A number of for-profit laboratories claim to be able to pinpoint specific food intolerances with simple tests the way doctors have been diagnosing food allergies for decades. The problem is, allergies and intolerances are completely different things.
'Allergy' Or 'Intolerance'?
When the human body encounters an allergen, the immune system kicks into high gear, producing an anti-body called Immunoglobulin E, which can be detected in blood samples.
Intolerances, on the other hand, don't involve an immune response but rather arise from deficiencies of enzymes crucial for the digestion of certain foods.
If someone has lactose intolerance, for instance, it is because their body doesn't produce enough lactase to break down milk.
Process Of Elimination
While some labs purport that the presence of another antibody, Immunoglobulin G (IgG), is a good indicator of intolerances, allergy scientists insist there is no good evidence that this is the case. Indeed, IgG shows up in blood after we eat almost anything.
Unfortunately for intolerance sufferers looking for a quick fix, the best way to find out what food is bothering them is brute trial and error. Commence with a fairly restrictive diet until the symptoms go away, then gradually reintroduce foods one-by-one.
If symptoms return after eating bell peppers, bell peppers are probably the culprit.
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- Food intolerance: common claims vs. the reality (Chicago Tribune)