By: Emily Hon, pediatric gastroenterologist
My tummy hurts!
As a mother and pediatric gastroenterologist, I hear this complaint often. Is it because my child needs to poop? Because she doesn’t want to go to bed? For many parents, this happens regularly after their child eats and they wonder: Does my child have a food allergy?
For most of these kids, the answer is no.
There are many reasons children have gastrointestinal (GI) complaints after a meal. These adverse food reactions can be divided into two large categories: immune-mediated and non-immune mediated. The immune-mediated category includes food allergies and celiac disease. Non-immune mediated disorders include food intolerances (such as lactose intolerance and gluten intolerance), irritable bowel syndrome and food poisoning.
The immune-mediated food reactions include the one most people think of when they think “allergic reaction”. This food allergy is the kind that can result in immediate hives, swelling (of lips, throat, face), wheezing, vomiting, diarrhea and/or anaphylaxis. These symptoms will occur within two hours (but usually within 30 minutes) of the ingestion when Immunoglobulin E binds to the food protein and histamine is released into the body. However, there are other types of food allergies that cause gastrointestinal symptoms such as chronic diarrhea, recurrent vomiting, blood in the stool, weight loss or difficulty swallowing. These GI food allergies are often diagnosed by history alone or with endoscopy by a gastroenterologist.
Celiac disease is also in this group of immune mediated reactions. It is the body’s reaction to gluten (a protein found in wheat, barley and rye) and can lead to inflammation in the gut, malnutrition, anemia and other problems. It is often diagnosed by a gastroenterologist and is treated with avoidance of gluten.
The non-immune mediated reactions include lactose intolerance - kids may have abdominal discomfort, bloating and diarrhea after drinking milk and ice cream. However, people with lactose intolerance may have no symptoms with small amounts of lactose and should also know that they are not at risk for anaphylaxis or a life threatening illness from lactose intake.
Irritable bowel syndrome is a common disorder in children that often includes repeated abdominal pain and changes in bowel movements that can be constipation, diarrhea or both. Although not a food allergy, lifestyle and diet changes are often helpful to improve this condition. It is also in the same category of non-immune mediated reactions as is food poisoning. This is usually easily diagnosed as it occurs within 24-48 hours of an ingested meal, often affects more than one individual and does not recur if the individual eats the same food again.
Why am I explaining this?
Because the smallest amount of food can cause IgE mediated food allergies - the type of “allergy” you think of when you picture a child needing an Epi-pen to save their life - will occur EVERY TIME a child ingests their trigger food. Therefore, if they vomit after four slices of pizza one night, but eat cow’s milk based yogurt two days later without a problem, they do not have an IgE-mediated milk allergy and should not get tested for it. They may have just eaten too much pizza (and who knows what else) that night!
Because anaphylaxis is a potentially life-threatening reaction when airways can narrow and blood pressure drops quickly, it is certainly important for patients with concerning symptoms to get evaluated and be treated for IgE-mediated food allergy. They also need to know how to strictly eliminate their food allergy triggers as the smallest amount can lead to anaphylaxis. As children, they must learn to read labels, ask how dishes are prepared when eating at restaurants and say no to foods at parties or with their friends. The majority of food allergies are caused by peanuts, tree nuts, fish, shellfish and milk.
The diagnosis of food allergies can be very complex. The most important part is not in testing, but in history. One must consider your child’s symptoms, the timing of symptom onset and which foods caused the symptoms.
Allergists and other physicians will most often use Immunoglobulin E (IgE) based blood or skin testing. These tests are scientifically proven to be helpful in diagnosing food allergies, but still require extensive training and history taking by the clinician who must take care in deciding which tests to order and how to analyze the results. When not used by an appropriately trained provider, these tests can actually be quite harmful to a patient.
However, there are also many tests available that are not at all scientifically proven to diagnose food allergies or sensitivities! Some of them are marketed to the general public and available over the counter. Others may be provided by functional medicine specialists, naturopaths or other providers. These tests are often costly and have limited to no evidence to back up their efficacy!
In some instances, they may offer a diagnosis of food sensitivity to someone experiencing a variety of symptoms (eg. fatigue, weight gain, brain fog) and recommend removal of several food groups. Symptoms may improve as patients begin removing highly processed or high-sugar-containing foods that would help most of us feel better. However, incorrect diagnoses of food sensitivities or allergies can lead to over restriction of food and malnutrition, unnecessary anxiety and financial stress to maintain these diets and, more importantly, missing other potential diagnoses.
The Guidelines for the Diagnosis and Management of Food Allergy in the United States, published by the National Institute of Allergy and Infectious Diseases (NIAID) specifically lists tests that are unproven and NOT RECOMMENDED for the diagnosis of food allergy. These tests include:
I recommend always talking to your pediatrician if you have any concern about food allergies. Of course, if you feel your child is truly having a serious reaction, you should call 911 immediately. Here are some great resources from the American Academy of Pediatrics guidelines for introducing new foods, monitoring your child’s food history and ensuring your physician uses tests recommended by the NIAID.
For more info:
Emily Hon grew up in Terre Haute, Indiana where she met Dr. M in high school. She is the mother to two spunky kids, wife to an internet entrepreneur and proud to be a pediatric gastroenterologist at Riley Hospital for Children in Indianapolis. She has a special interest in allergic gastrointestinal disorders, gardening, tennis and anything that keeps her active!