Clinical Practice

Allergy, Sensitivity, Tolerance: Three Words, Three Different Plans

Patients use allergy, sensitivity and intolerance interchangeably. Separating them — and mapping each to a specific immune marker — changes what you order, how you explain results, and what the plan looks like.

A patient tells you they are allergic to dairy. Ask two more questions and it turns out they get bloated a few hours after a latte, they have never had hives, and they have never been tested. Another patient says they have no allergies at all, then mentions they stopped eating bread years ago because it made them foggy. Both statements are useful. Neither is precise enough to build a plan on.

The vocabulary matters because each word points at a different biological question, a different marker, and a different clinical decision. Getting the language straight in the room — before results, not after — is one of the cheapest ways to make a food marker panel useful rather than confusing.

Allergy is the immediate question

When a clinician says allergy, they usually mean an IgE-mediated response: fast, reproducible, sometimes dangerous. Minutes to an hour. Lips, airway, skin. Patients who have this generally know it, and they have usually already been through scratch testing or an ED visit.

IgE is the marker that speaks to this question. An elevation here is not a diagnosis, and a clinician still weighs it against history and presentation — but the timeframe it points to is narrow and the clinical stakes are different. Avoidance in this category is not a trial. It is a standing instruction.

Sensitivity is the delayed question

This is where most of the frustrating cases sit. Symptoms that arrive hours or days later, that come and go, that seem to depend on quantity and combination and stress and sleep. Patients have often built long homemade avoidance lists trying to find the pattern on their own.

IgG and IgG4 are the markers relevant to delayed-response immune activity linked to foods. They give a clinician something to reason with instead of a food diary and a shrug. Two markers rather than one matters here: IgG and IgG4 do not carry the same implication, and reading them together gives a more textured picture than a single number would. NIH studies indicate at least 20% of the American population have food sensitivities, which is a useful frame for patients who assume this is a fringe concern.

Complement answers a different question again

C3b/d is not asking whether the immune system is engaging with a food. It is asking how loud the engagement gets. Complement can amplify a reaction substantially, which is why a modest antibody elevation paired with complement activity may deserve more attention than a higher number on its own.

For chiropractors, this is often the most clinically interesting marker on the panel. Soft tissue that keeps flaring, recovery that stalls between visits, symmetric complaints with no mechanical story — an amplification marker gives you a systemic input to consider alongside your structural findings, without asking you to abandon your usual reasoning.

Tolerance is where you are trying to end up

Intolerance, in strict usage, is not immune-mediated at all — lactase deficiency is the classic example. But the word patients actually need is tolerance: the amount of a food they can eat without a response they notice.

That framing changes the emotional temperature of the conversation. Patients hear a food marker panel as a list of things being taken away permanently. Tolerance reframes it as calibration. Most of the plan-building work — structured removal, then careful reintroduction, then a settled long-term pattern — is aimed at finding where each food sits rather than at indefinite elimination.

Why the distinction shapes the plan

The three words lead to three different instructions:

• Immediate-type findings: strict, permanent avoidance, no trial period, coordinated with whoever manages the patient's allergy care
• Delayed-response findings: time-limited removal, then structured reintroduction to establish a tolerance level
• Amplification findings: prioritisation — which foods to address first when the panel shows more than a patient can act on at once

For dietitians building a virtual service, this taxonomy is also the backbone of the deliverable. It turns 382 foods into three tiers a patient can hold in their head, and it gives you a defensible structure for the plan you hand over.

Saying it out loud

Plain language works. Something close to: "There are two different things going on with food and the immune system. One is fast and obvious, and we test for that. The other is slow and easy to miss, and that is where most of your symptoms probably live. We are going to look at markers for both, and then we will work out how much of each food you can actually handle."

That sentence sets expectations before anything is drawn. It also lowers the odds of the most common misread — a patient treating a delayed-response elevation as a permanent life sentence for a food they enjoy.

A note on access

For union members whose plans cover this testing at no cost, the vocabulary conversation is often the one that determines whether they use the benefit. Members who think they are being screened for allergies they know they do not have will decline. Members who understand that the panel also addresses the slow, unexplained symptoms they have stopped mentioning to anyone tend to say yes.

At-home serum collection means none of this requires new equipment or a longer appointment. What it requires is ten minutes of clear language, once, at the front end.