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

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

Does your child refuse to eat a certain food, or complain that it makes his “tongue hurt”? These could be signs of a food allergy, and should be taken seriously.

It is common for the symptoms of food allergy to vary by individual – and from reaction to reaction in the same person. Not everyone will get all the symptoms, which range greatly in severity from mild to severe (and even fatal): your throat may feel tight on one exposure to your allergen or you may get itchy hives on your skin and vomiting with the next.

The Range of Symptoms

-Tingling in the mouth
-Swelling of the tongue and throat / feeling of throat tightness
-Itchy skin, hives or skin redness
-Abdominal cramps
-Vomiting or diarrhea
-Breathing difficulty, wheezing
-Faintness due to a sudden drop in blood pressure

Anaphylaxis

Anaphylaxis is the severe form of allergic reaction. It involves one or more of the body’s symptoms; for example, the gastrointestinal tract, the respiratory tract, the skin and the cardiovascular system. A person experiencing anaphylaxis often has difficulty breathing, and the person could lose consciousness. Anaphylaxis puts a person at risk of death.

Anaphylactic reactions can come on quickly, and it’s impossible to know when a reaction will become severe. It’s important that people with food allergies are prepared for a reaction by always carrying an epinephrine auto-injector (either EpiPen or Twinject).

Experts recommend using epinephrine early if a person known to be at risk of anaphylaxis begins to show signs of allergy symptoms – don’t wait until the symptoms worsen, as it may become to difficult put a halt to the reaction once it’s in progress.

Symptoms reviewed by Dr. Susan Waserman

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.

Clarke and her colleagues surveyed close to 10,000 Canadians in the Surveying Canadians to Access the Prevalence of Common Food Allergies and Attitudes towards Food Labelling and Risk (SCAAALAR) study. They found that 3.2 per cent were allergic to one or more of peanuts, tree nuts, shellfish, fish and sesame. Of those, “at most, only 38.7 per cent reported receiving epinephrine,” while having a moderate to severe reaction, says Clarke.

It’s not clear whether these individuals had auto-injectors and simply didn’t use them, or if epinephrine wasn’t available to them. Either way, Clarke told Allergic Living that the numbers concerning.

“We certainly know that there is a problem here in the proper management, because one would like to see that almost everybody who is reporting a moderate to severe reaction would receive the epinephrine.”

Clarke says her team has dug into the data a little further to look at what type of people are likely to carry an auto-injector, but results of that analysis are not yet available.

The SCAAALAR study, which is partially funded by the allergy research network AllerGen, also looked at attitudes towards food labeling, particularly precautionary statements on food packages (such as “may contain” advisories), and attitudes of general population toward risk of food allergy in the context of environmental health risks. Results will be available in the coming months.

Highlights from SCAAALAR study

Allergies in the Canadian population

Published in the June 2010  issue of the Journal of Allergy and Clinical Immunology. View here.

Situation: There’s a friend at work you’ve often had lunch with. Lately, he’s decided it’s funny to tell the waiter “just bring her some water – she’s allergic to everything else.”

How to handle: Before your next midday meal with Don Rickles, prepare a sarcastic retort along the lines of “while my incredibly sensitive friend finds the idea of me doing a faceplant in my soup hilarious, I think I’ll just tell you about my life-threatening allergies instead.” If that doesn’t get the point across, ditch buddy boy and find a new lunchmate; preferably one who doesn’t find your serious health condition such a thigh-slapper.

Situation: Your new in-laws are desperate to have you two over for dinner, but you’re highly allergic to cats, and their beloved Mr. Tinkles is definitely the lord of the manor.

How to handle: You might as well be honest. Tell them about your allergy, and suggest that a meal in their beautiful garden would be a better option. (Hey, kissing up to the in-laws early is a good idea, especially if you’re planning to have kids.) It doesn’t hurt to lay some ground rules early either, in preparation for all those years and years of visits ahead. Ask if Mr. Tinkles could be confined to one room while you’re there, and suggest that, while you know your mother-in-law’s house is always spotless, maybe running the vacuum quickly before you arrive would, however, help your breathing. Bring a treat for the ball of allergenic fluff to show you don’t hate cats, really. And get your husband to agree to a late arrival and early departure, lest he bear the brunt of your coughing, snoring and wheezing all night.

Situation: A close friend asks you to be in her wedding party, but option two on the reception dinner menu is salmon – and you’re at risk of anaphylaxis to fish.

How to handle: Tell her that you’re willing to wear the seafoam green taffeta bridesmaid dress, but you’ll have to put your foot down when it comes to your ability to breathe unassisted. Speak
to the caterer ahead of time: can he assure that if you pick one of the other options, there will be no cross-contamination in the kitchen? If in doubt, bring your own meal and ask the caterer to have it served along with the others. Give a trusted friend the task of overseeing the handling of your food in the kitchen.If even a good whiff of fish has you reaching for the Epi or Twinject, tell the bride that, while you will be thrilled to precede her down the aisle, you’ll have to arrive at the reception after all fishy scraps have been cleared.

Situation: You’re out at a restaurant on a first date with an attractive, interesting fellow, who orders something you’re allergic to. Later, he leans in for a goodnight kiss.

How to handle: First of all, a kiss on the first date? OK, I’m old- fashioned, but a handshake or a hug should suffice. If your heart is already aflutter, best to be upfront. Calmly tell Dreamboat that he’s eaten something you’re allergic to, and that it’s just not safe for you to lock lips so soon after he’s eaten. Thank him for a wonderful evening and suggest getting together soon for a non-food date.

First published in Allergic Living magazine.
(c) Copyright AGW Publishing Inc.

To subscribe or order a back issue, click here.