Today, it seems as if every classroom has a little Henry or Jennifer who can't eat peanuts or wheat. So if you are caring for young children, chances are that you are familiar with food allergy, a potentially life-threatening condition that can cause many families severe distress.
According to the American Academy of Allergy, Asthma and Immunology, about 8 percent of children have food allergies, compared to 2 percent of adults. The good news those figures reflect is that some, though not all, food allergies can be outgrown over time, particularly when they stop eating the food.
Below, Jacqueline Pongracic, MD, division head of allergy, at Children's Memorial Hospital in Chicago, discusses how to recognize the signs of a food allergy, as well as how to ensure proper diagnosis and follow-up, so you can keep your child safe.
What is a food allergy?
It's a food reaction that happens through the immune system. That's important to understand because other types of food reactions exist, such as intolerances. An example of that would be lactose intolerance, which doesn't occur through the immune system but because of a lack of an enzyme in the gut that breaks down lactose.
What is happening in the body when one has a food allergy?
When someone has an allergy the immune system produces an allergy antibody that we call IgE, in response to a particular protein. Once IgE is produced, it circulates in the body until it encounters allergy cells. When the IgE encounters those cells, it attaches to them. Then the antibody waits like a guard watching for that particular protein.
Let's say an individual produces IgE antibody to egg. When that sensitive individual eats egg again, the egg protein will be absorbed and when it encounters the IgE specific for egg protein, the two join together. When that happens, the allergy cells release a variety of chemicals that can cause the signs and symptoms of an allergic reaction.
When do food allergies first appear?
Food allergy can begin at any point in life, but most commonly it begins in the first three years of life.
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What foods are children commonly allergic to?
The most common foods include egg, cows' milk, wheat, peanuts, soy and tree nuts. So that's a list of six foods that account for about 95 percent of reactions in children.
What kinds of reactions do people with food allergy have?
One of the important characteristics of reactions in food allergy is that the reaction typically occurs within minutes and always within one to two hours after eating the food. Another characteristic is that reactions occur each and every time that particular food is ingested.
The types of symptoms that occur can affect the skin, the gut, the respiratory tract, and even the cardiovascular system. Skin reactions include itching, redness, hives, or swelling. Gastrointestinal tract symptoms include abdominal cramps, nausea, vomiting or diarrhea. They may also include itching of the lips or the mouth. A more severe reaction may lead to swelling of the tongue.
Respiratory symptoms can be hay fever–type symptoms, such as sneezing, nasal congestion, runny nose and itchy, watery eyes. Throat tightness, coughing, wheezing, difficulty breathing or chest tightness may occur. One might have a fall in blood pressure, and an increase in heart rate. People might feel dizzy, or actually faint.
Very severe reactions are generally termed anaphylaxis. Unfortunately, food allergies are potentially fatal and it's estimated that perhaps 150 Americans die of a food allergy reaction each year. The fatalities are usually associated with an accidental exposure away from home to a food that that individual already knew they were allergic to.
How can parents distinguish between a colicky baby and one with a food allergy?
Food allergy may induce colic, but it's not the most common reason for it. If parents have a child who is very irritable or colicky, they should talk to their pediatrician about making a change in the baby's formula to see whether that results in any improvement. Suspicion of a food allergy would be increased if that fussy baby also has not only gastrointestinal symptoms, but also skin problems such as atopic dermatitis, also known as eczema, which is an allergic skin condition that is characterized by red, raised rashes that itch.
Can most food allergies be outgrown?
Children with allergies to cows' milk, egg, soy and wheat usually outgrow their allergy by the time they are five years old. If the children successfully avoid eating the food, they improve their chances of outgrowing the allergy. Other foods like peanuts and tree nuts, as well as seafood, tend to be lifelong food allergens for people. However, there have been two studies that have shown that as many as 19 percent of children outgrow their peanut allergy, particularly if they were diagnosed by their first birthday and if they have sustained successful peanut avoidance since then.
How does an allergist or an immunologist diagnose food allergy?
The approach to diagnosis begins with taking a thorough history focusing on the reactions. Then we do a physical examination to see whether there are other signs of an allergic process, such as the presence of atopic dermatitis.
If we feel that the likelihood of allergy is there, then the next step generally is to proceed with allergy skin tests. Allergy skin tests can be performed in as little as 20 minutes. They aren't painful. We do a test called a percutaneous skin test, which introduces the allergen into the very superficial layers of the skin. We always try to select the allergens that we think are relevant based on history. With the skin test, we're looking for whether or not there is a reaction characterized by an area of swelling surrounded by redness. Negative skin tests essentially rule out that a food allergy exists. Positive skin tests are harder to interpret, since these tests have a false positive rate of 60 percent.
If the skin test is negative but we have a strong impression that an allergy is present, we may do additional testing by doing a blood test called RAST. That is a way to measure the amount of allergy antibody for that particular allergen.
When do you do a food challenge?
A food challenge simulates the true exposure because it's a procedure where the individual eats the food under medical observation. A food challenge may be performed to confirm the diagnosis. Sometimes we do food challenges where we hide the identity of the food from the individual eating it, their family and even from the physician and nurse so there won't be any bias.
Sometimes we need to do a food challenge if we end up with a lot of positive skin tests, and we aren't sure which one is the culprit. Other times we use a food challenge to assure a family that a particular food is not the culprit.
Once a food allergy has been diagnosed, what steps do you take at that point?
Once we have established a diagnosis, we implement education and counseling for the family, and a medical treatment plan. Education is really critical because it's so difficult to implement an avoidance diet. We also refer the families to national (Food Allergy and Anaphylaxis Network) and local support groups. We also provide families with a written emergency healthcare plan so that in the event of an accidental exposure, they have a reference. We try to review the different scenarios that could play out and how we would like the family to handle those scenarios.
What can be done if someone has a reaction?
An Epi-pen is a device that injects epinephrine, which is a drug that can take away or lessen the symptoms of a reaction. If a child uses an Epi-pen, however, they should immediately call 911 or contact their local EMTs to get to a hospital facility as soon as possible because while epinephrine can be lifesaving, it doesn't always work.
We prescribe an Epi-pen, for the most part, to any child diagnosed with a food allergy who weighs more than about 22 pounds. Children with a history of anaphylaxis, peanut or tree nut allergy, and those who have both food allergy and asthma should receive an Epi-pen. The Epi-pen comes in two dosages: an Epi-pen for adults and a junior Epi-pen. We need to make adjustments and be a little bit more careful in infants who are smaller because the dose is too high.
How can caregivers protect children when they are out and about?
It takes a lot of effort, a lot of teamwork, and really good communication and education to try to keep kids safe. In schools, for example, the teacher, the principal, the school nurse, all should be informed about the child's condition. There should be a copy of this emergency health care plan in the school along with a supply of the emergency medications. It's useful for the child to have a Medic Alert bracelet.
Children need to be taught from an early age to be their own advocate. If somebody offers them something that if they can't confirm is safe for them, they shouldn't try to eat it. Similarly, they shouldn't trade lunches; whatever mom or dad sends in or approves for them is what they should be eating.
Do certain behavioral issues come up with children with food allergy?
The issues that I have seen in kids with food allergy include aversions to trying new foods. Some develop fairly limited diets because they just want to eat what's familiar to them because they know it won't make them feel sick. Other issues are dependency on the parents, particularly as the kids grow older and start to spend more time away from home. They may also experience anxiety about being in situations where they might be exposed to something, whether that's the school cafeteria, or going out to eat in a restaurant or being at a party.
How would someone know that a child had outgrown their food allergy?
It's very important for people to maintain contact with a food allergy specialist once their child has had a diagnosis. Since the prognosis is often good, you don't want that child to avoid that food indefinitely. Here at Children's Memorial Hospital, we recommend annual follow-up.
Are there myths about food allergy?
One is that there is a relationship between food allergy and behavioral problems such as ADHD. Another one is that a rotation diet, in which foods are rotated on a regular cycle according to their "food families," is a way to manage an allergy. Since reactions happen with each and every exposure to the food and since it generally takes only a small amount of food, there is no reason to think that reactions would go away just because you're on a rotation diet.
What is your overall advice to parents?
The guidelines from the American Academy of Pediatrics (AAP) encourage parents to delay introducing cows' milk until the child is one year old; to delay introducing egg until two years of age and to try to defer dietary introduction of peanuts, tree nuts, fish and shellfish until after three years of age. There is no AAP guideline for soy, but I suggest 12 months.
If you suspect your child has a food allergy, talk to your pediatrician. The more foods that you suspect, the more difficult it is for a primary care physician to conduct an evaluation and find the answer, so you may need to see a specialist. If there has been a history of a severe or life-threatening reaction, families should seek out a food allergy specialist. Also, if the child has very severe atopic dermatitis, particularly involving an extensive area of the child's body, that's a reason to see an allergy specialist as well. I would also suggest that the family learn more about food allergy. But parents need to be very careful about their sources of information; the Food Allergy and Anaphylaxis Network is an excellent source of information.
