Potential allergenicity of the novel food seaweed

Background: With a high protein yield, seaweed could be a novel and sustainable protein- rich food to support the increasing population and to meet the consumers’ demand for healthy, safe and environmental friendly foods. However, allergy to novel protein sources may occur and can be fatal when eaten. The aim of this project was to evaluate the potential allergenicity of seaweed and the effect of processing in an animal model of food allergy. Method: One brown and two red edible seaweed species were collected in Denmark and either fermented or left unmodified. The immunogenicity, sensitising and eliciting capacities were investigated in Brown Norway rats immunised i.p. with either PBS as control or the different seaweed extracts. Seaweed- specific IgG1 and IgE responses were analysed by means of different ELISAs and the clinical reactivity assessed by an ear swelling test. The protein profile and immunoreactivity were determined by SDS- PAGE and immunoblotting, respectively. Results: The protein profile differed between the different species and between the unmodified and fermented seaweeds. All three seaweed species were shown inhere immunogenicity and allergenicity, being able to raise specific IgG1 and IgE as well as elicit allergic reaction, however the magnitude of responses developed against the seaweed differed significantly. Fermentation was shown to reduce immunogenicity and allergenicity of the brown seaweed, in contrast to the red seaweed where no significant differences could be observed. Cross- reactivity was observed between unmodified and their fermented derivatives, as well as between red and brown species. Cross- reactivity between species was confirmed by immunoblotting. Conclusion: These results demonstrate the immunogenicity and allergenicity of seaweed, as well as cross- reactivity between not only phylogenetic closely related species but also between species with distant phylogenetic relationship. Further, fermentation may reduce immunogenicity and allergenicity, although the degree is dependent on the specific species.