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Get Your Children Good and Dirty
Researchers are discovering how crucial microbes are to our health and to avoiding a range of newly common diseases. So it’s time to get dirty, eat better and stop overusing antibiotics
By B. Brett Finlay and Marie-Claire Arrieta
Our friend Julia moved to a small free-range pig and poultry farm when her first child, Jedd, was a preschooler. When her second baby was born, she would strap him on her back every morning so that she could go to the chicken coop to pick up eggs. Jedd would chase and ride the chickens—and sometimes taste their feed and touch the fresh eggs. A couple of times, she even caught him chewing on something he had picked up from the ground.
At first, all of this caused Julia to freak out. But once she realized that Jedd wasn’t getting sick from these encounters with the chickens, she relaxed a bit. Her second child, Jacob, soon followed suit and never hesitated to get dirty on the farm. She once found him knee-deep in a cesspool of pig waste.
Her early worries that her children were going to contract diseases from all this messiness dissipated, and she was pleased to see that they remained healthy.
Was Julia being an irresponsible parent—or might we all have something to learn from her example?
For most of the past century, we have considered microbes bad news, and for good reason:
They cause disease, pandemics and death. Most human communities have experienced the benefits of medical advances like antibiotics, vaccines and sterilization, which have radically reduced the number and severity of infections that we suffer throughout life. Dying from a microbial infection is now a very rare event in the Western world, and, in the U.S., lifespans have increased by some 30 years since 1915—in large part because of success against infectious diseases.
Unfortunately, this progress has come with a price, as news reports have been telling us for some years now. Our anti-microbe mission has been accompanied, in industrialized countries, by an explosion in the prevalence of chronic noninfectious diseases and disorders. Diabetes, allergies, asthma, inflammatory bowel diseases, autoimmune diseases, autism, obesity and certain types of cancer are at an all-time high. The incidence of some of these disorders is doubling every 10 years, and they are starting to appear sooner in life, often in childhood.
All of these diseases have a genetic component, but their alarming growth cannot be explained by genetics alone. Recent studies find a direct link between the presence and absence of certain bacteria and all of the chronic diseases mentioned above. It turns out that the microbes within us are much more than quiet residents; they are an inherent part of our physiology, and altering them leads to disease.
Our own 2015 study (published in the journal Science Translational Medicine) found, for example, that 3-month-olds who had four particular microbes in their feces were much less likely to get asthma later in life. When those four microbes were introduced into mice, they protected against experimentally induced asthma, showing for the first time that alterations in gut microbes can drive the development of the disease. Lab experiments also have found that obese mice lose weight when they get a transfer of gut microbes from lean mice (and the reverse holds true as well, with lean mice growing fat after a transfer from obese mice).
The practical upshot of all this research is clear: Our health depends to a large degree on maintaining a robust and diverse community of microorganisms in our bodies—and establishing good gut-health as children is especially important.
During the first few months of life, the microbe community in our bodies is considerably less established and stable than later in life. Any drastic changes to it have a much higher chance of permanently altering our microbiota (as specialists call this world of tiny organisms within us) and our long-term health.
From the moment we are born, we begin getting colonized by bacteria, which kick-start a series of fundamental biological processes, including the development of our immune system. Before birth, the lining of our gut is full of immature immune cells. When bacteria move in, the immune cells react to them, changing and multiplying. They even move to other parts of the body to train other cells with the information they have acquired from these intruders. If deprived of this interaction, the immune system remains sloppy and immature, unable to fight off diseases properly.
In an ideal world, children would harbor a rich and diverse community of microbes without the threat of severe infectious diseases, but our current practices only address half of this equation.
Given how well bacteria respond to diet, eating a variety of foods is perhaps the best way to increase microbial diversity, and there’s no better time to do this than during the first few years of life.
As a practical matter, this means that we shouldn’t feed a baby only rice cereal for weeks until the package is finished. We should offer a variety of grains, including oats, rice, barley and quinoa. It’s also important to offer whole grains instead of refined ones. The Western diet is extremely low in fiber, and refined grains contain very little of it.
Protein-rich legumes, such as lentils, beans and peas, have an abundance of fiber and can be easily mashed for babies. Also try nontraditional starchy vegetables such as sweet potatoes, parsnips or cassava (tapioca) rather than just sticking to low-fiber veggies such as potatoes. For older children, add fermented foods, such as yogurt, kefir, sauerkraut and other pickled vegetables.
Most people in developed societies won’t crave these foods the same way that they crave the texture of macaroni and cheese or the like, but infancy is the best time to introduce good dietary practices.
For children, eating healthy foods becomes a habit in the same way as cleaning their room does: by doing it frequently.
Food isn’t the only way that we have altered our microbiota, however. Our microbes have perhaps taken the biggest hit from one of the best things humanity has ever invented: antibiotics. These wonder drugs have saved millions of lives and will save millions more in the future.
But antibiotics aren’t targeted missiles that kill only the bad bacteria causing infections; they are carpet bombs that kill good and bad bacteria indiscriminately. Research now suggests a link between the use of antibiotics in early childhood and problems such as obesity, diabetes, asthma, allergies, autism and inflammatory bowel disease.
Photo: Roberto Machado Noa/LightRocket/Getty Images
We ought to become more restrictive with the use of antibiotics in children. Parents shouldn’t assume that all infections have to be treated with these drugs. Upper respiratory tract infections and colds are often caused by viruses, so antibacterials won’t cure them. Most sore throats, especially if the child also has a runny nose and cough, are caused by viruses and don’t need antibiotic therapy. If a child has a mild ear infection, it’s reasonable to watch and wait for a few days to see if it gets better on its own before starting antibiotic therapy. Also, parents should consider giving probiotic supplements (with live bacteria and yeasts) to a child if he or she is being given antibiotics.
With the scientific information now available, parents can make informed choices about helping their children to develop a thriving microbiota. We are still years away from learning the whole story of how microbes contribute to our physical well-being, but what we know today is pretty convincing evidence that they are crucial, especially early in life.
For much of the past century, we have ignored, and often destroyed, the microbes that keep us healthy. It’s time now to correct the balance.
Dr. Finlay is a microbiologist specializing in bacterial infections and the Peter Wall Distinguished Professor at the University of British Columbia. Dr. Arrieta is an assistant professor in the Department of Physiology and Pharmacology at the University of Calgary. This essay is adapted from their new book, “Let Them Eat Dirt: Saving Your Child From an Oversanitized World,” published by Algonquin Books of Chapel Hill.