Multiple scientific studies have found that being raised on a farm exposes and desensitizes children to specific toxins and other particles in the air, which, in turn, may protect them from developing allergic and asthmatic responses to their natural environment.

Researchers in the United States and around the world who study asthma have a particular interest in children who are raised on farms because, statistically, farm kids have fewer problems with allergies, asthma, and hypersensitivities than other children. This may be due, in part, to a scientific theory known as the "hygiene hypothesis," wherein researchers speculate that the existence of fewer family farms has resulted in less contact between young children and natural microorganisms that thrive in a farm environment and help build immunity against allergies and asthma.

Study after study has shown that a significant number of children who grow up in a farming environment and, in particular, dairy farms, are somehow protected against allergies and asthma in ways that have nothing to do with the size and shape of their airways, or the workings of their lungs.

The role of genetics, if any, is unclear in these studies as it is in the study of asthma itself. Instead, this "farm effect" is linked to children's early and repeated exposure to farm animals and other agricultural products. And although allergies are related to asthma, studies indicate that the protective pathway for each condition appears to be different.

The Farm Effect

When researchers at the University of Arizona reviewed multiple studies of the "farm effect," they found three specific types of early exposure are responsible for this type of protection against asthma. These exposures included: spending time around cows, contact with straw (hay), and drinking raw cow's milk. Their findings, published in the October 2012 issue of the journal Current Opinion in Allergy and Clinical Immunology, indicate that this protection is somehow related to the diverse types of microbes found in a farm environment and in the whey proteins found in unpasteurized milk coming directly from cows.

A German study, published in the March 2013 issue of the professional journal Allergy, found that bacteria in farm dust has a protective effect against allergic airway inflammation in mice. Preliminary lab studies such as this one often pave the way for human studies that may help researchers understand the nature of this protective effect and, ultimately, how it can contribute to the development of better preventative efforts and treatments for everyone who might otherwise suffer from allergies and asthma.




Karen H. Calhoun, MD, FACS, FAAOA
Department of Otolaryngology, The Ohio State University

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