Study identifies which bacteria trigger the 'farm effect' that makes children less prone to allergies - Medical Xpress

What the report says

Medical Xpress reports that an international research team led by Professor Markus Ege of LMU University Hospital’s Dr. von Hauner Children’s Hospital and Helmholtz Munich has identified specific bacteria that may help explain why children raised around farms are less likely to develop asthma, hay fever and allergies. The findings, published in NEJM Evidence, address a long-standing question behind the “farm effect,” a pattern previously seen in observational studies worldwide.

According to the report, researchers analyzed samples and data from more than 1,000 children in rural European studies, including nasal swabs, mattress dust and, for 47 farm children, dust from cowsheds. Using genetic, metabolic and computer-modeling approaches, and checking findings against data from France and Finland, they narrowed the protective signal to a small group of Gram-positive bacteria, including Romboutsia timonensis and Glutamicibacter arilaitensis.

The study found that these bacteria, traced to cows’ digestive systems and barn air, are linked to microbial compounds such as kynurenine, xanthine, alpha-linolenic acid and stearidonic acid. The researchers reported that these substances can be inhaled and recognized by AhR and PPARγ receptors on human airway cells, receptors involved in immune regulation. The article says the bacteria together accounted for much of the farm-associated protection against asthma, and part of the protection associated with hay fever and atopic eczema.

The work matters because it moves the farm effect beyond broad correlation toward a proposed biological pathway: cows, barn microbes, bacterial metabolites, human receptors and reduced inflammatory overreaction. Medical Xpress notes that the findings could guide future laboratory work and, eventually, efforts to imitate the protective effect without requiring children to spend time in barns.