A study published in the July 2004 Journal of Allergy & Clinical Immunology shows that seafood allergies are much more prevalent than once thought, with more than 6.5 million Americans believed to be affected. The study "Prevalence of Seafood Allergy in the U.S." revealed that the onset of seafood allergy is likely to begin in adulthood, and frequent, severe reactions are reported by sufferers.

In all, about 11 million people -- roughly 1 in 25 Americans -- are believed to be affected by one or more food allergies, a disease triggered by the ingestion of certain foods that may cause life-threatening reactions, or anaphylaxis, according to The Food Allergy & Anaphylaxis Network (FAAN), a co-investigator of the nationwide survey.