What foods have tropomyosin?

November 18, 2025 •

4 min read

Invertebrate tropomyosins are a major cause of severe food allergies worldwide, especially concerning seafood. For individuals with a shellfish allergy, knowing what foods have tropomyosin is critical for preventing life-threatening reactions and managing symptoms effectively.

Quick Summary

Tropomyosin is the key allergen in shellfish, including crustaceans and mollusks, and is also found in mites and insects. This heat-stable protein can trigger severe cross-reactive allergic reactions and is not destroyed by standard cooking methods.

Key Points

Primary Sources: Tropomyosin is predominantly found in shellfish, specifically crustaceans like shrimp, crab, and lobster, and mollusks such as oysters, squid, and snails.
Heat-Stable Allergen: Unlike some other allergens, tropomyosin is highly resistant to heat and is not destroyed by cooking, frying, or boiling.
Cross-Reactivity with Inhalant Allergens: The protein shares high similarity with tropomyosin found in dust mites and cockroaches, meaning a pre-existing dust mite allergy can cause a subsequent reaction to shellfish.
Cross-Reactivity among Invertebrates: There is a high degree of cross-reactivity within crustacean species, and also to a lesser extent between crustaceans and mollusks.
Vertebrate vs. Invertebrate: While allergenic in invertebrates, tropomyosin in vertebrate animals like fish, poultry, and beef is generally not known to be a significant allergen.
Strict Avoidance is Key: Due to its stability and potency, allergic individuals must practice strict avoidance of foods containing tropomyosin to prevent potential systemic reactions, including anaphylaxis.

Tropomyosin is a protein integral to the muscle structure of many invertebrates, such as shellfish, insects, and arachnids. In vertebrates, including mammals and fish, a version of tropomyosin also exists, but is not typically allergenic. For many individuals, especially those with existing allergies, tropomyosin serves as a potent food allergen that can trigger allergic reactions ranging from mild to severe, including anaphylaxis. The presence of this heat-stable protein in various foods and non-food sources means that a simple cooking process will not eliminate the allergenicity. Understanding the primary dietary and environmental sources of tropomyosin is therefore essential for managing allergies and preventing adverse reactions.

Crustaceans: A Primary Source of Tropomyosin

Crustaceans are a major dietary source of tropomyosin and are one of the most common causes of food allergies worldwide. Their tropomyosin has a highly conserved amino acid sequence, leading to strong cross-reactivity among different crustacean species.

Shrimp (Penaeus species): Tropomyosin is the major allergen in shrimp and is often used as a benchmark for measuring shellfish allergy. Allergic reactions are frequently triggered by this abundant muscle protein.
Crab (Charybdis and Scylla species): This is another significant source of allergenic tropomyosin. Allergic individuals often show cross-reactivity to crab if they are allergic to shrimp.
Lobster (Homarus americanus): Like other crustaceans, lobster contains allergenic tropomyosin, Hom a 1. Allergic reactions are a common occurrence for sensitized individuals.
Crayfish (Procambarus clarkii): Found in both freshwater and marine varieties, crayfish also contain allergenic tropomyosin and contribute to cross-reactivity within the crustacean family.

Mollusks: A Significant Source of the Allergen

Mollusks are another major category of food that contains allergenic tropomyosin. However, while the allergenicity is well-established, the amino acid sequence of mollusk tropomyosin is less similar to that of crustaceans (around 60% identity), leading to potentially different cross-reactivity patterns.

Oysters (Crassostrea gigas): Oysters contain allergenic tropomyosin (Cra g 1) and can trigger allergic reactions in sensitized individuals.
Squid (Todarodes pacificus): Calamari is a common food source of tropomyosin (Tod p 1) and is linked to allergic reactions.
Clams (Ensis macha): Clams and other bivalves are known to contain allergenic tropomyosin that can cause allergic symptoms.
Snails (Helix aspersa): Consumed in many cuisines, snails contain tropomyosin (Hel as 1) and can cause severe allergic reactions, particularly in those with a dust mite allergy.

Cross-Reactive Invertebrate Sources

Sensitization to tropomyosin is not limited to food. Many people are first sensitized to tropomyosin through airborne particles from sources like house dust mites or cockroaches, which have similar protein structures to shellfish tropomyosin.

House Dust Mites (Dermatophagoides pteronyssinus): The tropomyosin in dust mites (Der p 10) shares a high degree of sequence homology with shellfish tropomyosin. This means that individuals with a severe dust mite allergy may experience a cross-reactive allergic reaction when consuming shellfish for the first time.
Cockroaches (Blattella germanica, Periplaneta americana): Cockroaches are another inhalant source of allergenic tropomyosin. Sensitivity to cockroach tropomyosin can also cause cross-reactivity with crustacean and mollusk allergies.
Edible Insects (Mealworms, Crickets): With the growing interest in edible insects as a sustainable food source, it is important to note that many insects also contain allergenic tropomyosin. This poses a potential cross-reactivity risk for people with existing shellfish or dust mite allergies.

Comparison: Invertebrate vs. Vertebrate Tropomyosin

The allergenic nature of tropomyosin differs significantly between invertebrates and vertebrates. Here is a brief comparison:


Feature	Invertebrate Tropomyosin (Shellfish, Mites)	Vertebrate Tropomyosin (Fish, Meat)
Allergenicity	High; a major food and inhalant allergen	Very low to non-allergenic; generally considered safe
Protein Structure	Similar across many invertebrate species, causing cross-reactivity	Different enough from invertebrate versions to not trigger a reaction in most cases
Heat Stability	Highly stable; retains allergenicity even after cooking	Less relevant due to low allergenicity, but structurally different from invertebrate forms

The Heat-Stable Nature of Tropomyosin

One of the most critical aspects of tropomyosin for allergy sufferers is its thermal stability. Unlike some other food allergens that can be denatured (and have their allergenicity reduced) through cooking, tropomyosin is highly resistant to heat. This means that boiled shrimp, baked crab, or fried calamari can still trigger a severe allergic reaction in a sensitized individual. Some studies even suggest that cooking can, in some cases, increase IgE-binding capacity through complex reactions, though the clinical relevance is still under investigation. This inherent stability requires strict avoidance of the allergen for allergic individuals, regardless of the preparation method.

Conclusion

For individuals with an allergy to shellfish, understanding which foods have tropomyosin is paramount. The list includes a wide range of popular crustaceans like shrimp, crab, and lobster, as well as mollusks like oysters, clams, and squid. Compounding the dietary risk is the significant cross-reactivity with environmental allergens such as dust mites and cockroaches, which can lead to primary sensitization via inhalation. Due to its high heat stability, cooking methods do not make tropomyosin-containing foods safe for allergic individuals. Therefore, meticulous label-reading and ingredient avoidance are the only sure-fire ways to prevent an allergic reaction. Consulting with an allergist for definitive diagnosis and management is the best course of action for anyone suspecting a shellfish or tropomyosin allergy.

Understanding the Origin of Tropomyosin Allergies

Allergenicity can stem from both ingestion and inhalation. The so-called "mite-crustacean-mollusk syndrome" is a well-documented phenomenon where sensitization to inhaled dust mite tropomyosin causes subsequent reactivity to ingested shellfish. This highlights that an individual may have never consumed shellfish but could still react severely due to an existing, unrelated allergy. In addition, new potential food sources like edible insects also carry a risk due to shared tropomyosin structure. Ongoing research continues to shed light on the complex nature of cross-reactivity and its diagnostic challenges.

For more in-depth research on allergenic tropomyosins and their cross-reactivities, consult this authoritative review: Allergenic tropomyosins and their cross-reactivities.

Frequently Asked Questions

Tropomyosin is a protein found in the muscle tissue of many animals, especially invertebrates like shellfish. It is a major allergen because a susceptible person's immune system mistakenly identifies the protein as harmful, triggering an allergic reaction.

No, cooking does not reliably destroy tropomyosin. It is a heat-stable protein that retains its allergenic properties even after being subjected to high temperatures like boiling, frying, or baking.

Yes, it is possible due to cross-reactivity with inhaled allergens like house dust mites. A person can become sensitized to tropomyosin by inhaling dust mite particles and then have an allergic reaction when consuming shellfish for the first time.

There is a high degree of cross-reactivity among crustaceans (like shrimp, crab, and lobster), so an allergy to one often means an allergy to all. Cross-reactivity with mollusks (like squid and oysters) is also possible but less pronounced.

No, not all seafood allergies are caused by tropomyosin. While tropomyosin is the most common allergen in shellfish, other proteins like arginine kinase can also cause allergic reactions. Fish allergies are also separate and typically caused by a different protein called parvalbumin.

Yes, it is common for individuals allergic to dust mites to also react to shellfish, due to the high similarity between the tropomyosin proteins found in both. This phenomenon is a well-documented example of cross-reactivity.

Currently, the primary management strategy is strict avoidance of the allergen. Research into allergen-specific immunotherapy for shellfish allergy is ongoing, but not yet widely available for routine clinical use.