Do allergy sufferers really have to do without fish?

Fish allergies do not always require complete fish abstinence

Many people suffer from a food allergy, with fish allergy being one of the lesser known forms, although it is quite common. Those affected react with symptoms such as indigestion, nettle fever or even an anaphylactic shock on fish consumption. So far, a lifelong fish waiver was the only option. But an international research team has now been able to prove "that fish allergy sufferers do not necessarily have to forego this healthy diet," according to the latest release from the Luxembourg Institute of Health (LIH).

In the case of a fish allergy, fish consumption was generally taboo for those affected so far. The advice to people with an allergy to fish was to completely avoid this food, reports the LIH. But the international research team was able to Annette Kühn and Professor Markus Ollert from the LIH Martin Sørensen from the University of Northern Norway in Tromsø now show that it is not always necessary to abstain from fish allergies. The researchers published their study results in the journal "Journal of Allergy and Clinical Immunology".

For many people, fish is a pleasure, but fish allergic people are advised so far to give up completely. However, they can often eat different types of fish and only allergic to certain types. (Image: Jacek Chabraszewski / fotolia.dom)

Fish allergies are relatively common

The fish abstinence from a fish allergy implemented so far is quite critical, as fish is usually a very healthy food. It is an important supplier of easily digestible proteins and provides the body with iodine and essential omega-3 fatty acids. However, fish is also a food that "very often causes a lifelong food allergy with significant symptoms," reports the LIH. An estimated 0.1% of the world's population is affected by this. However, in Luxembourg, where much fish is consumed and processed due to the high proportion of Mediterranean populations, these allergies are more common.

Different proteins triggers the allergic reaction

All fish allergic people have in common that their immune system reacts to certain proteins of the fish with the formation of antibodies. Often, this allergic reaction is caused by parvalbumin, "a protein that occurs particularly in the muscle cells of white meat of various fish species," explain the researchers. But be dr. Kühn and her colleagues have recently found evidence "that the fish proteins enolase and aldolase can trigger an overreaction," according to the LIH. Accordingly, not all fish allergic people are allergic to the same fish species.

Fish allergies do not respond to all fish species

The study author Dr. Annette Kühn reports: "In our study, we were able to show that about one in three affected people did not react allergically to individual fish species." In addition, they succeeded in "identifying certain markers by means of which individuals with an allergy to one or more fish species can be distinguished "This has great benefits for those affected, since some people with allergies can tolerate certain types of fish and thus - despite their hypersensitivity - would not have to do without this valuable source of protein.

In search of biomarkers

So far, it has been possible to find out "whether there is an allergy to many different types of fish, a so-called cross-allergy, only on the basis of very complex tests in which fish are given orally to fish", reports Dr. med. Kühn. Together with colleagues from Norway and Sweden, the researchers therefore tried to identify certain markers in the blood of patients, with which the respective form of the fish allergy can be determined. They fed cod, salmon and mackerel on 35 patients with proven fish allergy and then determined the antibodies in their blood.

Different antibodies detectable
In the course of their investigations, the researchers found that "allergy sufferers produce different antibodies, depending on whether they are hypersensitive only to parvalbumin or to the fish proteins enolase and aldolase," reports the LIH. For the first time, the researchers were able to prove that persons with a cross-allergy to several fish species can be differentiated by specific markers (antibodies). "This is important to avoid unnecessary nutritional restrictions, especially in allergic children who very often have multiple food allergies," says Martin. Sørensen.

New possibilities of allergy diagnostics
The results of clinic-related allergy research open up "completely new possibilities for molecular and therefore personalized allergy diagnostics", explains Dr. med. Kühn. Thanks to the specific antibodies, it will hopefully be possible in the future to "identify certain forms of fish allergy early and give the affected people sensible nutrition tips for risk prevention." At the same time, the new knowledge may help in the future to endanger people at risk from certain fish proteins to preserve and thus prevent the development of allergy. (Fp)