Fish and shellfish allergies are among the most common food allergies in adults globally, and both are recognised as separate major allergens under UK food law for good reason — they involve different proteins and are entirely distinct allergies. Being allergic to fish does not necessarily mean you're allergic to shellfish, and vice versa. Understanding both conditions carefully is essential for safe management.
Fish Allergy
Fish allergy is mediated primarily by a protein called parvalbumin, found in the muscle of most fish species. Parvalbumin is a stable protein — it survives cooking and is even released into steam during cooking, meaning sensitive individuals can react to fish cooking vapours. This is not a theoretical concern; there are documented cases of anaphylaxis from standing near a fish being cooked.
Cross-reactivity between fish species is common but not universal. Most people with fish allergy react to multiple species (because parvalbumin is similar across species), but some people tolerate certain fish while reacting to others. This individual variation makes blanket avoidance of all fish the safest default until individual tolerance is established through allergy testing and supervised challenge testing. Fish with lower parvalbumin content — including tuna and swordfish — are tolerated by some fish-allergic individuals, but this should never be assumed without testing.
Shellfish Allergy
Shellfish allergy involves a different protein — tropomyosin — and is a separate allergy from fish. Shellfish are divided into two groups: crustaceans (prawns, crab, lobster, shrimp, langoustine) and molluscs (oysters, mussels, clams, scallops, squid, octopus). UK food law specifically lists crustaceans and molluscs as separate allergens.
Cross-reactivity is highest within crustaceans (if you react to prawns, you're very likely to react to crab and lobster) and within molluscs. Cross-reactivity between crustaceans and molluscs is lower but exists. Shellfish allergy tends to be more severe than many food allergies — anaphylaxis risk is high, and the allergy is rarely outgrown in adults.
Hidden Sources
Fish appears in Worcestershire sauce (anchovies), some Asian sauces and pastes (fish sauce, oyster sauce), Caesar salad dressing, some pizza toppings, and processed foods where fish derivatives are used for flavour. Shellfish appears in some stocks and sauces, certain Asian cuisine components, and restaurant dishes where cross-contamination is a significant risk (shared cooking surfaces and oils in restaurants serving multiple seafood types).
Management at Vanda's Kitchen
At Vanda's Kitchen, full ingredient information is available for all products. Our approach to allergen management means that customers with fish or shellfish allergies can ask about any product with confidence and receive accurate information. As with all severe allergies, cross-contamination risk in any kitchen should be discussed specifically with staff before ordering.
Safe Food at Vanda's Kitchen
For people managing fish and shellfish allergies, Vanda's Kitchen near St Paul's Cathedral EC4 provides a genuinely safe food option in the City of London. Our kitchen is 100% nut-free — no nut products of any kind are present in our facility — and we are certified halal. Every item we produce is fully allergen-labelled with all 14 mandatory UK allergens, in compliance with Natasha's Law. Our 5-star food hygiene rating confirms independent verification of our food safety standards.
For corporate catering where allergen management is a priority, our approach eliminates the cross-contamination risks that make "allergen-friendly" claims from mixed kitchens unreliable. Read our complete guide for the full detail on our allergen management standards.
For related reading, see our posts on managing multiple food allergies and the 14 UK food allergens guide. For corporate catering enquiries, WhatsApp us or send an enquiry.
Safe, Inclusive Food From Vanda's Kitchen
For Londoners managing food allergies and intolerances, Vanda's Kitchen near St Paul's Cathedral EC4 provides a genuinely safe food environment in the heart of the City. Our kitchen is 100% nut-free — no peanuts or tree nuts enter our facility under any circumstances — and our food is certified halal by the independently verified Halal Friendly List. Every item is labelled with full allergen information covering all 14 mandatory UK allergens, in compliance with Natasha's Law.
Our 5-star food hygiene rating confirms that our food safety practices are independently assessed and verified. Our Selfridges Food Hall presence confirms that our food quality meets the standards of one of London's most demanding food retail environments. For people managing serious food allergies, this combination of safety and quality is rare in the London food market. Visit us in EC4, order corporate delivery via our team lunch page, or WhatsApp us to discuss your requirements. Read our allergy-friendly catering guide for more.
Why London Professionals Choose Vanda's Kitchen
Whether you are managing dietary requirements for a team, looking for a nutritious daily lunch, or sourcing catering for a corporate event, Vanda's Kitchen near St Paul's Cathedral EC4 provides a consistent answer. Our kitchen is 100% nut-free as a permanent standard — no exceptions, no special requests needed. We are independently certified halal through the Halal Friendly List. We hold a 5-star food hygiene rating and our products are stocked in Selfridges Food Hall.
Our food is freshly prepared daily from our EC4 kitchen, rooted in Filipino culinary tradition and designed to deliver both nutritional quality and genuine flavour. For corporate lunch delivery, team catering, and event food across London, we offer a complete solution with the allergen credentials, dietary certifications, and food quality that London's most demanding clients require. View our team lunch options, WhatsApp us, or send an enquiry — we respond the same day.