Many "allergies" are false alarms
By Jennifer Brown
The Denver Post
Posted: 02/03/2009 12:30:00 AM MST
Updated: 02/03/2009 12:36:40 AM MST
The list of foods that supposedly would trigger an allergic reaction in 18-month-old Alesha Virgin was long: dairy, eggs, peanuts, soy, rice, wheat, beans, beef, pork, watermelon, apples, bananas.
But it turns out, after her mother avoided them all for half a year, the toddler's allergies aren't nearly that extensive.
Doctors at National Jewish Health in Denver are discovering that up to two-thirds of allergies in children are misdiagnosed.
Blood tests for food antibodies and skin-pricking tests apparently aren't as reliable for diagnosing allergies as once thought, according to new research. National Jewish doctors, using a medically supervised allergy test called a "food challenge," have ruled out dozens of allergies diagnosed through blood tests.
"The best test of whether you are allergic to a food is whether you can eat it or not," said Dr. David Fleischer, a pediatric allergist at National Jewish. "There is a big misconception that there is more food allergy out there than there is."
The findings are significant given the rise in food-allergy diagnoses in children during the past decade. More children are on restricted diets, and families are paying for high-priced, hypoallergenic foods, perhaps unnecessarily.
From 1997 to 2007, reported food-allergy cases increased 18 percent among children under 18, according to the Centers for Disease Control and Prevention.
About four out of every 100 children have a diagnosed food allergy, according to a 2007 report from the National Center for Health Statistics.
The presence of antibodies for certain foods doesn't mean that person is allergic to the food and would have a physical reaction, Fleischer said.
Also, there is a lot of cross-reaction in diagnosing food allergies through antibodies — if a person is allergic to milk, a blood test might also make it seem the person is allergic to chicken and turkey, for example, Fleischer said.
Diagnoses cut in half
In their research, National Jewish doctors found that food challenges cut down diagnoses of allergies by at least one-half and maybe up to two-thirds.
They studied 125 children from around the world who came to the hospital's two-week program. On average, each child had been told he or she was allergic to eight foods. After food challenges, the average number of food allergies dropped to three or four.
"Lots of foods are taken out of people's diets unnecessarily," Fleischer said. "It complicates families' lives and children's lives."
Fleischer cautioned that parents should never attempt a food challenge at home but should find a hospital that performs the test. A food challenge typically costs from $200 to $400 for each food.
Previous research has found that about 25 percent of people think they have a food allergy when in fact only about 8 percent do, he said.