Food
Allergy SymptomsFood Allergies
Patricia Murray, RD, MEd
Food allergy or sensitivity is reported in four to eight percent of the pediatric population (Anderson, 1994.) Food allergies may be difficult to diagnose in the pediatric population, since children’s symptoms are exceedingly diverse. This article will define a food allergy, describe symptoms, define the different diagnostic tests for food allergy testing, and discuss treatment.
What is a food allergy? “A food allergy is any adverse reaction to an otherwise harmless food or food component that involves the body’s immune system” (AAAI, 1993). It is not to be confused with other types of adverse reactions to foods, such as food intolerance (e.g. lactose intolerance). Food allergy or sensitivity occurs only when the immune system is involved in causing the reaction. “A food allergen is the part of a food that stimulates the immune system of food-allergic individuals. A single food can contain multiple food allergens, the majority of which are likely to be proteins, not carbohydrates or fats” (AAAI, 1993).
Who is most likely to develop a food allergy? The ability to become allergic is often inherited, though a child can also develop a non-inherited food allergy. Children with one allergic parent have twice the risk of develop-ing food allergies as children without allergic parents. If both parents are allergic, then the chances are quadrupled for their children (AAIA, 1993). However, a child may have a completely different food allergy than that of the parent. For example, a parent who is allergic to peanuts may have a child who is allergic to milk, but not allergic to peanuts.
Food
Allergy Symptoms
Foods most likely to cause food allergy or sensitivity are milk and other diary products, eggs, fish, including shellfish, wheat, soy, peanuts, and other legumes (split peas, lentils, etc.), and tree nuts such as walnuts, almonds etc. Food allergy symptoms vary greatly in degree, time of onset, location and amount of food eaten. The same food can produce vastly different symptoms in different people. In a person with food allergies, different foods can cause different symptoms. Most documented allergic responses occur within two hours after ingestion of the offending food, although symptoms may be delayed up to 48 hours (Adam, 1987). Food allergies can be mild, moderate, or life-threatening.
Anaphylaxis is a potentially fatal condition in which several different parts of the body experience food-allergic reactions at the same time. Symptoms may include severe itching, hives, sweating, swelling of the throat, or breathing difficulty. In very sensitive people, smelling or even touching the allergic food may produce a serious reaction. Most fatalities occur outside the home, when, in spite of an allergy history, no emergency care action plan has been made.
A child may outgrow their food allergy. However a child with asthma and a food allergy is less likely to outgrow the food allergy.
Food Allergy Diagnosis
As a food allergy may or may not be difficult to diagnose, it is often helpful to have parents keep a food diary to record not only foods but symptoms. An allergy in a young child may be obvious when the child exhibits symptoms such as vomiting, hives and swelling after ingesting the offending food on more than one occasion.
The medical diagnosis is based on history of food allergy symptoms, physical examination, tests, trial elimination diets, and food challenge, all of which are done under the supervision of a qualified allergist. Dietitians can provide support to families throughout each of these phases of diagnosis (Adams, 1987).
The two most common food allergy tests are the IgE Rast blood test and skin prick tests. The blood test requires a small sample of blood be sent to the laboratory, where the amount of IgE antibody to the specific food is measured. The result is reported as a numerical value. Skin tests are performed by exposing a tiny area of scratched skin to the suspected food. This is done by pricking the skin with a small needle through a drop of the food
extract, or by using a pricking device that has been pre-soaked in the food extract. A positive skin test results in a mosquito-bite-looking reaction at the site of the test within minutes. Both of these tests can result in a false-positive. The tests can not diagnose the level of severity of the allergy.
The only definitive allergy test is the oral challenge; however, this test carries a risk of serious reaction. This test is done by giving gradually increased amounts of the suspect food under a doctor’s supervision while observing the child’s symptoms. Only trained medical professionals with emergency treatment immediately available should do these tests.
There are also food allergies, such as some gastrointestinal allergies, that are non-IgE mediated (they may be mediated by IgA, IgG, etc.). An oral challenge may be the only definitive method to diagnose such a food allergy (Sicherer, 1998).
Elimination diets can also be used for food allergies that do not cause anaphylaxis. Foods suspected of causing an allergic reaction are eliminated for two to three weeks to determine if symptoms disappear. During this phase it is important to monitor growth and proper nutrition, to prevent growth failure and malnutrition. An elemental formula or hypoallergenic may be beneficial during this phase. After two to three weeks, if improvements are observed, then the suspected foods are gradually reintroduced one at a time to see if symptoms reoccur, and with which foods (Taylor 1987).
Food Allergy Management
The primary treatment for managing food allergies is eliminating the offending food or foods. A diet should be planned carefully so that the child’s nutrient and calorie needs are met. If a major food group such as dairy products causes an allergy, a supplement or non-dairy formula may need to be added to the child’s diet. For a child that is tube-fed, the formula selection should be done with the physician and dietitian to be sure the formula does not contain any of the offending allergen. Elemental or hypoallergenic formulas are available.
An emergency plan should be in place for the child who has anaphylactic reactions or is at risk for anaphylaxis. Treatment is generally a subcutaneous injection of epinephrine (adrenaline), such as Epipen Jr., followed by an oral antihistamine, such as Benadryl. An identification bracelet should also be worn to alert medical personnel or other caretakers in case the child is unable to advocate for himself. Practice kits to learn how to use epinephrine are available from the Food Allergy Network (http://www.allergic-reactions.com/consumer/2_1.cfm) or your local pharmacy.
Parents must learn to read labels carefully to avoid allergens. Often, the offending food can come in different forms or have a variety of names. For example, a child allergic to milk must avoid whey, a protein found in milk. By law, a food ingredient must be listed on the label, but allergenic components can accidentally get into foods. In addition, food companies may periodically change the ingredients of a food that was originally allergen free. Parents will also need to be watchful when their child is in daycare, school, a restaurant, or at parties. A parent may want to seek assistance from a pediatric registered dietitian familiar with food allergies. Parents also need to be aware that a new method of growing produce, called biotechnology, may pose a risk to the allergic child. Genetic material from peanuts is being transferred to tomatoes and other produce to develop better-looking (but not necessarily better tasting) produce. The FDA is requiring that new products be labeled to identify common allergens (Schepers 1994).
Breastfeeding and Food Allergies
The literature is controversial, but it appears that while breastfeeding does not prevent food allergies from occurring, it may delay the onset and severity of the allergy. The diet of the mother during lactation would need to be allergen free, because food allergens can be transferred in breast milk (Zeiger, 1994). Breastfeeding is the preferred feeding for infants, including those with allergy to cow and soy milk. When breastfeeding is not possible, the American Academy of Pediatrics recommends use of a protein hydrolysate formula, such as Alimentum, for infants with clinical symptoms of allergic sensitivity. (See the table of infant/toddler/older child formula by type on page 7.) Delaying the introduction of solid foods until six to eight months may also be beneficial. Children should avoid highly allergenic foods such as dairy products, eggs, peanuts, soy, fish, and shellfish until 18 to 24 months or older (Kerner, 1989).q
Patricia Murray is a pediatric registered dietitian. She consults to the Children with Special Health Care Needs state nutrition program in NH through the Special Medical Services Bureau in Concord, NH and has been in practice for 20 years.
References
Adams, E.J. (1987). Nutritional care in food allergy. Nutrition News, 2(5).
American Academy of Allergy and Immunology (1993). Understanding Food Allergy. Milwaukee, WI:AAAI.
Anderson, J.A. (1994). Tips when considering the diagnosis of food allergy. Topics in Clinical Nutrition, 9(3), 11-19.
Kerner, J.A. (1989). Breast milk hydrolystate formulas are best for potentially allergic infants. Pediatrics 1989, 114-115.
Schepers, A. (1994). Biotechnology: Fooling with mother nature. Environmental Nutrition. 17(8),4.
Sicherer, S.H. (1998) Food Allergy Testing: Questions and Answers. Food Allergy Network News, 7(4), 1,7.
Taylor, S.L. (1981). Food Allergies and sensitivities. American Journal of Dietetics, 86(5),605.
Zeiger, R.S. (1994). Can food allergies be prevented? Food Allergy News, 3(4), 1,7.