Friday, October 4, 2013
Seafood comprises finned fish and shellfish, and both types of aquatic creatures can be allergens. Unlike many other food allergies that affect toddlers and young children (such as wheat, milk, or nut allergies), seafood allergy is more likely to start in adulthood and therefore less likely than other allergies to be outgrown. According to Food Allergy Research and Education (FARE) about 40% of people with fish allergy and 60% with shellfish allergy experience the onset as adults.
People who are allergic to finned fish are not necessarily allergic to shellfish and vice versa since these are different species with different allergy-producing proteins.
FARE states that the most common species to cause fish allergy are salmon, tuna, and halibut; other types are cod, pollock, snapper, eel, and tilapia. It may seem easy to avoid any one of these species if you have fish allergy but unfortunately, people with allergies to one type of fish are likely to have (or to develop) allergies to others. This cross-reactivity is due to the culprit protein, parvalbumin that is present in many fish species. Therefore, people with an allergy to one fish should steer clear of all fish.
In adults, an increased risk of severe asthma is linked to fish allergy. An allergist can perform comprehensive allergy testing and advise you on whether or not you may include certain, less reactive types of fish in your diet.
Besides the obvious fish salads and cooked fish dishes (such as ceviche, cioppino, and bouillabaisse), beware of hidden fish ingredients in foods you might not be aware of such as Caesar salad dressing, caponata, and Worcestershire sauce (which contain anchovies), Omega-3 supplements (there are vegan/plant-based varieties available), and gelatin which may be made from a fish base. Many soups and stews are also prepared with fish stock (fumet) so always ask if you are dining out. Don’t forget caviar (fish eggs).
Relatively mild symptoms of fish allergy are similar to those of other food allergies—swelling, itchy mouth, rash, wheezing; more severe reactions include anaphylaxis. More on that below.
Shellfish include two types of marine animals, each with their own types of allergy-producing proteins. Crustaceans such as shrimp, crab, lobster and similar species make up one class. Mollusks are a more diverse group; there are bivalves (such as mussels, oysters, scallops, and clams) gastropods (snails, abalone, limpets, periwinkles), and cephalopods (such as cuttlefish, octopus, and squid). Someone allergic to one type of shellfish may also be allergic to the others, or could only be allergic to the one type that causes allergic reactions.
You’ll know within minutes of eating shellfish if you are allergic. Mild symptoms are hives, rash, and itching, or a tingling in the mouth; moving up a notch is swelling of oral tissues or other parts of the body. As with other food allergies, shellfish allergy also may present with more severe (and sometimes life-threatening) symptoms such as congestion or trouble breathing, abdominal pain and gastrointestinal distress, lightheadedness or fainting, and even anaphylaxis.
Anaphylaxis constricts your throat and interferes with your breathing, and causes a severe drop in blood pressure which may lead to shock or loss of consciousness. It is advisable for individuals who are prone to severe reactions to carry injectable epinephrine to administer immediately to alleviate symptoms (often before going to the ER to be checked out).
Be advised that shellfish by-products are used in cosmetics, medicines, and creams so scrutinize labels or call the manufacturer with questions about ingredients. If you suspect shellfish allergy, a skin test or blood test can confirm this.
Things to Keep in Mind When Dining Out
Unfortunately, fish proteins become airborne during the cooking process so if you suffer from severe fish or shellfish allergy, certain restaurant environments may pose a big problem. Steam tables and stove tops in commercial or home kitchens can be danger zones depending on the severity of the allergy.
Also, just as with wheat and celiac disease, it’s important to avoid cross-contamination of the allergen on cooking utensils, pots/pans, and work surfaces—even cooking oil. Fish may be friend in the same oil as chicken or even vegetables. Ask in advance about whether the kitchen can use separate cookware or prep areas to prepare your food if this is an issue.
Suffice to say, with either kind of seafood allergy, sushi restaurants are probably not the best place to be, even if you choose vegetable sushi. See if the sushi chef can make your rolls with different mats and knives.