Food science and technology: Food Allergy
Food allergy is an abnormal response to a food caused by immunoglobulin E antibody. In children, the foods that most often trigger allergic reactions include egg, cow’s milk, peanut, tree nuts, soy, and wheat. For adults, this list includes fish and shellfish in addition to peanut and tree nuts. Allergic reactions can be life-threatening when these involve respiratory and/or cardiovascular distress; however, most reactions are not severe. There is no current FDA-approved therapy, so avoidance of relevant foods and access to epinephrine are recommended. Fortunately, several potential therapies are under study.
Understanding the natural history of food allergy is essential in managing patients with these disorders. Food allergy typically begins in the first 2 years of life. While some food allergies, such as cow’s milk and egg, are often outgrown, peanut and tree nut allergies are more likely to persist into adulthood. Although more than one third of parents will report adverse food reactions in their young children, the rates of verifiable IgE-mediated food allergy are much lower in the range of 6-8% at 1 year of age. Most childhood food allergy is acquired in the first or second year of life and then falls progressively until late childhood, after which the prevalence remains stable at approximately 3 to 4%
Cow’s milk allergy is the most common food allergy among infants and young children, affecting approximately 2.5% of children during the first 2 years of life. Resolution is gradual throughout childhood and adolescence with resolution occurring in 19, 42, 64, and 79% of children at ages 4, 8, 12, and 16 years, respectively. Egg allergy is one of the most common food allergies of childhood, and, like cow’s milk allergy, it is frequently outgrown during childhood or adolescence .The presence of egg allergy is a marker for subsequent sensitization to aeroallergens, as well as the later development of asthma .Egg allergy affects 1 to 2% of young children . The estimated overall prevalence in the USA in a national survey was 0.2%, based upon sIgE blood testing .
Peanut and tree nut allergies are frequently studied together as they coexist in up to 30 to 40% of patients. Allergy to peanut appears to resolve in approximately 20% of patients but it is unclear if a similar rate is true for tree nut allergy. Wheat allergy is also a common childhood food allergy that is usually outgrown by adolescence. IgE-mediated wheat allergy, which is separate from celiac disease has been reported to affect 0.4 to 1% of children in the USA and the UK, where wheat is pervasive in the diet. Childhood wheat allergy resolves in approximately 80% of patients by 5 years of age, but this rate appears to be lower and occur more slowly in children with food allergy and atopic dermatitis. Overall, tolerance was achieved by 29, 56, and 70% at 4, 8, and 14 years of age, respectively Natural history of adult food allergy: Food allergy has been estimated to affect nearly 2 to 5% of adults, compared with 6–8% of children. In a retrospective chart review, approximately 15% of patients with an initial food allergy diagnosis developed the problem as an adult .The same study found that age at first ureaction peaked during the early 30s, although there was a wide range. There are several factors that may lead to the development of sIgE and subsequent food allergy in an adult . In many cases, however, no predisposing exposures can be identified.
Despite the predominance of fish and peanuts, nuts causing the most reactions in adults, the most common form of IgE-mediated food allergy in adults is oral allergy syndrome or pollen-food allergy syndrome. OAS affects up to 5% of the general population in some studies It is a generally mild form of food allergy that is caused by contact of the mouth and throat with raw fruits and vegetables and sometimes nuts. The most frequent symptoms of OAS are itchiness or mild swelling of the mouth, face, lip, tongue, and throat, generally developing within minutes after eating raw fruits or vegetables. Since these reactions typically do not progress to cause a systemic issue, the number of reported reactions remains fewer than fish/seafood and peanuts nuts.
Of reported food allergy among adults, seafood i.e., fish, shellfish, and mollusks allergy is the next most common, with an estimated prevalence of 1 to 2% both in the USA and internationally. One study suggested that 40 to 60% of seafood allergies developed in adulthood, rather than in childhood. Most seafood-allergic patients are allergic to either one or more finned fish or one or more shellfish/mollusks. Seafood allergy is unrelated to radiocontrast allergy. Individuals with allergic disease as a group are three times more likely than individuals without these conditions to have a severe adverse reaction to intravenous iodinated contrast media. Most of this increased risk is believed to be related to asthma.
Peanuts and tree nuts are also commonly implicated in adults with food allergy. In most cases, the nut allergy developed in childhood and persisted into adulthood, unlike what is found with seafood allergies. Uncommon food Allergies: Food-dependent,exercise-induced anaphylaxis is a form of food allergy in which the patient only develops symptoms when ingestion of the culprit food is followed within a few hours by exertion or exercise. Symptoms do not develop if the food is eaten at rest or if the patient exercises without first eating the food. Thus, the connection between the food and exertion may not be recognized for some time. In addition, the reactions are unpredictable, which further complicates recognitionOccupational food allergy most often develops in patients who work in food processing. Common causes include fish, shellfish, wheat, other grains, fruits, and vegetables.
The aim of allergen-specific immunotherapy is to alter the allergic response to a food allergen so that the patient becomes desensitized or, possibly, tolerant to the specific food. Alternatively, some patients may receive benefit simply from an increase in the threshold dose of food required to trigger an allergic reaction. In these instances, patients would have some protection from accidental exposures and this enhanced safety often also improves quality of life.
Food allergen-specific therapies under investigation include oral, sublingual, and epicutaneous immunotherapy. Oral immunotherapy is under investigation as a potential approach to the treatment of food allergy. Ahigh rate of desensitization has been demonstrated in both randomized trials and observational studies of oral immunotherapy. The initial dose and dose increases are given under clinical supervision, whereas the remainder of the daily doses during the dose advancement phase and maintenance therapy are administered at home.
— Writer is a student at GCWUF (Government College and
University Of Faisalabad).