FOOD ALLERGY 101
The physicians of FAST OIT are dedicated to the diagnosis and management of food allergies. We understand how the diagnosis of food allergy can be a life changing event with far reaching quality of life implications. The following is a summary of our current understanding of food allergies, including diagnostic methods, management strategies, educational resources and future directions in treatment. We hope that this information will address most frequently asked questions and stimulate additional discussions with our physicians and clinical staff.
FOOD ALLERGY PREVALENCE IS ON THE RISE
The prevalence of food allergies in the general population (both children and adults) has clearly increased during the last 20 years. While newly recognized food allergy syndromes, changing definitions and increased availability of commercial allergy testing methods have no doubt contributed to some degree to the rising number of food allergy diagnoses, the incidence of confirmed cases of anaphylactic (life threatening) reactions to common foods has more than doubled during this period, from approximately 1% to 2-3% of the population. Several theories have been proposed to explain the rise in food allergy prevalence, ranging from environmental influences of modern Western society to the ways in which we introduce new foods to infants and young children. However, at this time none of these theories has yielded definitive answers or practical solutions to prevent the development of food allergies.
OVERVIEW OF FOOD ALLERGY DISORDERS
- Problems that we evaluate and treat
Although food allergies can present with a variety of different symptoms, the single defining feature of all food allergic disorders is an immunologic mechanism. Immediate allergic reactions (IgE-mediated hypersensitivity reactions), ranging in severity from hives to anaphylactic reactions, are among the most common problems for which patients are referred to our practice. Additional food allergy-related disorders with less clearly defined immunologic mechanisms that we evaluate and treat include atopic dermatitis (eczema), Food Protein-Induced Enterocolitis Syndrome (FPIES), and Eosinophilic Esophagitis (EoE). - Problems that we do NOT evaluate or treat
A notable immunologically mediated food hypersensitivity disorder that we are often asked to evaluate is celiac disease or gluten sensitive enteropathy. We generally refer patients with suspected celiac disease to GI specialists for proper diagnosis and management. In addition, we do not subscribe to the rising common misconception that gluten or casein sensitivities are underlying causes of Autistic Spectrum Disorder. Additional food sensitivity complaints for which we do not recommend our services include: (1) ADD/ADHD; (2) multiple chemical sensitivities; (3) Chronic Fatigue Syndrome; (4) provocation/neutralization therapy.
IgE-MEDIATED FOOD ALLERGIES
The hallmark of these disorders is the potential for life threatening allergic reactions (also known as anaphylaxis) occurring within minutes after ingesting a tiny quantity of the suspect food. Symptoms of anaphylaxis may include any of the following: hives (welts), eye or facial swelling, throat swelling, change in the sound of the voice, cough, wheezing, difficulty breathing, abdominal cramping, nausea, vomiting, dizziness, faintness, sudden quietness, cardiovascular collapse and death. Milk, egg, wheat, soy, peanut, tree nuts, fish and shellfish account for more than 90% of IgE-mediated food allergic reactions. Milk, egg and wheat allergy often begin during the first year of life as these foods are being introduced into the baby’s diet. Allergic sensitivity to these foods often resolves after 5-10 years of avoidance. By contrast, nut, fish and shellfish allergies are usually lifelong problems.
DIAGNOSIS OF IgE-MEDIATED FOOD ALLERGIES
The proper diagnosis of an IgE-mediated food allergy begins with a carefully obtained medical history to determine which food(s) may be responsible for an observed allergic reaction. Because such reactions typically begin within 60 minutes following ingestion, we can usually identify candidate foods for testing by obtaining a detailed history of the events leading up to the reaction. Allergy testing should be limited to the suspected food(s). Appropriate methods for confirming a suspected IgE-mediated food allergy include skin prick testing and serum specific IgE antibody (blood) testing. Each method has advantages and disadvantages highlighted in the table below. Your DFAC allergist will recommend the most appropriate testing method depending on a variety of factors applicable to your specific case. Regardless of the method selected, broad spectrum or “screening” food allergy testing should be avoided because a positive test without a correlating history of an allergic reaction is often a false positive result, leading to unnecessary anxiety and dietary restrictions. Most of the time there is good agreement between skin prick testing and blood testing but, in some patients there are significantly different results. Your DFAC allergist may recommend both forms of testing in some circumstances.
|
Testing Method Comparisons |
Skin Prick Testing | Serum IgE Antibody Testing |
| Sensitivity in Confirming a Diagnosis of Food Allergy (With Prior Reaction History) | Excellent (>95%) | Very good (85-90%) |
| False Positive Rate as a Screening Test (Without Prior Reaction History) | 50% | 50% |
| False Negative Rate | 5% | 10-15% |
| Location of Testing | Allergist’s Office | Laboratory |
| Associated Discomfort | Mild, brief discomfort with application followed by 20-60 minutes of itching | Pain and anxiety typical of any blood draw (venipuncture) procedure |
| Stopping Antihistamines Required 7-10 Days Before Testing | Yes | No |
| Time Required to Receive Results | 30 minutes | 5-7 days |
Additional specialized testing is sometimes needed to confirm or exclude a suspected food allergy when the patient’s history and/or allergy testing results are not entirely conclusive. Carefully designed and closely supervised graded food challenges represent the “gold standard” of food allergy diagnosis. These procedures are performed only in the Medical City Dallas DFAC office, require special scheduling and staffing assignments, and typically take 4-6 hours to complete.
MANAGEMENT OF IgE-MEDIATED FOOD ALLERGIES
Primary management of IgE-mediated food allergy is known as the Avoidance Management Strategy, which includes identification and avoidance of the offending food(s); having a written Food Allergy Emergency Action Plan; and prompt administration of auto injectable epinephrine to treat allergic reactions. Food allergen identification and avoidance requires careful attention to reading ingredient labels; asking specific questions regarding the ingredients of foods served in restaurants and social settings; and declining offers of foods whose exact ingredients cannot be verified. Because anaphylactic reactions may be triggered by ingesting very small quantities of the offending food, avoidance should also include manufactured foods with “may contain” disclaimers.
FOOD ALLERGEN AVOIDANCE AT SCHOOL AND OTHER SOCIAL SETTINGS
School and other social settings where foods are served present unique challenges for children with food allergies. Because young children cannot protect themselves from accidental ingestions of allergenic foods, extra precautions must be taken to keep them safe in these environments. Banning the offending food(s) from the classroom and cafeteria are appropriate safety measures in the preschool setting, as toddlers are notoriously messy eaters and also prone to sharing foods. An acceptable alternative for protecting young food allergic children is to establish a food allergen-free seating arrangement in the cafeteria. Because protective seating arrangements may stigmatize the food allergic child and lead to social isolation, such restrictions should be discontinued when the child becomes mature enough to read ingredient labels and to resist offers of treats.
FOOD ALLERGY EMERGENCY ACTION PLANS
A document with easy-to-follow instructions outlining steps to be taken in the event of an accidental ingestion of an allergenic food is an important component of food allergy safety at school. A Food Allergy Emergency Action Plan form should be requested from the school at the end of every academic year in order to allow ample time for you to schedule a follow-up visit with your allergist to review your child’s food allergies. They should furnish a Food Allergy Emergency Action Plan form if the school does not provide one.
PROMPT ADMINISTRATION OF EPINEPHRINE IS CRUCIAL TO SURVIVAL
Anaphylactic reactions to foods are potentially life-threatening. Even fatal reactions often begin with apparently mild symptoms. Because of this risk, we must maintain a healthy degree of respect for IgE-mediated food allergies, intervening as soon as we become aware of the accidental ingestion of allergenic food. Epinephrine is the only treatment that will reliably prevent the worsening of an anaphylactic reaction in progress. Failure to administer epinephrine early in the course of an allergic reaction (within 20-30 minutes) is one of the major predictors of fatal outcomes consistently cited in published studies. Antihistamines (e.g., Benadryl™), no matter how quickly they are given or how large the dose, can neither prevent nor treat a serious allergic reaction. Antihistamines and corticosteroids have their place as additional therapy, but only epinephrine treats the basic derangement involved in anaphylaxis. Giving antihistamines such as Benadryl™ first for treatment of an anaphylactic reaction is a mistake because doing so can mask the progression of more serious symptoms and delay the administration of lifesaving treatment.
The Food Allergy Emergency Action Plan example below highlights the importance of epinephrine and provides additional steps to be taken in the event of an anaphylactic reaction. Two equally acceptable brands of auto-injectable epinephrine (EpiPen™ and AuviQ™) are currently available. Adrenaclick™ is another auto-injectable epinephrine device offered as a generic substitute for the other products. Because all three devices have different features, training must be specific for the product prescribed. Additional educational materials and hands-on instruction regarding the indications and technique for administering auto-injectable epinephrine are available through DFAC.
ORAL IMMUNOTHERAPY – AN ALTERNATIVE TO THE AVOIDANCE MANAGEMENT STRATEGY
Many parents of children with IgE-mediated food allergies express frustration with the burdens associated with the Avoidance Management Strategy and food-allergic children often express sadness due to social isolation and bullying. Validated quality of life surveys of children with food allergies and their parents have shown lower scores than those with other chronic disorders such as diabetes and arthritis. With the goal of improving the quality of life for food allergic children and their parents, oral immunotherapy (OIT) protocols have been developed as an alternative to the traditional Avoidance Management Strategy. OIT involves administering increasing doses of the allergenic food(s) very slowly in order to achieve a state of desensitization, meaning the ability to eat the food on a regular basis with a much lower risk of an allergic reaction. The concept of desensitization is taken from subcutaneous immunotherapy for aeroallergens (“allergy shots”), a treatment that allergists have provided for more than 100 years. OIT must be performed under close supervision by an allergist who is experienced in this procedure. The procedure is demanding and requires careful attention to detail on the part of the physician, medical staff, and parents. However, the anticipated outcome of being able to eat allergenic food without fear of an allergic reaction is very rewarding for food-allergic children and their parents. Dallas Food Allergy Center has been routinely performing OIT procedures for non-resolving anaphylactic sensitivity to milk, egg, wheat, peanut and several tree nuts since 2009. To date, we have conducted more than 220 OIT procedures with an overall success rate of 85%. You may read more about this novel approach to managing food allergies on our website (www.dallasallergy.net).
FOOD ALLERGY AND ATOPIC DERMATITIS (ALLERGIC ECZEMA)
Atopic Dermatitis (A.D.) is a chronic inflammatory skin condition most commonly seen in children with inherited allergic tendencies. The rash typically begins during infancy, often starting on the face and neck and later progressing to the arms and legs. The rash may range in severity from scattered, mild dry patches to severely inflamed, cracked skin. Itching is almost always a problem associated with A.D. In fact, some have referred to this condition as “the itch that rashes” rather than “the rash that itches” because itching leads to scratching, which results in worsening skin irritation with additional itching and scratching. A comprehensive eczema treatment regimen — involving a combination of moisturization, skin barrier protection, topical anti-inflammatory medications, and oral antihistamines — is essential to breaking the vicious “itch-scratch-itch” cycle and controlling this chronic condition. Recognizing the triggers and aggravating factors for A.D. is also important for successful management. The most common aggravating factors include viral respiratory tract infection (“the common cold”), sweating, soaps, perfumes, synthetic fibers, and allergies.
Food allergy is seen in approximately 30% of children with A.D. Two interrelated problems commonly complicate the diagnosis of food allergy in the setting of A.D. The first is that high levels of allergic antibody (Immunoglobulin E or IgE) produced as a result of immune dysregulation in this condition may result in false positive allergy skin tests or serum IgE test results for multiple foods. A false positive allergy test result means that the patient has had no apparent allergic reactions to a food for which s/he has tested positive. Second, it is often difficult to correlate positive food allergy test results with A.D. because the condition may also be aggravated by a variety of other factors noted above. Because the most common food allergies involved in A.D. include foods of considerable dietary importance (including milk, egg, wheat, soy, sesame and nuts), it is very important to determine the relevance of a positive food allergy test in order to avoid unnecessary dietary restrictions.
The only way to determine whether or not food allergy may be driving chronic A.D. is to eliminate the food(s) in question for a sufficient period time to observe whether or not eczema improves (at least 14 days), followed by reintroduction of each suspected food individually under careful supervision by a qualified allergist performed in a properly equipped and staffed medical office. Because the reintroduction of an eliminated food may result in a life-threatening allergic reaction, this intervention should never be undertaken without first consulting your DFAC allergist.
FOOD ALLERGY AND GASTROINTESTINAL DISORDERS
EOSINOPHILIC ESOPHAGITIS (EoE)
EoE is an increasingly recognized, chronic disorder that results when eosinophils (a type of white blood cell usually associated with allergic disorders) infiltrate an individual’s esophagus. In young children, EoE often presents with symptoms of persistent abdominal pain, nausea, vomiting and poor appetite, which may result in difficulty gaining weight. Teenagers and adults with this disorder often complain of acid reflux symptoms (“heartburn”, “indigestion”) and solid foods getting stuck in the esophagus. With continued inflammation of the esophagus, individuals may develop strictures, which are bands of tissue that narrow the esophagus and prevent food from passing through easily.
An individual’s medical history and symptoms are important in suggesting the diagnosis of EoE. Other common gastrointestinal disorders (e.g., gastroesophageal reflux) should be ruled out. A diagnosis of EoE is confirmed with esophageal biopsies obtained by an esophagogastroduodenoscopy (EGD). This procedure, which is performed by a gastroenterologist, involves inserting a flexible scope through the mouth and down the esophagus while the patient is under sedation. The doctor examines the lining of the esophagus, stomach and the first segment of the small intestine for signs of eosinophilic inflammation and takes small pieces of tissue to be examined by a pathologist. The presence of high numbers of eosinophils on esophageal biopsies supports a clinical diagnosis of EoE.
As is the case with most chronic inflammatory disorders, EoE is more easily diagnosed than treated. Swallowing an inhaled topical corticosteroid medication (e.g., Flovent™ or Pulmicort™) on a daily basis represents the cornerstone of treatment. It may be necessary to take one of these medications for months or even years to keep the inflammation under control. Fortunately, these medications are poorly absorbed from the gastrointestinal tract into the bloodstream, so side effects are minimal with long term use.
Food allergy may play a role in approximately 50% of individuals with EoE. Foods most commonly implicated in EoE include milk, wheat, soy, egg, peanuts, tree nuts and seafood. Food allergy testing methods used in evaluating EoE include allergy skin prick testing, serum IgE testing, and patch testing. More than one kind of food allergy testing may be needed to identify foods suspected of driving the inflammation. The only way to correlate the results of food allergy testing with EoE is to obtain biopsies of the esophagus before and 2-3 months after eliminating the food(s) in question. Because dietary restrictions may lead to nutritional deficiencies and esophageal biopsies require anesthesia, the potential benefits and risks of such interventions must be considered carefully on a case-by-case basis.
EoE is a chronic, potentially lifelong condition. With the right treatment plan, however, individuals with this disorder can live full and productive lives.
FOOD PROTEIN-INDUCED ENTEROCOLITIS SYNDROME (FPIES)
FPIES is a food hypersensitivity disorder of suspected but unproven immunologic cause. Symptoms of FPIES typically begin during early infancy following the introduction of common dietary proteins, chief among these being cow’s milk and soy. Symptoms may range from fussiness and vomiting to chronic diarrhea and failure to gain weight. Stools are sometimes blood-streaked or even bloody. Dietary elimination followed by reintroduction of the offending protein several weeks later (as may occur in babies with multiple formula intolerances) may lead to very severe vomiting and diarrhea, resulting in dehydration and need for intravenous fluids replacement in and even shock in the most extreme cases.
Unfortunately, there are no available skin tests or blood tests to confirm or exclude a diagnosis of FPIES. The diagnosis is made based on clinical history alone after the exclusion of other possible causes of chronic gastrointestinal symptoms. Observing the resolution of symptoms with dietary avoidance of the offending food(s) and recurrence of symptoms with accidental ingestions is further supportive evidence of the clinical diagnosis. Prolonged dietary avoidance of the offending food is the only available treatment. An average of 5 years of dietary elimination is required for FPIES to resolve. The only way to confirm resolution of FPIES is to reintroduce the food into the child’s diet. Because gastrointestinal symptoms may be severe, food challenges for FPIES should only be performed in the DFAC office.
Food Allergy Resources
Food Allergy Support Organizations
Food Allergy, Research & Education (F.A.R.E., formerly FAAN)
Asthma and Allergy Foundation of America
American Academy of Allergy, Asthma, & Immunology
Consortium of Food Allergy Research (CoFAR)
Managing Food Allergies in School
School Guidelines for Managing Children with Food Allergies
Epinephrine Demonstration Video
Food Allergy Cookbooks
Allergen-Free Baking: Baked Treats for All Occasions Cookbook. By Jill Robbins (2007).
Allergy-Free Desserts: Gluten-free, Dairy-free, Egg-free, Soy-free and Nut-free. By Elizabeth Gordon (2010)
Bakin’ Without Eggs: Delicious Egg-Free Dessert Recipes from the Heart and Kitchen of a Food-Allergic Family. By RoseMarie Emro (1999)
The Divvies Bakery Cookbook: No Nuts, No Eggs, No Dairy. Just Delicious! By Lor Sandler (2010)
The Food Allergy Mama’s Baking Book: Great Dairy, Egg, and Nut-Free Treats for the Whole Family. By Kelly Rudnicki (2009)
A Taste of Freedom: Recipes for Passover (or Anytime) without Wheat, Dairy, Eggs, Nuts, and Fish. By Tamar Warga (2004).
What’s to Eat? The Milk-Free, Egg-Free, Nut-Free Food Allergy Cookbook. By Linda Marienhoff Coss (2000)
What Else is to Eat? The Dairy-Egg, and Nut-Free Cookbook. By Linda Marienhoff Coss (2008)
Specialty Food Manufacturers (DFAC does not endorse any vendor)
www.thereallygreatfoodcompany.com
www.unrefinedbakery.com/ (a Dallas based company)
Food Allergy Travel Translation Cards
Restaurant Resource
(AllergyEats is a peer-reviewed directory of restaurants in the U.S., rated by people with food allergies. This site is intended as a guide, not a guarantee.)
