Farm life protects children from allergic rhinitis symptoms into young adulthood
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Childhood on a farm protected against allergic rhinitis throughout young adulthood, whether or not children stayed on the farm through puberty, according to a study published in The Journal of Allergy and Clinical Immunology.
But growing up on a farm did not significantly protect children against wheeze, Sonja Strieker, MSc, research assistant with the Institute and Clinic for Occupational, Social and Environmental Medicine at Ludwig-Maximilians-University Hospital in Munich, and colleagues found.
The researchers examined data of 1,333 participants from the cross-sectional multidisciplinary study to identify the genetic and environmental causes of asthma in the European Community, or GABRIEL study, who lived in southern Germany and completed questionnaires at baseline and follow-up.
Approximately half of the participants were female, with a range of age 6 to 11 years at baseline and age 20 to 25 years at follow-up.
The researchers found an inverse association between farm living at baseline and symptoms of allergic rhinitis (4% vs. 10%; P < .001) and wheeze (8% vs. 12%; P = .02).
Whereas 66% of the participants who lived on a farm at baseline continued to live on a farm at follow-up, only 3% of those who did not live on a farm at baseline had moved to a farm at follow-up.
Also at follow-up, the prevalence of allergic rhinitis increased from 10% to 24% among those who did not live on a farm at baseline and from 4% to 10% among those who did. Although incidence increased in both groups, researchers noted the prevalence of allergic rhinitis was significantly higher in the group that had not lived on a farm (P < .001).
The prevalence of symptoms of wheeze remained similar between baseline and follow-up, but consistently higher among those who did not live on a farm at baseline (7% vs. 12%; P < .001).
According to adjusted generalized estimating equations models (n = 1,290), children who had always lived on a farm (OR = 0.35; 95% CI, 0.2-0.62) and those who moved away from a farm (OR = 0.36; 95% CI, 0.17-0.77) were less likely to experience symptoms of allergic rhinitis than those who had never lived on a farm.
The odds ratios for wheezing showed a reduced trend among those who ever lived on a farm but lost significance in the adjusted models.
Although they could not confirm a significant association between farm living and symptoms of wheeze, the researchers said their findings confirm the hypothesis that farm living is inversely related to allergic diseases in childhood and adulthood.
This protective effect may be due to the role of intestinal microbiota in preventing atopic diseases by balancing the ratio of Th1 and Th2 types of cells, the researchers wrote. Or, the exposure to the diverse microbial environment on farms may influence the microbiome of the upper airway and gut, they continued.
Due to a nonsignificant interaction term between farm living and follow-up, the researchers found that the protective effects of farm living remained constant through young adulthood whether participants had lived on the farm through follow-up or only at baseline.
Therefore, the researchers concluded, children enjoyed these protective benefits regardless of whether they moved away from the farm once they had reached puberty, indicating that the window for acquiring these benefits occurs in childhood.
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Kirsi M. Järvinen-Seppo, MD, PhD
These results are aligned with earlier reports from Europe and the U.S., although allergic rhinitis is less studied than asthma. Unfortunately, there are no simple applications based on these results yet to apply to clinical care. More research is needed to study the mechanisms of farm life protection.
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