What causes a shellfish allergy

Fish allergy symptoms are similar to those of other food allergies, and most happen within an hour of eating. They include:

  1. Stuffy nose and sneezing (allergic rhinitis)
  2. Hives (urticaria) or a skin rash
  3. Breathing difficulty (asthma)
  4. Generalized itching
  5. Belching, bloating, or flatulence
  6. Indigestion and stomach pain
  7. Diarrhea
  8. Headaches
  9. Nausea or vomiting

Symptoms may also develop by simply inhaling cooked fish or coming into contact with surfaces or utensils used to prepare fish.

In some cases, a skin reaction called contact dermatitis may develop by simply touching fish or fish residue.

In some people, a fish allergy may turn severe and lead the rapid development of anaphylaxis. This dangerous whole-body reaction is characterized by widespread rash, facial and tongue swelling, wheezing, shortness of breath, rapid heart rate, delirium, and a feeling of impending doom.

If not treated immediately with an injection of epinephrine and other emergency interventions, anaphylaxis can lead to shock, coma, cardiac or respiratory failure, and even death.


How are GM crops tested for allergens

The World Health Organization (WHO) and the Food and Agriculture Organization of the United Nations (FAO) established the Codex Alimentarius, a “Food Code” on  international food standards, guidelines, as well as codes of practice for the safety, quality, and fairness of international food trade.3 FAO and WHO states in a report on evaluation of GM food allergenicity that:

“…the characteristics of the novel gene products (proteins) must be evaluated in light of their similarities to known food and environmental allergens.

In addition, if an examination of the genetically modified food in comparison to its conventional counterpart reveals the presence of any unintended, new proteins resulting from the transformation events, these unintended, new proteins should also be assessed for their possible allergenicity using a similar approach.” 4

Testing for allergens is therefore conducted at the start of GM crop development and every throughout the research phase. Scientists test if the proteins in the GM crop match a known allergen.

If a match is found, additional studies are conducted. If the tests conclude that the GM crop has allergenic potential, then the development of that specific GM crop is stopped completely. On the other hand, if there is no matching protein and known allergen, the research continues but the new trait is continuously monitored for allergenic potential.5

The only documented case where allergenicity testing resulted to positive in an experiment was during the development of GM soybean with improved nutritional quality using a Brazil nut protein. The protein was identified as an allergen in the GM soybean variety, which led the scientists to stop the experiment, thus that specific variety of GM soybean did not reach the market.6

No commercially available GM crops contain unique allergens that are not available in conventional crops .6,7,8 The AllergenOnline database, which is managed by a group of allergy experts from every over the world, lists every known proteins that own been proven or may potentially cause allergic reaction.

The database does not show any allergen coming from genetic modification.8,9

With the rigorous testing and regulation implemented, consumers are ensured that every GM crops available in the market do not pose allergenic risk unless the conventional counterpart naturally contains allergens.8 For instance, if a person is allergic to soybean, he may own allergic reaction to GM soybean because it is compositionally equivalent with conventional soybeans.


Causes

Allergies are caused by an abnormal immune response to an otherwise harmless allergy trigger, known as an allergen.

When this happens, the immune system will release a substance known as immunoglobulin E (IgE), which causes mast cells and other blood cells to break open and release histamine into the bloodstream.

The normal role of histamine is to dilate blood vessels so that larger immune cells can access the site of an injury or infection. In the absence of an injury or infection, histamines can trigger the skin, respiratory, and gastrointestinal symptoms we recognize as allergic reactions.

The primary allergen responsible for a fish allergy is a protein known as parvalbumin. Parvalbumins vary little between diverse fish species, meaning that an allergy to one fish will generally result in an allergy to other fishes (a condition known as polysensitization).

Interestingly, while you may be allergic to diverse types of fish, having a fish allergy does not predispose you to a shellfish allergy.

A shellfish allergy involves an entirely diverse allergen known as tropomyosin, which is found in crustaceans and mollusks.

Fish Associated With Allergy

Among the more than 20,000 known fish species, there are several for which the risk of allergy is especially high. According to research published in the Frontiers of Immunity, they include:

  1. Halibut
  2. Cod
  3. Redfish
  4. Flounder
  5. Salmon
  6. Sea bass
  7. Trout
  8. Mackerel
  9. Swordfish
  10. Pilchard
  11. Tilapia
  12. Herring
  13. Carp
  14. Tuna

Other Foods

Beyond the fish itself, fish or fish byproducts are often used to make such favorite foods or condiments as Worcestershire sauce, Caesar salad dressing, caponata (Sicilian eggplant relish), taramasalata, and nuoc châm sauce.

Fish gelatin, derived from the bones and cartilage of fish, is often used as a setting agent in pepperoni, boiling dogs, and other types of processed meats.

Similarly, fish meal is commonly used in certain organic fertilizers.


Diagnosis

A fish allergy can often be recognized by the appearance of symptoms soon after you own eaten or been exposed to fish. To confirm that fish is the cause, an allergist may recommend two minimally invasive tests:

  1. Skin-prick tests involve the introduction of a little quantity of a suspected allergen beneath your skin. If you are allergic to one of several of the test samples, you will develop an inflamed bump (called a wheal) within 15 to 60 minutes.
  2. Blood antibody tests are used to check for the presence of an immune protein called an anti-parvalbumin antibody, which your body produces in response to a fish allergen.

If the tests aren’t conclusive, your allergist may recommend an oral food challenge. This is a procedure in which you eat a little quantity of fish to see if you own a reaction.

Because the response may be severe, it is only performed in the presence and under the direction of a medical professional who can deliver emergency treatment if needed.

An oral test should never be performed as an in-home experiment.

Differential Diagnoses

To ensure that fish is the source of your symptoms and not some other condition, your doctor may desire to explore other possible causes. One such example is scrombroiosis, a type of food poisoning in which high levels of histamine are produced as a fish begins to spoil.

Other reactions may be caused by naturally occurring fish toxins that can cause poisoning in humans.

Ciguatera, found in fish such as grouper, mackerel, and snapper, is the most commonly reported fish toxin illness globally. It causes gastrointestinal, neurological, and cardiovascular symptoms.

Less commonly, some people may experience cross-reactivity to chicken and fish in which a

Parvalbumins are extremely heat-tolerant and do not break below easily even after hours of cooking. As such, you may be just as sensitive to a piece of baked salmon as you are to raw sashimi.

What are the symptoms of food allergy?

Symptoms of food allergy can include hives, vomiting, stomach pain, dizziness, mouth/tongue and throat itching, and can even manifest as difficulty breathing, throat swelling, and in severe cases, coma and death.

Diagnosis

A fish allergy can often be recognized by the appearance of symptoms soon after you own eaten or been exposed to fish.

To confirm that fish is the cause, an allergist may recommend two minimally invasive tests:

  1. Skin-prick tests involve the introduction of a little quantity of a suspected allergen beneath your skin.

    What causes a shellfish allergy

    If you are allergic to one of several of the test samples, you will develop an inflamed bump (called a wheal) within 15 to 60 minutes.

  2. Blood antibody tests are used to check for the presence of an immune protein called an anti-parvalbumin antibody, which your body produces in response to a fish allergen.

If the tests aren’t conclusive, your allergist may recommend an oral food challenge. This is a procedure in which you eat a little quantity of fish to see if you own a reaction.

Because the response may be severe, it is only performed in the presence and under the direction of a medical professional who can deliver emergency treatment if needed.

An oral test should never be performed as an in-home experiment.

Differential Diagnoses

To ensure that fish is the source of your symptoms and not some other condition, your doctor may desire to explore other possible causes. One such example is scrombroiosis, a type of food poisoning in which high levels of histamine are produced as a fish begins to spoil.

Other reactions may be caused by naturally occurring fish toxins that can cause poisoning in humans.

Ciguatera, found in fish such as grouper, mackerel, and snapper, is the most commonly reported fish toxin illness globally. It causes gastrointestinal, neurological, and cardiovascular symptoms.

Less commonly, some people may experience cross-reactivity to chicken and fish in which a

Parvalbumins are extremely heat-tolerant and do not break below easily even after hours of cooking. As such, you may be just as sensitive to a piece of baked salmon as you are to raw sashimi.

What is food allergy?

Food allergy, which affects 1-2% of adults and 6-8% of children in the US, is defined as an immediate adverse reaction to components found in food products.

The allergic reaction is caused by pre-formed antibodies to food components which bind to special cells in the bloodstream, releasing chemicals which cause symptoms of an allergic reaction.

How is food allergy diagnosed?

Since reactions can be life-threatening, immediate diagnosis and treatment of food allergy is extremely significant. Allergies to food can be diagnosed at your allergist’s office by skin prick testing. This painless method involves putting a extremely little quantity of each food allergen just under the skin, with results available in 15 minutes. Sometimes, physicians measure allergy antibodies in the blood to diagnose and follow patients with food allergy.

The best test for food allergy, however, is to act out a “food challenge”, where the suspected food is eaten in increasing amounts under shut supervision at an allergist’s office. It is significant to note that allergies change over time, and new allergies can appear at any time regardless of age, so it is best to consult your allergist if you own any new reactions or concerns about food.

What are some common food allergens for children and adults?

The most common allergenic foods for young children are milk, egg, soy, and wheat.

Food allergy in adults is most commonly caused by peanut, tree nut, fish and shellfish. Approximately 80% of young children outgrow allergies to milk and egg; however, only 20% of patients with nut and shellfish allergies lose their allergic reactions over time.

How is food allergy treated?

Currently, treatment for food allergy is strict avoidance of the offending food. This involves reading ingredient labels and being extremely careful when dining exterior of the home. Symptoms of an allergic reaction should be treated with injectable epinephrine, also known as an EpiPen, which should be carried at every times.

In some cases, Benadryl can be used for mild reactions. There is new and exciting research in the field of food allergy which may eventually lead to a cure for both children and adults, however none of these therapies are approved at the present time.

If you suspect that you or your kid may own a food allergy, come and visit your allergist — we can help!

— By Dr. Katharine S. Nelson

Originally Written by Kate Grimshaw PhD RD November 2013
Updated by FARRP Faculty/Staff

Information on the packaging of food is how the food manufacturer passes information to the consumer.

The information can be divided into three types: an ingredients list, nutritional information and information about the manufacturer who produced the food product. Where appropriate, allergen information may also be provided.

Ingredients label

[NOTE This section only applies to the U.S. since the requirements of ingredient labelling can differ in other countries.]

In the U.S., the ingredients label can be placed either before or after the Nutrition Facts panel and it is of interest to numerous consumers who are concerned to know what they are eating. However, this information is essential to consumers with food hypersensitivities because it helps them determine whether a food is safe for them to eat.

Whilst the ingredient list gives the ingredients of a packaged food, food labelling law does not require that every ingredients need be listed if their presence does not own a function in the finished product. Some ingredients can be collectively labelled such as spices, flavors, and colors. This means that a food ingredient which can cause a reaction in food hypersensitive consumers may be in a food without being declared on the ingredients label.

To assist ensure this does not happen, the Food Allergen Labelling and Consumer Protection Act (FALCPA) was passed in the U.S. in 2004. This Act requires the presence of the eight major food allergens (which cause approximately 90% of hypersensitivity reactions to foods) in any packaged food to be declared using a name that is recognizable to consumers.

The FALCPA requirements only apply to foods and other products (pet foods and dietary supplements) regulated by the U.

What causes a shellfish allergy

S. Food and Drug istration (FDA). However, the U.S. Department of Agriculture has adopted the FALCPA requirements for the foods which they regulate (meat products, poultry products and egg products). Also, the Tax and Trade Bureau (TTB) that regulates labelling of alcoholic beverages in the U.S. has adopted the FDA requirements. So in practice every packaged foods sold in the U.S. own to adhere to the FALCPA requirements.

What about gluten?

FALCPA did not require the presence of gluten to be declared in food products but it did require the FDA to create and implement rules for the gluten free labelling of foods.

In 2007, the FDA issued a proposed law for the gluten free labelling of food. After numerous comment periods, on the 2nd August 2013, the FDA issued a press release regarding the new law about gluten free labelling which will need to be complied with by August 5th 2014. The law specifies that to use the term gluten free (and also «no gluten», «free of gluten» or «without gluten») a food

1) must not contain an ingredient that is a gluten-containing grain (e.g. spelt wheat);
2) must not contain an ingredient that is derived from a gluten-containing grain and that has not been processed to remove gluten (e.g.

wheat flour);
3) must not contain an ingredient that is derived from a gluten-containing grain and that has been processed to remove gluten (e.g. wheat starch), if the use of that ingredient results in the presence of 20 parts per million (ppm) or more gluten in the food (i.e. 20 milligrams (mg) or more gluten per kilogram (kg) of food);
4) does not inherently contain gluten; and that any unavoidable presence of gluten in the food is under 20 ppm gluten (i.e.

What causes a shellfish allergy

under 20 mg gluten per kg of food).»

Whilst numerous foods labelled as gluten free already meet the specifications of the new law, this cannot be assumed to be the case until the deadline of August 5th 2014. Further information on Celiac disease and its management can be found in the separate section of this website and also from the website of Beyond Celiac, formerly known as the National Foundation for Celiac Awareness.

What are the FALCPA requirements?

FALCPA requires that the presence of any of the eight major food allergens (known as the ‘Big Eight’) is declared on the ingredients list.

In addition to the ingredients list there may also be a ‘Contains’ statement which must either immediately follow the ingredients list or be next to it on the package.

What causes a shellfish allergy

If there is no ‘Contains’ statement on the package then the common English name for the allergen must be included in the ingredients list. However if a ‘Contains’ statement is used then the food may be listed in the ingredients list using just its chemical name e.g. sodium caseinate because milk from which it is derived will be listed in the «Contains» statement using its common English name.

The ‘Big Eight’ food allergens

Milk; Egg; Fish; Crustacean shellfish; Tree nuts; Wheat; Peanuts; Soybeans

If a «Contains» statement is used, it has to identify any of the ‘Big Eight’ which are present in the product.

What causes a shellfish allergy

The type of Fish, Crustacean Shellfish or Tree Nut must be declared in either the ingredients list or the «Contains» statement. ‘Soy or ‘Soya’ can be used instead of the term ‘soybean(s)’.

Examples of precautionary labels. The term in brackets [ ] may differ depending on the food concerned.
  1. «Manufactured in a facility that uses [egg] ingredients»
  2. «May contain [fish]»
  3. «Manufactured on equipment that processes products containing [peanuts]»
  4. «Manufactured in a facility which processes [egg]»
  5. «Manufactured on equipment that uses [milk]»
  6. «Manufactured in a facility that processes [tree nuts], but not on the same equipment»
  7. «Processed in a facility that uses [milk]»
  8. «Manufactured on shared equipment…may contain [peanuts, tree nuts, wheat, soy, milk…]»
What about other foods which may cause reactions?

(Updated 08/22/14)

Consumers who react to a food which is not one of the ‘Big eight’ cannot depend on the «Contains» declaration as it will not give information about food ingredients which are not one of the large eight (for example, sesame seeds).

To get information on these foods, the consumer needs to glance at the ingredients label. However, these foods would be declared on the ingredient label in most circumstances because these ingredients own a technical or functional effect in the food. Despite this the consumer still needs to study common names for ingredients derived from these foods e.g. tahini for sesame seeds. Another exception is the use of collective terms on ingredient lists such as spices, flavors, or colors which are not required to declare the presence of foods unless components are derived from the Large Eight.

Lupin (sometimes called lupine) is a legume belonging to the same plant family as peanuts.

Reports of severe allergic reactions to lupin are being monitored by the FDA. Allergies to a Legume Called Lupin: What You Need to Know

Nutritional Information

The nutrition facts box is where nutrient information about the food product is given.

Although this information is not as significant from a food safety stance for consumers with food hypersensitivities, it is significant as every consumers are encouraged to eat as healthily as possible. The information contained in the nutrition facts box can assist consumers make healthy choices.

Precautionary labelling

This is the type of labelling that uses terms such as ‘may contain’.

This type of labelling (also termed advisory labelling or defensive labelling) is strictly voluntary and not required by federal regulation. Consequently, situations when precautionary labelling may be used vary among food companies, as does the wording of the statements used (see Table for some examples but note this list is not exhaustive!!). FDA specifies that such labelling cannot be used as a substitute for excellent manufacturing practices such as allergen identification and control, cleaning of shared equipment, and segregation during processing.

Some consumers believe manufacturers use precautionary labels as a way to protect themselves from legal action in case a food causes a reaction. This is not typically the case since this type of label should only be used by food manufacturers when there actually is a possibility (however small) that the food may contain an allergen which is not an ingredient but may be present as a result of the manufacturing process.

We know this type of labelling is not liked by consumers but currently it is the only way for food manufacturers to inform consumers if there is a possibility that an allergen which is not part of the final product may be present in the food.

In the future, some restrictions may be placed on the use of precautionary labels but that is not yet the case.

From the above table detailing diverse examples of precautionary labels, it can be seen how manufacturers select to expression their precautionary statements can vary greatly. Consumers MUST NOT interpret this difference in wording as a difference in the likelihood that the stated allergen is present. Every precautionary labels mean the same thing, regardless of the words they use. They every mean that there is a possibility that an allergen which is not part of the final product may be present.

Consequently every precautionary labels must be treated with the same level of care, regardless of their wording.

Manufacturer information

The manufacturer’s, packer or distributer’s name, address and a contact telephone number must be on the food packaging, next to the ingredients list. This information is given in case the consumer would love to contact the manufacturer about something to do with the food product.

Reasons for contacting the manufacturer are generally to investigate about the product ingredients and the processing it may undergo or to inform the company that the food may own caused a reaction after it was eaten ( see section on «When to contact a food company’).

Pocket K No. 53: Anti-Allergy Biotech Crops

The human body has an immune system that naturally combats dangers to excellent health such as infection and allergy. According to Food Allergy Information, 1 to 5% of the global population has exhibited allergy to food.1 About 90% of allergic reactions are caused by eight types of food: eggs, milk, peanuts, tree nuts, fish, shellfish, wheat, and soy.

These foods may cause mild to severe reactions such as rashes, stomach upset, breathing and swallowing problems, and dizziness. The whole body can be at risk especially during anaphylaxis the most severe allergic reaction.2 Allergy is a serious condition, and thus introduction of novel food products such as GM food are carefully studied.


References

  • FAO. 2016. About CODEX. http://www.fao.org/fao-who-codexalimentarius/about-codex/en/.
  • Hortense D., K Konan, F Chen, M Egnin, and O Viquez.

    2007. Alleviating Peanut Allergy Using Genetic Engineering: The Silencing of the Immunodominant Allergen Ara h 2 Leads to Its Significant Reduction and a Decrease in Peanut Allergenicity. Plant Biotechnology Journal 6(2): 135-145. http://onlinelibrary.wiley.com/doi/10.1111/j.1467-7652.2007.00292.x/abstract.

  • It's safe to own a CT (computed tomography) scan with contrast dye when you own a shellfish allergy. The materials in the contrast dye used prior to a CT scan are not related to allergens in shellfish, and a recent study showed no increased risk of allergic reaction to contrast dye in people with shellfish allergy.

    Unless you own had an allergic reaction to contrast materials, you should not be worried about having a reaction just because you are allergic to shellfish.

  • Food Allergy Information. n.d. GMO and Food Allergy. http://www.foodallergens.info/Facts/GMO.html.
  • Genetic Literacy Project. 2014. Are GMOs Causing an Increase in Allergies? https://www.geneticliteracyproject.org/2014/04/16/are-gmos-causing-an-increase-in-allergies/.
  • ISAAA’s GM Approval Database. 2012. Event 7Crp#10. http://www.isaaa.org/gmapprovaldatabase/event/default.asp?EventID=223.
  • Wakasa, Y, H Takagi, S Hirose, L Yang, M Saeki, T Nishimura, O Kaminuma, T Hiroi, and F Takaiwa.

    2013. Oral Immunotherapy with Transgenic Rice Seed Containing Destructed Japanese Cedar Pollen Allergens, Weep j 1 and Weep j 2, against Japanese Cedar Pollinosis. Plant Biotechnology Journal 11(1): 66-76. https://www.ncbi.nlm.nih.gov/pubmed/17714439.

  • Seafood allergies and shellfish allergy are not caused by iodine. You're also not allergic to iodine just because you are allergic to shellfish or seafood. Shellfish and seafood also contain iodine, but that isn't what's responsible for food allergies. A recent study investigating the supposed relationship between iodine and seafood allergies found that there is not a relationship between reactions to iodine and seafood allergies.

    So you also don't need to avoid iodine just because you own a seafood or shellfish allergy.

  •  Lien QL, Y Lorenz, S Scheurer, K Fötisch, E Enrique, J Bartra, S Biemelt, S Vieths, and U Sonnewald. 2006. Plant Biotechnology Journal 4(2): 231-242. http://onlinelibrary.wiley.com/doi/10.1111/j.1467-7652.2005.00175.x/full.
  • FAO and WHO. 2001. Evaluation of Allergenicity of Genetically Modified Foods. http://www.fao.org/docrep/007/y0820e/y0820e04.htm.
  • You don't need to avoid the ingredient carrageenan.

    Carrageenan is actually a type of algae that's a common additive in a number of foods, including dairy products. Carrageenan is not associated with shellfish allergies and is safe to consume.

  • Gallo M. and Sayre R. 2009. Removing Allergens and Ruducing Toxins from Food Crops. Current Opinion in Biotechnology 20(2): 191-96. http://www.sciencedirect.com/science/article/pii/S0958166909000330.
  • GMO Answers. 2016. How are GMOS Tested for Allergies? https://gmoanswers.com/studies/infographic-how-are-gmos-tested-allergies.
  • Krath, BN, FD Eriksen, BH Pedersen, LJWJ Gilissen, WE Van De Weg, and LO Dragsted. 2009. Development of Hypo-allergenic Apples: Silencing of the Major AllergenMal d 1Gene in ‘Elstar’ Apple and the Effect of Grafting.

    The Journal of Horticultural Science and Biotechnology 84(6): 52-57. http://www.tandfonline.com/doi/abs/10.1080/14620316.2009.11512595.

    What causes a shellfish allergy

  • University of Nebrasta-Lincoln. 2016. AllergenOnline. http://www.allergenonline.org/.
  • GMO Answers. 2014. Are GMOs are Causing an Increase in Allergies? https://gmoanswers.com/ask/are-gmos-are-causing-increase-allergies-submitted-part-gmo-answers-top-consumer-questions-survey.
  • American College of Allergy, Asthma, and Immunology.

    What causes a shellfish allergy

    2014. Types of Allergies: Food Allergy. http://acaai.org/allergies/types/food-allergy.

  • Wen, S., N Wen, J Pang, G Langen, RA Brew-Appiah, JH Mejias, C Osorio, M Yang, R Gemini, CP Moehs, RS Zemetra, KH Kogel, B Liu, X Wang, D von Wettstein, and S Rustgi. 2012. Structural Genes of Wheat and Barley 5-Methylcytosine DNA Glycosylases and their Potential Applications for Human Health. PNAS 109(50): 20543-8.

    https://www.ncbi.nlm.nih.gov/pubmed/23184965.

  • Takagi, H, T Hiroi, L Yang, Y Tada, Y Yuki, K Takamura, R Ishimitsu, H Kawauchi, H Kiyono, and F Takaiwa. 2005. A Rice-based Edible Vaccine Expressing Multiple T Cell Epitopes Induces Oral Tolerance for Inhibition of Th2-mediated IgE Response. PNAS 102(48): 17525-17530. https://www.ncbi.nlm.nih.gov/pubmed/17276883.
  • Food Allergy Information. n.d. How Numerous People are Affected by Food Allergy? http://www.foodallergens.info/Facts/How_Many.html.
  • Shellfish allergy can happen any time in life.

    Adults and young adults may suddenly develop a shellfish allergy; it can appear at any age. They may never own had an allergic reaction to shellfish or seafood before, and suddenly own a severe reaction to shellfish. Shellfish allergy is rarely outgrown once it is developed, and generally extends to multiple types of shellfish. Crab, lobster, and shrimp are the most common allergens.

  • You can own an allergic reaction to shellfish without eating it.

    The proteins in shellfish and other seafood that trigger food allergies and allergy symptoms can be transmitted through the air when the fish is cooked. If you are in a restaurant or in the kitchen when shellfish are being cooked, you could still own an allergic reaction. Even just handling fish or smelling the steam of cooking seafood can trigger a serious allergic reaction in people who are extremely sensitive to seafood and shellfish.

  • You can take the supplement glucosamine. Often used to promote joint health, glucosamine is derived from the shells of marine life, not the fish themselves.

    The protein that triggers allergic reactions isn't included in the supplements, so glucosamine will not cause an allergic reaction in people with seafood allergies.

* Updated: October 2017

Next Pocket K: Plant Breeding Innovations: CRISPR-Cas9

It's no wonder that people who own a seafood or shellfish allergy are concerned and cautious about what they eat, where they eat, and what they're exposed to: Seafood allergies often cause severe, life-threatening reactions to someone who is allergic to fish or shellfish.

But various myths and fallacies are associated with shellfish and seafood allergies.

Though it's true that people with seafood allergies must be extremely careful about their exposure, they also need to know what myths are in fact, myths.

Here's the truth about shellfish and seafood allergies:

  1. Shellfish allergy can happen any time in life. Adults and young adults may suddenly develop a shellfish allergy; it can appear at any age. They may never own had an allergic reaction to shellfish or seafood before, and suddenly own a severe reaction to shellfish. Shellfish allergy is rarely outgrown once it is developed, and generally extends to multiple types of shellfish.

    Crab, lobster, and shrimp are the most common allergens.

  2. Seafood allergies and shellfish allergy are not caused by iodine. You're also not allergic to iodine just because you are allergic to shellfish or seafood. Shellfish and seafood also contain iodine, but that isn't what's responsible for food allergies. A recent study investigating the supposed relationship between iodine and seafood allergies found that there is not a relationship between reactions to iodine and seafood allergies.

    So you also don't need to avoid iodine just because you own a seafood or shellfish allergy.

  3. You don't need to avoid the ingredient carrageenan. Carrageenan is actually a type of algae that's a common additive in a number of foods, including dairy products. Carrageenan is not associated with shellfish allergies and is safe to consume.
  4. You can own an allergic reaction to shellfish without eating it. The proteins in shellfish and other seafood that trigger food allergies and allergy symptoms can be transmitted through the air when the fish is cooked.

    If you are in a restaurant or in the kitchen when shellfish are being cooked, you could still own an allergic reaction. Even just handling fish or smelling the steam of cooking seafood can trigger a serious allergic reaction in people who are extremely sensitive to seafood and shellfish.

  5. It's safe to own a CT (computed tomography) scan with contrast dye when you own a shellfish allergy. The materials in the contrast dye used prior to a CT scan are not related to allergens in shellfish, and a recent study showed no increased risk of allergic reaction to contrast dye in people with shellfish allergy.

    Unless you own had an allergic reaction to contrast materials, you should not be worried about having a reaction just because you are allergic to shellfish.

  6. You can take the supplement glucosamine. Often used to promote joint health, glucosamine is derived from the shells of marine life, not the fish themselves. The protein that triggers allergic reactions isn't included in the supplements, so glucosamine will not cause an allergic reaction in people with seafood allergies.

Seafood allergies are nothing to take lightly; it's always better to err on the side of caution rather than risk having a severe allergic reaction from coming into contact with shellfish.

Knowing the facts about these food allergies can assist make them just a bit easier to deal with, as you will be more certain of your possible risk.

Do bumblebees sting? Certain types of bees can, and it’s possible to own a negative reaction. Get details on the signs you’ve been stung by a bee, bee-sting treatment and remedies, and more in this comprehensive article on bee stings.Learn More

Learn more in the Everyday Health Allergy Center.

* Updated: October 2017

Next Pocket K: Plant Breeding Innovations: CRISPR-Cas9

It's no wonder that people who own a seafood or shellfish allergy are concerned and cautious about what they eat, where they eat, and what they're exposed to: Seafood allergies often cause severe, life-threatening reactions to someone who is allergic to fish or shellfish.

But various myths and fallacies are associated with shellfish and seafood allergies.

Though it's true that people with seafood allergies must be extremely careful about their exposure, they also need to know what myths are in fact, myths.

Here's the truth about shellfish and seafood allergies:

  1. Shellfish allergy can happen any time in life. Adults and young adults may suddenly develop a shellfish allergy; it can appear at any age.

    What causes a shellfish allergy

    They may never own had an allergic reaction to shellfish or seafood before, and suddenly own a severe reaction to shellfish. Shellfish allergy is rarely outgrown once it is developed, and generally extends to multiple types of shellfish. Crab, lobster, and shrimp are the most common allergens.

  2. Seafood allergies and shellfish allergy are not caused by iodine. You're also not allergic to iodine just because you are allergic to shellfish or seafood.

    Shellfish and seafood also contain iodine, but that isn't what's responsible for food allergies. A recent study investigating the supposed relationship between iodine and seafood allergies found that there is not a relationship between reactions to iodine and seafood allergies. So you also don't need to avoid iodine just because you own a seafood or shellfish allergy.

  3. You don't need to avoid the ingredient carrageenan. Carrageenan is actually a type of algae that's a common additive in a number of foods, including dairy products. Carrageenan is not associated with shellfish allergies and is safe to consume.
  4. You can own an allergic reaction to shellfish without eating it.

    The proteins in shellfish and other seafood that trigger food allergies and allergy symptoms can be transmitted through the air when the fish is cooked. If you are in a restaurant or in the kitchen when shellfish are being cooked, you could still own an allergic reaction. Even just handling fish or smelling the steam of cooking seafood can trigger a serious allergic reaction in people who are extremely sensitive to seafood and shellfish.

  5. It's safe to own a CT (computed tomography) scan with contrast dye when you own a shellfish allergy.

    The materials in the contrast dye used prior to a CT scan are not related to allergens in shellfish, and a recent study showed no increased risk of allergic reaction to contrast dye in people with shellfish allergy. Unless you own had an allergic reaction to contrast materials, you should not be worried about having a reaction just because you are allergic to shellfish.

  6. You can take the supplement glucosamine. Often used to promote joint health, glucosamine is derived from the shells of marine life, not the fish themselves.

    The protein that triggers allergic reactions isn't included in the supplements, so glucosamine will not cause an allergic reaction in people with seafood allergies.

Seafood allergies are nothing to take lightly; it's always better to err on the side of caution rather than risk having a severe allergic reaction from coming into contact with shellfish. Knowing the facts about these food allergies can assist make them just a bit easier to deal with, as you will be more certain of your possible risk.

Do bumblebees sting?

Certain types of bees can, and it’s possible to own a negative reaction. Get details on the signs you’ve been stung by a bee, bee-sting treatment and remedies, and more in this comprehensive article on bee stings.Learn More

Learn more in the Everyday Health Allergy Center.


Removing allergens through biotechnology

Genetic engineering has been used by scientists to decrease or get rid of plant-derived allergens in food crops through downregulation of deleterious genes or overexpression of preferable genes.10

An international team of researchers are developing a new variety of wheat with less gluten.

They suppressed the enzyme needed in making gluten in wheat, leading to GM wheat plants with 76.4% less gluten in its seeds.11 The study demonstrates that celiac patients may soon get a taste of wheat products love bread without getting sick.

Scientists are also seeking to reduce peanut allergy using genetic engineering. Ara h 2 protein, the allergen present in peanuts, was successfully eliminated in transgenic peanut seeds using RNA interference or gene silencing. The allergenicity of the transgenic peanut seeds was evaluated using sera from individuals with peanut allergy.

Results showed significant reduction in the antibody binding capacity of transgenic seeds compared to wild type. 12

Expression of tomato allergen Lyc e 3 was downregulated in transgenic tomato plants. The researchers suppressed the accumulation of Lyc e 3 through double-stranded RNAi inhibition leading to reduction of the allergen under detection limit (less than 0.5% of the wild-type protein). The allergenic potential of the transgenic tomato fruits was assessed by measuring the histamine release from sensitized human basophils exposed to transgenic and parental tomato extracts.

Results showed significant decrease (10 to 100-fold) in histamine release of human basophils exposed to transgenic tomato extracts as compared with the control.13

RNAi technology was also used by scientists in University of Copenhagen to produce hypo-allergenic Elstar apples. Expression of allergen, Mal d 1, was reduced by up to 10,000 fold. The transgenic apple plantlets were grafted to promote development of fruit-producing trees but suppression of the allergen remained the same.14

In 2007, anti-allergy rice, which has been proven to be effective in treating Japanese cedar pollinosis, was commercialized in Japan.

The transgenic rice was developed by scientists from the National Institute of Agrobiological Sciences, Japan. The transgenic rice seeds express 7crp gene modified cedar pollen allergens (Cry j 1 and 2) which give low antibody reaction but contain seven major human T-cell epitopes. These trigger mucosal immune tolerance to cedar pollen allergens. The anti-allergy GM rice is also considered as an edible vaccine against cedar pollen allergy.15, 16, 17

One of the common fears about biotechnology is that it may cause introduction of new allergens in food. However, no GM crops own been reported and documented to actually cause allergic reactions because of the rigorous monitoring conducted in every phases of GM crop development.

Instead of causing harm, biotechnology actually provides solution to allergy problems by enabling development of allergen-free or hypoallergenic food crops. These crops, when commercialized, will bring allergy- relief in the future and at the same time address malnutrition especially in developing countries.


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