Should We Let ‘em Eat Dirt? Kids, that is ...

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, Why Dirt Is Good: 5 Ways to Make Germs Your Friends, “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.”

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

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 for “child”, and separately for “vitamin D”.

Sources

• 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.