About this course:
The purpose of this module is to review the epidemiology and pathophysiology of food allergies and intolerances. It also covers the clinical manifestations, diagnosis, emergency treatment, and long-term management of individuals with food allergies.
The purpose of this module is to review the epidemiology and pathophysiology of food allergies and intolerances. It also covers the clinical manifestations, diagnosis, emergency treatment, and long-term management of individuals with food allergies.
After completing this learning activity, the nurse should be able to:
compare and contrast a food intolerance and a food allergy
review the epidemiology of food allergies in the US
describe the pathophysiology and clinical manifestations associated with food allergies
describe the evidence-based guidelines for the diagnosis of food allergies
discuss current emergency management for a mild or severe allergic reaction
describe the long-term management of individuals diagnosed with food allergies
Food allergies are a growing public health and food safety concern in the US. According to the National Institute of Allergy and Infectious Disease (NIAID) and the Centers for Disease Control and Prevention (CDC), food allergies are a condition that affects approximately 8% of children and 4% of adults in the US. This equates to 1 in 13 or approximately two students per classroom. In a person with a food allergy, the immune system reacts abnormally to a component of a food—sometimes producing a life-threatening response. Food allergy symptoms are most common in babies and children but can appear at any age (American College of Allergy, Asthma, and Immunology, [ACAAI], n.d.). Not all food allergies will develop into a life-threatening anaphylactic reaction; however, approximately 40% of children with food allergies have been treated in emergency departments (EDs). Each year in the US, food allergies account for about 30,000 ED visits, 2,000 hospitalizations, and 150 deaths among adults and children. According to the National Academies of Sciences, Engineering, and Medicine (NASEM), only a few specific foods comprise the majority of allergens responsible for allergic reactions, includ ing">ing milk, eggs, peanuts, tree nuts, wheat, soy, and seafood (ACAAI, n.d.; CDC, 2022a; NASEM, 2017; NIAID, 2018).
In 2010, the NIAID created the Guidelines for the Diagnosis and Management of Food Allergy in the United States. The document is considered a gold standard for diagnosing and managing food allergies. An allergic response can be mild (urticaria) to severe (anaphylaxis). While promising prevention and treatment strategies are being developed, no therapies are currently available to completely prevent or treat a food allergy. The only reliable option for the patient is to avoid the food allergen. Clinical studies are ongoing in patients with food allergies to help develop a tolerance to the allergen. Regardless, having a food allergy is a chronic disease that can influence a person's quality of life throughout the lifespan and, in some individuals, lead to death. Therefore, early recognition and education about managing food allergies, including specific foods to avoid, are essential to preventing serious health consequences (ACAAI, n.d.; NASEM, 2017; NIAID-Sponsored Expert Panel et al., 2010; US Food and Drug Administration [FDA], 2022).
Gathering data on the prevalence of food allergies is challenging; however, researchers have found that the prevalence has increased in the last three decades, particularly in Western countries. In particular, researchers have found that the prevalence of peanut allergies has increased in the last decade, and this was not a product of increased awareness of peanut allergies or improved diagnostic tools. Instead, the reason was simply an increase in people with allergies. The underlying causes of the increasing prevalence are still being researched. As a result, medical specialists, educational settings, and families are concerned about preventing and managing life-threatening adverse reactions (NASEM, 2017; US Department of Agriculture [USDA], 2016).
Definitions and Pathophysiology
According to the American Academy of Allergy, Asthma, and Immunology (AAAAI, n.d.), food intolerance, or food sensitivity, occurs when an individual has difficulty digesting or metabolizing a particular food, leading to symptoms such as intestinal gas, bloating, abdominal pain, and diarrhea. Food intolerance has no immunologic response. Most adverse food reactions in adults are due to food intolerances, which can arise from gastroesophageal reflux (GERD), gastrointestinal (GI) infections, metabolic diseases, digestive enzyme deficiencies, and disorders resulting from anatomic or neurologic abnormalities. Food intolerances are reported by 15% to 20% of the population and are more common in people with irritable bowel syndrome (IBS) and other GI disorders. Unlike food allergies, food intolerances involve the digestive system, with the amount of food directly impacting the severity of symptoms. Food intolerance reactions are similar each time the exposure occurs (AAAAI, n.d.; Commins, 2022).
A food allergy is "an adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food" (NIAID-Sponsored Expert Panel et al., 2010, p. S8). Food allergies can be either IgE-mediated or non-IgE-mediated, but IgE-mediated reactions are the most common. Sensitization refers to the presence of IgE antibodies directed against a specific antigen, indicating a positive test. Several factors can increase sensitization and subsequent food allergy; however, often, a predisposing factor cannot be determined (Commins, 2022; NASEM, 2017). Some examples of predisposing factors include:
pollen exposure and sensitization are present in most patients with oral allergy syndrome (OAS)
inhalation of contact occupational exposures (e.g., pesticides) can cause sensitization and subsequent food allergy reactions
repeated tick bites can lead to sensitization to red meat, and jellyfish stings can lead to sensitization to soybean products
a sudden dietary change for weight loss has been linked to food allergies, particularly to wheat or cow's milk
additives, artificial colors, and antibiotics in animal feeds are suspected of causing some food allergies (Commins, 2022)
The clinical manifestations of food allergies can vary based on the severity of the exposure. Acute urticaria is the most common manifestation of an IgE-mediated food reaction, usually appearing within minutes of the exposure. Food allergies rarely cause chronic urticaria. Food allergy symptoms can be widespread, with some symptoms appearing immediately and others delayed (Commins, 2022). See Table 1 for symptoms by body system that may directly result from a food allergy.
IgE-mediated reactions occur when IgE antibodies are formed in response to an antigen. These antibodies bind to macrophages, basophils, mast cells, and dendritic cells. When allergens enter the mucosal barrier and reach cell-bound IgE antibodies, mediators are released, causing vasodilation, mucous secretion, and smooth muscle contraction. The activated mast cells and macrophages release cytokines, which leads to prolonged inflammation, resulting in the signs and symptoms of food allergies. According to the NIAID (2011), milk, eggs, and peanuts account for the vast majority of IgE-mediated reactions in young children. Peanuts, tree nuts, and seafood (fish and crustacean shellfish) account for most IgE-mediated reactions in teenagers and adults. With an IgE-mediated food allergy, symptoms almost always occur immediately after eating the food. However, an allergic reaction may not occur after exposure if a minimal amount of the food is eaten or if the food, such as milk or egg, is extensively heated on the stovetop or baked in the oven (i.e., proteins are denatured with heat). OAS is another example of an IgE-mediated reaction, affecting up to 5% of the general population. OAS is a mild food allergy caused by raw fruits and vegetables coming in contact with the mouth and throat (Commins, 2022; Lopez et al., 2022; NIAIA, 2011).
Two types of non-IgE-mediated food allergies are FPIES (food protein-induced enterocolitis syndrome) and EoE (eosinophilic esophagitis). The definitions are included for reference but will not be discussed in further detail within this module. FPIES is a delayed food allergy affecting the GI tract leading to vomiting and diarrhea. These allergic reactions are triggered by ingesting food allergens like milk, grains, or soy. FPIES often develops when an infant is first introduced to solid food or formula. EoE is a chronic condition where large numbers of eosinophils are found in the esophageal tissue, causing inflammation. Symptoms of EoE can vary based on age, with infants and toddlers refusing to eat or not growing as expected. School-aged children are more likely to report recurring abdominal pain, vomiting, and trouble swallowing. In teenagers and adults, the esophagus can narrow, allowing food to get stuck and causing difficulty swallowing. Research has suggested that EoE develops from an allergy or sensitivity to a particular protein found in foods. Many individuals with EoE have a family history of allergic disorders such as asthma, rhinitis, dermatitis, or food allergies (AAAAI, 2020, 2022). See Table 2 for an outline of the differences between IgE-mediated and non-IgE-mediated reactions and how they are predicted to affect the patient (NIAID, 2011).
Diagnosing a food allergy is a multi-step process. Since testing to confirm or rule out a food allergy is not always accurate, the initial step is to obtain a detailed history of the foods, what quantity, and the severity of the reaction with exposure. A diet diary can be helpful to supplement the medical history, especially for chronic conditions. Additional discussion of family history of allergies should occur as well. Next, a focused physical examination can help identify signs consistent with an allergic reaction. The health care provider (HCP) will then determine if other medical conditions may be causing the symptoms. When the history and physical do not reveal a causative food allergen, allergy testing can be performed. The initial diagnostic test is a skin prick test (SPT). The suspected allergen or multiple allergens are injected directly under the surface of the skin. If an allergic reaction occurs, a raised bump or reaction occurs at the site. SPTs provide a means to detect sensitization rapidly. A negative SPT establishes the absence of an IgE-mediated reaction. However, a positive test does not confirm a food allergy, as 60% of positive tests do not reflect a symptomatic food allergy. Therefore, more definitive testing may be necessary (Commins, 2022; Lopez et al., 2022).
Serum tests can determine food-specific IgE antibodies (e.g., radioallergosorbent test [RAST]). The blood is sent to a laboratory to evaluate the presence of allergy-related antibodies using the radioimmunoassay test. The higher the concentration of IgE, the more severe the clinical reaction is likely to be. Researchers estimate that an IgE level exceeding the predictive diagnostic value translates to a 95% chance of experiencing an allergic reaction. An elimination diet is a less invasive option for determining a food allergy or sensitivity. Elimination diets involve completely avoiding suspected foods to determine if symptoms resolve. This method is not the most accurate and is not recommended in patients with a history of severe reactions, such as anaphylaxis, to certain foods. Unfortunately, an elimination diet will not distinguish between food allergy and intolerance. To confirm the diagnosis, an allergist may perform an oral food challenge. Food challenges are done by consuming the food in a medical setting to determine if the suspected food causes a reaction. Before the food challenge, the individual should eliminate the suspected food for 7 to 14 days. In addition, the individual should not take any medications that could interfere with the induced symptoms, such as antihistamines or beta-adrenergic bronchodilators. The test carries a risk of allergic reactions and anaphylaxis, so caution, constant monitoring, experienced personnel and equipment, and medications for managing reactions are required. Feeding a small amount of the suspected allergen and gradually increasing the amount mitigates some risk. The test is stopped at the judgment of the supervising health professional due to the onset of symptoms or at the patient's request (Commins, 2022; Keet & Wood, 2021; Lopez et al., 2022; NASEM, 2017).
Lifelong Management of Food Allergies
There is no cure for a food allergy. Once the specific food allergy has been diagnosed, complete avoidance is the only method to prevent complications. This is true for all types of food allergies, including IgE-mediated and non–IgE-mediated. Patients, HCPs, and all individuals responsible for preparing or obtaining foods for the patient should be educated on how to read ingredient labels to avoid specific food allergens. Nutritional counseling may be beneficial as well. Fortunately, some individuals may have relief from their food allergies as they age. Table 3 provides data regarding the likelihood of resolution of food allergies (ACAAI, n.d.; NIAID-Sponsored Expert Panel et al., 2010).
As stated previously, there is no cure for a food allergy. However, utilizing oral immune therapy (OIT) to prevent life-threatening reactions has been successful. Absolute food avoidance is challenging, placing people with severe food allergies at significant risk for anaphylaxis and death. OIT exposes participants to minute amounts of the allergen initially. The goal is to gradually increase the dosing of the food allergen to improve tolerance to a safe level. Patients must still be vigilant about avoidance of the allergen; however, if accidental exposure occurs, their reaction is ideally less severe. OIT, when successful, eliminates the risk of anaphylaxis or death. Studies have demonstrated the efficacy of starting OIT earlier in childhood. The option of participation in OIT should be given to patients with severe food allergies to improve safety and quality of life (Vickery et al., 2017).
Management of food allergies in schools is another critical area that must be addressed. In 2011, Congress passed the FDA Food Safety Modernization Act to improve food safety in the US. The goal was to shift from a reactive to a proactive plan (CDC, 2013). As a result, the US Department of Health and Human Services (HHS) and the Secretary of the US Department of Education created the Voluntary Guidelines for Managing Food Allergies in Schools and Early Care and Education Programs to help guide the management of food allergies and severe allergic reactions in children while in educational settings. According to the CDC (2022), the guidelines focus on recommendations for each of the five priority areas that should be addressed in each school or early care and education program's Food Allergy Management Prevention Plan (FAMPP):
ensure the daily management of food allergies in individual children
prepare for food allergy emergencies
provide professional development on food allergies for staff members
educate children and family members about food allergies
create and maintain a healthy and safe educational environment (CDC, 2022b)
Schools should reference these guidelines when formulating plans to address food allergies and food allergy reactions while children are in educational centers. This includes using emergency care plans (ECP) for each student with food allergies and individualized health care plans (IHP). The CDC's (2013) guidelines recommend the following interventions for school nurses to help students with food allergies cope physically and psychosocially/emotionally:
Participate in the school's coordinated approach to managing food allergies by planning and implementing the FAMPP, supporting partnerships with staff, parents, and doctors, and helping guide the policies and procedures at the school.
Supervise the daily management of food allergies for students by identifying students with food allergies, maintaining an ECP for each student, and assessing each student's ability to carry and self-administer an epinephrine (Epi-Pen) autoinjector if needed.
Prepare for and respond to food allergy emergencies by developing protocols, administering medications following school policy, training staff members, ensuring standing orders are in place, contacting parents, and documenting an emergency at school.
Help provide professional development on food allergies for staff by staying up to date and teaching staff members about food allergies regularly.
Provide food allergy education to students and parents by teaching self-management, detecting signs/symptoms of anaphylaxis, and adding food allergy material to classroom curricula.
Create and maintain a healthy and safe school environment by assessing the school environment regularly, ensuring that policies and procedures remain up to date with new and trending foods, working with counselors to provide emotional support to students with allergies, and promoting an environment that encourages reporting of any bullying behavior.
Treatment of Allergic Reactions
Once the diagnosis is confirmed, the nurse should educate the patient and family on food avoidance and how to respond to an allergic reaction. Nutritional counseling is ideal for better outcomes in food allergy patients. Reactions to food allergies vary by individual. Symptoms of a food allergy can include vomiting, abdominal cramping, urticaria, shortness of breath, wheezing, angioedema, syncope, or anaphylaxis leading to shock and circulatory collapse. Treatment of allergic reactions is based on the severity of the response. Patients are encouraged to take antihistamines for minor reactions, including itching or urticaria. Antihistamines are insufficient for an anaphylactic reaction. The gold standard of treatment for anyone having a severe allergic or suspected anaphylactic reaction is the immediate administration of epinephrine (EpiPen). There are no contraindications to epinephrine (EpiPen). Concern exists regarding appropriate dosing for pediatric patients; however, the potential risks associated with underdosing epinephrine (EpiPen) outweigh the potential risks of overdosing. The rapid administration of epinephrine (EpiPen) has been associated with optimal patient outcomes. Patients with a known severe food allergy should always carry two epinephrine autoinjectors (EpiPens) with them, should the first dose not work correctly or relieve all symptoms. Additionally, patients or parents must ensure the autoinjector (Epi-Pen) is not expired (ACAAI, n.d.). The recommended treatment plan for anaphylaxis due to a food allergy in a medical setting is as follows:
assess airway, breathing, and circulation; support all three as necessary following the American Heart Association (AHA) guidelines for basic life support (BLS)
start chest compressions if necessary
inject epinephrine (EpiPen) 0.3-0.5 mg (0.01 mg/kg for children) intramuscularly. It is better to overdose a child unintentionally than underdose them to ensure the efficacy of the medication and decrease the response severity
if there is no response to the first dose of epinephrine (EpiPen), activate/call the emergency response system
administer 8-10L of oxygen through a facemask as needed while monitoring pulse oximetry
intramuscular (IM) epinephrine (EpiPen) can be repeated every 5-15 minutes for up to three injections if the patient is not responding
establish intravenous (IV) access and begin infusing 0.9% normal saline as quickly as possible; in adults, 1-2 L should be given in the first hour; in children, 30 mL/kg in the first hour
consider administering 2.5-5 mg of nebulized albuterol in 3 mL of saline for respiratory distress; repeat as necessary every 15 minutes
if IM epinephrine (EpiPen) is ineffective, consider giving epinephrine intravenously
the nurse should continuously monitor for airway complications; consider advanced airway management as necessary
optional treatments (efficacy has not been established)
give diphenhydramine (Benadryl) 25-50 mg IV for adults, or 1mg/kg (max 50mg) for children
give cetirizine (Zyrtec)10mg by mouth if oral antihistamine can be safely administered
give methylprednisolone (Medrol, Solu-Medrol) 1-2 mg/kg (up to 125 mg) by mouth or IV; once the allergic reaction has resolved, there is no evidence that this medication needs to be continued (NASEM, 2017)
If multiple doses of epinephrine are administered, the patient will need to be monitored at the hospital for approximately 8 hours. However, if the patient is successfully treated in an office setting with a single dose of epinephrine (EpiPen), the recommended observation time is 30-60 minutes. Patient education should include early recognition of symptoms and immediate treatment of anaphylaxis. The nurse should review all signs and symptoms of a reaction with the patient and family. Again, the patient should be educated to always carry two epinephrine autoinjectors (EpiPens). Patient and family education should be provided regarding when and how to administer them. If the child is in school or early childhood education, informing teachers, administration, and school staff is essential (ACAAI, 2014; Lopez et al., 2022).
The prevalence of people with allergies has increased. As a medical community, we must evaluate the impacts this could have on our children and future generations' growth, safety, and quality of life. With the stated guideline of absolute avoidance of an allergen, there remains potential for nutritional deficiencies, particularly in children with milk, egg, and soy allergies. In 2015, the CDC created a tool kit for professionals working with students who have food allergies or have the potential to develop food allergies. The toolkit was created utilizing the Voluntary Guidelines for Managing Food Allergies in Schools and Early Care and Education Programs as a guide. Included are short pamphlets for superintendents, principals, teachers, school nutrition professionals, school transportation staff, and school mental health professionals. Per the CDC's (2013) Managing Food Allergies in School: The Role of School Nutrition Professionals, schools, school nurses, students, and any school personnel need to be educated to respond quickly to anyone having an allergic reaction. Early identification of allergic reaction symptoms, followed by early administration of epinephrine (EpiPen) and activation of the emergency response system, could prove to be lifesaving for a child having an allergic reaction. In addition to being prepared to treat an acute allergic reaction, school personnel, parents, and children must be educated about bullying, harassment, and teasing. It is imperative to educate parents, children, and educators on the dangers of bullying and the stressors these students already deal with due to their food allergies. Making these students feel safe and supported is of the utmost importance (CDC, n.d., 2013; Lopez et al., 2022).
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NIAID-Sponsored Expert Panel, Boyce, J. A., Assa’ad, A., Burks, A. W., Jones, S. M., Sampson, H. A., Wood, R. A., Plaut, M., Cooper, S. F., Fenton, M. J., Arshad, S. H., Bahna, S. L., Beck. L. A., Byrd-Bredbenner, C., Camargo, C. A., Jr, Eichenfield, L., Furuta, G. T., Hanifin, J. M., Jones, C., . . . Schwaninger, J. M. (2010). Guidelines for the diagnosis and management of food allergy in the United States: report of the NIAID-sponsored expert panel. The Journal of Allergy Clinical Immunology, 126(6 Suppl), S1-S58. https://doi.org/10.1016/j.jaci.2010.10.007
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Vickery, B. P., Berglund, J. P., Burk, C. M., Fine, J. P., Kim, E. H., Kim, J. I., Keet, C. A., Kulis, M., Orgel, K. G., Guo, R., Steele, P. H., Virkud, Y. V., Ye, P., Wright, B. L., Wood, R. A., & Burks, A. W. (2017). Early oral immunotherapy in peanut-allergic preschool children is safe and highly effective. Journal of Allergy Clinical Immunology, 139(1), 173-181. https://doi.org/10.1016/j.jaci.2016.05.027