Benjamin C. Remington

Establishment of Reference Doses for residues of allergenic foods: Report of the VITAL Expert Panel

In 2011, an expert panel was assembled to establish appropriate Reference Doses for allergenic food residues as a part of the VITAL (Voluntary Incidental Trace Allergen Labeling) program of The Allergen Bureau of Australia & New Zealand (ABA). These Reference Doses would guide advisory labeling decisions for use on food labels. Individual NOAELs and LOAELs were obtained from clinical challenges of food-allergic subjects. Statistical dose-distribution models (log-normal, log-logistic, Weibull) were applied to the individual NOAELs and LOAELs for each allergenic food. The Reference Doses, in terms of mg of total protein from the allergenic food, were based upon either the ED01 (for peanut, cows milk), the 95% lower confidence interval of the ED05 (for wheat, soybean, cashew, shrimp, sesame seed, mustard, and lupine), or both (egg, hazelnut) using all appropriate statistical dose-distribution models. Reference Doses were established for 11 allergenic foods ranging from 0.03 mg for egg protein to 10mg for shrimp protein. Reference Doses were not established for fish or celery due to poor model fits with existing data. Reference Doses were not established for other tree nuts beyond hazelnut and cashew because of the absence of data on NOAELs and LOAELs from individual subjects.

Threshold dose for peanut: risk characterization based upon diagnostic oral challenge of a series of 286 peanut-allergic individuals.

Clinical records of 286 consecutive patients reacting positively with objective symptoms to double-blind, placebo-controlled oral peanut challenges at University Hospital, Nancy, France were examined for individual No Observed Adverse Effect Levels (NOAELs) and Lowest Observed Adverse Effect Levels (LOAELs). After fitting to a log-normal probability distribution model, the ED(10) and ED(05) were 14.4 and 7.3mg (expressed as whole peanut), respectively, with 95% lower confidence intervals of 10.7 and 5.2mg, respectively. Compared to results from a previous study where the ED(10) was based upon individual peanut thresholds gleaned from 12 publications, a statistically significant difference was observed between the ED(50)s, but not the ED(10)s of the two probability distribution curves. The Nancy patient group contains more sensitive subjects than the group from the published literature thus contributing to the observed differences. Minimum eliciting dose-distributions for patients with histories of more severe reactions (grade 4 or 5; 40 subjects) did not differ significantly from those of patients with histories of less severe reactions (grades 1-3; 123 subjects). These data and this modeling approach could be used to establish population thresholds for peanut-allergic consumers and thereby provide a sound basis for allergen control measures in the food industry.

Allergen reference doses for precautionary labeling (VITAL 2.0): Clinical implications

BACKGROUND There has been a dramatic proliferation of precautionary labeling by manufacturers to mitigate the perceived risk from low-level contamination from allergens in food. This has resulted in a significant reduction in choice of potentially safe foods for allergic consumers. OBJECTIVES We aimed to establish reference doses for 11 commonly allergenic foods to guide a rational approach by manufacturers based on all publically available valid oral food challenge data. METHODS Reference doses were developed from statistical dose-distribution modeling of individual thresholds of patients in a dataset of more than 55 studies of clinical oral food challenges. Sufficient valid data were available for peanut, milk, egg, and hazelnut to allow assessment of the representativeness of the data used. RESULTS The data were not significantly affected by the heterogeneity of the study methodology, including little effect of age on results for those foods for which sufficient numbers of adult challenge data were available (peanut and hazelnut). Thus by combining data from all studies, the eliciting dose for an allergic reaction in 1% of the population estimated for the following were 0.2 mg of protein for peanut, 0.1 mg for cows milk, 0.03 mg for egg, and 0.1 mg for hazelnut. CONCLUSIONS These reference doses will form the basis of the revised Voluntary Incidental Trace Allergen Labeling (VITAL) 2.0 thresholds now recommended in Australia. These new levels will enable manufacturers to apply credible precautionary labeling and provide increased consumer confidence in their validity and reliability, as well as improving consumer safety.

Cysteine pKa depression by a protonated glutamic acid in human DJ-1.

Human DJ-1, a disease-associated protein that protects cells from oxidative stress, contains an oxidation-sensitive cysteine (C106) that is essential for its cytoprotective activity. The origin of C106 reactivity is obscure, due in part to the absence of an experimentally determined p K a value for this residue. We have used atomic-resolution X-ray crystallography and UV spectroscopy to show that C106 has a depressed p K a of 5.4 +/- 0.1 and that the C106 thiolate accepts a hydrogen bond from a protonated glutamic acid side chain (E18). X-ray crystal structures and cysteine p K a analysis of several site-directed substitutions at residue 18 demonstrate that the protonated carboxylic acid side chain of E18 is required for the maximal stabilization of the C106 thiolate. A nearby arginine residue (R48) participates in a guanidinium stacking interaction with R28 from the other monomer in the DJ-1 dimer and elevates the p K a of C106 by binding an anion that electrostatically suppresses thiol ionization. Our results show that the ionizable residues (E18, R48, and R28) surrounding C106 affect its p K a in a way that is contrary to expectations based on the typical ionization behavior of glutamic acid and arginine. Lastly, a search of the Protein Data Bank (PDB) produces several candidate hydrogen-bonded aspartic/glutamic acid-cysteine interactions, which we propose are particularly common in the DJ-1 superfamily.

Can we identify patients at risk of life‐threatening allergic reactions to food?

Anaphylaxis has been defined as a ‘severe, life‐threatening generalized or systemic hypersensitivity reaction’. However, data indicate that the vast majority of food‐triggered anaphylactic reactions are not life‐threatening. Nonetheless, severe life‐threatening reactions do occur and are unpredictable. We discuss the concepts surrounding perceptions of severe, life‐threatening allergic reactions to food by different stakeholders, with particular reference to the inclusion of clinical severity as a factor in allergy and allergen risk management. We review the evidence regarding factors that might be used to identify those at most risk of severe allergic reactions to food, and the consequences of misinformation in this regard. For example, a significant proportion of food‐allergic children also have asthma, yet almost none will experience a fatal food‐allergic reaction; asthma is not, in itself, a strong predictor for fatal anaphylaxis. The relationship between dose of allergen exposure and symptom severity is unclear. While dose appears to be a risk factor in at least a subgroup of patients, studies report that individuals with prior anaphylaxis do not have a lower eliciting dose than those reporting previous mild reactions. It is therefore important to consider severity and sensitivity as separate factors, as a highly sensitive individual will not necessarily experience severe symptoms during an allergic reaction. We identify the knowledge gaps that need to be addressed to improve our ability to better identify those most at risk of severe food‐induced allergic reactions.

Unintended allergens in precautionary labelled and unlabelled products pose significant risks to UK allergic consumers.

Allergens in food may pose a risk to allergic consumers. While there is EU regulation for allergens present as an ingredient, this is not the case for unintended allergen presence (UAP). Food companies use precautionary allergen labels to inform allergic individuals of a potential risk from UAPs. This study investigates the risk of an allergic reaction within the milk‐, wheat‐, hazelnut‐ and peanut‐allergic populations when ingesting UK foods across multiple product categories with and without precautionary allergen labelling.

Survey of peanut levels in selected Irish food products bearing peanut allergen advisory labels

Peanut allergy affects up to 2% of consumers and is responsible for the majority of fatalities caused by food-induced anaphylaxis. Peanut-containing products must be clearly labelled. Manufacturers are not legally required to label peanut if its inclusion resulted from unintentional cross contact with foods manufactured in the same facility. However, the use of allergen advisory statements alerting consumers of the potential presence of peanut allergen has increased in recent years. In previous studies, the vast majority of foods with precautionary allergen statements did not contain detectable levels of peanut, but no data are available on Irish food products. Thirty-eight food products bearing peanut/nut allergen-related statements were purchased from multiple locations in the Republic of Ireland and analysed for the presence of peanut. Peanut was detected in at least one lot in 5.3% (2 of 38) of the products tested. The doses of peanut detected ranged from 0.14 mg to 0.52 mg per suggested serving size (0.035–0.13 mg peanut protein). No detectable levels of peanut were found in the products that indicated peanut/nuts as a minor ingredient. Quantitative risk assessment, based on the known distribution of individual threshold doses for peanut, indicates that only a very small percentage of the peanut-allergic population would be likely to experience an allergic reaction to those products while the majority of products with advisory labels appear safe for the peanut-allergic population. Food manufacturers should be encouraged to analyse products manufactured in shared facilities and even on shared equipment with peanuts for peanut residues to determine whether sufficient risk exists to warrant the use of advisory labelling. Although it appears that the majority of food products bearing advisory nut statements are in fact free of peanut contamination, advice to peanut allergy sufferers to avoid said foods should continue in Ireland and therefore in the wider European Union.

Majority of shrimp-allergic patients are allergic to mealworm.

To the Editor: The growing world population motivates the exploration of new sustainable protein sources to ensure food security. Insects such as mealworm (Tenebrio molitor) are promising candidates, with active ongoing marketing efforts within America and Europe. This warrants assessment of the potential risks. Toxicologic and microbiological risks were assessed previously, but not the potentially allergenic risks. Pilot results suggest that shrimp-allergic patients might be at risk for mealworm allergy because IgE binding to tropomyosin and arginine kinase (major shellfish allergens) and sarcoplasmic calcium-binding protein and myosin light chain (minor shell fish allergens) was detected. Our aim was to investigate the allergic potential of mealworm in the shrimp-allergic population. Fifteen from 60 adult patients from the University Medical Center Utrecht with shrimp allergy based on specialist opinion and diagnostic testing were included in this double-blind, placebocontrolled food challenge (DBPCFC) trial, after testing positive in ImmunoCAP, skin prick test, basophil activation test, or immunoblot (see this article’s Online Repository at www.jacionline.org). All subjects gave written informed consent before participation. The study was approved by the local ethics committee (NL43731.041.13). Patients’ median age was 38 years (range, 19-69 years), and 47%were men. Symptoms by history ranged from oral symptoms to anaphylactic shock. Four patients had a positive diagnostic shrimp challenge in the past (Table I). None of the patients knowingly consumed mealworm proteins. Most had inhalant allergies to house dust mite (11 of 15) and pollen (11 of 15), and 9 patients had 1 or more other food allergies. All patients avoided eating shellfish.

Food allergy population thresholds: An evaluation of the number of oral food challenges and dosing schemes on the accuracy of threshold dose distribution modeling

For most allergenic foods, limited availability of threshold dose information within the population restricts the advice on action levels of unintended allergenic foods which should trigger advisory labeling on packaged foods. The objective of this paper is to provide guidance for selecting an optimal sample size for threshold dosing studies for major allergenic foods and to identify factors influencing the accuracy of estimation. A simulation study was performed to evaluate the effects of sample size and dosing schemes on the accuracy of the threshold distribution curve. The relationships between sample size, dosing scheme and the employed statistical distribution on the one hand and accuracy of estimation on the other hand were obtained. It showed that the largest relative gains in accuracy are obtained when sample size increases from N=20 to N=60. Moreover, it showed that the EuroPrevall dosing scheme is a useful start, but that it may need revision for a specific allergen as more data become available, because a proper allocation of the dosing steps is important. The results may guide risk assessors in minimum sample sizes for new studies and in the allocation of proper dosing schemes for allergens in provocation studies.

Sesame allergy threshold dose distribution

BACKGROUND Sesame is a relevant food allergen in France. Compared to other allergens there is a lack of food challenge data and more data could help sesame allergy risk management. The aim of this study is to collect more sesame challenge data and investigate the most efficient food challenge method for future studies. METHOD Records of patients at University Hospital in Nancy (France) with objective symptoms to sesame challenges were collected and combined with previously published data. An estimation of the sesame allergy population threshold was calculated based on individual NOAELs and LOAELs. Clinical dosing schemes at Nancy were investigated to see if the optimal protocol for sesame is currently used. RESULTS Fourteen patients (10 M/4 F, 22 ± 14.85 years old) with objective symptoms were added to previously published data making a total of 35 sesame allergic patients. The most sensitive patient reacted to the first dose at challenge of 1.02 mg sesame protein. The ED05 ranges between 1.2 and 4.0 mg of sesame protein (Log-Normal, Log-Logistic, and Weibull models) and the ED10 between 4.2 and 6.2 mg. The optimal food challenge dosing scheme for sesame follows semi-log dose increases from 0.3 to 3000 mg protein. CONCLUSION This article provides a valuable update to the existing clinical literature regarding sesame NOAELs and LOAELs. Establishment of a population threshold for sesame could help in increasing the credibility of precautionary labelling and decrease the costs associated with unexpected allergic reactions. Also, the use of an optimal dosing scheme would decrease time spent on diagnostic and thereafter on the economic burden of sesame allergy diagnosis.