No Link Found Between Allergic Reaction Severity and Allergen Amount

There is no association between severity of an allergic reaction to food and the quantity of an allergen, according to recent findings, suggesting that the eliciting dose may be considered an unpredictable marker for allergy severity.1

A new multi-centric study led to these findings, having been led in part by Alexandre Piletta-Zanin from the University Hospitals of Geneva’s Pediatric Allergy Unit in Switzerland. The investigators highlighted the need among those with food allergies for personalized information on their risk of reaction in real-life scenarios.

This desire for real-world scenario information for individuals with food allergies was noted by Piletta-Zanin et al. in particular with processed foods and in restaurants given variations observed in standardized food challenges in clinical settings.2

“This multicentric study aimed to investigate the relationship between the nature and amount of the allergen, the food consumed and the severity of the symptoms, in patients with accidental reactions recruited at emergency departments, school or daycare health service or at allergy clinics following a suspected food-induced allergic reaction,” Piletta-Zanin and colleagues wrote.1

Background and Trial Design

The investigative team comprehensively recruited their study subjects, assessing those of all ages who experienced an allergic reaction to food within Geneva, Switzerland, though their recruitment process was described as not strictly systematic. The team included participants if they had reaction experiences deemed to be consistent with an immediate food allergy.

Reactions decided to be consistent were characterized by related symptoms taking place within a 2-hour timeframe after consuming a suspected allergenic food product. Those with symptoms indicative of food intolerance, those who were shown to have delayed-onset reactions, or those with reactions taking place outside the recruitment period were not included.

The investigators’ recruitment period took place from December 2020 - December 2021, with subjects being identified through different sources such as pediatric emergency facilities, emergency departments at Geneva University Hospitals, and others. The research team gathered detailed medical histories from those with reactions suggestive of immediate food allergy, in addition to samples of the suspected allergenic foods.

The team conducted both retrospective and prospective allergy diagnostic assessments on participants. The collected food samples from subjects were also analyzed with the aim of assessing allergen content.

Major Findings

Over the course of their study period, the researchers contacted 263 individuals, with 147 being enrolled in the study once they met the aforementioned inclusion criteria. Among these, there were 115 food samples that had caused reactions which were collected by the team.

The investigators reported that none of the trial participants experienced more than a single reaction over the course of their research. Responses to the research team’s questionnaires suggested that tree nuts were the most frequently-reported food allergen, linked to 43 reactions, followed by cow milk (20 reactions), shellfish or fish (13), peanuts (8), and then eggs (6).

The team found that the most commonly-suspected food product had been chocolate, accounting for 16 reactions or over 10%. They added that nuts and milk were the presumed allergens in these particular cases.

Additionally, the investigative team determined that children had constituted a substantial portion of the individuals who had been impacted, adding that most reactions were triggered by prepackaged foods.

The investigators also reported that 7 occurrences involved products that had precautionary allergen labeling or no labeling for the allergen specifically in question. Reaction severity was also shown to have varied, notably highlighting that the quantity of allergens ingested did not reliably predict the allergic reactions' level of severity.

The researchers also found no statistical difference was identified in allergen quantity between reactions which were severe and those which were milder.

“In conclusion, we found that the severity of the reaction did not correlate with the consumed amount of the allergen,” they wrote. “Highly allergic patients may react severely to very small amounts and patients with less severe allergies may react mildly to larger amounts of allergen. It is therefore very important for a given individual to know their range of reactivity.”1

References

1. Piletta-Zanin, A., Scherl, A., Benhamou, A., Braendle, G., Caubet, J.-C., Graham, F., Grosgurin, O., Harr, T., Manzano, S., Nigolian, H., Ortelli, D., Pahud, J.-P., la Tour, A.T., Spechbach, H., Edder, P. and Eigenmann, P.A. (2024), The Severity of Allergic Reactions in a Real-World Environment Is Independent of the Eliciting Amounts of Foods. Allergy. https://doi.org/10.1111/all.16413.
2. N. Patel, D. C. Adelman, K. Anagnostou, et al., “Using Data From Food Challenges to Inform Management of Consumers With Food Allergy: A Systematic Review With Individual Participant Data Meta-Analysis,” Journal of Allergy and Clinical Immunology 147, no. 6 (2021): 2249–2262.