become extremely lax, and my boys now clamber up and down farm animals near our house and elephants in developing countries, wallow like hogs in every mud puddle they find, and eat fistfuls of olives with faces and hands still stained from exploring every corner of the garage and backyard.

To understand why I'm not too concerned about germs, and why you shouldn't be either, you need to grasp a concept called the "hygiene hypothesis," along with two other important hypotheses. In a nutshell, these hypotheses hold that when exposure to parasites, bacteria and viruses is limited early in life, children face a greater chance of having allergies, asthma and other autoimmune diseases during adulthood. But we're going to delve into them in a bit more detail.

Three Important Hypotheses

Although the idea that exposure to certain infections may decrease the risk of allergy is not new, Dr. David Strachan was one of the first to formally propose it as the "hygiene hypothesis" in scientific literature, in a 1989 article in the British Medical Journal. In the paper, Strachan pointed out that the allergic diseases hay fever and eczema were less common in children from larger families, and that children from larger families were probably exposed to more germs through their siblings. Since then, epidemiological studies have confirmed the protective effect of not just large family size, but also of growing up on a farm.

Then, in a 2003 article in a journal of immunology, Dr. Graham Rook proposed the "old friends" hypothesis, arguing that the exposures necessary to increase immunity are not actually developed in childhood or during any other recently evolved infectious exposure, but instead are derived from microbes present since hunter-gatherer times, when the human immune system was evolving. Rook proposed that the microbes that co-evolved with mammalian immune systems are ancient, and that we have become so dependent on them that our immune systems can neither develop or function properly without these internal microbes. These microbes include species that inhabit our skin, gut and respiratory tract, and also inhabit the animals we live with, and even organisms such as symbiotic bacteria, viruses and helminths (aka parasites or worms) that establish chronic infections or carrier states that we can actually tolerate and that help us develop specific immunoregulatory responses.

Finally, in the past several years, the "microbial diversity" hypothesis has emerged, which holds that the health and diversity of the bacterial species in our gut mucosa a key factor for strengthening the immune system (vs. simply colonization with a limited number of bacterial species). This makes sense, since Dr. Rook compared the embryonic immune system to a computer that contains many programs but sparse data. During gestation and childhood exposure to diverse organisms, the immune system builds a "database" that allows it to identify and respond to harmful agents in the internal or external environment. This microbial diversity hypothesis is also why I recommend vaginal delivery of babies (vs. C-section) when it's an option -- due to the importance of exposing a newborn baby to the variety of bacterial species in the vaginal tract.

Each of these hypotheses is based on the general concept of upregulation of the body's T cells in response to infectious agents -- and appears to be well supported by epidemiological data. Studies have proven that a variety of immunological and autoimmune diseases are much less common in developing countries than industrialized countries -- and that immigrants to industrialized countries from developing countries develop immunological disorders such as asthma and chronic inflammatory disorders in relation to the length of time since arrival in the industrialized area. Furthermore, while there's no evidence to support the idea that reducing our modern practices of cleanliness and hygiene would have any impact on rates of chronic inflammatory and allergic disorders, there is a significant amount of evidence that it actually increases the risks of infectious diseases!

10 Ways To Get Dirty

So now that you understand the reason why germ, bacteria, and even parasite exposure can be helpful for a child's developing immune system, it's time to delve into the nitty gritty: how to actually get dirty! Even if your child wasn't birthed via vaginal delivery (our kids were actually C-section babies) there are plenty of other ways to get your kids "dirty" -- and here are 12:

1. Let Your Children Taste Things -- Although your natural reaction may be to slap that handful of leaves, patch of dirty grass, clump of mud, or slightly-discolored snowball from your child's exploring hands, resist the urge! The same goes for their propensity to gnaw on the grocery shopping cart handles, lick random windows, and chew on the seat belts in the car. Allow your children to experiment touching, handling and even tasting the natural world around them.

2. Don't Be a Bottle Boiler -- Sure, just like any other dishes, you'll want to clean fluid and food residue from bottles (or pacifiers) every now and again via boiling or washing, but you don't need to be that parent that nukes the pacifier every time it touches the carpet or boils the bottle nipple after the dog sniffs it. Your children can eat or drink from slightly germ-tainted surfaces every now and again.

3. Avoid Antibacterial Soaps -- By constantly using antibacterial soaps and hand sanitizers, we may not only be inadvertently inhibiting immune development in our children, but may also be creating "superbugs" or increasing bacterial resistance to pharmaceutical and natural antibiotics in some bacteria. Stick to good old soap and water and avoid excessive hand washing.

4. Avoid Antibiotics -- Don't rush out and grab a Z-Pack, an antiviral medication or pump your kid full of antibiotics when they get a flu or become knocked down by a nasty bug. This can create similar bacterial resistance issues as antibacterial soaps. On the flip side, if you child is seriously down for the count with a flu, you may need to be worried about potential consequences such as pneumonia, bronchitis or sinutis. I recommend looking into natural ways to boost white blood cell count or introduce natural antiviral or antibacterial substances, such as astragulus, oregano, Echinacea, goldenseal and elderberry tinctures.

5. Visit Farms and Have Pets -- You don't need to fly to Asia and play with monkeys and elephants to expose your children to beneficial worms and germs. Instead, just go on the occasional field trip to your local farm to pet the sheep or feed the horses. In addition, pets count! Cats, dogs, gerbils, guinea pigs and even fish can expose children to a variety of germs, bacteria and other living organisms they might not otherwise encounter.

6. Increase Time With Other Kids -- We homeschool our twin boys, but we also go out of the way to put them into gymnastics, where they tumble around on a slightly dirty floor or mat surrounded by other children -- along with frequent visits to the gym's child care, basketball and soccer team participation, music camps, ski school, and a variety of extracurricular activities that exposes them to other children's sniffles, skin, and sweat.

7. Eat a Variety of Cultured Foods -- My wife is currently writing a cookbook called "Dirty Kitchen" -- alluding to the amount of lactofermentation and use of bacterial cultures she uses during food prep. I love this title because it alludes to the wide variety of bacteria in foods that can include natto, kimchi, kefir, pickles , yogurts, sauerkraut, rakfisk, poi, kombucha and even chocolate. Remember that it's variety that's important -- and simply feeding your child the same probiotic pill day after day is probably not going to be adequate stimulus for their immune system.

8. Play Outside -- I wish this tip could go without saying, but the sad truth is that the great percentage of children spend more time indoors on Wii and Xbox than they do outdoors getting dirty. On any nice afternoon, we kick our kids out into the backyard to explore, and since they were tiny toddlers, they always return with dirt under their fingernails (or possibly animal dung), mud around their noses and mouths, and weeds and wild grasses lodged in their clothes. These are all immune system boosters that far outweigh the inconvenience of having to wash dirty children. Which leads me to my next point...

9. Don't Bathe/Shower Every Day -- In our post-Victorian, cleanliness-obsessed culture, it can be tempting to give our children a daily warm bath, followed of course by a perfect hairdo and a color-coordinated outfit from the Gap. But sometimes it's OK to let the dirt ferment on your child. On many a summer day, our boys go two or three days getting dirty and playing outside without a bar of soap in sight -- and while they get a bit stinky and stained, this is a fabulous stimulus for their immune system.

10. Don't Do Excessive Laundry Loads -- Germs, dirt and bacteria thrive on clothing. Prior to reading the rest of this article, you may have been tempted to take this as a sign to do a daily load of laundry for any of your child's dirty items. And while you shouldn't necessarily send your child to school smelling or looking like a pigpen, it's OK to give clothes a few good wears before laundering -- in the same way that you don't need to be constantly boiling bottles and pacifiers. Most of the time, it's OK for kids to smell just a little bit like... kids.


While this list of ways to get your kids dirty is by no means comprehensive, hopefully it gets your wheels turning about exposing your children to (gasp!) pathogenic organisms -- including bacteria, worms, parasites, germs, fungus, viruses, and even other sick kids or dirty animals. This may be one of the best favors you can do for your kids, and you'll probably be giving them an advantage later in life, especially compared to children who grew up in a bubble. And who knows? Your own immune system might benefit a bit too, and you have one less reason to be grossed out when your little one sneezes in your face, coughs at the table, or tracks a trail of dirt into the house!