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Barnett J, Vasileiou K, Gowland MH, Raats MM, Lucas JS. Beyond labelling: what strategies do nut allergic individuals employ to make food choices? A qualitative study. PLoS One. 2013;8(1):e55293.
OBJECTIVE: Food labelling is an important tool that assists people with peanut and tree nut allergies to avoid allergens. Nonetheless, other strategies are also developed and used in food choice decision making. In this paper, we examined the strategies that nut allergic individuals deploy to make safe food choices in addition to a reliance on food labelling.
METHODS: THREE QUALITATIVE METHODS: an accompanied shop, in-depth semi-structured interviews, and the product choice reasoning task – were used with 32 patients that had a clinical history of reactions to peanuts and/or tree nuts consistent with IgE-mediated food allergy. Thematic analysis was applied to the transcribed data.
RESULTS: Three main strategies were identified that informed the risk assessments and food choice practices of nut allergic individuals. These pertained to: (1) qualities of product such as the product category or the country of origin, (2) past experience of consuming a food product, and (3) sensory appreciation of risk. Risk reasoning and risk management behaviours were often contingent on the context and other physiological and socio-psychological needs which often competed with risk considerations.
CONCLUSIONS: Understanding and taking into account the complexity of strategies and the influences of contextual factors will allow healthcare practitioners, allergy nutritionists, and caregivers to advise and educate patients more effectively in choosing foods safely. Governmental bodies and policy makers could also benefit from an understanding of these food choice strategies when risk management policies are designed and developed.
Maslova E, Granström C, Hansen S, Petersen SB, Strøm M, Willett WC, Olsen SF.
Peanut and tree nut consumption during pregnancy and allergic disease in children-should mothers decrease their intake? Longitudinal evidence from the Danish National Birth Cohort. J Allergy Clin Immunol. 2012 Sep;130(3):724-32.
BACKGROUND: The relation between maternal peanut intake during pregnancy and allergic disease development in children has been controversial. OBJECTIVE: We used data from the Danish National Birth Cohort to examine associations between maternal peanut and tree nut intake during pregnancy and allergic outcomes in children at 18 months and 7 years of age.
METHODS: We estimated maternal peanut and tree nut intake (n = 61,908) using a validated midpregnancy food frequency questionnaire. At 18 months, we used parental report of childhood asthma diagnosis, wheeze symptoms, and recurrent wheeze (>3 episodes). We defined current asthma at 7 years as doctor-diagnosed asthma plus wheeze in the past 12 months and allergic rhinitis as a self-reported doctor’s diagnosis. We also used alternative classifications based on registry-based International Classification of Diseases, Tenth Revision, codes and drug dispensary data. We report here odds ratios (ORs) comparing intake of 1 or more times per week versus no intake.
RESULTS: We found that maternal intake of peanuts (OR, 0.79; 95% CI, 0.65-0.97) and tree nuts (OR, 0.75; 95% CI, 0.67-0.84) was inversely associated with asthma in children at 18 months of age. Compared with mothers consuming no peanuts, children whose mothers reported eating peanuts 1 or more times per week were 0.66 (95% CI, 0.44-0.98) and 0.83 (95% CI, 0.70-1.00) times as likely to have a registry-based and medication-related asthma diagnosis, respectively. Higher tree nut intake was inversely associated with a medication-related asthma diagnosis (OR, 0.81; 95% CI, 0.73-0.90) and self-reported allergic rhinitis (OR, 0.80; 95% CI, 0.64-1.01).
CONCLUSIONS: Our results do not suggest that women should decrease peanut and tree nut intake during pregnancy; instead, consumption of peanuts and tree nuts during pregnancy might even decrease the risk of allergic disease development in children.
Rosenfeld L, Shreffler W, Bardina L, Niggemann B, Wahn U, Sampson HA, Beyer K. Walnut allergy in peanut-allergic patients: significance of sequential epitopes of walnut homologous to linear epitopes of Ara h 1, 2 and 3 in relation to clinical reactivity. Int Arch Allergy Immunol. 2012;157(3):238-45.
BACKGROUND: Peanut allergy is a frequent and potentially life-threatening food allergy. Despite the large taxonomic distance between the plants, peanut-allergic patients often react to tree nuts such as walnuts. While the allergens of peanut and walnut have a high degree of homology in their amino-acid sequences, it is unknown whether this similarity is responsible for the observed co-reactivity. Therefore, we analyzed the binding of specific IgE antibodies to sequential epitopes of peanut and walnut in peanut-allergic patients with and without walnut allergy.
METHODS: The IgE binding to previously described sequential epitopes of peanut and the homologous regions of walnut was assessed in 32 peanut-allergic patients using a peptide microarray technology. Twelve patients had a clinically relevant walnut allergy and 20 were tolerant to walnut. Inhibition assays with peanut peptides and corresponding walnut sequences were performed to show specific binding to sequential epitopes.
RESULTS: No differences in the recognition of sequential epitopes could be found between peanut-allergic patients with or without walnut allergy. Only a few patients showed IgE binding to walnut sequences that corresponded to sequential epitopes of peanut. In the inhibition assays, no relevant cross-reacting IgE antibodies could be detected for the peptides analyzed.
CONCLUSION: Our results indicate that although they share a rather high degree of homology with the corresponding regions of walnut allergens, the sequence stretches previously identified as sequential IgE binding epitopes of Ara h 1, Ara h 2 and Ara h 3 have no IgE binding equivalents in walnut allergens.
Ball H, Luyt D, Bravin K, Kirk K. Single nut or total nut avoidance in nut allergic children: outcome of nut challenges to guide exclusion diets. Pediatr Allergy Immunol. 2011 Dec;22(8):808-12.
BACKGROUND: Children with diagnosed nut allergy are typically advised by health professionals to exclude all nuts from their diets, irrespective of the outcome of allergy testing, to avoid inadvertent contact through contamination or the possible development of new allergies.
METHODS: In our service, as we feel greater diagnostic accuracy prevents dietary risk taking, we provide the facility for children with nut allergy the opportunity of controlled exposure to ‘other’ nuts irrespective of whether their allergy prick test (PT) results are positive or negative. We performed open food challenges on our paediatric day ward. The challenge food was administered by way of a homemade biscuit containing 8 g of each nut challenged and given in increasing visually measured doses.
RESULTS: Over the 5-year period from 2006, we challenged 145 children diagnosed as peanut allergic or tree nut allergic. In those with peanut allergy challenged to tree nuts, none of the 72 with negative PTs to tree nuts reacted on challenge whilst 7 of 22 (31.2%) with positive PTs did. In patients with tree nut allergy challenged to peanuts and/or other tree nuts, 3 of 38 (7.9%) with negative PT results and 5 of 13 (38.4%) with positive PT results reacted.
CONCLUSION: Children allergic to peanuts with negative allergy tests to tree nuts had no co-existing allergy, but were at risk of tree nut allergy where PTs were positive. Children with tree nut allergy were at risk of co-existing peanut or other tree nut allergy whether PTs were positive or negative. Oral challenges to clarify allergy status in all nuts show co-existing allergies even in young children and in so doing may reduce anxiety, minimize unnecessary dietary restrictions and prevent later episodes of anaphylaxis through uninformed exposure.
Barnett J, Leftwich J, Muncer K, Grimshaw K, Shepherd R, Raats MM, Gowland MH, Lucas JS. How do peanut and nut-allergic consumers use information on the packaging to avoid allergens? Allergy. 2011 Feb 14. doi: 10.1111/j.1398-9995.2011.02563.x.
BACKGROUND: Recent legislation has sought to improve the information printed on packaged foods relevant to the safety of food allergic consumers. We aimed to understand the complex risk assessment decisions made by peanut and nut-allergic adults when purchasing food, with particular reference to use of printed package information.
METHODS: The behaviour and ‘thinking aloud’ of 32 participants were recorded during their normal food shop, followed by a semi-structured interview. During the interview they were given 13 potentially problematic packaged foods, and asked if they would purchase the product and what their reasons were. Transcribed data from the shop, interview and 13-product task were analysed to explore use of allergy advice boxes, ingredients lists and other packaging information.
RESULTS: Some participants used the ingredients list as their primary check for allergens, but most used the allergy advice box. Package-based information was generally considered reliable, but some supermarket and brand labels were trusted more than others. Images and product names were used to draw inferences about the presence of nuts. A number of improvements were suggested by participants, particularly a request for more ‘nut free’ labelling.
CONCLUSIONS: Food labels were used in conjunction with nonpacket-based strategies (e.g. previous experience) to make choices. External factors (e.g. trust of manufacturer) informed interpretation of and confidence in labels. Images and product names, not intended by manufacturers as an allergen risk assessment aid, were also used to inform choices.
Leftwich J, Barnett J, Muncer K, Shepherd R, Raats MM, Hazel Gowland M, Lucas JS. The challenges for nut-allergic consumers of eating out. Clin Exp Allergy. 2011 Feb;41(2):243-9.
BACKGROUND: For individuals with a nut allergy, the avoidance of allergens is particularly challenging in situations where they are not preparing their own food. Many allergic reactions occur when eating outside the home.
OBJECTIVES: To identify and explore the challenges faced by nut-allergic individuals (NAIs) when they are eating in restaurants and other eating establishments.
METHODS: A qualitative interview study was conducted with 32 adults with a clinical history of allergy to peanuts and/or tree nuts.
RESULTS: The main strategies that participants adopted to manage the risk of allergic reactions when eating outside the home were avoidance and communication. They avoided types of restaurants, meal courses or particular foods. Seeking familiarity was a key strategy that enabled NAIs to reduce uncertainty and anxiety. Language differences were a major barrier to confident communication about food content. The need to check whether the food on offer may contain nuts was a source of social embarrassment for many participants and the desire to avoid this sometimes led to increased risk taking. Some did not disclose their allergy to restaurant staff as they feared a conservative reaction that would further constrain food choices. NAIs often have to plan where to eat out. The consequent lack of spontaneity was a source of regret to some.
CONCLUSION AND CLINICAL RELEVANCE: Communication patterns of nut-allergic adults are often grounded in legitimate everyday social considerations around embarrassment, choice and spontaneity. Education and training strategies are needed that recognize and take account of this. Focusing on communication deficits of NAIs may be unhelpful; responsibility for food safety must be shared with the food industry.
Kulis M, Li Y, Lane H, Pons L, Burks W. Single-tree nut immunotherapy attenuates allergic reactions in mice with hypersensitivity to multiple tree nuts. J Allergy Clin Immunol. 2011 Jan;127(1):81-8.
BACKGROUND: Allergic reactions to tree nuts are often severe and are outgrown in less than 10% of diagnosed patients.
OBJECTIVES: To determine whether treatment of underlying tree nut sensitization will prevent allergic reactions to cross-reacting tree nuts and to determine the effects of single-tree nut immunotherapy on true multi-tree nut sensitization.
METHODS: In the cross-reactivity model, cashew immunotherapy completely prevented allergic reactions on challenges with cashew or the cross-reactive pistachio. In the multisensitization model, mice with cashew plus walnut allergy were significantly protected from anaphylactic reactions on cashew challenge in both the cashew-alone and walnut-alone immunotherapy groups. Results from the walnut challenge demonstrated significantly decreased allergic responses in the walnut immunotherapy group, whereas mice in the cashew immunotherapy group experienced significantly lower symptoms. In the cross-reactivity model, immunotherapy effectively decreased IL-4 and IL-5 production and increased IL-12 relative to placebo while also inducing a 5-fold increase in specific IgG(1).
RESULTS: In the cross-reactivity model, cashew immunotherapy completely prevented allergic reactions on challenges with cashew or the cross-reactive pistachio. In the multisensitization model, mice with cashew plus walnut allergy were significantly protected from anaphylactic reactions on cashew challenge in both the cashew-alone and walnut-alone immunotherapy groups. Results from the walnut challenge demonstrated significantly decreased allergic responses in the walnut immunotherapy group, whereas mice in the cashew immunotherapy group experienced significantly lower symptoms. In the cross-reactivity model, immunotherapy effectively decreased IL-4 and IL-5 production and increased IL-12 relative to placebo while also inducing a 5-fold increase in specific IgG(1).
CONCLUSIONS: Single-tree nut immunotherapy can effectively decrease allergic responses in both the cross-reactivity and multisensitization mouse models. Further studies are needed to determine which single-tree nut immunotherapies will be most effective for specific multi-tree nut allergy profiles.
Worm M, Hompes S, Fiedler EM, Illner AK, Zuberbier T, Vieths S. Impact of native, heat-processed and encapsulated hazelnuts on the allergic response in hazelnut-allergic patients. Clin Exp Allergy. 2009 Jan;39(1):159-66
BACKGROUND: Pollen-associated food allergy is common. However, systemic reactions or even life-threatening anaphylaxis are rare.
OBJECTIVES: The aim of this study was to investigate the clinical impact of native, heat-processed and encapsulated hazelnuts (HN) in patients with proven HN allergy.
METHODS: One hundred and thirty-two patients with a positive history of HN allergy were recruited. Sensitization was confirmed by a skin prick test (SPT) and sIgE against HN. After an HN-free diet, double-blind placebo-controlled challenges were performed with increasing amounts of native and roasted HN. A subset of patients were given HN capsules to circumvent the oral mucosa. Basophil activation was measured by flow cytometry before and after provocation but also ex vivo using native and roasted HN extracts.
RESULTS: Three groups of HN-allergic patients were identified depending on their clinical reaction pattern. The dosages by which allergic reactions were elicitated varied for native HN from 0.01 to 2.0 g, with a median of 0.1 g, for roasted HN from 0.01 to 10.0 g, with a median of 0.23 g, and for encapsulated HN from 0.1 to 3.0 g, with a median of 0.3 g. Accordingly, the SPT was more frequently positive and resulted in greater weal reactions if native HN was used. This finding was confirmed by ex vivo basophil activation showing that significantly higher allergen extract concentrations (roasted>native) were necessary to induce 50% basophil activation.
CONCLUSION: Our data show that heat processing of HN reduces its allergenicity. SPT but also the basophil activation test can be used to determine the reactivity of an allergen extract.
Kulis M, Pons L, Burks AW. In vivo and T cell cross-reactivity between walnut, cashew and peanut. Int Arch Allergy Immunol. 2009 Jan;148(2):109-17
BACKGROUND: Examination of IgE cross-reactivity among nuts has been limited to in vitro experiments. Cross-reactivity studies of nuts at the T cell level are difficult to interpret because of the inability to determine which cellular responses are from a true sensitization and which are due to cross-reactivity. Using a mouse model in which the sensitizing nuts are controlled may provide novel methods to investigate in vivo and T cell cross-reactivity.
METHODS: C3H/HeJ mice were sensitized by intraperitoneal injection of cashew alone (monosensitized mice), or cashew plus walnut, utilizing alum as an adjuvant. Both groups underwent challenges to cashew, walnut and peanut, with subsequent monitoring of anaphylactic reactions. Anaphylactic antibodies were quantified by ELISA, and protein allergens were identified by Western blotting. Cellular responses were studied via splenocyte proliferation assay and measurement of secreted cytokines.
RESULTS: The monosensitized mice reacted to cashew and walnut during challenges, with significantly weaker reactions induced on challenge with peanut. Cross-reactive IgE to walnut and peanut were detected by ELISA, and the cross-reactive allergens were identified as vicilin proteins. In cellular assays, splenocytes from the monosensitized mice proliferated and produced IL-4 and IL-5 in response to cashew, walnut and peanut. The cashew- plus walnut-sensitized mice experienced stronger clinical reactions to walnut, recognized additional walnut allergens and secreted significantly more IL-4 and IL-5 in walnut-stimulated splenocyte assays compared to the monosensitized mice.
CONCLUSION: Cross-reactivity in vivo was found between cashew and walnut, while cross-reactivity among cashew, walnut and peanut was demonstrated at the T cell level. Copyright 2008 S. Karger AG, Basel.
Lindsay H. Allen. Priority Areas for Research on the Intake, Composition, and Health Effects of Tree Nuts and Peanuts. J. Nutr. 2008 138: S -1765. Available free at www.nuthealth.org
This article summarizes the main conclusions drawn from a conference on the health effects of nut consumption and identifies priority areas for future research. Individuals with higher intakes of nuts generally have higher intakes of many beneficial dietary constituents. More information is needed on nut composition, the bioavailability of nutrients, and other bioactive constituents. Better methods are needed to assess usual nut intake, including biomarkers, and the types, physical form, and amounts of nuts that are consumed. The feasibility of including nuts and seeds as a separate food group in the Dietary Guidelines should be tested, as should ways to increase nut intake. A moderate intake of nuts can be included in a weight loss regimen and further information is needed on whether nuts improve satiety as well as adherence to and efficacy of diets designed for weight reduction. There is substantial evidence that nut consumption reduces risk of cardiovascular disease. Future research should investigate their benefits for prevention of congestive heart failure, including clinical studies in patients with this condition, to evaluate the effects of nuts on markers of heart disease risk. Higher nut consumption is associated with lower risk of diabetes and associated cardiovascular disease. More remains to be learned about the effects of nuts on postprandial glycemic and insulin response, glycemic control, and improvement of disease risk factors in subjects with prediabetes and diabetes. Information is needed on nut-induced allergic reactions, including their prevalence and consequences, causes of sensitization, biomarkers of severe reactions, and cross-reactivity to different types of nuts.