It is estimated that 1%-2% of the United States population is
allergic to peanuts, tree nuts or both. Tree nuts that can trigger
allergic reactions include cashews, walnuts, almonds, hazelnuts,
pecans, macadamia nuts, pistachios, and pine nuts. Although research
has show that children allergic to peanuts have a 20% chance of
outgrowing their allergy, before this current research, previous
researchers thought that tree nut allergies lasted a lifetime.
A research team led by Robert A. Wood from Johns Hopkins University
School of Medicine, evaluated 278 children, ranging from 3 to 21
years old, to find out the percentage of those who will outgrow
their allergy. Because an oral food challenge is currently the
best way to prove that a child has outgrown their food allergies,
researchers also sought to determine what level of tree nut specific-IgE
in the blood would be a safe level before testing the child in
Results of the study found that about 9% of children allergic
tot ree nuts outgrow their allergy. This percentage includes those
children who have had a pervious severe allergic reaction. The
study also found, unfortunately, that children who are allergic
to multiple types of tree nuts are unlikely to outgrow their allergy.
Also, 58% of children with tree nut specific IgE levels of less
than 5 kilounits per liter passed an oral challenge.
Based on these findings, researchers recommend that children with
a current tree nut allergy be re-evaluated periodically by their
allergist/immunologist to find out whether they have developed
a tolerance and whether an oral challenge should be given.
Although an ideal cut-off has not been determined, researchers
suggest that oral challenges should be taken into consideration
for children four years old or older and who have less than five
kilounits per liter of tree-nut specific IgE in their blood.
Because an allergy to tree nuts was previously thought to last
a lifetime, few patients in the past ever underwent a re0evaluation
to find out if their allergy still existed. Instead, these patients
were instructed to avoid tree nuts and were prescribed epinephrine
to take in case they had a severe allergic reaction. But now, thanks
to new research, it is apparent that periodic reevaluation of a
tree nut allergy is warranted. While only 9% will outgrow their
allergy, researchers stress that it is important that these patients
be identified so that they no longer need to worry about this otherwise
potentially deadly allergy.