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.
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 F
olyols. 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.
Crustacean Allergy is not currently linked with any allergic syndromes.
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
Articles and Journals
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
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