Tropomyosin, the allergenic protein in shrimp, is also found in dust mites, cockroaches and other insects. The goal of the study was to determine whether there was a strong correlation between shrimp, cockroach and dust mite IgE levels.

Researchers at New York’s Mount Sinai School of Medicine examined blood samples of asthmatic children from seven inner-city areas across the United States. The children who had a high exposure to cockroaches at home had significantly higher levels of shrimp IgE than children who had low exposure to cockroaches.

There was not a high correlation between dust mite exposure and shrimp IgE levels.

Allergen

Where It Hides

Alternate Names

• ethnic foods: fried rice, paella, spring rolls, sushi (California rolls)
• caponata (Sicilian relish)
• gelatin, marshmallows
• pizza toppings
• salad dressings
• sauces, for example, marinara, Nuoc Mâm, steak and Worcestershire
• spreads, for example, taramasalata (fish)
• deli meats, hot dogs (from gelatin)
• compost or fertilizers
• lip balm/gloss
• pet food
• deep fryers (used to cook fish, shrimp as well as other foods)

• kamaboko

Sources:
-ImmunoCAP
-Canadian Food Inspection Agency

It’s crucial that people with a severe allergy to seafood carry epinephrine (brands include EpiPen, Auvi-Q, Allerject) with them at all times, as well as other medications, such as antihistamines and inhalers, that may be recommended by their allergists.

It’s also important to remember that epinephrine is considered an emergency measure – not a treatment – so people should avoid taking unnecessary risks. But with a few simple precautions, people with allergies to seafood should be able to lead full, normal lives.

What’s Safe?: It’s possible to be allergic to just one or two forms of fish or shellfish – for example, some people can eat lobster but not scallops, while others can eat cod but not salmon. But because there is a high level of cross-reactivity within the food groups, many need to avoid either fish or shellfish in all their forms.

It is important to note, however, that the key allergens in fish and shellfish are completely unrelated, so even if you are allergic to shellfish, finned fish might be just fine. (There are people who are allergic to both fish and shellfish, but this is rare.) If you’re unsure of what’s OK and what’s not, make sure to talk it over with your allergist.

Acceptance: Most people with seafood allergies develop them later in life, which can be tricky, because they may be accustomed to eating without restrictions. “But I’ve never had a problem with seafood,” is a common refrain, so sometimes people take unnecessary risks and try to eat the food that has caused them to react. But once you have a seafood allergy, it’s very important to avoid the allergen altogether, as the allergy can worsen with more exposure.

Know What You’re Eating: Seafood comes in many different forms.
Shellfish can include mollusks such as clams, mussels, and oysters, as well as crustaceans such as shrimp, lobster and crabs. Other forms include squid (the main ingredient in calamari), octopus, prawns, periwinkle, limpets, abalone, cockles, quahogs, snails (or “escargot”), langoustines and sea urchins. The most allergenic type of shellfish is shrimp.

There are many different types of fish, including anchovies, bass, bluefish, catfish, char, chub, cod, eel, flounder, grouper, haddock, hake, halibut, herring, mackerel, mahi-mahi, marlin, monkfish, perch, pickerel, pike, pollock, rockfish, salmon, sardines, shark, smelt, snapper, sole, sturgeon, swordfish, trout, tuna, turbot, whitefish and more.

It is very important that you understand the different names of the food you are allergic to, and carefully read all food labels so you can avoid them.
See: Label Aware

One thing to be cautious of with seafood allergies: imported foods. Not all countries have the stringent labeling requirements of the United States, Canada and the European Union. Don’t take chances if you suspect fish or shellfish could be ingredients of an import.

Next Page: Hidden Sources

Maybe you feel like you’re going to be sick to your stomach, or feel your throat tightening and your lungs beginning to wheeze. You may feel flushed and hot as your face turns beet red. Maybe you break into hives from head to toe, or feel like you’re going to pass out as your heart takes off like a bullet train.

Chances are that you are having an allergic reaction to seafood – the most common culprits in the allergy world.

What’s The Problem?

Seafood can be divided into two groups: shellfish and fish. Shrimp is behind most of the reactions, and shellfish as a group – which can include oysters, mussels, scallops, squid, crab, snails and many more – tends to be more problematic than finned fish. (In one survey by FAAN and Mount Sinai researchers, two per cent of respondents reported a shellfish allergy, whereas just 0.4 per cent reported an allergy to fish.)

Symptoms of a reaction to seafood can include flushing and swelling in the face, mouth and throat; digestive tract symptoms such as nausea and diarrhea; itching and hives; difficulty breathing; lightheadedness or faintness; a sudden drop in blood pressure and a rapid heartbeat.

In severe cases, a person may experience anaphylactic shock, a reaction that includes one or more of the body’s systems and can result in cardiac arrest and death.

Widespread Incidence

A whopping 2.3 per cent of Americans are allergic to some form of seafood, whether it’s fish, crustaceans or mollusks. In Canada, 1.69 per cent of people are allergic to shellfish and 0.48 per cent are allergic to fish. What’s more, a 15-nation study showed the incidence is similarly high right around the world.
See: Seafood Allergy Statistics

Because of its high incidence, Health Canada has named both shellfish and fish “priority food allergens”, which means tougher labeling rules for Canadian manufacturers. Other regions, including the United States and Europe, have also included seafood on their lists of top allergens.
See: Label Aware

It’s a Grown-Up Thing

What’s different about seafood allergies is that they are largely an adult phenomenon. In Canada, 1.69 per cent of adults have shellfish allergy, compared to just 0.5 per cent of children. According to the FAAN-Mount Sinai survey, 2.8 per cent of adults in the United States reported a seafood allergy, as compared with just 0.6 percent of children.

This can be especially problematic, since most adults are accustomed to eating seafood, so when they react, it doesn’t seem to make sense to them. Often they dismiss earlier, less severe reactions as food poisoning or simply “something they ate”; but then they get a tough lesson in science as the allergy grows more severe and the reactions more extreme.

Unfortunately, once an adult develops a shellfish allergy, he or she likely has that allergy for life.

Next page: Seafood Allergy Myths

While allergists stress that severe reactions to airborne food particles are extremely uncommon, there are some instances in which allergenic food proteins can get into the air and potentially cause trouble.

According to Dr. Scott Sicherer of the Jaffe Food Allergy Institute at Mount Sinai School of Medicine in New York, foods with proteins that are stable to cooking can get into the air during heating – and if they then get into the airways of someone who has a severe enough allergy to that food, they can lead to allergic symptoms.

For instance, allergic persons who are exquisitely sensitive to fish or shellfish can react to tiny aerosolized proteins that float in the air when seafood is being fried, steamed or boiled. There may be an increased risk of this in seafood restaurants where large quantities are being prepared and served piping hot.

In fact, airborne reactions are not just a concern for the seafood allergic. Commonly fried foods such as eggs, and powdery forms of some foods can cause similar problems if they get kicked up into the air.

Dried egg powder, soy flour and wheat flour are common culprits behind airborne food reactions, and some people who are able to eat wheat can get respiratory symptoms when they inhale it – a condition that is not uncommon in food processing and has been dubbed “Baker’s Asthma”. A similar condition called “Crab Asthma” is prevalent in the fish processing industry.

Sicherer says that some foods are less likely to get aerosolized – for example, oily and inert peanut butter – which is why they don’t present as much of an airborne danger.

Symptoms from aerosolized food proteins can range from hives and itching to more serious effects including asthma – but Sicherer strongly emphasizes that the risk of anaphylaxis from exposure to airborne food allergens is very low.

Bottom line: Small exposures to inhaled allergens are not usually a problem, but more significant exposures should be avoided. If you’re allergic to seafood, walking past a fish shop or a seafood restaurant likely won’t cause any harm; but sitting in a seafood restaurant for a long period may have you saying, “Check please!”

If you answered ‘peanut’, that’s incorrect. But you could hardly be blamed given that legume’s notoriety. The right answer is seafood – from fish to crustaceans and mollusks.

At a time when every “must-try” new restaurant is an over-priced sushi bar, an astounding 2.3 per cent of Americans are now allergic to one form or another of seafood. (There is no such specific Canadian data, but general rates of allergic prevalence are considered comparable.)

If that incidence comes as a surprise, however, you’re in good company. Even the researchers who surveyed 5,500 households for the Food Allergy & Anaphylaxis Network in Virginia and the Mount Sinai School of Medicine in New York to arrive at this finding were taken aback.

“We said, ‘can this be real?”‘ recalls Anne Munoz-Furlong, founder and former CEO of FAAN and co-author of the resulting seafood prevalence study published in 2004. “We learned that shellfish and fish is about double the incidence of peanut and tree nut combined.”

In fact, the researchers reviewed the data to see if something was, well, fishy. But it wasn’t. Those who were accepted as allergic in the detailed phone survey “were very clear in their answers and the symptoms were very clear,” says Munoz-Furlong. Supporting those findings was a 15-nation study that showed similarly high levels of seafood allergies.

Shrimp was the most common cause of reactions in the FAAN-Mount Sinai survey. In fact, shellfish as a group – crustaceans and mollusks – proved by far the larger cul­prit, with 2 per cent of survey participants reporting shellfish allergy while 0.4 per cent reported fish.

Another eye-opening finding was that this is largely an adult phenomenon. The survey found 2.8 per cent of adults were seafood allergic compared to 0.6 per cent of children. And that can be one of the most difficult aspects of this condition – since it strikes grownups, who’ve been eating for years as they pleased, they often don’t know what hit them.

What happened to Chris Oleson is not uncommon. The 41-year-old is a self‑described “beach guy” who lives in San Francisco and grew up surfing on the California coast.

One day in 2002, he was with his wife Julia at an upscale sushi restaurant. He’d eaten about five or six very tasty” items from the trays on offer, when a waiter approached. “Sir, your ears are turning red. You may want to get that checked out,”‘ Oleson recalls him saying.

Oleson was suddenly rather feverish and unwell, but he wasn’t that concerned. He and his wife just thought he was com­ing down with a bug and had better get home. Oleson has asthma, and on the drive home an attack started coming on. He was also feeling woozy when Julia said, “you know, you’ve got hives.”

By the time they got through the door at a nearby hos­pital, Oleson was staggering. He lost consciousness on a stretcher.

There would still be protein traces and no one is suggesting that the one in 50 Americans who are allergic to shellfish (the family that includes shrimp, lobster, clams and crab) begins tucking into a well-boiled chowder.

But the study, published in the Journal of Food Science in January, shows promising results on the possibility of lowering the allergenic properties of shrimp. Tropomyosin (TM) is the main allergen in seafood, including shrimp.

Food scientists have found that boiling shrimp for 10 minutes seems to reduce the  allergenic potency. Researchers compared raw and boiled shrimp that had been ground and freeze-dried and found that the boiled shrimp had fewer allergenic properties than its raw counterpart.

While a far cry from a cure, lead researcher Guang Ming Liu believes the findings are a step in the right direction: “Understanding the allergenic properties of shrimp as affected by the cooking process is critical for shrimp allergic individuals.”

Fish: includes salmon, tuna, cod.
Crustaceans: includes shrimp, lobster, crab.
Mollusks: snails, bivalves (mussels, scallops, oysters), squid.

Cross-Reactions

Within a seafood group …

Dr. Scott Sicherer, author of Understanding and Managing Your Child’s Food Allergies and associate professor of medicine at the Mount Sinai School of Medicine’s Jaffe Food Allergy Institute, concludes from his 2006 review of seafood allergy studies:

- That 30 to 50 per cent of those with an allergy to one of the seafood groups will react to more than one type of fish or shellfish.

However, you can also be allergic to just one type of fish or shellfish. It’s even possible to be allergic to just one type of shrimp.

- That it is common for people to be allergic to more than one shellfish. Sicherer finds up to 80 per cent who are allergic to one crustacean may be sensitized to others, and “40 per cent may react upon ingestion.”

In one study reviewed, blood samples from nine patients with shrimp anaphylaxis reacted to the proteins of 13 crustaceans and mollusks. As well, he finds between 10 and 15 per cent allergic not only to other crustaceans, but to mollusks as well.

- That the risk of reacting to more than one fish is high. Sicherer suggests to speaking to your allergist: “Your allergist may take into consideration the severity of your allergy, test results, and dietary preferences to determine what it is you can and can not eat.”

- That about 50 per cent with a mollusk allergy react to more than one mollusk.

Between shellfish and fish …

According to Sicherer, only about 10 per cent react to both, which have quite different key allergenic proteins (tropomyosin in shellfish; parvalbumin in fish).

Remember, however, that there may be cross-contact between the two groups at grocery seafood counters or in restaurants.

Sources: UpToDate 2006; interview Dr. Scott Sicherer

Label Aware – Fish and Shellfish Allergy

Reading labels is a way of life when you have fish or shellfish allergies. Before eating anything in a package, be sure to read the label carefully. Look for hidden sources of fish or shellfish and other names for fish or shellfish.

Also be on the lookout for precautionary statements. These are statements that indicate an allergen may be in the food, due to cross contamination during processing. Examples of precautionary statements include: “May contain fish” and “Manufactured in a facility that also processes shrimp and crab.”

Allergists generally advise people with fish or shellfish allergies to avoid all products that include precautionary statements about their allergen.

If you are ever uncertain about whether a food product is safe for you, call the manufacturer to confirm. When in doubt, don’t eat it.

In Canada, new regulations (2012) require food manufacturers list priority allergens in plain language on packaging, rather than using rarely known specific names – ie. tarama or orange roughy (fish) or quahaugs (shellfish). The ingredients within listed ingredients that are priority allergens would also have to be shown. For example, manufacturers couldn’t simply list “gelatin” if the source of the gelatin is a priority allergen, such as fish.

More on Canada’s 2012 Food Allergen Regulations.

In the United States, the Food Allergen Labeling and Consumer Protection Act went into effect in 2006. FALCPA requires manufacturers to use plain language when listing the top 8 priority allergens, and to declare all allergens either in the ingredient list, or in a “Contains:” statement at the end of the list.

The allergens included in this regulation are milk, eggs, fish, shellfish, tree nuts, wheat peanuts and soybeans. The Canadian regulations also add sesame and mustard as priority allergens, while separate legislation requires companies to declare sulfites if they are present at more than 10 parts per million, or if they had a technical or functional effect in the food.

Both the United States and Canada are studying ways to regulate the precautionary statements used on packaged food labels.

Fish allergy is less common, affecting 0.18 per cent of children and 0.56 per cent of adults.

In general, food allergy is on the rise in North America and other developed countries In Canada, an estimated 7.5 per cent of people have food allergies, representing more than 2.5 million people. In the United States it’s estimated that 12 million Americans (or just under 4 per cent of the population) have food allergies.

A major study in the United States recently found that cases of peanut allergy in children more than tripled in a decade, and that more than 3 million Americans now have a peanut or nut allergy.

Here are the rates of some of the major allergens in Canada and the U.S.

CANADA

Source: Surveying Canadians to Assess the Prevalence of Common Food Allergies and Attitudes towards Food LAbelling and Risk (SCAAALAR) study. Published in the Journal of Allergy and Clinical Immunology, June 2010.

UNITED STATES

Peanut, Tree Nut or both:
Children -  2.1 %
Adults – 1.3 %

Source: US prevalence of self-reported peanut, tree nut, and sesame allergy: 11-year follow-up. Published in the Journal of Allergy and Clinical Immunology, June 2010.

Milk and egg allergy are both common in children. In the United States, 2.5 per cent of children under the age of 3 have a milk allergy. Egg allergy affects 1.5 to 3.2 per cent of children.

The good news is many children outgrow their allergies to milk and egg. Research shows 80 per cent of milk allergy is outgrown by age 16, while 68 % of egg allergy is outgrown by that age.

Source: AAAAI