Fish allergies have become an increasing global health concern, affecting up to 6% of children. This study focused on the safety of canned fish products for those with fish allergies, examining major allergenic fish proteins (allergens), including parvalbumin (PV), tropomyosin (TM), and collagen, found in various canned fish varieties such as salmon, tuna, and sardine.

Dr Thimo Ruethers, Research Fellow at the Tropical Futures Institute (TFI) at James Cook University (JCU) in Singapore, and Adjunct Lecturer to JCU’s Australian Institute of Tropical Health and Medicine (AITHM), emphasised the significance of their research: "Our study reveals the complexity of the impact food processing, species and product choice have on the safety of canned fish. It's not straightforward, and the findings have important implications for individuals with fish allergies."

The study involved 53 fish-allergic children and evaluated 17 canned fish products produced by 9 different manufacturers. Results revealed that 66% of suffering patients exhibited antibodies called immunoglobulin E (IgE), specific to canned fish products. These antibodies recognise fish proteins, triggering allergic reactions upon consumption ranging from mild skin rash to life-threatening anaphylaxis. Furthermore, the study illustrated patients display product-specific varying levels of sensitivity to this interaction.

One of the key findings of the study was that canned fish displayed significantly reduced PV content compared to conventionally cooked fish, implying lower allergenicity. However, despite this reduction, the study revealed that PV and other heat-stable fish allergens like TM and collagen maintained their IgE-binding capacity in canned fish, suggesting that these allergens could still pose a risk to fish-allergic individuals.  Importantly, TM seems to accumulate during processing.

The study also uncovered variations in allergenicity among different canned fish species. Notably, canned sardines exhibited stronger IgE binding for a significant portion of patients compared to canned salmon and tuna. Contrary to common belief, PV in canned fish was found to withstand the high processing temperatures involved in canning, challenging the assumption that these harsh conditions destroy allergenic proteins.

The research team's conservation analysis indicated that cross-reactivity to TMs of different fish species is more likely to occur than with PVs. Therefore, patients who exhibited strong IgE binding to TM might be advised to avoid canned fish entirely.

"The variations in allergenicity among different canned fish species reveal the need for a better approach to managing fish allergies," added Professor Andreas Lopata, TFI and AITHM group leader.

In light of these findings, the researchers recommend an individualised approach to canned fish consumption for those with fish allergies. Before incorporating canned fish into their diet, individuals should undergo thorough evaluation, which may involve yet-to-be-improved allergy tests for heat-stable fish allergens and supervised oral food challenges.

The study underscores the need for further research and the development of diagnostic tools capable of identifying fish-allergic patients who can safely tolerate canned fish products. It also emphasises the importance of considering individual sensitivities and conducting oral food challenges when assessing the suitability of canned fish for individuals with fish allergies.

This research will be presented at the Asia Pacific Association of Allergy, Asthma and Clinical Immunology (APAAACI) 2023 International Conference in Singapore (23-26 October 2023).

PAPER

Taki AC, Ruethers T, Nugraha R, Karnaneedi S, Mehr SS, Campbell DE, Lopata AL. Thermostable allergens in canned fish: Evaluating risks for fish allergy. Allergy. 2023; 00: 1-14. doi: 10.1111/all.15864

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Learn more about allergy diagnosis, fish product labelling and management challenges,  allergens in fish, crocodile meat allergy, safe alternatives to fish, and evaluating food safety in sustainable alternative food sources.

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Contacts

Dr Thimo Ruethers [email protected]

Professor Andreas Lopata [email protected]

Media: Ms Pinky Sibal [email protected]