The study, published in Clinical Pediatrics, is the first to map food allergies across US, revealing that population density is key factor to risk of having an allergy.
In particular, the research shows that children in big cities are more than twice as likely to have peanut and shellfish allergies compared to rural communities – though the study also found that are equally severe irrespective of population density.
"We have found for the first time that higher population density corresponds with a greater likelihood of food allergies in children," said lead author Dr Ruchi Gupta of Northwestern University Feinberg School of Medicine, USA.
"This shows that environment has an impact on developing food allergies.”
Gupta said 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."
The study (found here) included 38,465 children, 18 years and under, who comprised a representative sample of U.S. households. Their food allergies were mapped by ZIP (postal) code.
Here are the key findings of the study:
- In urban centers, 9.8% of children have food allergies, compared to 6.2% in rural communities – almost a 3.5% difference.
- Peanut allergies are twice as prevalent in urban centers as in rural communities, with 2.8% of children having the allergy in urban centers compared to 1.3% in rural areas.
- Shellfish allergies are more than double the prevalence in urban versus rural areas; 2.4% of children have shellfish allergies in urban centers compared to 0.8% for rural.
- Food allergies are equally severe regardless of where a child lives, the study found.
- Nearly 40% of food-allergic children in the study had already experienced a severe, life-threatening reaction to food.