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Even the most beautiful rose has been through the dirt.
—ANONYMOUS
If a healthy soil is full of death, it is also full of life: worms, fungi, microorganisms of all kinds. . . . Given only the health of the soil, nothing that dies is dead for very long.
—WENDELL BERRY, THE UNSETTLING OF AMERICA
IN BRIEF: Avoiding all germs is a mistake. Dirt, and the rich world of microbes it contains, can be good for all of us, especially kids. There is a lot of evidence suggesting benefits from more exposure to microorganisms. Also, many hygiene products contain potentially dangerous chemicals and can irritate and dry out our skin.
According to folklore, the concept of hygiene was born thanks to the mythical Hygieia. Hygieia was the daughter of Asclepius, the Greek god of medicine. Asclepius carried a staff with a snake wrapped around it, which inspired the medical symbol still in use to this day. According to some versions of the myth, the snake would whisper the secrets of the earth in Asclepius’s ear, helping him to be effective as a physician. He was so effective that he was able to cure death, a practice that angered the gods and caused Zeus to hurl a lightning bolt at him, incinerating him.
Hygieia’s contribution to the healing arts was less dramatic but equally important. She would bathe and clean the sick in her father’s hospitals. Her story provides evidence that the ancient Greeks recognized the importance of cleanliness in helping to restore health to the sick. But it took some time for hygiene’s full significance to be realized.
For centuries humans have bathed and washed their hands regularly, but it wasn’t until more recently, with the advent of germ theory, that society started to understand the extent to which disease is spread by person-to-person contact. This emerging realization led to many positive public health initiatives. In 1854, British physician John Snow realized a deadly London cholera outbreak was caused by cesspools contaminating water supplies.
Today our water supplies thankfully remain generally free of contamination and of most (but unfortunately not all) harmful chemicals, and we have many important hygiene practices that continue to prevent the spread of disease and save lives. But sometimes in our germaphobic world, with our sanitized, wash-our-hands-twice-just-to-be-sure-and-if-in-doubt-get-the-antiseptic-out culture, we are killing not only bad bacteria and germs but many good ones as well. There is a good deal of evidence all this hygiene is making us less healthy and more susceptible to allergies and autoimmune conditions. It appears that like so many other behaviors we’ve examined in this book, cleanliness is best when practiced in—you guessed it—moderation, along with common sense.
It turns out that dirt, and the army of invisible, often helpful bacteria that comes with it, can be good for us. According to the ironically titled hygiene hypothesis, most modern environments are too clean for children to get exposure to the variety of germs necessary for their immune system to develop properly, making them more susceptible to possible illnesses and allergies.
Allergies occur when the immune system reacts to something it may not need to react to, like the body’s version of a car alarm system’s going off when an innocent bystander walks nearby. Many studies have suggested that when children are exposed to more bacteria early on in life, their immune systems are better able to recognize true threats.
One of the immortal traditions of childhood is the five-second rule, which holds that if you drop food on the floor and pick it up before five seconds have passed, it’s fine to eat. This rule doesn’t hold scientific water, as bacteria can adhere to food as soon as it makes contact with the floor. But proponents of the hygiene hypothesis suggest it’s okay for parents to allow their children to follow the natural dirt-accumulating instincts of childhood. They also say kids should play in the dirt and mud, and parents should not fight their children’s propensity to lick things (all within reason, in places where there are no likely contaminants—that is to say, none of these rules apply to public bathrooms or barnyard floors or anywhere there’s a good chance of coming in contact with excrement of any kind).
When we delivered babies at home in Oregon back in the 1970s, we noticed that many of our patients tried to be as sterile around the newborn as possible. They would not allow anyone but the immediate family to come near the baby right after birth. Even though these were home births, the family often would continue to wear white gowns, surgical masks, and even plastic gloves to “protect” the infant from germs long after the baby was born.
The main exception to this practice were some of the more recent immigrant families, who once the baby was born would sing, dance, and pass him or her around to what seemed like all of their family and friends. At first this practice made us nervous, to say the least, but we soon found that the babies who were kept as sterile as possible suffered from more allergies and colds than the babies who had been passed around and “exposed.” We never completed an actual clinical study, but this was definitely our observation.
Today the evidence in support of this dirt- and germ-welcoming practice is compelling. A 2016 study reported in The New England Journal of Medicine found that Amish children who grew up close to barnyard animals had far lower rates of allergies and asthma than Hutterite children who were raised away from animals, despite the two groups having similar genetic ancestry and lifestyles.1
Previous studies have found a similar association between farm living and decreased incidence of asthma.2 There’s also further research suggesting that children who put their hands in their mouths are less likely to develop allergies. Researchers in New Zealand studied about 1,000 people from their birth in the 1970s until they were thirty-eight years old. They found that those who were thumb-suckers or nail-biters tended to develop common allergies less often than those who kept their hands away from their mouths most of the time. This association continued even when the researchers adjusted for confounding factors.3
Another study found an association between the soap used in baby wipes and an increased chance of allergies in mice, suggesting that the use of baby wipes on human babies could increase a child’s chance of developing allergies.4
When it comes to adding more dirt—and therefore more beneficial microdiversity—to your life, dogs are a big help, as all of us who have ever had a wet dog walk through our living room know. Our four-legged friends seem to help re-create some of the conditions of farm living because of the way they track in germs—from stepping in dirt, rolling in mud, smelling excrement, and all the other charming and gross things dogs do. Having a dog around the house can raise levels of fifty-six different classes of bacteria compared with having a cat in residence, which raises only twenty-four different classes. Cats are naturally cleaner, and yes, in this instance, that is counterintuitively a bad thing.5
“A child growing up with a dog will have a 13 percent reduction in the likelihood of developing asthma, which seems remarkable when you remember that the majority of immunologists associated with asthma therapy regard dogs as ‘causes’ of the disease, or at least active exacerbations, rather than protectors,” write Jack Gilbert and Rob Knight in Dirt Is Good. “Similarly, those growing up on a farm will have a 50 percent reduction in the likelihood of developing asthma, for many of the same reasons.”
Gilbert and Knight add, “When scientists first started to tease apart the hygiene hypothesis, they found tight correlations between the likelihood of a child developing an allergy or asthma and the number of plant and animal species found within one mile of his or her home. Local biodiversity seems to play a role in mediating your child’s immune experience.”6
In addition to pet ownership, strategies for increasing your microdiversity favored by proponents of the hygiene hypothesis include gardening and not oversanitizing your house. That doesn’t mean it should be dirty or dusty, but it shouldn’t be like a sterile hospital operating room either. Use bleach sparingly and wash dishes by hand when you can. Cleaning dishes by hand in hot water doesn’t kill as many bacteria, which sounds gross but is actually a good thing, as research indicates that people from households where dishes were handwashed have fewer allergies and less asthma than those from households where dishes were washed exclusively in the dishwasher.7
The health benefits of a little dirt extend to adults as well as children. In our efforts to sterilize everything in life, what we’re doing is making ourselves less adaptable, less flexible, less accepting, and less healthy mentally, emotionally, and physically. Even when it comes to diet, sterile is not always best. Although stricter hygienic methods in controlling harmful bacteria is important, the natural tendency of substances like breast milk, raw milk, and raw cheese to promote a normal intestinal microbiota in humans is important for a healthy immune system.
When it comes to handwashing, the best bet, as always, is common sense. There are times when it’s appropriate and other times when it is overdone. While research into exactly where and when washing hands is best is still forthcoming, Justin and Erica Sonnenburg, both microbiologists at Stanford University, share the commonsense approach that they use with their own kids in their book The Good Gut. “We often do not have our children wash their hands before eating if they have just been playing in our yard, petting our dog, or gardening,” they write. “However, after visiting a shopping center, hospital, petting zoo, or other area that is more likely to harbor pathogens from other humans or livestock, washing hands is mandatory. We also increase the frequency of washing during cold and flu season or if we have potentially come into contact with chemical residues (e.g., pesticides).”8
While it’s true that washing our hands can help prevent the spread of colds and other ailments, most of us can avoid using antiseptic and antibacterial wipes or gel. Even alcohol wipes, which are better, can dry out our hands and skin, as can the overuse of soap and shampoo.
Sometimes it’s not hygiene that’s a problem; it’s what we use in pursuit of hygiene that can cause health issues. Products designed to keep us from smelling, sweating, and looking like humans can be brimming with potentially harmful ingredients. These products include shampoo, toothpaste, mouthwash, deodorant, and antiperspirant. Even something that seems as innocuous as soap may not always be our friend.
In September 2016, the U.S. Food and Drug Administration banned the sale of soap containing a number of chemicals—including triclosan and triclocarban—that have been shown to be harmful in animal studies. About 40 percent of soaps then on the market included triclosan or triclocarban, with triclocarban making its way into many bar soaps and triclosan an ingredient in many liquid soaps.
The move came after years of lobbying from public health experts who sounded the alarm after it was demonstrated that these chemicals could disrupt the reproductive system and metabolism in animals. Many feared they would have a similar effect on humans, and the widespread use of the chemicals—which the Centers for Disease Control and Prevention found in the urine of three-quarters of Americans—also could increase bacterial resistance to antibiotics.
As expected, not everyone supported the FDA’s decision. The American Cleaning Institute, an industry group, opposed the rule and released a statement, saying: “The FDA already has in its hands data that shows the safety and effectiveness of antibacterial soaps. Manufacturers are continuing their work to provide even more science and research to fill data gaps identified by the FDA.”9
So far the FDA has not reconsidered its stance, and although triclosan and triclocarban are no longer used in soaps, they are still permitted in a wide range of products, including toothpaste, mouthwash, deodorant, laundry detergent, fabrics, toys, and even baby pacifiers.
These are not the only antibacterial chemicals causing concern. So when using cleaning products, be sure to read the labels and understand the ingredients of products you use as best as possible. Most often old-fashioned, all-natural soap and water will do the trick just fine.
The study of dirt and bacteria exposure is continuing to yield intriguing results. For instance, there is research looking at whether helminth—parasitic worm—infections can help regulate the immune system and therefore be used as a treatment for some autoimmune-like conditions, including inflammatory bowel conditions, multiple sclerosis, asthma, and atopy.
As Helena Helmby, a researcher from the London School of Hygiene and Tropical Medicine, wrote in a 2015 paper, “Without doubt there is overwhelming evidence from animal studies that helminth infections exert strong immunomodulatory activity and are able to inhibit, alter and modify other ongoing immune responses.” She adds that “some promising data has been achieved using human helminth therapy but many questions remain to be investigated.”10
If a treatment using parasites grosses you out, you may not be a fan of this next treatment: fecal transplants. A healthy colon is teeming with good bacteria, but sometimes it is killed off as a result of a poor diet, or overuse of antibiotics. Certain types of bad bacteria, like one called Clostridium difficile, or C. diff., can overpopulate the colon, causing the condition C. diff. colitis, a potentially debilitating disease that sometimes can be deadly and is infecting an increasing number of Americans.
Still classified as an experimental treatment, a fecal transplant— or bacteriotherapy, as it is known in polite society—consists of taking stool from a person with a healthy, bacteria-rich colon and placing that stool, after it has been tested for infectious disease, inside the colon of a person with colitis, most often by means of a colonoscopy. For C. diff. colitis, these treatments have a cure rate of greater than 90 percent, with no significant side effects reported to date, according to Johns Hopkins Medicine, where the treatment is offered.11 There are also early results indicating the treatment can be effective for other autoimmune diseases, including irritable bowel syndrome, Crohn’s disease, and ulcerative colitis.
Speaking of fecal matter, cleaning up with toilet paper after using the bathroom is not as hygienic or potentially healthy as using a bidet, the cleaning method favored by much of the rest of the Western world. So seize the bidet. Whenever our good friend and colleague, the late famed professor of urology and homeopathic medicine Dr. Francisco Eizayaga, would come to America to teach, he would say, “I miss three things: my beloved wife, my dear children, and my bidet . . . but in the opposite order.”
Parasitic worms, bidets, and fecal matter aside, the takeaway here is that bacterial exposure, in the right instances with commonsense precautions, can be healthy. Many germs are bad, but getting rid of all of them can be even more dangerous. So don’t be a germaphobe. Take steps to be less obsessed with sterile conditions. You can start by taking a hike in the woods, walking barefoot in the grass, or just playing in a park. And bring some raw milk or cheese along for a snack. In other words, get down and dirty.