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Pediatric Update

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Pediatric Update

 
Fall 2006

Living with Food Allergies

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For parents of the 3 million school-age children with food allergies, daily life can be a frustrating struggle to find a diet that won’t ignite a distressing reaction.

Food allergy affects multiple aspects of a child’s health, as well as that of the family as a whole, notes Talal A. Chatila, M.D., chief of the UCLA Division of Immunology, Allergy and Rheumatology. “Parents experience a dilemma about which foods to allow and which foods to avoid. These issues extend beyond the family, to the school and the community. As physicians, we need to manage all of these aspects of the problem with a comprehensive care approach to prevention and therapy,” he says.

Severe food-allergic reactions account for about 30,000 emergency room visits and 150 to 200 deaths every year. While any food can potentially be the source of an allergic reaction, peanuts, eggs, milk, shellfish, wheat, tree nuts, soy and fish together account for about 90 percent of all food allergies. The reaction occurs most often when the body’s immune system produces immunoglobulin E (IgE) antibodies in response to antigens in the offending food, triggering the release of histamine, prostaglandins and leukotrienes. Symptoms can range from the relatively mild, such as tingling in the mouth or hives, to swelling of the tongue and throat, respiratory impairment, drop in blood pressure or loss of consciousness. Gastrointestinal reactions are not uncommon. In extreme responses, anaphylaxis and death can occur. Symptoms typically begin within minutes to two hours.

Early onset of atopic dermatitis, often at around 2 months of age, is one sign of a potential food allergy. Babies with severe eczema, or with persistent vomiting or diarrhea that does not resolve with formula change, and babies who fail to thrive, can benefit from a thorough evaluation to pinpoint specific food allergies or to rule out food sensitivity and thus avoid unnecessary restrictions while allowing the pediatrician to proceed to other diagnoses.

Food allergies can be difficult to accurately diagnose and challenging to manage. It is not uncommon for skin tests to indicate multiple sensitivities but not all might be clinically relevant. Likewise, says Maria Garcia-Lloret, M.D., co-director of the UCLA Allergy Clinic, a positive result on the RAST (or radioallergosorbent test) blood test for IgE antibodies “does not necessarily mean that the child is allergic to the substance in question.” Levels of specific IgE can predict the likelihood of a generalized reaction for certain foods, but for many others the presence of specific IgE in the blood does not indicate a clinically meaningful allergy. Eliminating a particular food from the diet should not be recommended on the basis of a RAST test alone.

An accurate history, including a complete family history, is very important for correctly diagnosing a food allergy. A diary kept over one to two weeks that lists all foods consumed, reactions and how long before onset also will, along with a physical examination and lab tests, assist in determining what, if any, food or foods are causing symptoms. If a practitioner is facing a complex food-allergy issue or is uncertain or uncomfortable about a diagnosis, it is best to refer to specialized care, such as that available at the UCLA Food Allergy Clinic. The clinic is a comprehensive resource that offers the expertise of an immunologist and a nutritionist trained in dealing with food-allergy issues. In addition, the clinic can provide resource materials both to physicians and to members of the community.

Vigilance Is Essential

There is no cure for a food allergy, and strict avoidance of allergycausing foods remains the only certain prevention. Parents of children with a severe allergy who are at risk for anaphylaxis always should carry an EpiPen. Teens and young adults who are allergic to peanuts or tree nuts and also have asthma appear to be at increased risk for severe or fatal allergic reactions. There should be a clearly defined written plan of action—including a list of symptoms and doctor’s treatment instructions—for handling accidental ingestion, and others who are commonly around the child, such as teachers, school nurses and daycare workers, also should be educated about how to handle an emergency.

Allergenic products can show up in all kinds of foods and parents should be vigilant about reading ingredient labels of any processed food. In January of 2006, the Food and Drug Administration enacted regulations requiring that food labels clearly state if food products contain any ingredients that have protein derived from the eight major allergenic food groups. Avoiding an allergenic food is not terribly problematic if a child is found to be allergic to just one type of food, but sensitivity for multiple foods is not uncommon. “Suppose the parent of a child who has a positive skin test for 12 different foods keeps that child on a very restrictive diet and stops all of them—the child is going to become malnourished,” Dr. Chatila says. “It’s not an atypical scenario.” Perhaps of those 12 foods, only two or three are clinically relevant.

A double-blind, placebo-controlled food challenge is the gold- tandard test to ferret out which sensitivities are clinically relevant. A food challenge, Dr. Chatila cautions, should only be carried out in a medical environment and under strictly controlled conditions. “This is a test that requires a comprehensive medical setup. We want to avoid precipitating a severe reaction, hence it is essential to have a hospital’s resources behind you,” Dr. Chatila says.  

Allergies On the Rise

Like other allergies, the incidence of food allergy is on the rise. Studies have indicated that the number of children under 5 years old who are allergic to nuts, for example, doubled between 1997 and 2002, to 1 in 125. “We are seeing more food-related conditions such as eczema, allergic esophagitis, allergic gastroenteritis and urticaria,” says Dr. Garcia-Lloret. It is not clear why the incidence of food allergies is increasing. Increased exposure to peanuts or peanut-containing products early in life has been implicated in some studies. Other studies suggest it has to do with food processing—maybe roasting peanuts rather than boiling them alters the proteins in a way that makes them more allergenic. In addition, lifestyle appears to be a determining factor: The increased incidence of food allergies is being observed predominantly inWestern industrialized countries like the United States, Great Britain and Scandinavia.

“Maybe because we are living in cleaner environments, or maybe because of pollutants we weren’t exposed to before, or maybe because of antibiotics taken early in life, the bacterial composition of the gut has changed, leading not only to an abnormal permeability, but also to an altered interaction between the mucosal immune system and ‘harmless’ foreign substances such as foods,” Dr. Garcia-Lloret says.

If that is the case, one therapeutic approach to addressing food allergies might be through probiotics—recolonizing the gut with beneficial microflora in an effort to prevent the onset of food allergies. A fellow in UCLA’s Food Allergy Clinic is, in fact, initiating research in this area. Researchers elsewhere are examining the efficacy of herbal approaches to prevention and treatment. While conventional allergy shots are not effective in the treatment of food allergies, protocols of oral desensitization are being presently investigated. “Interest in the study of the pathogenesis of food allergy has risen exponentially in recent years,” Dr. Garcia-Lloret says.“We can reasonably expect that in the next few years, the management of food allergies will extend well beyond the EpiPen and dietary restrictions.”

While food allergies in adults tend to be life-long, many children do grow out of allergies, Dr. Garcia-Lloret notes. “The chances of becoming tolerant to a particular food depend on the age of onset and on the food in question. Children who had a food allergy before 3 years of age should be retested in grade school. Some children follow restricted diets when, in fact, they are no longer allergic and can begin to enjoy foods that once were off-limits,” she says. On the other hand, children and adolescents with no prior history of food allergy who begin to experience symptoms such as recurrent hives or gastrointestinal disturbances may have developed an allergy to a certain food. All of which serves to illustrate that there are no easy answers when it comes to food allergies.





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