INTERVIEWED BY EMILY FREEHLING
The National Institutes of Health estimates that food allergies affect approximately 5 percent of children and 4 percent of adults in the United States. Awareness and knowledge about food allergies is important for almost any parent these days, whether it’s to help them manage their own or their child’s allergies, or to help them understand how to safely pack snacks and treats for school, sports, birthday parties or other group activities. Allergy Partners of Fredericksburg has helped many families on the journey of diagnosing, treating and managing food allergies. As our March Expert, Allergy Partners’ Dr. Nicholas Klaiber, a board-certified allergy immunology physician who treats both pediatric and adult allergy and immunology patients, offers knowledge on the latest research about food allergies in children.
QWhat are the most common food allergens in children?
The biggest foods causing allergic reactions in children are:
- Tree nuts
Sesame is on the rise as an allergen, and we may see that added to the list of allergens that must be listed in bold at the end of nutritional information on food packaging.
QAre we seeing an increase in the prevalence of food allergies?
We have seen a huge increase in the prevalence of food allergies over the last 50 years. Part of the cause of this increase is the practice of delaying the introduction of allergenic foods to infants. This was recommended in the past, but recent research shows that these recommendations were actually counterproductive and have contributed to the increasing prevalence of food allergy.
Another reason for the dramatic increase in food allergy prevalence is explained by the hygiene hypothesis. The hygiene hypothesis is based on the notion that a lack of exposure to particular infections during early childhood hinders the development of the immune system. Without these infectious exposures, the immune system never learns to regulate itself properly. All allergies are an overreaction of the immune system to harmless molecules from the environment.
The most common type of food allergies are dependent upon a molecule produced by the immune system called IgE. IgE production is stimulated by a type of white blood cell called a TH2 cell. One of the primary roles of TH2 cells is to fight off intestinal parasites called helminths. Infections with the helminths used to be ubiquitous across the globe. Through public hygiene programs however, we have virtually eliminated helminth infections within the USA and other industrialized nations. It is in precisely these countries (industrialized nations) where we have observed the largest increases in food allergy, asthma, eczema and allergic rhinitis. TH2 cells from individuals growing up in modern environments are no longer exposed to the parasitic worms they would normally be fighting off.
Foods that are the most common allergens share certain molecular characteristics that may essentially trick the immune system into thinking they are parasites, thus leading to IgE production and a subsequent allergy against these substances.
QWhat is the latest advice to parents on how to introduce foods that are common allergens?
We no longer advise parents to delay the introduction of the most common food allergens. This is due to the ground-breaking Learning Early About Peanut (LEAP) study, published in the New England Journal of Medicine during 2015. This study found that the early introduction of peanuts to infants between four and six months old decreased the rate of peanut allergy in children later in life. The results of this study triggered a change in the American Academy of Pediatrics (AAP) recommendations for high risk infants (those with eczema or siblings with food allergies).
We now know that delaying the introduction of certain foods actually makes a child more likely to develop an allergy because their immune system doesn’t get a chance to learn to recognize that food in the body. So today we are trying to encourage a broader diet early on. Of course, there are still foods that should never be fed to infants, including honey, undercooked meats and foods that cause choking hazards.
Pregnant women should also be encouraged to eat peanuts and peanut butter while pregnant and breastfeeding, as data indicate that this, combined with early introduction of peanuts, produced the lowest overall rates of peanut allergy in children.
Remember that infants are not born sensitized to particular foods. With these practices, we are trying to get the body accustomed to these foods before it develops an allergy.
QWhat about children with eczema, or a family history of food allergies?
Eczema can be the first sign that someone is going to have a food allergy, and the LEAP study actually found that children with eczema benefited the most from early introduction of peanut. Subsequent research indicates that the concept of early introduction preventing food allergy likely extends to other hyper-allergenic foods like eggs and milk, however, this research is still ongoing.
At Allergy Partners, we also specialize in treating patients with eczema because it is an immunologic disease that is often linked to other allergies. We can screen young children with eczema for food allergies in our office and help parents introduce foods safely into the diets of these children with the goal of reducing their chances of developing a food allergy as they get older.
QHow should parents safely introduce peanuts and other potentially allergenic foods to infants?
We encourage parents to introduce peanuts to infants as early as six months, or when they have started solid food. Remember that peanuts and peanut butter are both choking hazards. We advise using smooth peanut butter mixed with a small amount of breastmilk or formula. A finger dipped in this mixture is generally the most common method for first introduction of peanut to infants. In the LEAP study infants were given peanut butter three times per week starting at age 4-6 months.
When you do introduce a new food, if there is going to be an allergic reaction it will typically occur within 30 minutes of the child consuming that food, but a reaction could take as long as two hours to manifest. Often first reactions are not serious, but this is not always the case. An itchy skin rash (hives), vomiting, diarrhea and trouble breathing immediately after consuming a food are signs of an allergic reaction.
If you suspect a food allergy, the diagnosis should be confirmed by a physician who is board certified by the American Board of Allergy and Immunology (ABAI). An oral food challenge is the gold standard for diagnosing food allergy because there is a high rate of false positives with skin and blood tests for food allergies. In the absence of symptoms of food allergy, introduction of age-appropriate new foods should occur one at a time, with no more than one new food per day.
QDo kids outgrow food allergies?
Studies indicate that the potential for children to outgrow a food allergy depends upon which food they are allergic to. Milk and egg are among the most common food allergies in infants. Thankfully, the data indicate that up to 90 percent of infants with milk and egg allergy will eventually outgrow their food allergies.
For nuts the situation is almost directly reversed. Eighty percent of children diagnosed with a nut allergy will have this food allergy for life. That is why we want to emphasize the early introduction of peanuts and tree nuts because these are allergies are much more likely to stick with the child longer if they develop. The potential for food allergy status to change over time is why we suggest that children food allergies should follow up at least once yearly with an allergist until they reach adulthood.
QFor children with serious allergies that can cause anaphylaxis, how do you work with families to manage that risk?
Once a food allergy is confirmed, every child requires a food allergy action plan. This is a written plan that will go home with them and go to their schools. It graphically outlines the treatment protocol. This form is required by all public schools, most private schools and daycares. We want to make sure the child always has an epinephrine autoinjector, or EpiPen, available and that adults he or she is with know how to use it. This goes for home, school, sports, relatives’ houses, eating out and sleepovers—anywhere the child goes. Antihistamines such as Benadryl will not stop a true anaphylactic reaction—only epinephrine can do this.
We hold annual educational programs for school nurses. Awareness in schools has increased markedly in recent years, as the prevalence of food allergies has grown. We want people to be aware that exposure to a food allergen can have potentially life-threatening consequences that are preventable if treated appropriately.
QWhat are the benefits of having a food allergy diagnosed early?
We have a lot more options today than we used to in treating allergies. Studies indicate that starting therapy for food allergy at a younger age improves the likelihood that an allergy can be eliminated.
For peanut allergies, an increasingly common treatment option is a process known as oral desensitization therapy. Desensitization can take the form of sublingual immunotherapy (SLIT) or oral immunotherapy (OIT). OIT and SLIT both work by introducing tiny amounts of the allergen in a controlled setting. For some patients we may start with doses as small as a hundred thousandth of a milligram. The dose is given every day and then increased every two weeks as tolerated.
The ultimate goal of current therapies is risk reduction. They have been shown to decrease the chances of anaphylaxis with accidental exposure to food allergens. While some children may ultimately lose the allergy completely (we call these patients long-term non-responders) after OIT, many will simply gain an increased tolerance to their food allergens. We try to emphasize the fact that desensitization is a marathon and not a sprint.
We also see other options on the horizon for food allergic patients. An FDA advisory panel recommended approval late last year of the first-ever pill to treat peanut allergies, called Palforzia, which uses peanut flour to treat allergies in children. This is a fast-developing field, so hopefully we will have even more options in the years to come. We have certainly moved far past the approach of just diagnosing allergies and telling the patient to avoid that food for good.
Stay tuned to the Fred Parent Facebook Page and subscribe to the Fred Parent YouTube channel for a video interview later this month with Dr. Klaiber about common allergy questions.