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12-06-2012 | Immunology | Article

Childhood food allergies 'more common in urban than rural areas'


Free abstract

MedWire News: Food allergies are more prevalent among children living in urban centers than in those living in rural areas, US researchers have discovered.

It is estimated that the prevalence of food allergy has increased by 18% in the USA over the past decade, and 40% of affected children have a history of severe reactions, ranging from hypotension to an anaphylactic event.

Noting that there are supposed regional variations in food allergy prevalence, Ruchi Gupta, from the Children's Memorial Hospital in Chicago, Illinois, and colleagues developed a survey to assess participant reports of children's food allergies, including the date of onset, method of diagnosis, and reaction history, alongside demographic data.

This was administered to a nationally representative, population-based, cross-sectional sample of US households with at least one child aged less than 18 years. This yielded a total sample of 38,465 children, 51.1% of whom were male. The mean age of the children was 8.5 years.

Multiple logistic regression analysis revealed that the likelihood of food allergy increased significantly with decreasing latitude, at an odds ratio versus northern latitudes of 1.3 for middle latitudes and 1.5 for southern latitudes.

The prevalence of food allergy significantly differed between urban centers and rural areas, at rates of 9.8% and 6.2%, respectively. There were also significant differences in the individual prevalence of common allergens, with peanut and shellfish allergy ranging from 2.8% and 2.4%, respectively, in urban areas to 1.3% and 0.8%, respectively, in rural areas. Only milk and soy allergy affected a similar proportion of children regardless of area.

The risk for food allergy, adjusted for geographic area, race/ethnicity, gender, age, household income, and latitude, remained significantly greater in urban centers compared with rural areas, at odds ratios of 1.5 and 1.2, respectively, the team reports in Clinical Pediatrics.

In conclusion, Dr Gupta commented: "This shows that environment has an impact on developing food allergies. Similar trends have been seen for related conditions like asthma. The big question is - what in the environment is triggering them? A better understanding of environmental factors will help us with prevention efforts."

By Liam Davenport

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