You're probably less likely to see an Amish kid carrying around an inhaler, because they don't seem to get asthma as often as other kids—and researchers think it's due to the cows, Live Science reports. In a study published in the New England Journal of Medicine, University of Chicago genetics professor Carole Ober and her team wanted to see why kids raised Amish-style seem to benefit from extra immunity against the disease. They selected blood samples from 30 kids ages 7 to 14 from an Indiana Amish community, as well as from 30 kids of the same ages from a South Dakota Hutterite community—a group similar to the Amish in terms of their genetic history, cultural values, and lifestyle, including a belief in big families, breastfeeding, and the shunning of modern electronic conveniences; even their diets are similar. The scientists also collected dust from 10 homes in each community.
None of the Amish kids in the study had asthma, but six of the Hutterite kids did, matching closely with results from previous studies. The researchers also found Amish blood samples had a better "innate immune response" (i.e., higher levels of immune cells called neutrophils, per Gizmodo), and the dust from Amish homes seemed to protect mice from asthma-like responses to allergens, while Hutterite dust did not. The scientists theorize microbes from Amish dairy farms, which kids are exposed to consistently starting at a young age, may provide protection. Hutterites tend to live in more industrialized, communal communities, where farms are further away from each household. While Ober admits it's "not very practical" to put a cow in every household, she says if we can isolate which microbes are helpful, they could perhaps be sprayed in the air. (A 22-year-old Amish ran a full marathon decked out in Amish garb.)