Food allergy in adolescents and adults

There has been an increase in the prevalence of food allergy in the last few decades. Adult food allergy may represent persistence of reactions that commenced in infancy and early childhood or it may be initiated in adulthood through new sensitizations. Persistence of peanut allergy is an example of the former situation. Approximately 20% of children will develop tolerance to peanuts, so there will be an increasing number of individuals reaching adulthood where this problem will need ongoing management. In addition to peanut, tree nuts, fruits, vegetables and seafood are implicated as common causes of food allergy in adulthood. Sensitization may occur directly to a food allergen or indirectly through cross-reactivity with an aeroallergen. Adults may present with a spectrum of clinical manifestations from oral allergy syndrome to fatal anaphylaxis. The management of food allergy consists of appropriate education regarding avoidance of implicated foods, modifying potential risk factors for anaphylaxis, such as asthma and prompt recognition and treatment of acute reactions.     

Prevalence of wheat allergy in Japanese adults

BackgroundWheat is one of the most common causes of food allergies. The exact prevalence of wheat allergy has not been well delineated in Japanese adults.MethodsWe enrolled 935 adults in a cohort study established by Shimane University in order to examine the determinants of lifestyle-related diseases. A screening was conducted by a questionnaire-based examination and a detection of serum omega-5 gliadin-specific IgE. Subjects who tested positive in the questionnaire-based examination and/orthe serum omega-5 gliadin-specific IgE test were further examined by detailed interviews and skin prick tests.ResultsA total of 22 subjects were picked up by the screening process, and 17 of these were further examined by secondary testing. Only two subjects were conclusively identified as having wheat allergy.ConclusionsThe prevalence of wheat allergy in Japanese adults was found to be 0.21% by using a combination of questionnaire-based examination, skin prick test and serum omega-5 gliadin-specific IgE test.     

Why can patients with baker's asthma tolerate wheat flour ingestion? Is wheat pollen allergy relevant?

Diagnosis in patients sensitised to multiple pollens is difficult due to the relationship between pollen and food allergens. Misdiagnosis is often a cause for unsuccessful specific immunotherapy. Wheat is a potent allergen source and is one of the causes of baker's asthma, food and pollen allergy. Recently, we have performed a study on pollen sensitisation in our area, where cereal crops are very important. The clinical data from 19718 patients reviewed showed that grass pollen was the main source of clinical symptoms (6369 patients, 32.30% of asthmatics). However, wheat and cereal crop pollen showed very low prevalence. On the other hand, patients with wheat flour allergy after ingestion and/or with baker's asthma were not sensitised to wheat pollen, despite it containing some common allergens. In the same way, all our asthmatic bakers (135 patients) tolerated the ingestion of bread. Here we try to explain the reason for these surprising observations.     

Food allergy as a risk factor for asthma morbidity in adults.

BACKGROUND: The objective of this study was to evaluate the relationship between food allergy and asthma morbidity in adults. METHODS: We interviewed a cohort of persistent asthmatics from an inner-city clinic. Allergies to food were assessed by patient report of convincing symptoms of acute allergic reactions. Outcome variables included health resource utilization and medication use. RESULTS: The prevalence of allergy to fish, peanut, tree-nut, shellfish, and seed allergies were 3%, 3%, 3%, 13%, and 1%. Patients with allergies to > 1 food had increased asthma hospitalizations, ED visits, and use of oral steroids (p < 0.05 for all comparisons). Specifically, allergy to fish was associated with a greater risk of health resource utilization and increased frequency of oral steroid use (p < or = 0.03 for all comparisons). CONCLUSIONS: Self-reported allergy to foods was associated with worse outcomes, suggesting that food allergy may be a risk factor for increased asthma morbidity in adults.     

Food allergy

Food allergy encompasses a range of disorders that result from adverse immune responses to dietary antigens. This group of conditions includes acute, potentially fatal reactions, and a host of chronic diseases that mainly affect the skin and gastrointestinal tract. Tools for diagnosis and management have not changed much in the past two decades, and include the clinical history, physical examination, tests for specific IgE antibody to suspected foods, elimination diets, oral food challenges, and provision of medications such as epinephrine for emergency treatment. However, much research in the past few years has enhanced our understanding of the clinical, epidemiological, and immunological aspects of these disorders. In this review I will discuss these advances and incorporate them into an improved diagnostic and management scheme. Additionally, emergent diagnostic, treatment, and prevention strategies are reviewed.     

Food allergy

Opinion statement Although many emerging therapies demonstrate theoretical and practical promise, strict elimination of the allergenic food remains the only proven therapy for food hypersensitivity. Given such therapeutic limitations, accurate diagnosis and thorough patient education are critical for proper management. This is particularly important for individuals with anaphylactic potential, as food allergy is currently the single leading cause of anaphylaxis treated in hospital emergency departments [1,2].     

Food allergy in irritable bowel syndrome: The case of non-celiac wheat sensitivity

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal disorders, having a prevalence of 12%-30% in the general population. Most patients with IBS attribute their symptoms to adverse food reactions. We review the role of diet in the pathogenesis of IBS and the importance of dietary factors in the management of these patients. The MEDLINE electronic database (1966 to Jan 2015) was searched using the following keywords: “food”, “diet”, “food allergy”, “food hypersensitivity”, “food intolerance”, “IBS”, “epidemiology”, “pathogenesis”, “pathophysiology”, “diagnosis”, “treatment”. We found 153 eligible papers; 80 were excluded because: not written in English, exclusive biochemical and experimental research, case reports, reviews, and research otherwise not relevant to our specific interest. We selected 73 papers: 43 original papers, 26 reviews and 4 letters to the editor. These papers focused on IBS pathogenesis, the association between IBS and atopy, and between IBS and food allergy, the relationship between IBS and non-celiac wheat sensitivity, the role of diet in IBS. Pending further scientific evidence, a cautious approach is advisable but the concept of food allergy should be included as a possible cause of IBS, and a dietary approach may have a place in the routine clinical management of IBS.     

Allergenicity of wheat flour

Food allergy to wheat flour is a pathology that is found less frequently than coeliac disease or respiratory allergy to flour; it seems however to be a constant argument. Our study used a panel of 28 patients diagnosed with food allergy to wheat flour. Our objective was to characterise the reactivity of type IgE and IgG antibodies of these patients with regard to the different classes of proteins of wheat flour so as to establish an antigenic profile of the allergens of wheat in the framework of food allergy to flour. Our results show the implication of different classes of wheat proteins and notably the major reserve proteins (gliadins and glutens) in food allergy.     

Food allergy diagnosis

The diagnosis of food allergies (FA) relies upon the sequential use of different means and tools, according to a decision tree. Ten clinical characteristics point to a potential FA. A diary for food consumption during a week surveys all labellings, in order to detect masked food allergens. The second step is based on skin prick tests to natural foods, and epicutaneous tests to a few proteins (casein, gluten...). Biological tests using multi detection tests of specific IgEs to numerous allergens are not advised owing to the frequency of clinically not relevant in vitro cross-reactivity. Single determination of specific IgEs, have a 95% predictive positive value of high levels in cases of allergy to milk, egg, fish and peanut, and can spare oral challenges. The primary use of biological tests is not currently advised but may be of interest in litigious cases. Standardized oral challenges are the golden standard. Eviction regimens are an alternative used for cow's milk allergy in infancy, or for suspected digestive allergies in adults.     

Gastrointestinal allergy in adults

The prevalence of food allergy reaches 3% in the adult population. Chronic gastrointestinal allergy is a rare entity: 4.2% of food allergies in adults, and represents 3.2% of all intestinal disorders. Non-specific symptoms are the rule but eosinophilic gastrointestinal disorders are the subject of much interest. Endoscopy and biopsies of the gastrointestinal tract help the differential diagnoses. Food allergy is suspected from the patient's history leading to skin tests and laboratory tests identifying a sensitization but allergy is only confirmed by standardized challenges or eviction diets over a sufficiently long period. New types of investigations coupling oral challenges to foods to gastroenterological techniques should be studied further.     

Food allergy: from diagnosis to treatment

Adverse food reactions, an adverse health effect arising from an immune or nonimmune response that occurs reproducibly on the exposure to a given food, can be divided into toxic and hypersensitivity reactions. When an immunologic mechanism has been shown, hypersensitivity food reactions should be referred to as food allergy that may be IgE- or non-IgE-mediated. Food allergy diagnosis is mainly guided by a correct and accurate history and physical examination, thus leading to prick test and elimination diets. The treatment gold standard is still represented by an elimination diet together with antihistamines and corticosteroid usage in order to reduce the gastrointestinal and potentially life-threatening systemic symptoms. Other treatments are currently under investigation with promising results.     

Wheat flour allergy: an entire diagnostic tool for complex allergy

Wheat proteins are involved in respiratory allergy, contact allergy and food allergy. Wheat allergens involve in these pathologies are well-known. However, establishment of wheat allergy diagnostic can be sometimes difficult on account of the complex allergenic composition of skin prick test (SPT) solutions of wheat flour. Therefore, we have studied specific IgE reactivity from patient sera with wheat food allergy, and characterized allergenic composition of wheat SPT solutions by specific antibodies directed to wheat allergens. The results showed that 20 of the 25 sera analyzed contained specific IgE to at least one wheat protein fraction. Among positive sera, 75% have specific IgE to water/salt soluble fraction, 85% to native gluten fractions and 65% to wheat isolate fraction. The results showed also that SPT solutions of wheat flour contained major food allergens from each allergenic fraction. These results highlighted the importance of using fractions, which constitute the whole wheat allergenic pattern, during specific IgE reactivity analyses. Moreover, we have observed that wheat isolate extract (results of food industrial process) contained not only modified allergens (neo-allergens) involve of specific food allergy to wheat isolate but also some native allergens involve in wheat food allergy. Thus, these results showed the importance to use, for wheat in vivo diagnosis together wheat SPT solutions (gluten extract and wheat isolate) in order to differentiate wheat food allergy to specific wheat isolate allergy.