Should We Let ‘em Eat Dirt? Kids, that is...
American children’s overly sterile surroundings and overprotective parents may pose dangers to their health
by Craig Weatherby
Fans of the comic strip “Peanuts” will remember the little boy nicknamed Pigpen, who ambled about in a perpetual cloud of dust and dirt.
Recent findings indicate that Pigpen’s prospects of developing a healthy immune system would have better than his fictional peers’ chances—thanks precisely to his status as a human dirt magnet
In fact, excessively clean environments and lack of outdoor play may be partly to blame for the rise of asthma and allergies in recent years.
Seemingly “icky” bacteria and worms may be crucial to ensuring that growing children develop immune systems that can tell harmless organisms and foods from truly toxic things.
As immunologist Mary Ruebush,, Ph.D., writes in her new book, Dirt is Good, “What a child is doing when he puts things in his mouth is allowing his immune response to explore his environment… the most delightful sights for a parent should be a young child covered in dirt from an active afternoon of outdoor play.”
|Farm life builds balanced immunity|
Intriguing findings suggest that because kids who grow up on farms get exposed to a wider range of organisms, this helps their bodies build balanced immune systems.
For example, bacteria strains isolated from farm cowsheds appear to possess strong allergy-protective properties (Debarry J et al. 2007).
And it seems to matter which kind of farm a child is raised on, because some environments are linked to lower risk of asthma more than others.
The farm-related factors that German researchers found most protective against asthma in children on farms were pig keeping, consuming raw farm milk, more time spent in animal sheds, and handling hay and silage (Ege MJ et al. 2007).
Dr. Ruebush also decries the overuse of anti-bacterial soaps, which reduce kids’ exposure to harmless bacteria while doing little to reduce common colds and other innocuous infections, which actually help the immune system calibrate itself.
The idea is that if children aren’t exposed to dirt, bugs and bacteria early in life, their bodies never learn to tell real threats from the myriad harmless matter that surrounds them and invariably finds its way into kids’ mouths, ears, noses, and lungs.
Unless they are exposed to a reasonably full range of normal environmental “stuff”, children’s immune systems may become hyper-sensitive and mount the inappropriate, excessive responses that characterize allergies, asthma, and inflammatory skin and bowel disorders (Romagnani S 2004; Hersoug LG 2006).
Worms and microbes as health food
The so-called “hygiene hypothesis” of allergies and asthma holds that the microorganisms and worms ingested by kids when they play in and around soil and dirt actually aid the development of healthy immune systems.
In fact, it’s looking like, as an article in The New York Times reports, “…worms may help to redirect an immune system that has gone awry and resulted in autoimmune disorders, allergies and asthma” (See “Babies Know: A Little Dirt Is Good for You”).
The Times article notes that recent research results link the sterile environments of Western countries to immune system disorders like multiple sclerosis, Type 1 diabetes, inflammatory bowel disease, asthma and allergies, rates of which have risen steadily in the U.S. and other developed countries.
Scientists at Tufts University report that parasitic worms—cestodes, nematodes, and trematodes—are routinely found in the intestines of people in less-developed
|The worms kids don’t need|
Our society seems to have acquired an aversion to “dirt” so extreme that it may be promoting an epidemic of immune-system disorders.
That said, some environmental parasites are to be avoided. School-age children are particularly at risk for parasitic roundworms.
In the United States, pinworm is the most common of all roundworm infections in school-age children. It is spread mainly by child-to-child contact—not through soil or dirt—and is found most often in family groups, daycare centers, schools, and camps.
We found this comment on the Web site of the National Institute of Allergy and Infectious Disease:
“Folklore is filled with fantastic descriptions of symptoms and abnormal behavior attributed to pinworm infection. In fact, many people have no symptoms at all. Of those who do, the symptoms are usually mild and barely noticeable.”
For more information, see the Parasitic Roundworm Diseases page at the National Institute of Allergy and Infectious Diseases (NIAID).
Also called helminths, these worms suppress strong immune responses to ingested substances (including helminths themselves), and their absence from Western populations may account for the high rates of inflammatory bowel disease (IBD) in the First World, and low rates of IBD in the Third World (Weinstock JV and Elliott DE 2009).
Studies underway in the United States and various countries are testing “worm therapies” against immunological diseases such as inflammatory bowel disease (Ruyssers NE et al. 2008).
Of course, this is not an argument for eating undercooked meats full of parasitic worms, or for living amidst human filth.
Instead, it is an argument for increased exposure to the natural environment, which allows the bodies of infants and toddlers to sort minor irritants from truly dangerous things, and not overreact to the former so strongly that the response itself becomes a debilitating disease.
And of course, tiny invaders aren’t the only aids to optimal child health: search our newsletter archive.
- Debarry J, Garn H, Hanuszkiewicz A, Dickgreber N, Blümer N, von Mutius E, Bufe A, Gatermann S, Renz H, Holst O, Heine H. Acinetobacter lwoffii and Lactococcus lactis strains isolated from farm cowsheds possess strong allergy-protective properties. J Allergy Clin Immunol. 2007 Jun;119(6):1514-21. Epub 2007 May 3.
- Ege MJ, Frei R, Bieli C, Schram-Bijkerk D, Waser M, Benz MR, Weiss G, Nyberg F, van Hage M, Pershagen G, Brunekreef B, Riedler J, Lauener R, Braun-Fahrländer C, von Mutius E; PARSIFAL Study team. Not all farming environments protect against the development of asthma and wheeze in children. J Allergy Clin Immunol. 2007 May;119(5):1140-7. Epub 2007 Mar 8.
- Hersoug LG. A reformulation of the hygiene hypothesis: maternal infectious diseases confer protection against asthma in the infant. Med Hypotheses. 2006;67(4):717-20. Epub 2006 May 22.
- Romagnani S. The increased prevalence of allergy and the hygiene hypothesis: missing immune deviation, reduced immune suppression, or both? Immunology. 2004 Jul;112(3):352-63. Review.
- Ruyssers NE, De Winter BY, De Man JG, Loukas A, Herman AG, Pelckmans PA, Moreels TG. Worms and the treatment of inflammatory bowel disease: are molecules the answer? Clin Dev Immunol. 2008;2008:567314. Review.
- Weinstock JV, Elliott DE. Helminths and the IBD hygiene hypothesis. Inflamm Bowel Dis. 2009 Jan;15(1):128-33.