Food intolerance
The short answer
A reproducible adverse reaction to a food that does not involve the immune mechanism behind a true food allergy. The distinction matters practically rather than academically, because it decides which tests can say anything useful.What is not settled
Because the mechanism is not the allergic one, allergy testing is answering a different question, and a negative allergy panel does not settle an intolerance either way. Several widely sold panels claim to identify intolerances directly and rest on far less than their marketing implies.
What it gets confused with
Each of these takes one pair and separates them on what can actually be measured.
- Is it IBS or a food intolerance?
Three things get called a food reaction: immune allergy, enzyme deficiency, and fermentation. They need different tests, and one common panel is not one.
- Is it MCAS or a food intolerance?
Three different things get called a food reaction and one word covers all of them. Which one you have decides which test means anything.
- Is it SIBO or a food intolerance?
Both produce symptoms after eating, and the timing overlaps more than most pages admit. The useful split is fermentation versus enzyme versus immune.
How it gets tested
What each test physically measures, and what a negative does not rule out.
- Tests that are not SIBO tests
Stool panels, food sensitivity panels and organic acid tests are sold for overgrowth questions. What each measures, and why that differs.
Eating with it
Where the food advice comes from and where it contradicts itself.
- Eating out and travelling
The practical problems are social and logistical, not clinical, and they end more diets than symptoms do. Worth planning for rather than improvising.
Where this sits on the site
This page is an index rather than an article. It exists so that a label has one place to start from, and so the 5 pages above are reachable without knowing which section we filed them under. The pages themselves are where the work is.
Common questions
- Is this page a diagnosis of Food intolerance?
- No. Nothing here can tell you what you have. What these pages do is show you what separates one label from another, what each test can physically measure, and where the published sources disagree, so that the conversation you have with a clinician is a better one.
- What is genuinely unsettled about Food intolerance?
- Because the mechanism is not the allergic one, allergy testing is answering a different question, and a negative allergy panel does not settle an intolerance either way. Several widely sold panels claim to identify intolerances directly and rest on far less than their marketing implies.
Related
- Small intestinal bacterial overgrowthAn overgrowth of bacteria in the small intestine, diagnosed in practice by a breath test that measures gases rather than bacteria. Where that gap matters, and what it does not rule out.
- Mast cell activation syndromeA syndrome with two competing sets of diagnostic criteria that do not agree. What each one requires, what that disagreement means for you, and what it overlaps with.
- Histamine intoleranceA proposed reaction to dietary histamine with no agreed confirmatory test. Why the published food lists contradict each other, and what the blood test does and does not show.
- Irritable bowel syndromeIBS is defined by symptom criteria and by ruling other things out, not by a test that confirms it. Why that makes overlapping labels so common.