The Luxembourg Institute of Health (LIH) has suggested that having a fish allergy does not necessarily mean having to avoid eating fish altogether.

Up until now, the general recommendation for those with a fish allergy has been to completely abstain from eating fish. However, an international research team, including Dr Annette Kühn and Professor Markus Ollert from the Luxembourg Institute of Health (LIH) and Dr Martin Sørensen from the University Hospital of North Norway in Tromsø, has proven that someone who is allergic to fish does not necessarily have to completely avoid eating it.

Dr Kühn from LIH’s Department of Infection and Immunity commented on the team’s findings that: “We showed in our study that about one third of the fish allergic patients tolerated specific types of fish. We were also able to identify certain markers, by which it is possible to distinguish between those allergic to only one type of fish and those allergic to several fish species.”

The international team of scientists published its results in the October issue of the scientific journal for allergic diseases, the “Journal of Allergy and Clinical Immunology”.

The LIH highlighted that whilst fish is an important source of digestible protein and provides the body with iodine and essential omega-3 fatty acids, it is one of the foods to which many people develop a life-long food allergy with severe symptoms. Worldwide, an estimated 0.1 % of the population suffers from an allergy to fish. The fish allergy rate is even higher in Luxembourg.

Some allergic patients suffering from fish allergy can tolerate certain varieties of fish and so, despite their hypersensitivity, could still enjoy this valuable source of dietary protein. The scientists together with colleagues from Norway and Sweden have now identified certain markers in the blood of patients, which will simplify the laboratory diagnosis of fish allergies. The team gave cod, salmon and mackerel to 35 patients with a proven fish allergy and then measured certain antibodies in their blood. The immune system of allergic patients produces antibodies as an overreaction to certain proteins in the foods to which they are allergic. In most cases, individual with a fish allergy react to parvalbumin, a protein produced essentially in the muscle cells of various species of white fish. Recently, however, Dr Kühn and her colleagues showed that the fish proteins enolase and aldolase can also trigger a hypersensitive reaction.

In their most recent study, the scientists determined that fish allergic patients produce different antibodies depending on whether their hypersensitivity is to parvalbumin alone, or also to enolase and aldolase. Dr Kühn and colleagues have thus proven for the first time that it is possible to stratify patients with a cross-allergy to several types of fish by specific markers (antibodies). This knowledge could potentially help allergy researchers in the future to prevent individuals at risk from developing a sensitivity to certain fish allergens, and thus prevent full allergic disease.