Fish, including tuna, plays an important role in nutrition worldwide. Fish supplies proteins, healthy polyunsaturated fatty acids and fat-soluble vitamins. However, fish is one of the most common causes of food allergies in both adults and children and persists for life.
Identification
Tuna is an important commercial fish, both for the fishing industry and as a farmed commodity. A member of the Thunnus genus, tuna thrives in salt water and includes many species: bluefin, bigeye, yellowfin, skipjack, albacore, blackfin and bonito. The flesh of the tuna fish varies from white to dark red. Although best eaten fresh, canned tuna is popular for sandwiches, salads, casseroles and packaged meals. Tuna is also eaten raw, as in sushi or sashimi.
Allergens
An allergic reaction to tuna happens as a result of the immune system over-responding to a foreign protein perceived as harmful. It releases antibodies, known as immunoglobulin E, or IgE, to protect the body. This produces a reaction with the allergen to produce histamines that affect the skin and respiratory and digestive tract. The protein parvalbumin, found in the muscle of fish, is responsible for almost all fish allergies. Hence, individuals allergic to tuna are likely to react to other species of fish. Although finfish and shellfish allergies are not the same, many people are allergic to both.
Causes
If you are allergic to tuna, consuming any type of fish may result in an allergic response. The mere smell of fish can trigger asthma in sensitive people. Reactions to tuna can be caused by inhaling the steam, such as when boiling or simmering fish, especially in confined spaces. The heat releases the food proteins responsible for the allergens. Skin contact with tuna may result in a mild localized reaction, such as itching or redness. Be cautious of cross contamination from oil that has previously been used to fry fish, or pots or dishes that have been used to prepare or store tuna. A reaction, reported by InformAll Database, outlined a case of an individual who displayed an allergic reaction after kissing someone who had recently eaten fish.
Symptoms
An allergic reaction to even a small amount of tuna or other fish can be immediate or take up to 24 hours. Common symptoms of a fish allergy are similar to symptoms from other food allergies. Reactions can affect the skin, producing hives, eczema, itching or swelling. Digestive disorders may occur, including heartburn, upset stomach, diarrhea, vomiting, cramps and gas. Symptoms that are more serious may include shortness of breath, wheezing, lightheadedness or fainting. In extreme cases, anaphylaxis may develop, which can be life threatening and requires immediate medical attention.
Prevention
Fish remains allergenic after cooking and canning. To prevent an allergic reaction from fish, you must be vigilant and avoid consuming it in any form. It is important to read the label and ask about ingredients before eating a food that you have not prepared yourself. Often fish is found in unexpected sources, including pizza toppings, salad dressings, Worcestershire sauce, meatloaf, barbeque sauce, bouillabaisse and imitation fish.
Considerations
Allergy to fish should not to be confused with a toxic reaction to histamine in spoiled fish, which often produces the same symptoms. The Saiseikai Kanagawaken Hospital in Yokohama described eight cases of allergy-like food poisoning resulting from eating spoiled yellowfin tuna. Symptoms included headaches, facial flushing and palpitation. A high amount of histamine was found in the fish. Conclusions, published in the Tokyo journal “Internal Medicine,” recommended that allergy-like clinical symptoms after the ingestion of food, should be recognized as possible food poisoning.
References
- InformAll Database: Tuna
- Noreast.com: A Guide to the Tunas of the Western Atlantic Ocean
- European Food Information Council; Food Allergy and Food Intolerance; 2006
- Food Allergy Initiative: About Food Allergies Overview
- Beyond Allergy: Fish Allergy; 2007
- The Food Allergy & Anaphylaxis Network: Fish Allergy
- “Internal Medicine”; An Outbreak of Allergy-Like Food Poisoning; S. Ohnuma, et al.; 2001
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