FRIDAY, Nov. 9 (HealthDay News) -- Early new research offers some hopeful findings for parents of children with food allergies.

One new study suggests that some children with hen egg allergies could safely consume such eggs if they are baked at a high enough temperature for a long enough time. What's more, investigators suggest that parents who start to incorporate such cooked eggs into their child's diet may actually help them develop a broader tolerance to eggs than by avoiding eggs altogether.

A second study argues that many allergic children will outgrow their condition by age 10, allowing them to safely expand their eating options over time.

However, two experts strongly advised caution in introducing allergy-causing foods back into children's diet and said that this must only be done under medical supervision.

Both studies were scheduled for presentation this week at the annual meeting of the American College of Allergy, Asthma and Immunology in Anaheim, Calif.

Dr. Rushani Weerasooriya Saltzman, an attending physician in the division of allergy and immunology at the Children's Hospital of Philadelphia, led the egg-allergy study.

"Hen's egg is one of the most common food allergens in children," Saltzman said, noting that upwards of 600,000 American children are currently diagnosed with the condition. "Fortunately, most patients will outgrow their egg allergy by late childhood. However, until one may outgrow his or her egg allergy, egg avoidance can cause significant dietary limitations and considerable impacts on quality of life."

But heat-driven changes in the protein structure of eggs can make them safe for allergic children, Saltzman's team found. "(And) furthermore," she said, "those who can tolerate these extensively heated egg products appear to outgrow their allergy to regular or 'native' egg at an accelerated rate when compared to those patients with egg allergy who maintain strict avoidance to egg."

The team conducted 36 "oral food challenges" that involved exposing patients diagnosed with an egg allergy to three eggs that had been baked into a standard cake/bread recipe for a half hour at 350 degrees.

More than half (56 percent) of the patients displayed tolerance to the food, leading the authors to conclude that a majority of patients had outgrown their condition. And this, they said, could lead to such patients being able to embark on a much more diverse diet and perhaps the development of even greater food tolerance down the road.

A second study team led by pediatrician Dr. Ruchi Gupta, at Lurie Children's Hospital of Chicago, conducted a survey to assess how much the eight most common food allergies in U.S. children younger than 10 persisted or waned with age.

The survey found 2,120 children aged older than 10 with known food allergies. Of these, 28 percent were found to have developed food allergy tolerance at some point following their initial diagnosis.

Children who had been diagnosed with an egg allergy before 10 years of age were the most likely to go on to outgrow their allergy, followed by those with a milk allergy diagnosis.

Specifically, 55 percent of egg-allergic children and 45 percent of milk-allergic kids ultimately developed tolerance to each respective food at an average age of about 6 and 7 years.

But only 16 percent of those with tree nut allergies and 14 percent of those with shellfish allergies went on to outgrow their condition. And both groups did so at later ages -- nearly 12 years old for shellfish allergy and almost 10 years old for tree nut allergy.

Those who outgrew their food allergies were found to be much less likely to experience severe reactions such as trouble breathing or anaphylaxis.

Boys were more likely to outgrow their allergy than girls. Kids with initially severe allergies faced worse odds than those diagnosed with a mild to moderate allergic condition.

John Lehr, chief executive officer of the Food Allergy & Anaphylaxis Network, said that while the study findings are encouraging, parents must nonetheless be careful when considering how to handle childhood allergies.

"We are encouraged by studies that show certain food allergies such as egg can be outgrown and that some children can tolerate egg in baked form," Lehr said. "But we want to caution that parents of children with food allergies must never attempt to reintroduce food allergens into their child's diet on their own -- this must be done under the supervision of an allergist."

Lona Sandon a registered dietitian and an assistant professor of clinical nutrition at the University of Texas Southwestern Dallas, agreed about the need for caution.

"In some cases, children do appear to outgrow allergies," she said. "But parents should be cautious about foods that have caused past reactions. In the case of egg allergies, there may be something different about the egg cooked into a baked product than eating a fried egg. Could it be the dose of the egg protein or maybe the change in the protein structure as a result of baking that makes it different and less allergenic? It is hard to say. And we do not know at what age allergies might subside."

"The bottom line is to be cautious in trying foods that contain ingredients that have been known to cause severe allergic reactions," Sandon said. "Reactions tend to get worse each time. It would be wise to meet with an allergist before trying to reintroduce foods that have been known to cause reactions."

Because the studies were presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

More information

For more on children and food allergies, visit the Food Allergy and Anaphylaxis Network.