Allergies to shellfish are more common amongst Americans than previously thought and twice as prevalent as nut allergies, according to a survey conducted at the Mount Sinai School of Medicine in New York.

It concluded that as many as 1 in 50 US adults may have an allergy to seafood, with shrimp, crab and lobster causing the most problems. Researchers also found that seafood allergies usually do not emerge until adulthood and can occur even in those with no history of allergies.

Women were more likely to report seafood allergies than men, though it was more common amongst boys than girls.