A retrospect study into the utility of allergen components in walnut allergy.
Walnut (Juglans regia) and Pecan (Carya illinoinensis) are members of the Juglandaceae family. Walnut and pecan appear similar and share high protein homology with the result that most walnut allergic individuals are also allergic to pecan nut. Walnut is a common allergy in tree nut allergic individuals in the United States and the United Kingdom (1) and has been associated with severe and fatal reactions. The diagnosis of a nut allergy has been shown to negatively influence quality of life (2). However, walnut and pecan nut are a healthy source of protein and found in a variety of foods. Unlike many other nuts, walnut and pecan are easily shelled and therefore free from contamination with other nuts and safe for consumption if walnut and pecan tolerant. It is important therefore to accurately diagnose the presence of allergy or tolerance to walnut and/or pecan in individuals where food allergy is suspected.
Food allergy in children.
Food allergy represents a highly up-to-date and continually increasing problem of modern man. Although being present in all ages, it most often occures in children aged up to three years. Sensitization most often occurs by a direct way, but it is also possible to be caused by mother's milk, and even transplacentally. Predisposition of inadequate immune response to antigen stimulation, reaginic or nonreaginic, is of non-selective character so that food allergy is often multiple and to a high rate associated with inhalation and/or contact hypersensitivity. Also, due to antigen closeness of some kinds of food, cross-reactive allergic reaction is also frequent, as is the case with peanuts, legumes and tree nuts or cow's, sheep's and goat's milk. Most frequent nutritive allergens responsible for over 90% of adverse reactions of this type are proteins of cow's milk, eggs, peanuts, tree nuts, wheat, soy, fish, shellfish, crustaceans, and cephalopods. Allergy intolerance of food antigens is characterized by a very wide spectrum of clinical manifestations. Highly severe systemic reactions, sometimes fatal, are also possible.The diagnosis of food allergy is based on a detailed personal and family medical history, complete clinical examination, and corresponding laboratory and other examinations adapted to the type of hypersensitivity and the character of patient's complaints, and therapy on the elimination diet. A positive effect of elimination diet also significantly contributes to the diagnosis. Although most children "outgrow" their allergies, allergy to peanuts, tree nuts, fish, shellfish, crustaceans, and cephalopods are generally life-long allergies.
Thermal processing effects on peanut allergen Ara h 2 allergenicity in mice and its antigenic epitope structure.
Ara h 2 was purified from peanuts that were thermally treated by various processes, including boiling, glycation, frying and roasting. The allergenicity of Ara h 2 in Balb/c mice and the influence of thermal processing on the structural characteristics, and binding capacity of three core antigenic epitopes were studied. The results demonstrated that boiling, glycation and frying induced the down-regulation of the allergenicity of Ara h 2 in Balb/c mice, the collapse of its tertiary/secondary structure, and a reduction in the core epitope binding capacity; roasting showed a comparable allergenicity and the weakest inhibitory effect on core epitope binding capacity. These results indicate that thermal processing causes alteration of the protein structure and core epitopes of Ara h 2, and may affect its allergenicity.
Dietary Fiber and Bacterial SCFA Enhance Oral Tolerance and Protect against Food Allergy through Diverse Cellular Pathways.
The incidence of food allergies in western countries has increased dramatically in recent decades. Tolerance to food antigens relies on mucosal CD103+ dendritic cells (DCs), which promote differentiation of regulatory T (Treg) cells. We show that high-fiber feeding in mice improved oral tolerance and protected from food allergy. High-fiber feeding reshaped gut microbial ecology and increased the release of short-chain fatty acids (SCFAs), particularly acetate and butyrate. High-fiber feeding enhanced oral tolerance and protected against food allergy by enhancing retinal dehydrogenase activity in CD103+ DC. This protection depended on vitamin A in the diet. This feeding regimen also boosted IgA production and enhanced T follicular helper and mucosal germinal center responses. Mice lacking GPR43 or GPR109A, receptors for SCFAs, showed exacerbated food allergy and fewer CD103+ DCs. Dietary elements, including fiber and vitamin A, therefore regulate numerous protective pathways in the gastrointestinal tract, necessary for immune non-responsiveness to food antigens.
Global Perceptions of Food Allergy Thresholds in 16 Countries.
BACKGROUND: Food allergy is a growing global health issue that affects daily life and food purchasing habits. Quality data on the global consumer perspective of food allergy is limited, particularly about thresholds and food labeling risk. Many individuals with food allergy are counseled that small amounts of allergen can potentially cause life-threatening reactions, and to avoid foods with Precautionary Advisory Labeling (PAL). The purpose of this study was to understand attitudes of consumers about food allergy thresholds and food purchasing habits related to PAL in sixteen countries. METHODS: A questionnaire was distributed by patient support groups in 16 countries to consumers with food allergy. The questionnaire gathered opinions about food allergy thresholds and PAL purchasing habits. RESULTS: 9,689 respondents from 16 countries completed the survey.19% of respondents stated they would purchase a food containing their allergen if the amount present would not cause a reaction and 3% would purchase a food if the amount of allergen present would cause a mild reaction. When asked about labeling, 16% of respondents reported that they would purchase food with a "may contain" statement, 25% would purchase food labeled "may contain traces of allergen", and 41% would purchase products labeled "manufactured in a facility that also processes allergen". CONCLUSIONS: Findings suggest that understanding of food allergen thresholds and precautionary allergen labelling is limited and consumers may develop their own risk assessment based on labels, which are not based on clinical validation. Improved awareness of thresholds, standardization of PAL, and clinical validation are needed globally. This article is protected by copyright. All rights reserved.
Impact of peanut consumption in the LEAP Study: Feasibility, growth, and nutrition.
BACKGROUND: Early introduction of peanut is an effective strategy to prevent peanut allergy in high-risk infants; however, feasibility and effects on growth and nutritional intake are unknown. OBJECTIVE: We sought to evaluate the feasibility of introducing peanut in infancy and explore effects on growth and nutritional intake up to age 60 months. METHODS: In the Learning Early About Peanut Allergy trial, 640 atopic infants aged 4 to 11 months were randomly assigned to consume (6 g peanut protein per week) or avoid peanut until age 60 months. Peanut consumption and early feeding practices were assessed by questionnaire. Dietary intake was evaluated with prospective food diaries. Anthropometric measurements were taken at all study visits. RESULTS: Peanut was successfully introduced and consumed until 60 months, with median peanut protein intake of 7.5 g/wk (interquartile range, 6.0-9.0 g/wk) in the consumption group compared with 0 g in the avoidance group. Introduction of peanut in breast-feeding infants did not affect the duration of breast-feeding. There were no differences in anthropometric measurements or energy intakes between groups at any visits. Regular peanut consumption led to differences in dietary intakes. Consumers had higher intakes of fat and avoiders had higher carbohydrate intakes; differences were greatest at the upper quartiles of peanut consumption. Protein intakes remained consistent between groups. CONCLUSIONS: Introduction of peanut proved feasible in infants at high risk of peanut allergy and did not affect the duration of breast-feeding nor impact negatively on growth or nutrition. Energy balance was achieved in both groups through variations in intakes from fat and carbohydrate while protein homeostasis was maintained.
Processing Effects On Tree Nut Allergens: A Review.
"Tree nut" is a broad term for classification of nuts that include cashews, almonds, hazelnuts etc. Reports of mild to adverse immune reactions following the consumption of these nuts has been on a rise in recent years. Currently, about 1.2 - 2% of the world's population suffer from sensitivity to tree nuts. The only solution is complete abstinence from the allergy causing tree nut which is not feasible in most cases due to issues like cross contamination or their presence in the form of hidden ingredients in processed foods. Various studies have shown that food processing can effectively vary the secondary structures of the allergenic protein which in turn influences their functional properties. But, the impact of these processing methods on tree nuts allergens is mixed. This review gives an update on the recent findings on how conventional and novel processing methods influence the tree nut allergens.
Mass spectrometric analysis of allergens in roasted walnuts.
Thermal processing of allergenic foods can induce changes in the foods' constituent allergens, but the effects of heat treatment are poorly defined. Like other commonly allergenic tree nuts, walnuts often undergo heat treatment (e.g. roasting or baking) prior to consumption. This study evaluated the changes in solubility and detectability of allergens from roasted walnuts using tandem mass spectrometry methods. Walnuts were roasted (132°C or 180°C for 5, 10, or 20min) and prepared for LC-MS/MS using sequential or simultaneous extraction and tryptic digestion protocols. The LC-MS/MS data analysis incorporated label-free quantification of relevant allergens and Maillard adduct screening. In some proteins (2S albumin, LTP, and the 7S globulin N-terminal region) minor changes in relative abundance were observed following roasting. The mature 7S and 11S globulins, however, showed significantly increased detection following roasting at 180°C for 20min when using the simultaneous extraction/digestion protocol, possibly due to increased digestibility of the proteins. The results of this study indicate that individual walnut allergens respond differently to thermal processing, and the detection of these proteins by LC-MS/MS is dependent on the protein in question, its susceptibility to proteolytic digestion, the degree of thermal processing, and the sample preparation methodology.
Component-Resolved Diagnosis of Peanut Allergy and Its Possible Origins of Sensitization in China.
BACKGROUND: Clinical and immunological characteristics of food allergies vary depending on geographic regions. Little is known about peanut allergy in China. The aim of this study was to investigate the peanut sensitization profile in China. METHODS: Thirty-eight participants with immunoglobulin E (IgE)-positive responses to peanuts (peanut-sensitized) were included in our study, and clinical characteristics were evaluated. Total and specific IgE reactivity against peanuts, other plant-derived foods, pollens, and related allergen components were determined. RESULTS: Eighteen patients were symptomatic when exposed to peanuts. The majority of them presented with systemic reactions. More than half of the peanut-sensitized subjects also suffered from mugwort pollinosis and peach allergy. In patients with both peanut and peach allergies, reactions to peanuts were the same as or severer than those to peaches. Positivity rates of IgE response to rAra h 1-3, 8, and 9 in the peanut allergy group were 5.6, 11.1, 5.6, 22.2, and 83.3%, respectively. 66.7% (12/18) of the peanut-allergic patients were monosensitized to rAra h 9. Anti-nArt v 3 [mugwort nonspecific lipid transfer protein (nsLTP)] IgE positivity in the peanut allergy group was significantly higher than that in the asymptomatic peanut-sensitized group. In Ara h 9 (peanut nsLTP)-sensitized patients with mugwort pollinosis, anti-nArt v 3 IgE levels were remarkably higher than anti-rAra h 9 (peanut nsLTP) IgE levels as well as anti-Pru p 3 (peach nsLTP) IgE levels. CONCLUSIONS: Ara h 9 was the major allergen of peanut, and Ara h 9 monosensitization was the most common peanut sensitization pattern in our population. Furthermore, there was a strong correlation between peanut sensitization and mugwort pollinosis, as well as peach allergy, in our country.
Diagnostic Value of Antigen-Specific Immunoglobulin E Immunoassays against Ara h 2 and Ara h 8 Peanut Components in Child Food Allergy.
BACKGROUND: Peanut allergy is one of the most severe food allergies in children. The diagnostic gold standard is the oral food challenge (OFC). However, OFC has inherent risks and is time consuming. The measurement of specific immunoglobulin E (sIgE) to peanut components in blood detects peanut sensitization, but the decision point predicting allergy is still unclear. The aim of this study was to determine the diagnostic value of these tests for the evaluation of child peanut allergy. METHODS: In this retrospective study, 81 children were referred for peanut allergy. The diagnosis of peanut allergy was based on the clinical context and a positive OFC. Levels of sIgE against whole peanuts or peanut components (Ara h 2 and Ara h 8) were determined by immunoassay. RESULTS: The Ara h 2 sIgE assay has the best negative predictive value (0.93) and positive predictive value (1) at a cutoff of 0.1 kU/l. Ara h 2 sIgE titers can predict the risk of anaphylaxis (<0.44 kU/l, low risk; >14 kU/l, high risk). The Ara h 8 sIgE assay is not able to discriminate peanut-allergic patients but can be used to evaluate possible cross-reactions to birch pollen with a low risk of anaphylaxis. The best diagnostic strategy is to first determine the Ara h 2 sIgE level and, if negative, evaluate Ara h 8 sIgE. CONCLUSIONS: We propose an algorithm for a better use of peanut component sIgE immunoassays that should improve their diagnostic value and avoid unnecessary OFC.