Key Allergens

Crustaceans are a group of invertebrates which include lobster, prawn, scampi, crab and shrimp. Note in Europe that crustaceans and molluscs are considered to be 2 separate food groups whose allergens need to be declared in packaged food. In the US these are both grouped under the term 'shellfish'.

The WHO allergen index covers 21 species of crustaceans linked to allergic reactions and 7 main groups of allergens.

15 species of invertebrates have been found to contain the allergen Tropomyosin, which is a protein found in exoskeletons.

Arginine Kinase allergens have been found in 6 species, mostly in shrimp.

Myosin allergens have been found in 6 species, mostly shrimp and crab. Myosin is a protein found in animals involved in movement and muscle contraction.

Sarcoplasmic calcium binding protein allergens have been found in 5 species of shrimp and crab. These are proteins found in the muscle of crustaceans.

These identified allergens are related to food allergy - there are an additional 146 allergens identified in this group which link to airborne and airway allergens, which means just cooking crustaceans can be a problem for sufferers of this allergy.

Food Intolerances

Food is low in FODMAP Food is low in salicylates Food is moderate in sulphites Food is high in histamine

Crustaceans are a food which can be high in histamine, so is not suitable for people following a low histamine diet. The amount of histamine starts to increase once caught, so improperly handled and refridgerated fish can cause what is called 'scromboid poisoning'. The symptoms of this are very similar to a severe allergic reaction, so are often confused.

High histamine and high sulphites often go hand in hand. Crustaceans are also considered to be moderate in sulphites. Very freshly caught and cooked food is lower in sulphites and those that are processed, smoked, canned or preserved are higher in sulphites. Sulphites are inorganic salts used in preservations and have the potential to cause symptoms of food intolerance to those sensitive to sulphites, this food intolerance is more common in asthmatics. An improvement in symptoms can be made with a change to a low sulphite diet.

FODMAP is linked to plants, so most meats and fish are low in FODMAP and suitable for people following a low FODMAP diet. FODMAP stands for Fermentable oligosaccharides, disaccharides, monosaccharides and polyols. Foods high in FODMAPs can cause symptoms of food intolerance, affecting the gastro intestinal system and this can be mistaken for a true IgE food allergy.

Like FODMAP, salicylate intolerance is linked to plants, so crustaceans are suitable for people following a low salicylate diet. Salicylates have the potential to cause gastrointestinal food intolerance symptoms in people who are sensitive to salicylates.

You can read more about Food Intolerances on the dedicated Food Intolerance Page.

Associated Syndromes

Crustacean Allergy is not currently linked with any allergic syndromes.

Cross Reactivity

Crustacean allergy is linked to shellfish allergy; oysters, abalone, squid and snail all contain the main allergen - tropomyosin.

Catfish, some types of salmon and tilapia are types of fish which have also been identified as containing the allergen tropomyosin, there may be cross reactivity between eating certain types of fish and crustaceans.

There is a link between insect allergies and crustacean allergy, this is again attributed to the common allergen - tropomyosin. This is tropomyosin as an airborne allergen in dust mites, termites, cockroaches and silverfish.



Allergen Encyclopedia - Crab

Allergen Encyclopedia - Shrimp

Science Direct - Tropomyosin

ACAAI - Shellfish Allergy

Food Allergy Canada - Crustaceans and Molluscs

Anaphylaxis Campaign - Shellfish

Healthline - FODMAP Foods

ATP Science - Salicylate Foods

Histamine Intolerance Foods

Sulfite Foods

Articles and Journals

Allergen Diversity and Abundance in Different Tissues of the Redclaw Crayfish (Cherax quadricarinatus), 2024

A detailed intake-status profiling of seafoods in adult food–protein–induced enterocolitis syndrome patients, 2023

IgE-Mediated Shellfish Allergy in Children, 2023

Accidental Reactions to Foods: Frequency, Causes, and Severity, 2022

Part II: Insect allergies—Inhalation and ingestion: A survey of the literature and our own cases, 2022

Prevalence and Characteristics of Shellfish Allergy in the Pediatric Population of the United States, 2020

Cross-allergenicity of crustacean and the edible insect Gryllus bimaculatus in patients with shrimp allergy, 2019

Crustacean Allergy in South Africa, 2017

Shellfish allergens: tropomyosin and beyond, 2016

In vivo diagnosis with purified tropomyosin in mite and shellfish allergic patients, 2016

Insects and Their Connection to Food Allergy, 2016

Shrimp allergy beyond Tropomyosin in Italy: clinical relevance of Arginine Kinase, Sarcoplasmic calcium binding protein and Hemocyanin, 2014

Snow crab allergy and asthma among Greenlandic workers – a pilot study, 2012

Selective Allergy to Lobster in a Case of Primary Sensitization to House Dust Mites, 2009

Tropomyosin: An Invertebrate Pan–Allergen, 1999

Let me know if you found any of these interesting or useful. If you spot an article or research that you think is interesting you can message me or tag me on Facebook or Twitter - links at the bottom of the page.

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