Dusty farms prevent allergies

Growing up on a dairy farm protects children from allergies, hay fever and asthma, a new study has shown.

One third of children in the western world have a dust mite allergy, but previous studies have shown that, among children who grow up on farms, that rate is halved.

Now researchers from Ghent University in Belgium have performed experiments on mice and on human lung cells to establish the basis for the protective effect of farm life.  

Farm dust, they found, prevented mice from developing asthma as a result of a dust mite allergy. Animals exposed mice to the dust for 14 days before they received an intervention designed to trigger dust mite allergy were universally protected from asthma. Control mice not exposed to farm dust, however, were not protected.

By examining cultured human lung cells, the team found that farm dust exposure blocked inflammatory responses to dust mite allergens. This inflammatory response of the lung's so called "barrier cells" would normally be experienced by allergy sufferers. The farm dust blunted this response.

"We found that farm dust protects children from developing allergies by changing the lung structural cells in a profound manner," says study author Bart Lambrecht.

So is the secret to preventing dust mite allergies to take a deep breath of dusty farm air?

"When you grow up in a too clean an environment, it's like your lungs have lost track; they don't know anymore what's dangerous or not and they will react to anything."

But, Lambrecht explains, to reap the full benefit, children need to be exposed to this dusty air very early in life, ideally before the age of one.

"At this stage of life your immune system is developing, so there's still a lot of flexibility in the immune system and it needs to be educated."

Perhaps as a result, some entrepreneurial farmers in the Netherlands and Germany are opening day care centres on dairy farms to help parents to expose their children to these allergens.