In the Aesop fable The City Mouse and the Country Mouse, country life is shown as more peaceful than urban life.
It turns out country life is healthier too, at least in terms of childhood allergies.
Children raised on farms have lower rates of asthma than urban kids. Drinking raw milk, exposure to cows and/ or exposure to straw are all linked to lower asthma rates of children on dairy farms. Although the “Farmhouse Effect” is well recognized, it is not completely understood.
In a recent study, scientists compared the allergic reaction (not asthma) of (i) mice born and raised in a farmstall, (ii) mice raised in labs, and (iii) mice raised in labs for four weeks and then moved to a farmstall. The researchers found that the earlier the mice are exposed to the farm environment, the stronger the farmhouse effect. (Other studies have shown that when women work on dairy farms when pregnant, their children will have lower rates of asthma.)
At least two mechanisms seem to be at play. One is the constant exposure to bacteria and viruses found on a farm. The immune systems of children (and embryos) are activated by each encounter with disease-causing organisms; this allows their immune system to develop moderate responses to threats. Without this exposure (i.e., in more sterile environments such as laboratories and suburban houses), their immune systems are more likely to over- react to non-dangerous stimuli thus triggering autoimmune reactions including allergies and asthma.
The gut biome — the microorganisms in the intestinal tract — also varied between the lab and farm mice. The types and relative abundance of gut microorganism has been linked with many aspects of health, including immune system response and allergies.
While scientists toil away in their labs trying to understand the key to the farmhouse effect, farm kids can splash in the mud and play in the barn and improve their immune systems at the same time.
Sources: The farming en- vironment protects mice from allergen-induced skin contact hypersensitivity. Christophe P. Frossard, Vladimir Lazarevic, Nadia Gaïa et al. Clinical & Ex- perimental Allergy, 2017. (doi: 10.1111/cea.12905; Epub ahead of print); The farm effect, or: when, what and how a farming environment protects from asthma and allergic dis- ease. G. Wlasiuk and D. Vercelli. Current Opinion in Allergy & Clinical Im- munology. 2012. Volume 12. Issue 5. pp: 461-6; Maternal farm exposure/ ingestion of unpasteurized cow’s milk and allergic disease. Erika von Mutius, Current Opinion in Gastroenterology. 2012. Volume 28. Issue 6. pp: 570-576.
- Janet Wallace