Recently, I wrote a sharepost about a large study that focused on the health benefits of a Mediterranean diet. While the study definitely got my attention about how I eat, not everyone will feel the same way. That’s because the large quantity of fish that is part of this particular diet can cause allergic reactions in many people.

After doing a little research, I found that there is a difference in types of allergies related to seafood. For instance, Nemours’ KidsHealth reports that a shellfish allergy isn’t the same as a seafood allergy because seafood (such as tuna or salmon) and shellfish (such as shrimp or clams) are biologically different.  Therefore, you may be allergic to some types of seafood, but not to others.

Shellfish Allergies

There are two different types of shellfish allergies, since there are two different types of shellfish. The first is to crustaceans, which includes shrimp, crab or lobster. The second type of allergy is to mollusks, which includes clams, mussels, oysters and scallops.

This type of allergy can develop at any age. In fact, people who have been able to enjoy shellfish in the past may develop this type of allergy. Food Allergy Research & Education (FARE) points out that approximately 60 percent of people who have this type of allergy experience their first allergic reaction when they are adults. However, most people who develop an allergy to shellfish will not outgrow it later in life, unlike some food allergies which can ease over time.

Furthermore, not everyone is allergic to both types of shellfish. Most allergic reactions are seen when someone who is allergic to a particular type of shellfish eats it. However, some people can have an allergic reaction to just touching a particular type of shellfish or breathing in vapors as the shellfish is cooked.

The reaction to this type of allergy can vary from a mild reaction to a very serious one that includes anaphylaxis that can result in symptoms on the skin or in the gastrointestinal system, the respiratory system or the cardiovascular system. These symptoms can include difficulty breathing, tightness/constriction in the throat, hoarseness, trouble speaking, wheezing, nasal stuffiness, coughing, nausea, vomiting, abdominal pain, a racing heartbeat or pulse, itchy skin, tingling, redness or swelling.  These types of reaction require immediate treatment through administering epinephrine. Therefore, it is important for people who have a shellfish allergy to avoid the type of shellfish that can trigger any type of reaction.

Shellfish sometimes can be found in food, such as Bouillabaisse, cuttlefish ink, glucosamine, fish stock, seafood flavoring and surimi. People who have shellfish allergies should avoid seafood restaurants (due to the possibility of cross-contamination) as well as Asian restaurants, because they often use fish sauce as a flavoring base.

Fish Allergy

People who have this type of allergy may be allergic to a specific type of fish but not to every type of fish.  This type of allergy can develop at any age, even if the person has eaten the type of fish before without a reaction. In fact, FARE reports that about 40 percent of people who have this type of allergy actually have their first allergic reaction when they are adults.  The most common fish that people are allergic to are salmon, tuna and halibut. Other types of fish that often cause allergic reactions include bass, catfish, cod, flounder, halibut and trout. More than 50 percent of all people who are allergic to one type of fish also will turn out to be allergic to other types of fish.  Once they have developed, fish allergies tend to continue for the rest of a person’s life.