There are, without question, few conditions that cause more widespread parental concern and confusion than food allergies. Because of the potential for severe consequences, such as swelling of the lips or throat, breathing problems or, in the extreme case, sudden death, parents justifiably are concerned for their children's safety. This concern extends beyond the home, to school, birthday parties, summer camp, and other activities. In addition to classical food allergy, children are frequently labeled food allergic primarily because of intestinal symptoms such as colic, vomiting and diarrhea. Other groups of children may be placed on avoidance diets because of frequent colds, eczema, hives and other rashes, and asthma. Thus, a myriad of symptoms or diseases are ascribed to "food allergy".
Even physicians have difficulty organizing the possibilities and explaining to parents some of the subtleties of food allergies and related conditions, and those that may mimic these problems. The problem may be aided by agreeing on a definition, which is not always an easy task for the medical establishment. However, for the purposes of this discussion, a food allergy will be defined as a group of symptoms associated with a food that can potentially cause harm to more than one organ or body system at a time. An example is the patient who has vomiting, and develops hives and difficulty breathing after eating peanuts. This association is made stronger if the patient has a positive skin test to the food in question, confirming the presence of a specific IgE, the unique antibody responsible for a particular allergy. This is different from the problem of intolerance, where the problem lies in the inability to digest a particular food, such as milk and other dairy products (lactose intolerance), because of an enzyme deficiency. The distinction between skin test-positive food allergies and other food related problems is important because food allergies can potentially lead to very severe symptoms or even fatalities.
What are the main symptoms of food allergy? The first warning sign often begins in the mouth and throat. Lip tingling, mouth and throat itching, and lip swelling may occur within seconds of contact with the offending food. A person may also experience nausea or may actually vomit and/or have diarrhea. A feeling of flushing or itchiness may ensue. Within ~ minutes to 2 hours, sensitive persons may develop hives on their skin and often swelling of the face and throat. In most severe reactions, breathing problems, that resemble asthma, as well as dizziness, weakness and fainting (true loss of consciousness) may develop rapidly and be fatal if not treated quickly (anaphylactic shock).
Not all children with food allergies experience all the symptoms. Most commonly, the symptoms do not involve more than localized itching in the mouth and an episode of hives. Commonly, young infants will have their eczema flare when they eat certain foods. This happens within 30 minutes to 2 hours after eating. Itchiness will develop and, over the next six to eight hours, the child' s eczema may flare badly. This type of reaction, although seldom leading to anaphylaxis, is uncomfortable for the child.
Another group of patients, who suffer from hay fever, may get lip and tongue tingling and a feeling of swelling in the mouth when they eat fresh fruits and vegetables. They have ns real prsblems with the cooked variety. These patients rarely develop a severe total body reaction. Again, it may not be life-threatening to eat the food, but the symptoms are nevertheless bothersome. Sometimes, children with unexplained hives, poor growth or asthma suffer from a food allergy.
What are the main foods implicated in allergic reactions? In our pediatric population, there are seven "offenders" that account for over 90% of food allergies. They are milk, eggs, fish, wheat, soy, peanut* and tree nuts. This list is likely influenced by the prevalence of these foods in our diets. In countries where peanuts are not eaten, peanut is not a major cause of allergy. Rice allergy, which in North America is rare, is more common in Asian countries. This observation and other scientific evidence suggests that avoidance of these allergens in the early months of life may decrease the risk offood allergy in later life. Many food allergies are life long; however, some of the most common allergies seen in infancy, such as milk, egg, soy and wheat allergies, disappear in almost 70% of children by the age of 5 years. If a less common food is suspected as a cause of symploms, the parent should discuss this with the child's doctor to arrange appropriate testing and treatment.
What arc the best tests for food allergies? A good history taken by a physician who has experience with these problems is the most important aspect of the assessment of an allergic child. Many concerns about food allergies can be dispelled by paying attention to certain important facets of the history. What are the areas of the body affected? Do the symptoms recur every time a food is eaten? How long after eating the food does the problem occur? These and other questions help discern if there is a real food allergy, an intolerance caused by enzyme deficiency or no real problem at all. After a good history, it is often important to confirm the allergy with skin tests. Allergy skin testing is a very sensitive indicator of whether or not the food is significant in producing the reaction that has occurred. A positive history and skin test is a good indicator that the problem is, indeed, allergic. Negative skin tests suggest that perhaps a different food is the cause of the problem or that the symptoms are not caused by allergy. Skin tests may be performed with the fresh food itself, or with commercially-available allergy testing products. For some children, especially if they have severe eczema or are very young, a blood test for allergy, known as a RAST test, may be performed. Be wary of blood tests that are touted as a way to screen many foods at once or that promise to explain symptoms other than those classic for food allergies. These tests are often very costly and do not generally measure the antibodies related to development of allergies. Muscle strength testing after eating or touching a food or food tests using drops of food placed under the child's tongue have not been scientifically substantiated as reliable indicators of food allergy.
Food challenges are occasionally suggested by the physician if skin tests are negative or if there is still a question about the diagnosis. These should only be done by physicians with experience in food allergy. They are safe, since these tests generally start with extremely small amounts of the food substance in question, with increasing doses being given if the patient tolerates the previous amount taken. If someone can eat a significant amount of a specific food with no symptoms developing within two hours, they are likely not allergic to the substance in question. Food challenges can be very useful in complicated cases of food allergy.
How are food allergies treated? The most important facet of the treatment is the elimination and avoidance of the substance from the child' s diet. This may be a hardship in some cases, such as in egg, milk or wheat allergy. This approach entails reading labels carefully and knowing the commercial synonyms for products listed on labels; for example, milk can be listed as whey, casein or lactoserum. This is a critical part of food allergy treatment since, in very sensitive patients, contact with even small amounts of a food can lead to severe symptoms or even death.
There are also medications that are given to treat symptoms in case of accidental food ingestion. Antihistamines such as diphenhydramine (Benadryl) should be given if any contact with a food allergen is suspected, especially if there are symptoms such as hives, or skin and/or throat itchiness. In case of a more severe allergy, adrenaline (Epi-pen, Ana-kit) injected rapidly under the patient' s skin can be life saving. Your physician should explain how and when to use adrenaline if your child requires this medication.
It is unfortunate that our bodies do not always appreciate some of the finer foods in life. However, it is more unfortunate that several people die each year from food allergies. If you suspect food allergy, discuss this matter with a physician. The testing and counseling of your child may be crucial to his/her overall well being in the future.
* The peanut is a legume, like peas, rather than a nut.