New food allergy guidelines quash atopic dermatitis assumptions

April 1, 2011

Parents may be unnecessarily urging their children to avoid certain foods under the mistaken belief that allergies may be triggering kids' atopic dermatitis, according to a physician.

Key Points

New guidelines from the National Institute of Allergy and Infectious Diseases (NIAID) regarding food allergies aim to clarify the known risk factors for sensitization to foods and to address the role of atopic dermatitis (AD) in food allergies.

"Parents, and some physicians, would love to believe that AD was caused by allergies, and that the identification and avoidance of the allergen would cure the AD," says Lawrence F. Eichenfield, M.D., chief of pediatric and adolescent dermatology, Rady Children's Hospital and Health Center, San Diego, and professor of pediatrics and medicine (dermatology), University of California, San Diego, School of Medicine.

"While foods can cause a variety of clinically significant effects, including urticaria, contact urticaria, GI effects and occasionally flares of eczema, it is rare to have a specific allergy trigger that, when avoided, 'fixes' the AD," he says.

Food allergy risks

The effort to develop the guidelines was coordinated by a committee of 34 professional medical organizations, federal agencies and patient advocacy groups, and a 25-member expert panel was selected to draft the guidelines. Dr. Eichenfield served on the NIAID expert panel.

Among key points highlighted in the guidelines are that known risk factors for the development of sensitization to food and confirmed food allergies include a family history of atopy and the presence of AD.

Experts note that children with moderate to severe AD may in fact have a 30 to 40 percent rate of having at least one true food allergy.

Due to the increased risk, the guidelines recommend that "children less than 5 years of age with moderate to severe AD should be considered for evaluation of food allergies to milk, egg, peanut, wheat and soy if the child has persistent AD in spite of optimized management and topical therapy, or if the child has a reliable history of an immediate reaction after ingestion of a specific food."

Establishing AD facts

A popular theory behind the factors that make children with AD more susceptible to food allergy, in addition to allergic rhinitis and asthma, is that the disease compromises the skin barrier, opening the door to the "atopic march," Dr. Eichenfield says.

"It may be that intrinsic barrier dysfunction, such as those described with filaggrin mutations, 'sets up' the skin to be more permeable, allowing antigen exposure, sensitization and inflammation," he says. "This is just a theory for now."

Even when children with AD are tested for food allergies, parents and physicians should remember that standardized testing can be flawed, giving the false impression that the child has a true food allergy.

In fact, only one out of five or six positive results from specific serum IgE tests for standard foods such as milk represent a true, clinical allergy, according to Dr. Eichenfield.

"If children undergo testing without an understanding of the problems with testing, they may be labeled 'allergic' even though they only have sensitization to the allergen, not true food allergy," he says.

When a true food allergy has not been documented or proven, food avoidance is not recommended as a means of managing AD, asthma or eosinophilic esophagitis, according to the guidelines. Dr. Eichenfield says evidence on the use of food avoidance as a therapy for AD was considered very poor.

There is not enough evidence to recommend routine food allergy testing prior to the introduction of allergenic foods to children at a high risk of having a reaction as a means of prevention, he says.

What (not) to avoid

Furthermore, while some experts may recommend avoidance of highly allergenic foods in the first year of life as a precaution, there is also a concern that introducing foods to infants too late could set children up for allergies.

The NIAID guidelines, in fact, recommend that "the introduction of solid foods should not be delayed beyond 4 to 6 months of age. Potentially allergenic foods may be introduced at this time as well."

Regarding infant formula, the expert panel approved of the use of hydrolyzed infant formulas among infants who are not exclusively breast-fed: "The use of hydrolyzed infant formulas, as opposed to cow's milk formula, may be considered as a strategy for preventing the development of food allergies in at-risk infants who are not exclusively breast-fed."

The panel emphasized, however, that it "does not recommend using soy infant formula instead of cow's milk infant formula as a strategy for preventing the development of food allergy or modifying its clinical course in at-risk infants."

In terms of responding to a food allergy reaction, Dr. Eichenfield says he recommends that parents and physicians make use of epinephrine-injecting EpiPens (epinephrine, Dey Pharma).

"Dermatologists should know about EpiPens and prescribe them for anyone who has had a clinically significant allergic reaction to food," he says.

Disclosures: Dr. Eichenfield reports no relevant financial interests.