Food for Thought -- Understanding
Food Allergies in Kids
Washington University in St. Louis
Every year, thousands of parents learn of their children's food
allergies following a reaction that can affect many body systems, including the
respiratory system, the gastrointestinal tract, skin or cardiovascular system.
About 2 million school age children have a food allergy, and one child in 20
under age 3 has a food allergy.
Food allergies develop when the immune system misinterprets a food as harmful
and develops an immune response against the food. Before experiencing an
allergic reaction to a food, a child must have been exposed to the food at least
once before, which can occur through breast milk. If a child develops allergy
antibodies (called IgE) to a food protein, reexposure to that food may be
accompanied by a release of histamine and other chemicals. These chemicals
produce the allergic symptoms.
Allergies of any kind are often inherited. A child with two allergic parents
is more likely to develop food allergies than someone with one allergic parent,
even if the parent’s allergy is to something other than food, such as pollen.
Leonard Bacharier, M.D., assistant professor of pediatrics at Washington
University School of Medicine in St. Louis and an attending physician in
pediatric allergy and pulmonary medicine at St. Louis Children's Hospital, said
some evidence shows that starting babies too early – before age 4-6 months – on
solid food increases the risk of food allergies.
“There are many different recommendations about what age to allow certain
foods, making it confusing and frustrating to many parents,” he says. “However,
general guidelines suggest delaying the introduction of the common and most
dangerous offenders as long as possible – at least until age 2. In addition,
exclusive breastfeeding for the first four to six months of life appears to
decrease the likelihood of subsequent allergy.”
Specifically, the American Academy of Pediatrics offers the following
guidelines of when to introduce certain foods: after age 1 – cow’s milk; after
age 2 – eggs; and after age 3 – fish, shellfish, peanuts and tree nuts (such as
almonds, cashews and walnuts).
The eight foods that cause 90 percent of food allergies include:
• Tree nuts (walnuts, pecans, pistachios, Brazil nuts, cashews, almonds and
Symptoms of an allergic reaction can range from mild to severe, and may
include one or more of the following:
• Hives (a red intensely itchy rash)
• Tingling sensation in the mouth
• Swelling of the tongue and/or throat
• Difficulty breathing, coughing and/or wheezing
• Nausea and vomiting
• Abdominal cramps
• Drop in blood pressure
• Loss of consciousness
• Anaphylaxis is a combination of several of these symptoms and is a life
threatening medical emergency.
The only effective approach for the treatment of food allergy is dietary
avoidance, Bacharier says.
“While this may sound simple, it actually requires extreme dedication and
attention to detail,” he says. “Parents of food allergic children must become
experts at reading ingredient labels on all foods. Peanuts, soy, wheat, milk and
eggs are common ingredients of many packaged foods.”
In addition to looking for terms like “milk” or “egg” in ingredient lists,
parents must learn to recognize the other terms used on labels which indicate
the presence of milk or egg proteins, such as casein and albumin. Government
agencies have been working toward improving food ingredient labeling so food
allergic consumers can more easily determine which foods they may need to avoid.
“As a general rule: if a product doesn't have a label, people with food
allergies should not eat that food,” Bacharier says.
Even with meticulous attention to dietary contents, accidental ingestions
occur. Patients who have experienced a significant allergic reaction to a food
should always carry and know how to use injectable epinephrine and
antihistamines to treat reactions. Especially in the case of children with food
allergy, people who are commonly around the patient, such as teachers or daycare
workers, should also know how and when to use the injectable epinephrine. Those
with food allergies should also wear an identification bracelet that describes
It’s important to properly and accurately diagnose a food allergy. Surveys
suggest that more than 25 percent of households believe that at least one family
member has a food allergy. However, when patients are carefully evaluated by an
expert in food allergy, the overwhelming majority of patients are found to not
be allergic to the suspected food. Talk to your child’s pediatrician about the
tests that are available.
The good news is that most children allergic to milk, soy, egg and wheat will
lose their sensitivity as they grow. The majority of children with allergy to
milk or egg will be able to eat these foods by school age. However, about 2
percent of people have food allergies as adults, with the majority having
developed them as children. While allergy to egg and milk carry a good prognosis
in terms of being “outgrown” during childhood, allergy to peanuts, tree nuts,
fish and shellfish are generally lifelong.
Washington University School of Medicine's full-time and volunteer faculty
physicians also are the medical staff of Barnes-Jewish and St. Louis Children's
hospitals. The School of Medicine is one of the leading medical research,
teaching and patient care institutions in the nation, currently ranked fourth in
the nation by U.S. News & World Report. Through its affiliations with
Barnes-Jewish and St. Louis Children's hospitals, the School of Medicine is
linked to BJC HealthCare.