People who grow up on farms are less likely to suffer allergies in later life, a new study suggests.
Women who grew up on farms are also more likely to have better lung function than those who do not, the researchers found.
The study, published in the journal Thorax, examined data on more than 10,000 people aged 26 to 54 across 14 countries.
Participants were asked where they had lived before the age of five - on a farm, in a village in a rural area, a small town, a suburb of a city or an inner city.
They were also asked about other aspects of life such as the number of siblings and pets they had and when they started school or nursery.
Their health was measured including tests for lung strength, antibody levels and self-reported allergic symptoms, including nasal symptoms, asthma, hay fever and whether they had a wheeze. Almost one in 10 (9.2 per cent) participants had lived on a farm during the first five years of life and 27 per cent lived in inner cities.
Children who grew up on a farm were more likely to have had pets, older siblings and to have shared a bedroom in their early childhood.
As adults, they were 54 per cent less likely to have asthma or hay fever and 57 per cent less likely to have allergic nasal symptoms than those living in an inner city.
Farm children were also 50 per cent less likely to have asthma than any of the other groups.
Overall, those who grew up on a farm were 53 per cent less likely to be sensitised to allergens than those who grew up in urban areas, the authors found.
Women who had grown up on a farm had stronger lungs than those who had lived in an inner city.
"Consistently across 14 countries, this analysis shows that early-life exposure to farm environments is protective against subsequent adult allergic diseases," the authors wrote.
"The consistency of the findings across multi-country settings suggests that farming effects may be due to biological mechanisms rather than socio-cultural effects that would differ between countries.
"A novel finding was that women who grew up on a farm had higher lung function and only mild heterogeneity was observed across 14 countries."
Growing up on a farm has been linked to a reduced risk of allergies in childhood but little research has examined the link between farm life in childhood with allergies in adulthood until now. It has been theorised that exposure to increased loads of microbes such as viral, bacterial and parasitic agents associated with farming environments could contribute to the so-called "farm effect". - PA