In 2001, one in 14 people in the U.S. had asthma, which causes coughing, wheezing and shortness of breath. In 2009, the figure was one in 12, and the prevalence of the disease continues to grow. According to data from the Centers for Disease Control and Prevention, more than 10 percent of grade-school children currently have the disease, for which there is no cure. Research published last week in The New England Journal of Medicine, though, indicates a possible cause of the disease, and may well lead to a way of preventing it.
The study, of two insular farming communities, lent credence to what is often referred to as the “hygiene hypothesis,” the theory that, contrary to what many of us living in highly developed countries have taken as an assumed truth, very clean environments are not necessarily good for us, and can even lead to some diseases. The mechanism assumed to be at work is the lack of challenges in the earliest years of life to the immune system, which, the hypothesis suggests, must be stimulated during those crucial developmental years by germs of different types in order to be able to protect in later years from microbe-borne disease.
The recent study’s investigators had noticed that the two farm-based societies, the Amish of Indiana and the Hutterites of North Dakota, evidenced widely different rates of asthma. The disease was very prevalent among the Hutterites, with 15 to 20 percent of the population affected; however, it affected only two to four percent of the Amish.
Both groups have similar European roots, genetic backgrounds and lifestyles. Both favor large families, have simple diets and receive little exposure to tobacco smoke or polluted air. While both groups also keep meticulously clean homes, the researchers noted, the Amish, unlike the more industrialized Hutterites, don’t use electrical machinery on their farms, and their children play in the family barns.
The researchers looked at the immune cells in 30 children from each community, and were astonished to find that there were, in the words of an author of the study, “whopping differences with very, very different cell types and cell numbers.”
All of the Amish children, it was found, had a large proportion of neutrophils — white blood cells crucial to the immune system — and none of them had asthma. The Hutterite children all had far fewer neutrophils in their blood, and six of them had asthma.
The researchers then analyzed dust from the Amish and the Hutterite homes. The Amish dust, unlike the Hutterite, contained considerable debris from bacteria.
The respective dust samples were then tested on mice, which exhibit signs of allergic reactions to allergens. Researchers placed some dust from each sample repeatedly into the rodents’ airways.
“We found exactly what we found in the children,” Dr. Donata Vercelli, an associate director of the asthma and airway research center at the University of Arizona, said. “If we give the Amish dust, we protect the mice. If we give the Hutterite dust, we do not protect them.”
Medical experts are impressed by the study and foresee that the sort of bacteria in the protective dust could be harnessed for a therapeutic intervention to prevent asthma.
The study, like others that have similarly supported the “hygiene hypothesis” with regard to other diseases, remind us that our medical and lifestyle assumptions — like the supposition that “cleaner is better” — aren’t always borne out as true. (Though parents can still rightfully insist that their children clean their rooms.)
Last week also brought news that the Departments of Agriculture and Health and Human Services had quietly dropped their longtime recommendation of dental flossing. It turns out that there is a dearth of evidence at present that, as it has been touted to do for decades, flossing supports tooth or gum health.
There have been a number of other medical advice revisions in recent years, from once-routine tests that are no longer recommended, to surgeries that were considered useful but turn out not to be. One such intervention, “spinal fusion,” which welds together vertebrae to relieve back pain from worn-out discs, was carefully studied and found to be no better than alternative nonsurgical treatments.
The Torah charges us with taking all logical steps to protect our health. And that means utilizing, to the degree possible, the medical understandings and treatments of our times. But studies like the asthma one should remind us of what we should all know to be true: Only the Torah is perfectly true and eternal. Scientific and medical “truths,” by contrast, are always subject to revision.