Are Your Child’s Tummy Troubles due to an Allergy or Food Intolerance?

It’s a fact of life: all kids get an upset tummy or diarrhea from time to time. But your child’s tummy trouble has been off and on for months, and you’re beginning to think it could be something he’s eating. Could it be a food allergy, or a food intolerance? And what’s the difference between the two?

People use the terms interchangeably, but they are actually very different. Food allergies are caused by an abnormal immune system response: your body mistakenly identifies a specific food as harmful, and produces antibodies to fight it. The next time you eat that food, the antibodies alert your immune system and your body releases histamines and other chemicals into your bloodstream, causing an allergic reaction, which can include anything from hives to trouble breathing to more severe reactions that can even be fatal.
Food intolerance, on the other hand, does not involve the immune system. An intolerance occurs when the body can’t digest a food or food component properly, because the required enzyme is absent or not working properly. For example, people with a milk intolerance are unable to digest lactose, the sugar found in milk products. Normally, the enzyme lactase helps to digest these sugars and absorb them into the bloodstream. But people with low lactase levels can’t digest the sugars properly and they ferment in the large intestine, causing symptoms like cramping, flatulence and diarrhea.
“Food intolerance is much more common than food allergy,” says Dr. Mark Greenwald, an allergist and associate professor in the department of pediatrics at the University of Toronto. “True food allergies occur in about one percent of the population, but a much higher percentage believe they have them, when in fact, they probably have a food intolerance. Intolerances are much harder to confirm – we don’t have great testing for them at this point. I basically define a food intolerance as any food or food group that troubles the child’s gastrointestinal system, that is not immune-related.”
If you think your child might have an allergy or intolerance, Dr. Greenwald says the first step is to take him to the doctor, and ask for a referral to an allergist. “We do not suggest people start trying to diagnose things on their own, or eliminate things from their child’s diet. Elimination diets are a good technique, but if done improperly, they can create deficiencies. They’re actually extremely difficult to do, and require supervision and a support system in place to do them safely and effectively.” The allergist may perform a skin “prick test” to determine if your child has allergies – “still the gold standard in allergy diagnosis,” says Dr. Greenwald.
The good news? Even if your child is diagnosed with a food allergy, he will very likely outgrow it, with the exception of peanut allergies, of which only 20 to 40 percent are outgrown. And food intolerances are transient as well; the enzyme deficiency often heals or changes as the body matures, and the intolerance eventually goes away. “Food allergies in children often evolve into environmental allergies as adults – what we call the Allergic March,” says Dr. Greenwald. “But food intolerances usually just go away, and they are not a predictor of future problems.” 

Allergy vs. Intolerance

Food Allergy

CAUSE: an immune system response
SYMPTOMS: can include hives or a rash, swelling of the lips, face, tongue and/or throat, tingling in the mouth, trouble breathing, dizziness and fainting. Can also include gastrointestinal symptoms like those of a food intolerance.
NOTE: Requires a first exposure to a food to “prime” the allergy – after that, even a very small amount of the food can cause a reaction; can be fatal if allergy is anaphylactic.


Food intolerance
CAUSE: a reaction in the digestive tract
SYMPTOMS: usually gastrointestinal (bloating, gas, nausea, diarrhea) but can also include headache, fatigue and “brain fog” (inability to focus)
NOTE: Often less severe than a food allergy – person can sometimes eat small amount of the food without a reaction.

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