Approximately one out of 13 children under age 18 are allergic to at least one food, though many of them will outgrow their allergy by the age of 16. As a child’s immune system matures, the child might naturally begin tolerating the food proteins that earlier caused problems. However, individuals with mature immune systems – older children and adults – can develop allergies to foods they used to enjoy eating.
There are no definitive answers about who will develop a food allergy, outgrow it, or why allergies can disappear only to return years later. What exists is a growing pile of research and statistics that paint a fuzzy picture about who might develop an allergen tolerance.
Some Basic Odds
Approximately one-quarter of children with a food allergy will outgrow it—the earlier a child’s first reaction, the more likely that child will do so. The greatest chance of developing a natural tolerance goes to those with mild to moderate reactions who are allergic to one food and have eczema as their only symptom.
Boys are more likely to outgrow their allergy than girls, black kids are less likely to outgrow an allergy than white kids, and reactions to milk, eggs, soy, and wheat are the most likely to be outgrown. However, a small percentage of those who start tolerating an allergen develop an eosinophilic esophagitis reaction to the same allergen months or years later.
Fish and shellfish allergies usually begin later in life, and tend to be lifelong.
Peanuts and Tree Nuts
Peanut and tree nut allergies can start at any age, but usually begin during childhood. Roughly ten percent of kids with a tree nut allergy will outgrow it.
The statistics are a bit better for peanut allergy sufferers, about 20 percent of them stop reacting. Developing a tolerance to peanut protein usually occurs by age six—after age ten the odds are significantly less.
The tendency to develop peanut protein tolerance may be detected early. In an Australian study, infants with peanut allergy were more likely to outgrow it by four years of age if they had lower levels of antibodies and small wheal size in response to skin prick tests.
Milk, Eggs, Soy, and Wheat
Young children allergic to milk, eggs, soy, and wheat can outgrow the problem by age five or six, but it may take longer. Most milk, egg, and soy allergies resolve by the age of 16.
Some kids lose their milk and egg allergy sooner by eating extensively heated forms of milk or egg, such as milk or egg baked into cookies or muffins. The dry heat used in baking disrupts or alters the allergen protein. However, introducing an allergic child to baked egg and milk products should only be done under a doctor or allergist’s supervision since anaphylaxis is possible.
Other research reveals that egg-allergic kids who develop a tolerance have immune systems producing increased amounts of cytokine interleukin-10, an anti-inflammatory protein. They also manufacture fewer levels of two other cytokines involved in allergic responses. The role of these three cytokines in protein tolerance is being studied with other food allergies as well.