We’ve talked before about how food allergy trends vary around the world, but in today’s post we’ll discuss the findings of a recent study which found that food allergy trends also vary from place to place within the United States.
The study, which was published in the scientific journal Clinical Pediatrics, looked at data from a representative sample of nearly 40,000 US children. A survey was sent to a randomly selected group of families with children, asking parents about whether or not their child had food allergies, when and how the allergies were diagnosed, and the history and severity of allergic reactions for each allergen. Using the family’s zip code, the children were categorized according to where they live, specifically according to their latitude and whether they live in an urban or rural area.
- The researchers found that the oddsof having a food allergy are significantly higher in southern latitudes, in comparison to northern latitudes. In other words, the rate of food allergies in the US seemed to increase as you move from the north to the south.
- The study also found a significantly higher prevalence of food allergies in urban vs. rural areas. The prevalence of food allergies in urban areas is 9.8% and only 6.2% in rural areas. Interestingly, the prevalence rate for the specific types of allergies also varied. While milk and soy allergies seemed to be consistent among all areas, peanut, shellfish, fin fish, egg, tree nut, and wheat allergies varied significantly by urban/rural status.
- The odds of having a food allergy were significantly higher in more densely populated regions; however, the severity of the allergic reaction did not seem to be related.
This is the first study of its kind here in the US, however, a similar study in Australia also found a correlation between geographic remoteness and childhood food allergy. That study showed that remote areas have significantly less sales of hypoallergenic infant formulas and prescriptions for EpiPen injections (even after adjusting for socioeconomic factors). Similar to the US study, the Australian study also found that although urban/rural status affects the prevalence of food allergies, it does not seem to affect the severity of food allergies. Several previous studies have shown a similar association between urban/rural status and the frequency of atopic diseases, like asthma, eczema, allergic rhinitis, and allergic conjunctivitis.
Should we all move to rural, remote, areas in the north to reduce our children’s chances of developing food allergies? No, at least not yet. It’s important to distinguish between association and causation. Although an association was found between geography and food allergies, this doesn’t mean that food allergies are actually caused by where you live. These findings provide valuable insight into factors which influence food allergies and may help researchers to better understand how and why allergies develop. However, more research is needed to fully understand the role that geography plays and whether or not we may be able to reduce the chances of food allergy by changing where we live.
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