Increasing population density corresponded with increasing prevalence of food allergies in children, according to recent study results.
Ruchi S. Gupta, MD, MPH, and researchers analyzed data from a national sample of 38,465 children aged 18 years or younger, part of a population-based, cross-sectional survey administered between June 2009 and February 2010.
The researchers used multiple logistic regression models to examine the association between geographic location and food allergy and allergy severity. Food allergies reported to induce the following symptoms were included in the study: anaphylaxis, angiodema, coughing, other oropharyngeal symptoms, eczema, flushing, hives, low blood pressure, pruritus, trouble breathing, vomiting or wheezing.
Results showed that 9.8% of children living in urban centers (95% CI, 8.6-11) had food allergies vs. 6.2% of children living in rural areas (95% CI, 5.6-6.8).
The researchers found that peanut allergy was twice as prevalent in children living in urban centers than children living in rural communities (2.8% vs. 1.3%, respectively). More children living in urban centers also had reactions to shellfish vs. children living in rural areas (2.4% vs. 0.8%). Only milk and soy allergy appeared to affect a similar number of children regardless of the population density, according to the researchers.
Food allergy was most prevalent in Nevada, Alaska, Georgia, Florida, New Jersey, Delaware, Maryland and the District of Columbia, data showed. The distribution of food allergy was significantly higher the southern and middle latitudes (OR=1.5; 95% CI, 1.3-1.8) than northern latitudes (OR=1.3; 95% CI, 1.1-1.5).
The severity of food allergies did not correspond with population density, the researchers said.
Gupta and colleagues wrote that many theories have been proposed to explain the differences of atopic disease between urban and rural settings.
“Among them, the hygiene hypothesis suggests that exposure in early life to certain microbial agents associated with rural living may protect against atopy,” they wrote. “Alternatively, the many ambient pollutants encountered in urban areas have been implicated in the pathogenesis of atopic disease.”
Disclosure: The Food Allergy Initiative provided financial support for the research, authorship and publication of the study. The researchers report no relevant financial disclosures.