Pediatric Food Allergies on the Rise
Food Safety Update
November 29, 2009
This study piggy-backs on a brief report the CDC put out last year that showed an increase in self-reported food allergy, as reported in the National Health Interview Survey. In the current study, researchers expanded upon findings from the NHIS by examining trends in self-reported food allergy by race and ethnicity, trends in other allergic conditions, and data showing a rise in visits to physician offices, emergency departments, and hospital-based clinics with diagnoses related to food allergies.
“We took a closer look at trends in hospitalizations due to food allergy and found that the increase was primarily due to increased reporting of food allergy as an existing condition for people going into the hospital for other reasons, rather than due to an increase in hospitalizations primarily related to food allergy,” says Amy Branum, a statistician with the CDC National Center for Health Statistics. “This may also support an increase in prevalence.”
A food allergy is a reaction to a food that triggers an immune system response because the body perceives the food to be harmful. The most common reaction occurs when the body creates immunoglobulin E (IgE) antibodies to the food. Since food is taken internally, and not just contacted through the nose and eyes, systematic allergic symptoms can result, ranging from mild to severe. Food allergic reactions that do not involve IgE antibodies at all are primarily gastrointestinal immune responses to foods, many of which occur in infants and are later outgrown.
When someone actually has a reaction, symptoms usually begin in the mouth with a tingling sensation, a metallic taste, burning or itching. Some people have more severe first symptoms like hives, swelling of the lips, nausea, abdominal cramping, wheezing or shock. The most common foods that cause allergic reactions in children are peanuts, cow’s milk, eggs, soy, tree nuts and wheat. Adults can add fish, shellfish, and fruits and vegetables to that list.
In the current study, almost four percent of U.S. children were found to have a food or digestive allergy, as reported by their parents. The rate of skin allergy increased as well, from 7.9% in 1997 to 8.9% in 2007. Meanwhile, the study also reported 9% of children tested positive for IgE antibodies from peanut allergy, 7% tested positive for IgE antibodies from egg allergy, 12% from milk, and 5% from shrimp according to another large health survey, the National Health and Nutrition Examination Survey. IgE tests suggest an increased risk or past history of an allergy.
Hispanic children had the lowest overall prevalence of food allergy, as compared to non-Hispanic whites and non-Hispanic black children. However, Hispanic children also had the greatest increases over time of parent-reported prevalence of food allergy. Young children were found to have a higher prevalence of food allergy as compared to older children. Trends in reported food allergies in relation to gender were similar over time.
“There have been some theories put out about the rise in allergic conditions. TheHygiene Hypothesis is a popular one based on the premise that children today are raised in much more sterile, ‘cleaner’ environments compared to several years ago. It is hypothesized that this more sterile environment leads to under-development of a child's immune system, which may put them at risk for allergic reactions to things like mold, dust, and food,” says Branum. “Although there have been some positive findings related to the Hygiene Hypothesis, there has not been enough conclusive evidence to point to that as the culprit.”
Unfortunately, the only current treatment for a food allergy is avoidance. This is particularly difficult when the allergy is to a food commonly found, like wheat or corn, or to multiple foods. Branum says that it is important for a person with food allergy to be educated about reading labels and asking questions of restaurant personnel and other food preparers in case they are unsure. Labeling has been very helpful for many with food allergies, although cross-contamination may still occur and this information is not always evident on packaging.
In the meantime, she says, more research is needed to determine if the rise of food allergies comes from increased awareness and reporting, sterile living conditions, changing populations – or some combination of factors.
“We need to treat this information seriously and think about putting together studies which would help to address the questions of causation,” Branum adds.