Food Allergies 101
Robert P. Lindeman, MD, PhD
Natick Pediatrics, PC
Many of my patients are concerned about the apparent increase in food allergies among children. And with good reason: A food allergy can be a serious, even life-threatening problem. This is why it is important to see your child’s pediatrician if you suspect your child may have a food allergy. You shouldn’t try to diagnose and treat a food allergy based on a newspaper article. There is no substitute for the careful history, physical exam, and laboratory testing that only your child’s doctor can perform.
Food allergies occur most often during the first two years of life. When I diagnose a food allergy, it is almost always one food alone, or at most two foods that a child will be allergic to. Among infants and toddlers, the four big culprits are cow’s milk, eggs, peanuts, and tree nuts. In young children milk, egg, peanut, tree nuts, soy, and wheat account for the majority of food allergies.
What is a Food Allergy?
The human immune system is designed to seek out and destroy "foreign invaders" that enter our bodies. Food allergies happen when certain proteins in food are mistakenly identified as foreign invaders. When a person eats a food he or she is allergic to, within a range of minutes to about two hours the immune system sets off a chain of events leading to a number of possible symptoms. These include tingling in the mouth or tongue swelling, rash, eczema, and, most typically, hives (raised flat bumps often with pale centers). Other reactions include vomiting, belly cramping, diarrhea, wheezing and severe difficulty breathing. Rarely (thankfully, very rarely) food allergy reactions can be fatal.
Food Allergies are common
Fortunately, however, they are not as common as most people think. While 1 out of 4 Americans believe they have a food allergy, careful studies have shown the rate to be much lower: only about 1 out of 20 children have true food allergy. That’s common enough for most people to be concerned. Food allergies are more common if at least one parent or a sibling has a food allergy.
So if it’s not a food allergy, what is it?
What about the children who seem to have a food allergy, but really do not? Many of these children have food intolerance rather than food allergy. Food intolerance is a reaction to food that does not involve the immune system.
For instance, many people confuse lactose intolerance with milk allergy. Children with lactose intolerance have difficulty digesting milk sugar. As a result, when these children eat milk products, they may develop belly pain, bloating, or diarrhea. There are a number of terrific lactose-free products available which can take care of this problem. If lactose-free diary products do not solve the problem, true allergy may be the cause.
But whereas milk allergy can occur in newborns, true lactose intolerance almost never does. To add to the confusion, there is another condition with the word "intolerance" in its name: When breast milk or formula doesn’t seem to be agreeing with an infant, the reason is most likely a condition called "breast milk intolerance" or "formula intolerance". Or, the baby might have reflux or colic. Unlike milk protein allergy, these conditions often resolve without treatment. If the problem persists or gets worse, parents should talk to the baby’s pediatrician.
The difficulty with telling a food allergy from food intolerance is they both give patients some of the same symptoms. These symptoms are almost always related to the intestines: nausea, bloating, diarrhea. Unlike true allergies, however, food intolerances tend not to give rashes, and they never cause hives. The only way to tell the difference for sure is to have an allergist perform specific allergy tests. These are usually skin-prick tests and/or blood tests for antibodies against particular food proteins.
Diagnosing Food Allergy
Most pediatricians, me included, don’t do allergy testing in the office. We usually send these patients to see an allergist. Allergists perform a number of studies, including skin-prick testing, blood (RAST) testing, and controlled food challenges. I would caution parents not to try a food challenge themselves if they suspect food allergy in their children. It is usually the allergist who will prescribe an allergy treatment plan.
Treating Food Allergies
There is no cure for food allergies. The #1 treatment for all allergies is avoidance. For parents with food-allergic children, this means becoming expert label readers. This is not as easy as it sounds! There are many tips and tricks to learning how to read food labels, how to deal with restaurant menus, and how to feed your food-allergic child on vacation. Resources to help these families can be found below. If your child has been diagnosed by an allergist with a true food allergy, you should have at least two rescue injectors (e.g. Epi-Pen or Epi-Pen Jr.) in your possession. One stays with the child at home or on the road, and the other stays at the child’s school or daycare. The latter should be accompanied by a note from a physician indicating the nature of the child’s allergy, and the circumstances in which the injector should be administered.
Do children outgrow Food Allergy?
About 1/3 of all food allergies go away over a one- to two-year period, especially if the food is completely avoided. It is important to know that the typical tests done for these allergies may remain positive though the child is no longer in danger of serious allergic reaction. Unfortunately, children only rarely outgrow allergies to peanuts and tree nuts.
Can Food Allergies be prevented?
The honest answer is "we don’t know". Nevertheless, there are several clues that suggest that keeping certain foods away from infants may help. The theory is that if a baby is not exposed, or "sensitized" to a particular food, then there is less chance of becoming allergic to that food. We know that infants who are exclusively breast-fed for the first 6 months of life are less likely to develop eczema or wheezing, two allergic-type conditions. I suggest to my breastfeeding mothers that they avoid eggs, peanuts, and tree nuts while breastfeeding. It has been shown that proteins from these foods can be secreted in breast milk. If the mother herself has a history of food allergies, I sometimes suggest avoiding fish, shellfish, wheat, and even milk products!
Once a child starts eating solids, I suggest that the parents avoid giving milk products until the child is 12 months old. The American Academy of Pediatrics recommends holding off on egg products until age two, and avoiding fish, shellfish and peanuts until age three. Realizing that it is difficult -- if not impossible -- to avoid some of these things in a seemingly non-allergic child, I usually recommend sticking to these tougher guidelines only if there is a family history of food allergies.
Resources for Parents
The best source of information on food allergies is the Food Allergy and Anaphylaxis Network (FAAN). They host a superb web site at http://www.foodallergy.org. Among the services provided by FAAN is an email system to alert members to products that have been identified as sources of food allergens. There you will also find lists of books and other resources for parents and children. I am indebted to FAAN for providing much of the factual information detailed above.
For more information about Natick Pediatrics, or to talk to the doctor, please call the office at (508) 655-9699.
Medical Office Building
MetroWest Medical Center
Leonard Morse Campus
67 Union Street, Suite 305
South Natick, MA 01760
(508) 655-9699
(508) 655-2984 fax
Posted: February 14, 2003
