Who is Likely to Outgrow a Food Allergy?
“Will my child outgrow the allergy—and when?” This is typically one of the first questions parents ask when a child is diagnosed with a food allergy. Two recent studies shed light on this important issue.
Few large studies have explored which factors could help predict whether or not a child will achieve tolerance—that is, outgrow an allergy. Between June 2009 and February 2010, Dr. Ruchi Gupta and colleagues (Ann & Robert H. Lurie Children’s Hospital, Chicago) surveyed the families of 40,104 children nationwide—the largest study of this kind to date. The researchers analyzed data for nine common food allergies: milk, peanut, shellfish, tree nuts, egg, fin fish, wheat, soy, and sesame.
The study, published online in the Annals of Allergy, Asthma and Clinical Immunology in July 2013, found that 3,188 children surveyed currently had a food allergy, while 1,245 had outgrown one. Key findings of this FARE-funded study include:
- A little more than a quarter of the children—26.6%—outgrew their allergies, at an average age of 5.4 years old.
- Children who were allergic to milk, egg, or soy were most likely to outgrow their allergies. The likelihood of outgrowing shellfish, tree nut, and peanut allergies was significantly lower.
- The earlier a child’s first reaction, the more likely that child was to outgrow the allergy.
Other factors that contributed to outgrowing an allergy included having a history of only mild to moderate reactions, being allergic to only one food, and having eczema as the only symptom. Conversely, children with severe symptoms (trouble breathing, swelling, and anaphylaxis) and multiple food allergies were less likely to achieve tolerance.
- Black children were less likely to outgrow their allergy than white children.
- Boys were more likely to outgrow their allergy than girls.
Dr. Gupta and her team conclude that, while more studies over longer periods of time are needed to confirm these findings, this data can improve the management of food allergies and aid in counseling food allergy families.
Outgrowing Peanut Allergy
Peanut allergy is one of the most common food allergies among children. In the United States, the number of children with peanut allergy more than tripled between 1997 and 2008.
This allergy tends to be lifelong; only about 20 percent of children are fortunate enough to outgrow it.
A Canadian research team reports that children are most likely to outgrow their peanut allergy by age six. After age 10, the chance of spontaneous resolution (i.e., of outgrowing the allergy) is much lower, according to this study, which was published online in the Journal of Allergy and Clinical Immunology: In Practice on June 27.
Between 1998 and 2011, the researchers, led by Dr. Anne Des Roches (Centre Hospitalier Universitaire Sainte-Justine, Montreal), followed 202 children with peanut allergy from early childhood (18 months or younger) to adolescence. To confirm their diagnosis and monitor their allergies, the children periodically received skin prick tests, along with blood tests, which measured the amount of peanut IgE in their blood. (IgE is the antibody that triggers the symptoms of a food allergy.)
Starting at age five, children whose blood tests showed a comparatively low level of peanut IgE also had the opportunity to undergo food challenges, the most accurate test available.
At the end of the study, 51 of the original 202 participants—just over 25 percent—had outgrown their allergy. Further, 80 percent of the children in this group were allergy-free before age eight. Tests also showed that these children had low levels of peanut IgE in their blood. In children who remained allergic, the amount of peanut IgE in the blood increased over the years.
The Canadian team concluded that their findings are consistent with a previous study by researchers in Australia, which followed 267 children over five years. They recommend additional studies to examine “whether spontaneous resolution may still occur in this population in late adolescence or early adulthood.”
The studies discussed here help us understand the nature and progression of food allergies. For more information about progress in the field of food allergy, please visit www.foodallergy.org/research.
This article was originally published in the Summer 2013 issue of FARE’s Food Allergy News. Read more of the newsletter here.