Individuals who grew up close to farms apparently have lower allergen sensitivity, and living near livestock can curb allergies even among adults.
In a research published April 30 in the Occupational & Environmental Medicine, 2,443 adults aged 20 to 72 years were studied to determine the relationship of residential distance to livestock farms and risk of allergies.
The researchers found that those who lived within 327 meters from livestock are 21 percent less likely to acquire allergies compared to those who lived 500 meters and beyond.
They also looked at similarities of people living near cattle or pig farms — except for poultry farms — and found the same allergen resistance. However, blood tests of this group of individuals revealed a tendency to develop immune conditions related to asthma, food allergies, and eczema.
"Farming is actually one of the few environmental exposures consistently linked to respiratory allergies," said study author Lidwien Smit of Utrecht University. "It's important because the number of people affected by respiratory allergies has sharply increased over the last few decades."
Protection Against Farm Allergens
From the participants' blood samples, the research team measured the allergy antibodies to house dust mites, grass, and domestic pets like cats and dogs.
Almost 30 percent of the participants had allergies typically due to grass and house dust mites. About one-third had also lived on a farm during their childhood, and interestingly, those who showed apparent protection from allergens grew up on a farm.
However, the researchers conclude that living on farms does not necessarily reduce allergen sensitivity. Smit said future studies can explore if diverse microbes present on wind-borne dust from farms condition the immune system to fight off allergies.
Low Sensitization Continues After Childhood
Grethe Elholm of Aarhus University in Denmark commented that focusing on cleanliness may be harmful for the health.
"Farms may be considered dirty and smelly, but they might actually be doing our immune system a favor," Elholm said.
Elholm's statement is supported by the results of a similar study published in 2005 in Occupational & Environment Medicine. The research team conducted prick test and questionnaire in 17 municipalities of Kuopio Province (formerly Kuopio County) to determine the risk of sensitization to allergens in individuals who did and did not live on farms.
The study found that sensitization to allergens due to farming environments is not restricted to early childhood. It is also possible that adults who expose themselves to farm environments have a decreased risk of sensitization to pollens and pets.
"A lifelong exposure to a farming environment might decrease the risk of allergic diseases by decreasing the risk of sensitization to those allergens, which are most often associated with these diseases," the researchers concluded.