New research from the U.S. Centers for Disease Control shows that childhood food allergies have skyrocketed in the last decade.

In a study published in Pediatrics, the journal of the American Academy of Pediatrics, CDC researchers compared two periods, 1993-1997 and 2003-2006, and found an 18 per cent rise in self-reported food allergies between these periods.

The CDC researchers also found that visits to the ER for food allergy reactions nearly tripled between the time periods.

There was no significant difference between boys and girls; however reported food allergies have increased the most among Hispanic children since the 1990s.

The study also notes that in 1995, nine per cent of U.S. kids tested positive for antibodies to peanuts, a sign of peanut allergy.

The researchers, led by Amy M. Branum of the National Center for Health Statistics at the CDC, say while many reports have suggested that food allergies in children are on the rise, few resources have been available to make reliable estimates.

For their study, the researchers analyzed information from national health surveys that included information on parent-reported children's food allergies, visits to ambulatory care clinics for treatment of allergies, and allergy-related health care usage from 1993 to 2007.

"Reported food allergy is increasing among children of all ages, among boys and girls, and among children of different races/ethnicities," the team writes.

"However, it cannot be determined how much of the increases in estimates are truly attributable to increases in clinical disease and how much are attributable to increased awareness by physicians, other health care providers, and parents."

It's also not clear what has brought on this mini-epidemic of allergies, notes Beatrice Povolo, the programs & services director at Anaphylaxis Canada.

"That's the question we're all struggling with, including the researchers, to really understand why there's been such a significant increase. And unfortunately, there's not one specific explanation," she said.

One of the most common theories deals with over-sanitizing, or the "hygiene hypothesis." This is the theory that says because modern society has become so obsessed with sanitizing, our children's immune systems are no longer fighting traditional pathogens but instead looking for other things to attack, including common foods that are otherwise harmless.

Genetics can also play a role, notes Povolo, so if a parent has food allergies, their children are more like to have allergies. There are also worries that parents introduce allergenic foods to children too early in life, which can overwhelm tiny immune systems, she says.

Other theories include low rates of breastfeeding in some demographic groups, and problems caused by food processing. There is also greater awareness of food allergies now, so children are being better diagnosed.

The CDC study is the first to make nationally representative trend estimates of food allergy prevalence in the U.S. As well, the CDC study characterizes some food allergy characteristics according to race/ethnicity, which few studies have done until now.

Povolo notes there is currently a study being conducted in Canada to examine the prevalence of food allergies in children here. She expects that since our eating habits and lifestyles are similar to those in the U.S., it will reveal similar statistics.

According to Health Canada, the most common food allergens in Canada are: peanuts, tree nuts, shellfish, fish, milk, egg, wheat, soy and sesame.