Does your birthplace, and your parents’, influence food allergy risk?
Published Online: November 11, 2011
Although it is known that immigrants to developed countries generally have lower rates of sensitization to respiratory allergens that those born in developed countries, less is known about food allergy, and even less about how parental immigration status may influence the risk of allergy.
In an article in The Journal of Allergy and Clinical Immunology (JACI), Keet et al examined data from a nationally representative survey (the National Health and Examination Survey 2005-2006) to determine how personal and parental immigration status affect the rate of food sensitization among more than 3,500 children and adolescents. In their clinical practice, they had noted a seemingly high rate of food allergy among the children of immigrants, and so hypothesized that personal and parental place of birth might affect the risk of food allergy differently.
The researchers found that those born outside of the US had the lowest rate of food sensitization, but if they moved to the US before the age of two years, the risk increased so that it was more similar to those born in the US. However, the highest rate of food sensitization was found among those who were born in the US to foreign-born parents, even after accounting for race/ethnicity and other factors.
Differences in allergic sensitization between residents of developed and developing countries have long been noted. These results are usually explained by the “hygiene hypothesis”, in which early exposure to certain microbes results in fewer allergies. Whether, and how, these kinds of exposures affect cross-generational risk of allergy is not clear. The observation that children of immigrants have a high rate of food allergy suggests that not only does earlier maternal exposure to a less “hygienic” environment not protect her children from developing food allergy, but it may even predispose them to it. More research will be needed to determine whether this novel hypothesis is true.
The Journal of Allergy and Clinical Immunology (JACI) is the official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.