Seafood and Iodine: An Analysis of a Medical Myth

http://www.medscape.com/viewarticle/523258


Someone raised this issue with me recently:

Medscape Allergy & Immunology
Seafood and Iodine: An Analysis of a Medical Myth
Mark T. O'Hollaren, MDDisclosures
February 16, 2006

Allergy Asthma Proc. 2005;26:468-469

This study enrolled 75 patients over a 2-year period, 60 of whom were confirmed to have shellfish allergy. Of these individuals, 92% believed that it was the Iodine in the fish or shellfish that was responsible for their allergic reactions. When asked about their source of information, most stated that they had learned about it in a magazine or over the Internet.

The study author conducted a survey of Iodine content in common foods and found that although seafood had a higher content of Iodine than nonseafood items, the daily intake of iodine was much higher overall from ingestion of nonseafood items. It is well known that the immunoglobulin (Ig)E-mediated allergic reaction accompanying the ingestion of seafood is due to a reaction to the fish or shellfish protein, not the iodine itself. Therefore, the study author concluded that any phobias about iodine in seafood are unfounded, and better public education is needed in regard to this common misconception.

There is a very common misconception among the public that those who are allergic to seafood are actually reacting to the iodine in the seafood. It is known that those who are allergic to seafood are reacting to proteins in the fish or shellfish, not the iodine. This misconception may create a problem when these patients need a diagnostic x-ray requiring radiocontrast media (which may contain iodine). In this situation, patients assume that they are allergic to the radiocontrast media because it may contain iodine. This can cause great anxiety among patients scheduled for such tests, and has created problems for radiologists and allergists who receive calls from these worried patients.

Abstract