Seafood (Including Fish, Molluscs & Crustaceans)

This spotlight article concentrates on allergies to Seafood, covering Fish, Molluscs and Crustaceans which make up 3 of the EU’s 14 major food allergens.

Seafood allergies are one of the most common food allergies in the UK, and with global consumption of seafood increasing its essential to know what to look out for along with the symptoms and reactions it can cause.

There are many factors which have contributed to the increase in seafood consumption, some of these include:

• Fish and shellfish are coming into the UK from countries which have a big supply, and these foods are available plentifully.
• Supermarkets and food outlets having access to supplies of seafood.
• The nutritional value of these foods and the health benefit coming from the protein, vitamins and minerals they contain.
• Holiday destinations such as the Meditteranean being popular where seafood is a standard part of the diet.

Allergies and intolerances to seafood can develop at any time in someone’s life, and the food in question might have been consumed before with no signs of allergic reaction or intolerance. Once this allergy surfaces, it is likely to be for the person’s whole life, its rare for someone to outgrow a seafood allergy.

What to look for

Seafood is the collective term for the 3 allergen groups covered in this article. Fish have their own allergy group, and shellfish are divided into the two separate groups of Molluscs and Crustaceans.

Fish: Most fish are covered in scales and have fins, they also fall into the classification of ‘Vertebrates’ meaning they have a backbone.

This includes but is not limited to the following: Anchovy, Mackerel, Sea bream, Basa, Monkfish, Snapper, Cod, Perch, Swordfish, Cuttlefish, Pike, Trout, Eel, Seabass, Pilchards, Tuna, Grouper, Plaice, Turbot, Flounder, Pollock, Whitebait, Haddock, Salmon, Whiting, Hake, Sardine, Halibut.

Crustaceans: These are Invertebrates (they have no backbone), jointed legs and a segmented body. 

Examples of the above include but are not limited to: Crab, Lobster, Shrimp, Crayfish, Prawn, Scampi.

Molluscs: Also invertebrates, they are also soft-bodied inside and some have a shell.  Those that have a shell that opens and closes are referred to as ‘bivalve molluscs’, these include mussels or scallops.

Examples of molluscs include but is not limited to the following: Abalone, Octopus, Snail, Clam, Oyster, Squid (or calamari), Cockle, Periwinkle, Whelk, Mussel, Scallop.

Symptoms & Reactions

Allergic reactions to seafood can be mild, moderate or severe, ranging from swollen lips, vomiting, dizziness and collapsing. The most severe form of an allergic reaction is anaphylaxis which can be caused by an allergy to seafood, this is caused by the human body reacting to the proteins within the seafood. The body sees this as harmful and mounts a response against the proteins. The following are possible reactions which can happen, the individual with the allergy can experience one or more of the following:

Mild to moderate symptoms:

• Hives (rash)
• Tingling Mouth
• Swelling of the lips, face, tongue or throat
• Itching
• Nausea
• Vomiting
• Abdominal pain
• Diarrhoea

Severe symptoms:

• Difficult or noisy breathing
• Wheezing
• A persistent cough
• Chest tightness
• Hoarse voice
• Difficulty swallowing

Cross-contact can occur when one food type comes into contact with another food and their proteins (the substance which is an allergenic) mix together. For people with a very high sensitivity to the seafood, symptoms can surface from eating, inhaling or even handling seafood in any environment.

Fish and prawn specifically, can be very robust when exposed to heat or cooking and can even become airborne in steam or cooking vapour and also present in oil used to cook seafood in a wok, pan or fish fryer.

Cross-contact can be direct, where an allergen was included in a food and then removed, or indirect, which is where the allergen is not directly applied and the same tool or utensil is used for food with and without the allergenic proteins.

Alternatives, Replacements & Subsitutues

Replacements are usually something that isn’t saught for someone with a seafood allergy, and a solution is to avoid eating fish and shellfish altogether. However, for some sufferers, it’s essential they ensure they don’t accidentally come into contact with seafood, as well as still maintaining the intake of protein and omega-3 fatty acids which can be gained from consuming fish and shellfish. Below are some examples of how to do this.

Fish and shellfish are an excellent source of protein which is a vital nutrient for the human body; however, protein can be consumed through meat, poultry and grains. These all provide reasonable alternatives to crustaceans providing the individuals don’t have an allergy to any of those foods.

Omega-3 fatty acids found in fish and shellfish, are also found in a number of other foods such as; Walnuts, flaxseed oil, canola oil, Brussel sprouts, spinach and kale. These are all high in omega-3 fatty acids and are suitable replacements.

A tried and tested safe option when looking for suitable foods for shellfish allergy sufferers is to look for Kosher foods as individuals adopting a Kosher diet only eat fish with scales, avoiding all shellfish. Eating Kosher foods is an excellent alternative to shellfish, providing safe alternatives, and low risk of cross-contamination.