A recent retrospective analysis indicates that utilizing crushed sesame seeds or tahini in oral food challenges could provide more precise assessments of sesame sensitivity compared to employing whole seeds.
Key Findings on Challenge Forms and Reaction Severity
In pediatric patients who underwent anaphylaxis during challenges with crushed seeds, the median cumulative dose was markedly and statistically lower than in those with milder reactions (0.96 g versus 5.76 g; P=0.004). Similarly, the median threshold dose—the amount of the last ingested portion before a reaction—for crushed seeds showed a significant difference (0.68 g versus 4.00 g; P=0.005).
For challenges involving tahini, the sesame-based paste, the median threshold dose difference between anaphylaxis cases and less severe reactions approached but did not achieve statistical significance (0.474 g versus 1.896 g; P=0.063). The researchers, led by Aimee Huynh, MBBS, from Sydney Children’s Hospital, noted that referral bias might have influenced these results in the tahini group.
In contrast, oral food challenges using whole sesame seeds revealed no statistically significant differences in either cumulative or median threshold doses when comparing anaphylaxis to milder reactions. Notably, the doses associated with anaphylaxis in this group were considerably higher (3.25 g cumulative and 5.10 g threshold) than those observed with crushed seeds or tahini.
Explaining the Differences in Protein Exposure
These observations lend support to the theory that intact sesame seeds limit the exposure of sesame proteins to IgE antibodies, primarily because these proteins are encased within the seed coat. This reduced accessibility may explain the higher doses required to elicit reactions.
The study authors recommended avoiding intact sesame seeds for oral food challenges in children, as they could produce falsely elevated threshold results or even false negatives. Instead, they advocated for the use of tahini or crushed sesame seeds to ensure more reliable outcomes.
Furthermore, relying on whole sesame seed challenges might give a misleading sense of tolerance to all sesame forms. This concern is bolstered by the higher anaphylaxis rate in the tahini group, even accounting for potential referral and selection biases.
Expert Perspectives and Clinical Practices
Stephanie Leeds, MD, from Yale School of Medicine in New Haven, Connecticut, who was not part of the research team, affirmed that these results align with longstanding clinical knowledge. She explained that numerous sesame-allergic individuals fail to react to whole seeds but are sensitive to more concentrated preparations like tahini. According to Leeds, the majority of food allergy specialists routinely opt for tahini or sesame flour in diagnostic oral food challenges.
Leeds emphasized that for diagnostic purposes, employing a concentrated sesame product represents best practice. For patients already confirmed to have sesame allergy, she suggested that families might benefit from targeted challenges with sesame seeds or sesame oil to assess tolerance specifically to those forms.
Background on Sesame Allergy Prevalence
Sesame seed allergies rank among the most prevalent IgE-mediated food allergies. Similar to tree nut allergies, sesame sensitivity often persists from childhood through adulthood. Various sesame preparations are employed in oral food challenges, though prior research has indicated variability in patient tolerance across these forms.
To investigate whether the sesame form impacts challenge results, the researchers performed a retrospective review of pediatric cases from four Australian clinics. Australia currently lacks a standardized national protocol for sesame oral food challenges, which adds context to the variability observed.
Study Methodology and Data Sources
Data collection periods varied by institution: from 2007 to 2019 at Sydney Children’s Hospital, 2018 to 2021 at Royal Children’s Hospital in Melbourne and Epworth Allergy Specialists Richmond Hospital, and 2014 to 2021 at Queensland Children’s Hospital in Brisbane.
The analysis compared challenge outcomes—such as threshold doses (the final dose before reaction onset), cumulative doses, and anaphylaxis rates—across groups based on sesame form: whole seeds, crushed seeds, or tahini. Cases involving other foods in the challenge were excluded to maintain focus.
Given differences in protocols and dosing across centers, the team standardized comparisons by calculating sesame protein amounts ingested by participants in each group.
A positive challenge was defined by anaphylaxis or objective symptoms including skin manifestations, angioedema, oropharyngeal issues, gastrointestinal distress, or multi-organ involvement.
Participant Demographics and Referral Patterns
The study included 307 participants: 53 challenged with whole sesame seeds, 163 with crushed seeds, and 91 with tahini. For whole and crushed seed groups, the primary referral reason was a skin prick test wheal of 3 mm or larger combined with a history of sesame reaction (49.1% and 36.2%, respectively). In the tahini group, 38.5% were referred based on a skin prick test wheal of at least 3 mm without prior sesame ingestion history.
Reaction Rates and Symptom Profiles
Overall, 34% of participants reacted during their challenge: 57% in the whole seed group, 26% in the crushed seed group, and 35% in the tahini group. Among reactors, skin symptoms were most frequent (74%), followed by oropharyngeal symptoms (51.9%).
Anaphylaxis occurred in 9.12% of all participants, accounting for 26.9% of reactions. A greater proportion of tahini-challenged children experienced anaphylaxis compared to the other groups, though this did not reach statistical significance. Referral and selection biases may have contributed to this pattern.
Insights on Bias and Future Research Directions
Leeds commented that it would be valuable to examine reactivity differences to sesame products within the same individuals, rather than across centers. She highlighted the probable role of referral and selection biases, as noted by the authors, in shaping the findings.
These results, published in the Journal of Allergy and Clinical Immunology: Global, underscore the importance of selecting appropriate sesame forms for oral food challenges to accurately gauge sensitivity, particularly in light of sesame’s recent designation as the ninth major food allergen in the U.S.
