Diagnosis and Management of Food Reactions and Food Allergies

Educational Objectives

The goal of this program is to improve management of food reactions. After hearing and assimilating this program, the clinician will be better able to:

1. Use oral immunotherapy in IgE-mediated food allergies.
2. Compare allergies to cow's milk and eggs with peanut and tree nut allergies in children.
3. Optimize management of pollen food allergy syndrome.

Summary

IgE-mediated food reaction symptoms: reactions to specific food proteins that can occur immediately or be delayed by hours; symptoms include flushing, itching, hives, swelling, respiratory problems, digestive problems, and a sense of impending doom; women may also experience uterine contractions

Pathophysiology: food-specific IgE antibodies, bind to mast cells in various tissues; when the allergenic food is encountered, the interaction between IGE and food proteins triggers mast cell degranulation, releasing mediators like histamine, tryptase, prostaglandins, and leukotrienes to cause symptoms

Diagnosis: in some cases, a clear history of consistent reactions to a specific food is sufficient for diagnosis; further testing can create challenges; skin prick testing, food-specific IgE, and oral food challenge are tools for evaluation of food reactions; skin prick test and IgE panels are not recommended in the absence of clinical symptoms

Skin prick test: method of allergy testing involves applying allergens to the skin and observing for a reaction; histamine and saline are used as positive and negative control substances, respectively; accuracy can be affected by various factors, and test can have risk in patients with uncontrolled asthma or life-threatening anaphylaxis

Reliability: sensitivity and specificity of the test is dependent on the specific food; more reliable results seen for traditional or classic allergenic foods such as milk, eggs, peanuts, tree nuts, soy, fish, and shellfish; for fresh fruits, vegetables, and meat, prick-prick testing is more reliable compared with commercial extracts

Caveats: skin prick testing does not indicate severity of the reaction; in pediatrics, a wheal size of 7 to 8 mm has a 95% positive predictive value; IgE–specific assays are widely available, convenient, and are not affected by antihistamines; IgE levels does not predict severity of the reaction, although higher IgE levels increase chances of true positive results

Management Therapies

Epinephrine therapy: involves obtaining a detailed history, diagnosing food allergens, educating about anaphylaxis, and prescribing an epinephrine auto-injector; in children, avoiding foods based only on test results can increase the risk of developing true IgE-mediated food allergies, especially in individuals with low IgE levels

Standard of care treatment: includes food avoidance and use of epinephrine when necessary; Food Allergy Research and Education (FARE) guidelines for managing anaphylaxis recommend using epinephrine and seeking medical help for a severe symptom such as shortness of breath, dizziness, fainting, throat swelling, mouth swelling, total body hives, or repetitive vomiting or ≥2 mild symptoms after ingesting a known allergic food; the goal is to prevent the progression of the reaction to anaphylactic shock; use of epinephrine can be indicated if food consumed for any symptoms; it can be indicated even without symptoms, particularly for individuals with a history of rapidly progressing severe reaction

New Therapies

Oral immunotherapy (OIT): potential therapy for IgE-mediated food allergies, aiming to achieve long-lasting tolerance by gradually increasing the allergenic food dose; current allergy treatments offer temporary tolerance and raise the threshold for severe reactions; OIT may increase allergic reactions, so its use requires careful decision-making; it is potentially more effective in young children because their immune systems is more plastic; Peanut Allergy Powder (PALFORZIA) is only Food and Drug Administration (FDA)-approved therapy for peanut allergy (for ages 4-17); involves increasing doses of peanut protein, alongside avoidance and an epinephrine auto-injector; adverse events can include anaphylaxis and milder reactions; not recommended for those with uncontrolled asthma or eosinophilic gastrointestinal disorders; doses should be avoided in conditions like hot showers, strenuous exercise, viral illness, fasting, and sleep deprivation because they lower the reaction threshold

Epicutaneous immunotherapy: involves introducing small doses of food protein through the skin to reduce the severity of allergic reactions from accidental ingestion; while there are currently no FDA-approved therapies in this category, it is an emerging approach in the treatment of food allergies

Monoclonal antibodies (MOAB): such as omalizumab, FDA-approved for asthma and other indications, have shown reduction in risk for severe reactions upon accidental ingestion of allergenic foods; omalizumab is used as an adjunctive therapy in OIT; phase III trials are under way for other MOAB, such as dupilumab

Allergenics and Their Tolerance

Milk and eggs: most children outgrow allergies to cow's milk, eggs, and wheat by adolescence, but peanut and tree nut allergies are less likely to be outgrown; skin prick tests and food-specific IgE measurements can indicate the development of tolerance over time; ≈70% of individuals with milk or egg allergies can tolerate extensively baked milk or egg (their introduction can increase overall tolerance)

Fish and shellfish allergies: primarily occurring in adults; fish and shellfish allergies are caused by different allergens, with cross-reactivity being rare; some people may be allergic to specific types of fish or shellfish but can tolerate others; assessing individual tolerance can offer nutritional, social, and psychological benefits by enabling a diverse diet

Scombroid fish poisoning: a non-IgE-mediated reaction, can occur when spoiled fish with high levels of histamine are consumed; symptoms include flushing, diarrhea, and vomiting; immediate treatment with antihistamines and epinephrine is effective; it is not an allergic reaction to fresh fish

Legumes and tree nut allergies: cross-reactivity between peanuts and other legumes, such as soy, peas, and lentils, is often overestimated; 1% to 5% of individuals allergic to one legume react to another; cross-contamination should be avoided

Pollen food allergy syndrome: individuals with a pollen food allergy may experience symptoms such as oral itching, tingling, and swelling after consuming raw fruits and vegetables, but patients can tolerate these foods in cooked form; caused by cross-reactivity between labile proteins in these foods and pollen proteins

Management: involves avoiding specific food in the form that triggers reaction; mildly symptomatic patients can continue consuming the food while using oral or intranasal antihistamines to reduce symptoms; treating underlying allergic rhinitis can effectively manage it; allergen immunotherapy may also induce long-lasting tolerance; severe reactions or individuals with airway obstruction risk factors may require an epinephrine auto-injector; exercise and alcohol can lower the reaction threshold; certain foods like peanuts, tree nuts, and mustard are more likely to cause systemic reactions and may necessitate the epinephrine use; testing, including component testing, can differentiate oral allergy syndrome from true IgE-mediated allergies and provide prognostic information for guiding treatment decisions

Latex food syndrome: condition involves cross-reactivity between food plants and natural rubber latex, often leading to anaphylaxis; latex allergy usually precedes food allergy, with common cross-reacting foods including banana, avocado, chestnut, and kiwi; diagnosis can be aided by fresh fruit prick testing; management includes monitoring food intake, reducing exercise and alcohol, and avoiding common allergenic foods

Food-dependent exercise-induced anaphylaxis: condition involves anaphylaxis triggered by certain foods like wheat, nuts, and shellfish when consumed close to exercise; management involves IgE testing, avoiding trigger foods 4 to 6 hr before and 1 hr after exercise, and considering cofactors; alpha-gal syndrome, linked to tick bites, causes delayed reactions to mammalian meats, requiring IgE testing and meat avoidance

Food protein-induced allergic enterocolitis syndrome (FPIES): non-IgE-mediated condition characterized by delayed gastrointestinal symptoms, typically affects infants, with cow’s milk or soy as triggers; in adults, FPIES can occur with any food, and the diagnosis is based on history; patients often recover when fasting; severe episodes resembling food poisoning and sepsis require additional evaluation

Readings

Melchior C, Algera J, Colomier E, et al. Irritable bowel syndrome with food-related symptoms. United European Gastroenterology Journal. 2022; 10 (6): 594-600. doi: 10.1002/ueg2.12265; Rodriguez O, Brod B, James W. Impact of trends in new and emerging contact allergens. International Journal of Women’s Dermatology. 2022; 8 (1): e006. doi: 10.1097/JW9.0000000000000006; Rukasin C, Phillips E, Stone C. Advances in immunoglobulin E mediated antibiotic allergy. Current Opinion in Pediatrics. 2022; 34 (6): 609-615. doi: 10.1097/MOP.0000000000001171; Shahid R, Pradhan S, Singh S. A challenging case of recalcitrant hyper-IgE syndrome successfully treated with omalizumab. Indian Journal of Paediatric Dermatology. 2022; 23 (4): 318-321. doi: 10.4103/ijpd.ijpd_36_22.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose. Dr. Xi’s lecture includes information related to the off-label or investigational use of a product, therapy, or device.

Acknowledgements

Dr. Xi was recorded at the 50th Annual USC Internal Medicine for PCPs and Subspecialists, held April 17-20, 2023, on Maui, HI, and presented by the Keck School of Medicine of the University of Southern California. For more information on upcoming CME activities from this presenter, please visit https://keckusc.cloud-cme.com/. Audio Digest thanks the speakers and presenters for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 1.25 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 1.25 CE contact hours.

Lecture ID:

IM703201

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.