In their new book, two microbiologists argue that bacteria exposure is important for childrens' health.

Kids are too Clean
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How can you raise healthy kids? According to a new book, the key is letting them eat dirt.

In their new parenting book, Let Them Eat Dirt, microbiologists Marie-Claire Arrieta and Brett Finlay argue that letting your kids get a little dirty is imperative to their overall well-being. According to The Guardian, the "war on dirt" that has emerged in recent years—along with a barrage of sterilizing wipes and antibacterial hand gels—has taken its toll on the population's health. Arrieta and Finlay suggest that a surge in non-infectious ailments (think allergies, asthma, and autoimmune diseases) are as a result of this itch to over-sterilize.

The reason is in your gut. Microbes—the world's smallest life forms, a great many of which live inside our bodies—have gotten a bad rap. "We have been having a war against microbes for 100 years because they cause infection," says Finlay. "If you look at the mortality tables—even for 50 years ago—it's mainly infectious diseases. And by bringing in clean water, clean food, vaccines, antibiotics, hand washing and sanitation, we have done a great job getting rid of them."

However, there is a risk that comes with killing off all microbes, because while some cause infections, many are responsible for keeping the body's digestive and immune systems running smoothly. So, when microbes are wiped out, gut health and power against outside infections can also be compromised.

The authors argue that microbes train the immune system into understanding when another microbe is harmless or not, so if you're never exposed to germs, that system will never develop. This is why your kids should get proper exposure to mysterious sandbox objects.

Another object that can help kids get exposure to microbes? Their mother's breast. "A child who breastfeeds constantly will be latched on to skin which, microbiologically speaking, is very dirty," says Arrieta, who herself used to be an overly cautious parent. "With my first child I sterilized everything my baby came into contact with and then I realized the American Pediatric Association doesn't recommend that, while other studies show it increases the risk of allergies and asthma."

While Arrieta doesn't suggest throwing hygiene completely out the window, she hopes her book will be able to relieve some of the stress of parenting while simultaneously aiding in kids' health. "Hand washing is important—after the bathroom or before eating, or playing with someone sick... but the rest of the time it is less so and it can be detrimental," she says.