The Fish Allergy Diet Guide

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Avoid finned fish with a fish allergy.. John Kuczala/Getty Images

Fish allergy tends to be a lifelong allergy, with about 40% of people with fish allergy experiencing their first reaction as an adult. The most common kinds of finned fish causing an allergic reaction are salmon, tuna and halibut, although other fish such as Pollock, cod, snapper and eel are also common. Over half of individuals who are allergic to one finned fish will be allergic to another, so those with fish allergy are usually advised to avoid all fish.

You can test for a specific fish allergy, however.

Fish allergies are similar to shellfish allergies in that they are more likely than many food allergies to start during adulthood and less likely than other allergies to be outgrown. While fish is easier than many other allergens to avoid, a fish allergy is often quite severe.

Fish Allergy Symptoms:

Fish allergy is linked to an increased risk of severe asthma in adult patients. Fish has also been linked with oral allergy syndrome (in which the mouth itches or tingles after eating an allergen, usually fruit or vegetables) in people with occupational contact with fish. The greatest risk from fish allergies is anaphylaxis, a severe systemic reaction in which the body releases large amounts of histamine, causing tissues throughout the body to swell. This can cause life-threatening breathing, cardiac, and gastrointestinal symptoms. Anyone with a fish allergy should carry medication prescribed by their doctor at all times.

Cross-Reactivity:

There is high allergic cross-reactivity among different types of fish, meaning that people with allergies to one type of fish are likely to have (or to develop) allergies to other types of finned fish. This is due to a protein called parvalbumin which is present in many fish. For this reason, most people with an allergy to one fish are advised to avoid all fish (including eel and shark).

Some fish, especially tuna and mackerel, are considered less allergenic than others. If you would like to include some fish in your diet, ask your allergist about arranging additional allergen testing to assess what fish might be safe for you.

Diagnosis:

Fish allergy is usually diagnosed by a medical doctor (allergist) after a medical history, physical examination, and food allergy testing are performed.

One allergy that may masquerade as a fish allergy is an allergy to a fish parasite called Anisakis simplex. This parasite is considered a major allergen and, like fish allergies, can cause severe allergic reactions including anaphylactic shock. If you have a severe allergic reaction after eating fish but testing is negative or inconclusive, consider asking your allergist to test you for an allergy to this parasite. Anisakis larvae can be killed by freezing or cooking, but they can still trigger allergies after being killed, so people with Anisakis allergies should avoid fish and shellfish altogether.

Treatment:

The treatment for fish allergy is the elimination of fish from the diet.

How to Avoid Fish:

As one of the most common allergens in the United States, fish is covered under the Food Allergy Labeling and Consumer Protection Act (FALCPA). This requires that manufacturers label the presence of fish in clear language on food labels, either in the list of ingredients or following the word "contains" after the ingredient list. Fish is not a particularly common hidden ingredient and generally appears as its own species in ingredient lists. People with fish allergies should know how to read an ingredients label and learn the names of many different types of fish for maximum safety.

Foods to Avoid with a Fish Allergy:

There are many species of finned fish, so a complete list of fish to avoid is not possible for this article. However, some of the most common types of fish include:

  • Anchovies
  • Bass
  • Catfish
  • Cod
  • Flounder
  • Grouper
  • Haddock
  • Hake
  • Halibut
  • Herring
  • Mahi Mahi 
  • Perch
  • Pike
  • Pollock
  • Salmon
  • Scrod
  • Swordfish
  • Sole
  • Snapper
  • Tilapia
  • Trout
  • Tuna

Foods that Commonly Containing Fish:

  • Caesar salad dressing
  • Worcestershire sauce
  • Ceviche (fish or shellfish "cooked" in an acidic citrus marinade)
  • Caviar
  • Gelatin (when made from the skin and bone of fish)
  • Cioppino (a fish stew)
  • Nam pla (Thai fish sauce)
  • Bouillabaisse (a fish stew)
  • Fumet (fish stock)
  • Surimi (an imitation or artificial fish or shellfish)
  • Pissaladière (an open tart that looks like pizza; made with anchovies)
  • Omega-3 supplements (if you would like to take these, look for vegan varieties made from flaxseed or other plant-derived oils)
  • Caponata (eggplant relish)

Eating Out with Fish Allergies:

There are recorded instances of inhalation reactions due to aerosolized fish proteins (fish proteins being released into the air upon steam cooking), so people with fish allergies should avoid hibachi-style communal grill restaurants if fish is on the menu.

Seafood restaurants, sushi bars, and ethnic restaurants such as Thai establishments are high risks for cross-contamination due to the close proximity of fish and non-fish items. Another source of potential cross-contamination is frying oil; if fish has been fried in oil, people with fish allergies should avoid eating any other food fried in the same oil.

Living with Fish Allergies:

Fish is an easier allergen to avoid than many of the other "big eight" allergens. It is less pervasive in the Western diet than wheat, soy, or dairy, which are much harder to avoid.

That's not to say that living with a fish allergy is easy. The major challenges are avoiding high-risk situations for contact with fish and managing the risk of severe asthma (where applicable) and anaphylaxis. Reading labels for fish is reasonably simple in grocery stores. Communication in restaurants, however, is vital; higher-end restaurants, especially, may use small amounts of fish to flavor dishes that may not indicate the presence of fish on the menu. 

Managing asthma and anaphylaxis risk both depend on communication with your doctor and keeping any prescribed medication close at hand - a rescue inhaler, in the case of asthma, and injectable epinephrine in the case of anaphylaxis.

Fish In Wine or Beer

Isinglass, a type of gelatin made from the air bladders of certain fish, is mostly collagen and may be commercially used to clarify beer or wine. Those with fish allergy and risk for anaphylaxis should avoid wine and beers clarified with isinglass.

Sources:

Joneja JV. The Health Professionals Guide to Food Allergies and Intolerances.

Sicherer S. Food Allergies: A Complete Guide for Eating When Your Life Depends on It

Moneo, Ignacio, et al. "Sensitization to the Fish Parasite Anisakis simplex: Clinical and Laboratory Aspects." Parasitology Research June 17, 2007 (Epub).

Van Do, T., et al. "Allergy to Fish Parvalbumins: Studies on the Cross-Reactivity from 9 Commonly Consumed Fish." Journal of Allergy and Clinical Immunology Dec. 2005 116(6): 1314-20.

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