Fish, shellfish and seafood are among the world's most important food sources, and they're widely used in most of the world's cuisines. They're an important source of low-fat, high-quality protein, and also provide diners with a tasty way to increase their consumption of healthy omega-3 fatty acids. Unfortunately, they're also among the most common and dangerous food allergy triggers. Major predators such as swordfish present other potential health hazards, as well.
Several kinds of adverse reaction can be caused by foods, and only some of those are actually allergies. Allergic reactions are caused by your immune system mistaking a harmless food protein for a dangerous virus or other infection. Its massive response to a non-existent threat can create symptoms ranging from mildly annoying to life-threatening. Foods that provoke an allergic reaction are called allergens, and fish are among the most widespread and dangerous of allergens.
The swordfish is a large, free-swimming predator that lives most of its life in the open ocean. It's distantly related to both mackerel and tuna, and like the larger species of tuna it has very firm, pale flesh with a texture reminiscent of meat, rather than fish. This makes it a favorite during barbecue season, since swordfish is one of a handful of fish that can stand up to grilling just as well as a steak. Swordfish also lends itself to more sophisticated fine-dining dishes.
Fish, shellfish and crustaceans such as lobster and crabs are all common allergens. Being allergic to one doesn't necessarily mean being allergic to all three, but as a rule those who are allergic to one species of fish or shellfish are usually allergic to others. Allergic reactions are always triggered by a protein, and most species of fish share several of the same proteins. However, the "Annals of Asthma, Allergy and Immunology" printed a paper in 1996 detailing the case of a patient who was specifically allergic to swordfish, and swordfish only.
Other Health Concerns
Swordfish's potential as an allergen is not the only health concern associated with the species. They are among the small handful of fish most heavily contaminated with mercury, thanks to their position at the top of the food chain. Swordfish should be eaten no more than once a month at most, and pregnant women should avoid it entirely. Swordfish is also a potential threat for histamine poisoning. Certain species, including swordfish, produce large quantities of histamines as they deteriorate, If your swordfish is not absolutely fresh, histamine poisoning can make you seriously ill.