According to a new study, family histories of particular allergies might not be the best predictor of a child’s risk of having that same food allergy. That’s not to say that there isn’t a genetic aspect of allergies, only that, in the absence of accurate allergy tests, many parents might not actually know what they are allergic to at all. Rates of food allergies are rising. One in every 13 children have a food allergy. Examining allergies within the family is an important part of understanding the nature of food allergies and how to assess risks that children may face.
— Kitchology (@Kitchology) October 5, 2016
The new paper, published in the medical journal Annals of Allergy, Asthma and Immunology, which is the official publication of the American College of Allergy, Asthma, & Immunology, detailed the findings of research from a family-based food allergy study in Chicago. Participants in the study had to have a child with a food allergy, confirmed by a positive skin test or blood test and symptoms typical of an allergic reaction to food within two hours of eating the food. Symptoms used to verify the food allergy in the children were hives, wheezing, difficulty breathing, throat tightness, chest tightness, difficulty swallowing, fainting, and vomiting, Medical News Today reported. The most common food allergies among the children were peanut (37.3 percent), milk (29 percent), and egg (22.1 percent).
The study showed that while parents of allergic kids were more allergic than the general population, the results of allergy tests and the self-reports of allergies that the adults believed they themselves had were very commonly conflicting.
“Parents of kids with food allergies had a higher rate of positive blood and skin tests to foods than the general population,” admitted allergist and co-lead author Dr. Melanie Makhija, but of the 2,477 parents, only 28 percent of those who self-reported a specific food allergy ended up testing positive for having that food allergy. Conversely, 14 percent of parents who believed that they themselves had no food allergies at all actually tested positive for peanut and sesame allergies. Moms were more likely than dads to report having a food allergy, but dads were significantly more likely to be sensitized to both foods and environmental allergens.
“Of the total participants who responded to the questionnaire, 13.7 percent of parents reported having a food allergy. There were 3.6 percent of parents reporting allergy to shellfish, 2.1 percent to milk, 2.1 percent to peanut, 2.1 percent to tree nuts, 1.4 percent to fish, 1.1 percent to egg, 1.0 percent to soy, 0.9 percent to wheat, and 0.3 percent to sesame.”
A press release about the study stresses that allergists have been specially trained to test for food allergies and diagnose the results. For the study, a total of 1,252 mothers and 1,225 fathers of allergic children were given questionnaires about their history of atopic diseases, food allergies, demographics, and home environment. They also sat through skin prick testing and sIgE serum tests to check for allergies to nine different foods (egg white, sesame, peanut, soy, milk, shrimp, walnut, cod fish, and wheat) and environmental aeroallergens like cat dander and dog dander. Allergen sensitization was defined in the study as having an sIgE level greater than 0.35 kUA/L or a positive skin test with a mean wheal diameter at least 3 mm greater than the saline control.
— No Nuts Moms Group (@nonutsmomsgroup) October 13, 2016
So, in a bizarre finding, over two-thirds of parents of allergic children were actually sensitized to either a food or an aeroallergen, but just 28.4 percent had sensitization to the allergen that they thought they did, according to the study. The authors say that while the results indicate that parents of children with allergies are more likely to be allergic themselves, the study indicates that family history questionnaires might not be the best way to assess a child’s risk for a food allergy.
“Our study suggests that using parental report of food allergy as a risk factor is unreliable.”
The authors say that infant eczema would be a better indicator of a child’s risk of acquiring a future food allergy.
— Dermatology Nottm (@CebdNottm) October 12, 2016