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16-01-2012 | Immunology | Article

Farming lifestyle link to reduced asthma risk confirmed


Free abstract

MedWire News: Results from a French study confirm that individuals who grow up in a farming environment are at a reduced risk for childhood- and adult-onset asthma.

"According to the hygiene hypothesis, the decrease in early contacts with infectious agents, in particular through contacts with livestock, could explain the increase in prevalence of asthma and allergies, and several studies have been conducted regarding farming lifestyle and asthma," explain Raphaelle Varraso (INSERM, Villejuif, France) and team.

They say that such studies have indicated a reduced risk for asthma in childhood and adulthood associated with living on a farm, but "no study has yet examined asthma in childhood and in adulthood, taking the farming environment in childhood and diet in adulthood into account simultaneously."

To address this, the researchers studied 54,018 women, aged 43-68 years, from the Mutuelle Générale de l'Education Nationale, a national health insurance plan covering predominantly teachers.

All of the participants completed questionnaires in terms of lifestyle in childhood, diet in adulthood, and asthma diagnoses in childhood and adulthood.

The three indicators of a farming lifestyle in childhood included having farming parents, being born in a rural area, and exposure to cattle. Dietary patterns were divided into three: a "prudent" pattern (high intake of fruit and vegetables), a "Western" pattern (high intake of pizza/salty pies, desserts, cured meats, and pasta), and a "nuts and wine" pattern (high intake of nuts and seeds, salty biscuits, olives, wine, and fortified wine).

Overall, 12% of the participants had a farming lifestyle during childhood.

The prevalence of asthma in childhood and adulthood was significantly lower in participants who had a farming lifestyle in childhood than in those who did not.

Specifically, compared with participants who did not have a farming lifestyle in childhood, those with farming parents, those born in a rural area, and those exposed to cattle were 46%, 21%, and 31% less likely to have childhood asthma, respectively, after accounting for age, pets in childhood, body mass index and other confounding factors. They were also a respective 28%, 13%, and 22% less likely to have asthma in adulthood than participants who did not have a farming lifestyle in childhood, after adjustment.

Dietary patterns (prudent, Western, and nuts and wine), did not modify the association between farming lifestyle and adult-onset asthma, the researchers note.

Varraso and team conclude in the European Respiratory Journal: "Results from this large French survey further support the hypothesis of contact with livestock and of a farming lifestyle resulting in lower asthma prevalence, particularly during in childhood."

By Mark Cowen

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