Approach Considerations
The only proven medication therapy against a food allergy is strict elimination of the offending food allergen from the diet and avoidance of any contact with the food by ingestion, skin contact, inhalation, or injection.
In 2010, Guidelines for the Diagnosis and Management of Food Allergy in the United States were published. These provide evidenced-based, expert panel recommendations for the diagnosis and management of food allergies. [68] The guidelines do not cover issues for schools, which are of interest to pediatricians, but a 2010 Clinical Report reviews this topic area. [69]
Injectable epinephrine is the drug of choice for the initial management of a food-induced anaphylactic reaction. Ensure that the patient has self-injectable epinephrine readily available at all times. Advanced medical therapy of food allergen–induced anaphylaxis may include antihistamines, bronchodilators, histamine 2 (H2) blockers, corticosteroids, and administration of intravenous fluids, glucagon, and oxygen. In severe anaphylaxis, ventilatory and circulatory support may be needed.
Diet
A properly managed, well-balanced elimination diet (eg, allergen restriction) can lead to resolution of symptoms and help to avoid nutritional deficiencies.
Educate the patient and family about how to properly read food labels and identify common words used for indicating the presence of the food allergen of concern. US labeling laws now require major allergens (ie, egg, milk, wheat, soy, peanut, tree nuts, fish, crustacean shellfish) to be identified as ingredients on manufactured food products using plain English terms. Note that not all potential allergens are included and that some may be subsumed under terms such as spices or natural flavor. Advisory labels (eg, may contain) are not regulated, are voluntary, and may reflect variable risks.
Meal preparation must consider avoidance of cross contact (eg, through shared utensils or fryers) of allergens with otherwise safe foods.
With elimination diets, exclude only those foods confirmed to provoke allergic reactions. Review obvious and hidden sources of food allergens. Be aware of the potential for exposures by routes other than ingestion, such as skin contact, or inhalation. This concern is particularly problematic for foods while they are being cooked, because proteins are dispersed in the steam (eg, frying fish, boiling milk). Educate patients about the potential for food allergens to be present in medications and cosmetics.
Anticipate potential candidates for food allergen cross-reactivity, such as the following: [2]
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Eggs and chicken (< 5% of patients have both allergies)
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Cow milk and beef (10% of patients with milk allergy react to beef)
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Cow milk and goat milk (>90% allergic to cow milk also react to goat/sheep milk)
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Fish (>50% allergic to any finned fish are reactive to all types)
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Peanuts and other legumes (< 10% with a peanut allergy react to other legumes)
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Soy and other legumes (< 5% with a soy allergy react to other legumes)
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Wheat and other grains (25% with a wheat allergy react to rye and barley)
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Tree nuts and other nuts (>50% with an allergy to a tree nut react to others)
Encourage avoidance of high-risk situations (eg, buffets, picnics) where accidental or inadvertent ingestion of food allergens can occur. Instruct patients to discuss their food allergies with restaurant and food establishment personnel.
Emergency Plan
Despite following stringent avoidance measures for clinically relevant food allergens, accidental or inadvertent ingestions may occur. Therefore, patients must be instructed on actions to take in the event of a reaction. A concise written plan for the treatment of allergic reactions resulting from accidental exposure to a patient’s food allergen should be developed. Have copies of this plan available in appropriate places (eg, daycare, schools, work locations, college dormitory advisors). Examples of such a plan can be downloaded from www.foodallergy.org.
Patients with food allergies should be advised to obtain and wear medical identification jewelry indicating their food allergies.
Ensure that the patient has an emergency contact number available (eg, 911, their physician's office phone number, or a local emergency department) that can be used in the event of a major food-induced allergic reaction.
Anticipatory guidance measures cannot be overemphasized; for example, educate the patient about potential sources of accidental exposure to relevant food allergens (eg, daycare, school, travel, picnics, dining out).
Emergency Medications
Injectable epinephrine is the drug of choice for the initial management of a food-induced anaphylactic reaction. Ensure that the patient has self-injectable epinephrine readily available at all times. Also ensure that the patient receives proper training regarding when and how to use the injection device. An antihistamine should also be available. Patients with food allergies and asthma should always have access to a rapid-acting bronchodilator.
Self-injectable epinephrine is typically available by prescription (ie, EpiPen, EpiPen Jr, Adrenaclick 0.15 mg, Adrenaclick 0.3 mg, Auvi-Q 0.15 mg, Auvi-Q 0.3 mg). These devices should be stored properly (avoiding extremes of temperature) and replaced before the expiration date.
Pharmacologic Therapies
There are currently no curative therapies for food allergy. Injection immunotherapy is an accepted treatment for anaphylactic allergy to insect venoms and for environmental allergies, but it poses a high risk for food allergies (anaphylaxis to injected native food proteins). [70, 71]
Immunotherapy
The FDA approved the first immunotherapy for peanut allergy in early 2020. Peanut (Arachis hypogaea) allergen oral powder (Palforzia) mitigates allergic reactions that may occur with accidental exposure to peanuts. It is indicated for mitigation of allergic reactions, including anaphylaxis, that may occur with accidental exposure to peanut in patients with a confirmed diagnosis of peanut allergy.
Approval was supported by a phase 3 trial of patients with peanut allergy for allergic dose-limiting symptoms at a challenge dose of 100 mg or less of peanut protein (approximately one-third of a peanut kernel) in a double-blind, placebo-controlled food challenge. Of the 551 participants who received AR101 or placebo, 496 were 4 to 17 years of age; of these, 250 of 372 participants (67.2%) who received active treatment, as compared with 5 of 124 participants (4.0%) who received placebo, were able to ingest a dose of 600 mg or more of peanut protein, without dose-limiting symptoms, at the exit food challenge (difference, 63.2 percentage points; 95% confidence interval, 53.0 to 73.3; P< 0.001). Efficacy was not shown in the participants 18 years of age or older. [5]
Investigational treatments
Studies are under way to determine if oral, sublingual, or epicutaneous immunotherapy is safe and effective for food allergies, with some promising results. [4] Additional studies are needed to define the safety profile and side effects (short term and long term) and to determine whether treatment affects resolution of the allergy (tolerance without repeated dosing of the allergen) or desensitization (an increased threshold while undergoing dosing). A strategy using anti-IgE antibodies (omalizumab) in conjunction with oral immunotherapy is also under investigations as it may allow faster up-dosing with fewer side effects.
Studies are under way to determine whether therapies with modified food proteins are safe and effective. Promising results from a phase II study support Viaskin Milk as the first potential treatment for IgE-mediated cow's milk protein allergy (CMPA). The study, which evaluated the efficacy and safety of three dose regimens of Viaskin Milk (150 µg, 300 µg, 500 µg) in 198 milk-allergic patients, found a statistically significant desensitization to milk in children ages 2 to 11 years treated with Viaskin Milk 300 µg for 12 months. [72]
Additional therapeutics may in the future be derived from investigations of cytokine and anticytokine therapies, as well as from the evaluation of traditional Chinese medicine.
Consultations
Consultation with a board-certified allergist/immunologist should be considered when food allergy is suspected or confirmed.
Consultation with a nutritionist or nutrition service is invaluable in the overall management of food allergies. The elimination diet can be reviewed and appropriate substitutions can be recommended. Dietary deficiencies can be anticipated and prevented.
Consultation with a gastroenterologist is also useful in the evaluation of selected patients. For example, patients who present with possible anatomic gastrointestinal abnormalities, eosinophilic esophagitis or gastroenteritis, failure to thrive, and malabsorption syndromes may benefit from consultation with an allergist and a gastroenterologist.
Prevention
Early introduction
The Learning Early about Peanut Allergy (LEAP) study addressed the possibility that early ingestion of peanut, rather than delay, may prevent peanut allergy. [73]
The UK study randomized 640 infants aged 4-11 months at high risk for developing peanut allergy, as defined by having severe eczema, egg allergy or both, to ingest or to avoid peanut to age 5 years. Infants were skin tested with peanut at screening and excluded if they had large test results (>4 mm) on the assumption they were already allergic. Two cohorts were identified: those with negative peanut skin tests (not sensitized) and those with skin test wheals 1-4 mm (sensitized). Infants were randomized 1:1 for avoidance or early consumption (6 g peanut protein/week); 542 were not sensitized to peanut at enrollment. Among the non-sensitized cohort, 13.7% in the avoidance group and 1.9% in the consumption group had peanut allergy at age 5 years (p< 0.001), an 86% reduction. In the sensitized group, the corresponding rates were 35.3% and 10.6%, respectively (p=0.004), a 70% reduction. Overall, those randomized to early ingestion experienced a relative risk reduction of 80%.
A follow-up study had the peanut-tolerant children avoid peanut for a year and undergo re-testing with results suggesting that the children had maintained the benefit even when not eating peanut so frequently. [74]
A Consensus report suggests that infants at high risk, like those in the LEAP study, be evaluated (by testing and possibly a medically supervised feeding) to determine if they can have peanut introduced into the diet early, as early as 4-6 months, to potentially prevent peanut allergy. The report substantially suggests following the LEAP study approach to testing and feeding, which includes using infant-safe forms of peanut protein. [75]
Another study randomized infants, who were not selected for high risk, to early feeding of a variety of allergens from 3 months of age. This study did not show a prevention effect in the intention-to-treat analysis. [76]
