Food for Thought -- Understanding Food Allergies in Kids

Source: 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:

• Peanuts
• Shellfish
• Fish
• Tree nuts (walnuts, pecans, pistachios, Brazil nuts, cashews, almonds and coconut)
• Eggs
• Milk
• Soy
• Wheat

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)
• Eczema
• Tingling sensation in the mouth
• Swelling of the tongue and/or throat
• Difficulty breathing, coughing and/or wheezing
• Nausea and vomiting
• Abdominal cramps
• Diarrhea
• Drop in blood pressure
• Loss of consciousness
• Death
• 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 the allergy.

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.