A study of 80 children with peanut allergies - aged four to 14 - revealed that some children completely lost their potentially serious or life-threatening allergy.
Researchers at Johns Hopkins Children's Center and Arkansas Children's Hospital made the discovery and also found that for those who grow out of their allergies, there was a low risk of recurrence.
"Although we once thought peanut allergy was a lifelong problem, we now believe certain children, namely those with low levels of allergy antibodies, may outgrow it," said senior author Dr Robert Wood, of the Johns Hopkins Children's Center.
"Because of these findings, and the tremendous burden peanut allergies can cause for children and their families, I recommend that children with peanut allergy be retested on a regular basis, every one or two years."
The researchers found that children were more likely to outgrow their peanut allergy if they had low levels (less than 5 kilo units of antibody per litre) of peanut-specific IgE, the antibodies produced by the immune system that cause allergic reactions. These antibodies can be measured with a blood test that is widely available.
Although a high level of peanut IgE (more than 5 to 10 kilo units) is typically associated with a clinical allergic reaction, it is not possible to predict the severity of the reaction based on IgE levels only.
Experts say peanut allergies, which affect approximately one to two per cent of young children, are on the rise. Peanut allergy typically occurs with symptoms in one of the first few exposures to peanut. The allergy can be triggered by as little as 1/1000th of a peanut and is the leading cause of anaphylaxis, the life-threatening allergic reaction that can constrict airways in the lungs, severely lower blood pressure, and cause swelling of the tongue or throat and sometimes death.
Diagnosis of peanut allergy is based on clinical history along with skin prick test, measurement of allergen-specific immunoglobulin E (IgE), and clinically supervised oral food challenges. Once the diagnosis is confirmed, the current management approach has been strict avoidance of the food. This is obviously not ideal since it is difficult to avoid completely peanut and tree nuts and accidental exposures can occur.
Current information suggests that only about 20 per cent of people with peanut allergy, and less than 10 per cent of those with tree nut allergy, acquire tolerance. Peanut allergy also has a recurrence rate of 8 per cent.
The strict avoidance approach has been challenged recently by clinician researchers in the UK who have argued that such a strategy has not reduced the incidence of peanut allergy and that exposure early in life may be important for developing tolerance (McLean & Sheikh 2010). Ongoing research and clinical trials, due to report their findings in 2013-2015, may provide clarity on these issues.
In the meantime, if you have any concerns regarding peanut, tree nut or other food allergies, it is best to check these with your doctor who can provide you with the best advice for you or your children.
References
Fleischer DM, Conover-Walker MK, Christie L, Burks AW, Wood RA (2003) The natural progression of peanut allergy: Resolution and the possibility of recurrence. Journal of Allergy and Clinical Immunology 112: 183-189.
McLean S, Sheikh A (2010) Does avoidance of peanuts in early life reduce the risk of peanut allergy? British Medical Journal 340: 593-594.
Pansare M, Kamat D (2009) Peanut allergies in children - a review. Clinical Pediatrics 48: 709-714
Skripak JM, Wood RA (2008) Peanut and tree nut allergy in childhood. Pediatric Allergy and Immunology 19: 368-373
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