Researchers have identified a small group of bacteria originating in the cow gut that appear to account for most of the long-observed protection farm children have against asthma, tracing a path from barn air to the human immune system for the first time.
The analysis, published in NEJM Evidence, examined more than 1,000 children in European rural health studies. Nine gram-positive environmental bacterial genera, scored together, explained roughly two-thirds of the association between farm exposure and lower asthma rates in a mediation analysis, and about half of the protection against hay fever and atopic eczema. The effect was independent of gram-negative farm-associated bacteria.
