Living in an urban area could increase your child's chances of having a peanut or shellfish allergy.
Children who live in urban zones are more likely to suffer from food allergies than those in rural areas. The results of a study mapping allergies by geographic area have shown kids living in big cities are twice as likely to have allergies to seafood and nuts than those in rural areas.
The study, published in the July issue of Clinical Paediatrics, has shown population density plays a part in the likelihood of a child developing a food allergy. “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,” said lead author Ruchi Gupta, M.D.
The study included 38,465 children 18 years old and younger, their food allergies were mapped by zip code. The key findings were:
- 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 communities.
- 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% in rural communities.
- 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.
Exposure to some bacteria good for children
Food allergy is a serious and growing health problem. An estimated 5.9 million children under age 18, or one out of every 13 children, now have a potentially life-threatening food allergy, according to 2011 research by Gupta.
Past research has shown an increased prevalence of asthma, eczema, allergic rhinitis and conjunctivitis in urban areas versus rural ones. One hypothesis is that exposure early in life to certain bacteria associated with rural living may protect against hereditary hypersensitivity to certain allergens. Or, many pollutants encountered in urban areas may trigger the development of these allergies.
“Nobody ever ate kiwis”
A lack of correct diagnosis and understanding means global allergy data is hard to come by. One thing researchers are realizing is the importance of crossing borders when studying allergies. Not only are people becoming more globally mobile, but food is too.
“One of the classic examples [in the USA] is that we never used to see kiwi allergy, but no one ever ate kiwis. Now everybody eats kiwis and we have lots of kiwi allergies,” Hugh Sampson a professor of paediatrics and immunobiology at the Mount Sinai School of Medicine said.
“Everything is so global now. We’re getting exposed to foods that we never had before.”
The increasing influence of a Western diet could explain the increase in food allergies worldwide as people eat food they are not genetically used to. This, however, cannot account for the increase in allergies in the U.S. itself. Peanut allergies in American children doubled from 1997 to 2002.
“The Chinese eat the same amount of peanut per capita as we do, they introduce it early in a sort of a boiled/mushed type form, as they do in many African countries, and they have very low rates of peanut allergies,” said Sampson. Americans tend to prefer the dry roasted sort and introduce it to older children.
This suggests allergy rates may be related to how and when the food is introduced as much as with the food itself.
Have you or your children experienced a food allergy? How did you introduce common allergy foods to your child? Let us know in the comments below.