Food Allergies
Food allergies are a complex topic, rife with assumptions and without a lot of good studies. Here’s a rundown of what we do know.
What is a food allergy?
A food allergy is when the body’s immune system consistently reacts to a component in a food that your child eats. There are a few different ways the immune system can do this. The first is an immediate reaction, which can be hives/urticaria, swelling, itching, rash and wheezing. Another way is more subtle and slower, with the gut itself slowly becoming inflamed and irritated as it is exposed to the particular component over time.
Wait, what about eczema?
Eczema in children is often blamed on food allergies, especially cow milk allergies. While it is true that food allergy can cause eczema, most of the time eczema is not caused by a food allergy. In one study among children with eczema less than 10% of children had eczema triggered by food allergies. The fact that many children with eczema may also have food allergies confuses the picture.
What about things like lactose?
There are many reactions that your gut can have to foods or food additives that are not actually allergies-the immune system is not involved. Lactose, for instance, needs a particular chemical to break it down and if your child’s gut doesn’t have it, then pain and diarrhea may occur. Another example would be food dyes. While some people may have an actual allergy to food dyes, most symptoms are not caused by the immune system.
How common are food allergies?
About 8% of children will have a food allergy. The most common food allergies in children are milk, eggs, peanuts, tree nuts, and wheat. Shellfish and fish allergies are more common in adults, but do occur in children.
How do I know if my child has a food allergy?
The most obvious way is if your child has a reaction to a food within a few hours of eating it. Unfortunately it isn’t always that clear, as there may be more than one food eaten, or there were no ‘new’ foods (a child can often eat a food many times before they become allergic to it). The best thing to do is keep a diary of the reactions your child is having and what foods have been eaten. Also note if your child has had any medications or done any exercise around the same time as some food allergies only occur with exercise or certain medications.
Aren’t there tests for food allergies?
There are three main tests for food allergies. The most accurate but also most dangerous is the food challenge. In this test a child is given small amounts of a particular food in a controlled situation to see how they react. Obviously it can be quite dangerous since some foods can cause a severe reaction, so this test is only done when absolutely needed and only by experienced allergists who are ready for a bad reaction.
The two tests most often done are the blood and skin prick test. These can be done by your allergist or sometimes by your pediatrician. The problem with them is that they are not highly accurate. A positive test means that your child may react to a food, but doesn’t mean they will. A negative test is pretty accurate, but once in a while it can be negative when the child is truly allergic.
Because of the challenges of testing, the best way to determine if your child has a food allergy is a history of reacting consistently to a particular food, and ruling out other possible illnesses that might look similar.
Can food allergies go away?
Food allergies early in life can slowly improve over the next few years. Certain allergies – like milk, egg, soy, and wheat – are more likely to resolve, while others – peanuts, tree nuts – are more likely to stay. How bad the initial allergy was can also affect the chances of growing out of the allergy.
How do you treat food allergies?
Recently a therapy has been developed for peanut allergy. It’s not meant as a curative, but to decrease the risk of a severe anaphylactic reaction from an accidental ingestion. The treatment can only be done by certified providers, and does require going to the facility several times for treatment.
Otherwise food allergies are treated by avoiding the food your child is allergic to. For those with severe reactions, epinephrine auto-injectors are given to carry with them or their parents in case of anaphylaxis.
Can food allergies be prevented?
As with asthma, eczema, and other allergic conditions, there’s not a lot we can do to prevent food allergies from happening. One thing that has been noticed, however, is that introducing foods likely to be allergens early in life decreases the risk of food allergies, so giving bits of milk, fully cooked eggs, wheat, and peanut butter even as early as 4 months old may be beneficial. You may want to check with your pediatrician.
Bottom line.
Food allergies do exist, but aren’t as common as people think. The best thing to do if you think your child has a food allergy is keep a record of what when and what your child eats and what sort of reactions you are seeing. Then take your diary to your pediatrician and have a discussion.
Links.
Food allergies at Children’s Mercy.
