A new study from Johns Hopkins University School of Medicine indicates that food allergy rates may not be rising, but instead be more prevalent due to better diagnosis and care. It could also indicate that current understanding of allergies is not complete.
The study analyzed 5,000 stored blood samples collected between 1988 and 1994 and between 2005 and 2006. Food-allergy-specific immunoglobulin E (IgE) was measured from the samples and compared.
The study found that IgE presence has not changed despite food allergies being 50 percent higher.
This finding indicates that the higher rate of food allergy we have now is not likely due to environmental factors or changes, but instead is more likely due to changes in diagnosis and awareness.
Overall, the team found no increase in the number of children sensitized to peanuts, milk or eggs, while the number with antibodies to shrimp actually decreased. "We were really very surprised," says Keet. "It hasn't only been self-reported food allergy rates that have risen but emergency room visits and hospitalizations for food allergies as well.
The team theorizes that the rise in allergies is more to do with diagnosis and knowledge than with rates increasing. In the past, for example, people may have just stopped eating a food they learned they were sensitive to, but did not report it or receive testing and a diagnosis for food allergy.
Another alternative is that IgE is not as important to food allergy as once thought. It is believed that IgE levels are essential for food-specific allergies to occur, but it's also known that some people with food-specific IgE do not necessarily react to that food with an allergy.
"These results raise the question of whether something has changed in the relationship between food-specific IgE and clinical food allergy over the past few decades," says Emily McGowan, M.D., assistant professor of medicine at the Johns Hopkins University School of Medicine and the first author of this study.