Outgrowing Allergies

This is the most common question that I receive. Do you think your son will ever outgrow his allergies? My answer is, “I doubt it.” It would be wonderful to think that he would outgrow his allergy to peanuts, tree nuts, sesame, fish and shellfish…however the likelihood is not great. With as many allergies as he has, and as severe as they are – he has said he doesn’t want to ever eat peanuts even if he were to outgrow them!

Some allergies, especially peanuts, tree nuts and shellfish will rarely disappear when they are severe early in life and in abundance. According to a study in the November 2005 Journal of Allergy & Clinical Immunology (JACI), 9% of children with a tree nut allergy will outgrow this allergy, yet it is less likely to be outgrown if a child has multiple nut allergies. Up to 20% of children with a peanut allergy have been found to outgrow their peanut allergy, and once again if they are allergic to multiple foods, the allergy is less likely to be outgrown. Recent studies indicate that once a peanut allergy is outgrown the best method to keep the allergy at bay is to regularly eat peanuts!

The odds aren’t great for your child with multiple food allergies to outgrow their nut allergies, and therefore they are generally considered life-long and complete avoidance of the offending food is always the prescription.

According to research from Johns Hopkins Children’s Center published in Science Daily in December 2007, milk and egg allergies now appear to be more persistent and harder to outgrow:

“In what are believed to be the largest studies to date of children with milk and egg allergies, researchers followed more than 800 patients with milk allergy and nearly 900 with egg allergy over 13 years, finding that, contrary to popular belief, most of these allergies persist well into the school years and beyond.

The bad news is that the prognosis for a child with a milk or egg allergy appears to be worse than it was 20 years ago, says lead investigator Robert Wood, M.D., head of Allergy & Immunology at Hopkins Children’s. Not only do more kids have allergies, but fewer of them outgrow their allergies, and those who do, do so later than before.

Researchers caution that their findings may reflect the fact that relatively more severe cases end up at Hopkins Children’s, but they believe there is a trend toward more severe, more persistent allergies.

The findings also give credence to what pediatricians have suspected for some time: More recently diagnosed food allergies, for still-unknown reasons, behave more unpredictably and more aggressively than cases diagnosed in the past. We may be dealing with a different kind of disease process than we did 20 years ago, Dr. Wood says. Why this is happening we just don’t know.

Earlier research suggested that three-quarters of children with milk allergy outgrew their condition by age 3, but the Johns Hopkins team found that just one-fifth of children in their studies outgrew their allergy by age 4, and only 42 percent outgrew it by age 8. By age 16, 79 percent were allergy-free.

Similar trends were seen in the egg-allergy group. Only 4 percent outgrew this allergy by age 4, 37 percent by age 10, and 68 percent by age 16.

The Hopkins Children’s team found that a child’s blood levels of milk and egg antibodies-the immune chemicals produced in response to allergens-were a reliable predictor of disease behavior: The higher the level of antibodies, the less likely it was that a child would outgrow the allergy any time soon. Pediatricians should use antibody test results when counseling parents about their child’s prognosis, researchers say.

One encouraging finding: Some children lost their allergies during adolescence, which is later than believed possible, suggesting that doctors should continue to test patients well into early adulthood to check if they may have lost their allergies.

Milk and egg allergies are the two most common food allergies in the United States, affecting 3 percent and 2 percent of children, respectively.

Don’t be disappointed if your child is still allergic to foods well after the 5 year old mark! Each child’s immune system is different, and there are plenty of adults allergic to foods who have learned to have profitable, productive lives!

There is a type of allergy blood test called an Immunocap RAST that can help predict an allergic reaction or outgrowing a food allergy.  The Immunocap is a type of RAST test that utilizes Pharmacia equipment.  This is a specific type of RAST test.  Dr. Hugh Sampson, one of the foremost food allergy researchers, has developed positive predictive values and negative predictive values for this test.  Dr. Sampson is a Professor of Pediatrics and Biomedical Sciences at the Mount Sinai School of Medicine. He is Chief of the Division of Allergy & Immunology in the Department of Pediatrics, Director of the Jaffe Food Allergy Institute, and Director of the General Clinical Research Center at the Mount Sinai Medical Center.

He found that a score of 14 is a positive predictive value for peanuts, and thus likely to indicate a reaction.  The negative predictive value is a score of less than 0.35 for peanuts.  At this level, a child has an 85% probability of not having a reaction, therefore has likely outgrown their allergy. Here are the rest of the predictive values for common allergens:

95% predictive (or greater)
Egg = 7.0, if less than 2 years old then 2.0
Milk = 15.0, if less than 2 years old then 5.0
Peanut = 14.0 (100% predictive)
Fish = 20 (100% predictive)
Tree nuts = 15 (approx. 95%)
Soybean = 30 (73% predictive)
Wheat = 26 (74% predictive)

If you believe that your child has outgrown his/her food allergies, your allergist may suggest a food challenge be performed in their office. Your child will be given a small amount of the food and then be carefully monitored to determine if there is any reaction. Some children will test negative to a food on a skin prick test or a RAST test, yet still have reactions to the food if eaten. These tests can be anxiety producing for the parent and the child. This is especially true if no reaction is expected.

NEVER would you want to perform your own food challenge at home! If you believe that your child has outgrown an allergy, speak with your physician or allergist about a food challenge in their office.

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