Education and special settings
In general, efforts of patients allergic to nuts to control avoidance at home can be quite successful, though there are certain circumstances and situations that remain high risk for cross-contamination and accidental exposure. Most cases of nut anaphylaxis in children do occur in the home, but this includes first reactions to peanut, with 76% occurring at home.18,21,49 Particularly in nut allergy, reactions outside the home tend to be more severe and are more likely to be treated with epinephrine.50 Of children who have already been diagnosed with peanut allergy, accidental exposures occur at an annual incidence rate of only ~14.3%,51 less frequently than previously reported, but up to 20% of children with a known food allergy (not specific to nuts) will develop a reaction at school at some point. In addition to school or day care, children’s parties, restaurants, and bakeries are also high risk for cross-contamination and accidental exposure.50 For these reasons, the education of patients and parents regarding high-risk situations is of great importance. When available, utilizing a registered dietician may be especially helpful. Printed information is also useful for patients and parents not only to read for themselves, but also to distribute to other caregivers. Encouraging children not to accept food from strangers, or to check with a parent or trusted caregiver about unknown or unlabeled foods helps them take ownership of their food allergy and will bring attention to adults who may be unaware of specific dietary restrictions.
Within a comprehensive plan for the child with nut allergy, it is important to include all caregivers as studies have demonstrated deficiencies in symptom recognition, particularly in schools.52 Most peanut and tree nut reactions at school occur in the classroom and are due to utilization of nuts in craft projects or nut exposure during celebrations such as for a birthday. Other settings for potential food reactions include the playground or off-site field trips, when there may be less direct supervision or less opportunity to control for potential exposures.50,52 A medical identification bracelet or necklace can be helpful in these circumstances, in order to easily identify food allergies to those unfamiliar with the patient.
Of all patients with a known peanut allergy, 60% will have an accidental peanut exposure within 5 years.20,53,54 In contrast to children, food reactions in adults more commonly occur in restaurants, followed by home, workplace, or school.55,56 Specifically for nuts, commercial catering is an additional risk factor, accounting for 68% of reactions.57 Anaphylaxis to inhaled food allergens has been reported, mostly for seafood, when vapors during cooking become carriers for airborne protein allowing physical contact of protein with mucous membranes. Peanut has also been reported to cause allergic reactions via inhalation, though most studies are based on self-reported symptoms and have not been positively confirmed with inhalation challenge.58 In fact, casual contact of peanut butter has been studied in peanut-sensitized children and neither intact skin exposure nor inhalation was shown to elicit systemic or respiratory reactions.59 This point becomes important when counseling patients and parents about potential exposures such as the school lunchroom or on airplanes.
Of food reactions in restaurants, most occur in Asian establishments and in ice-cream parlors or bakeries, with desserts as a common meal.60 Asian restaurants can be particularly problematic for patients allergic to nuts as the use of nuts and seeds in cooking tend to be more common, along with utilization of pans for multiple meal preparations (risk for cross-contamination). It is important for patients to notify the staff of the restaurant about their nut allergy, as in most cases of food reactions in restaurants, this has not been done. Specifically for nut allergy, it has been stated that someone in the establishment would have known nut was an ingredient, if attention was called to the allergy. Staff surveys have indicated a false sense of security with 25% believing that removing an allergen from a finished meal or consuming only a small amount of allergen is safe. Additionally, 35% believed that fryer heat would destroy allergens, and half of staff surveyed considered a buffet safe so long as it was kept clean.61
Nut oils are sometimes used for cooking and preparing food in various restaurants, such as fried items in fast-food restaurants, and may provide a potential source for allergen exposure. In general, nut oils when highly refined are tolerated in patients allergic to nuts. However, due to varied standards in the refining processes, there remains some risk for reaction when allergic individuals consume nut oils, especially crude oil. Gourmet-style peanut oil, however, is cold-pressed and contains a significant amount of protein. Peanut oil specifically has been studied via double-blind oral challenge in peanut-allergic individuals and found to be safe when refined, while crude peanut oil did elicit some clinical reactions. Due to potential variations in protein content between different preparations, it is generally recommended to avoid foods containing peanut oil.62,63
When reviewing anticipatory guidance for possible reactions, education regarding potential for future severe reactions despite severity of previous reactions is also extremely important. A common misconception is that severity of past reactions will predict future outcomes.64 For example, if a child developed hives upon his first reaction to peanut, the parents may assume each additional exposure will only elicit hives, and the condition is (inappropriately) thought of as a “mild allergy”. The provider should discuss that regardless of previous symptoms, any future accidental ingestion may result in a severe, life-threatening reactions. One study from 2005 used double-blind, placebo-controlled food challenges in patients allergic to peanuts and found poor correlation between severity of reported reactions and reactions elicited in the challenge. Furthermore, only the most recent community reaction predicted severity of challenge-based reactions, but even this association was weak.64